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Perceptrdal ond Motor Skills, 1965, 20, 335.368. @ Southern Universities Press 1965 Monograph Supplement 1-V20

PATTERNS O F PERCEPTUAL-MOTOR DYSFUNCTION I N CHILDREN: A FACTOR ANALYTIC STUDYL

A. JEAN AYRES" U?~iversity of Southern California

CONTENTS Method 338 Results 344 Discussion and Conclusions 354 Overview 364 References .. .. 367

Summa~y.-Analysis of test scores made by 100 children with and 50 without suspected perceptual deficits lead to hypothesizing five syndromes characterisdc of dysfunction: ( a ) developmental apraxia, distinguished by deficits in motor planning, tactile perception and finger identification; ( b ) tactile, kinesthetic and visual perceprual dysfunction in form and position in space; ( c ) tactile defensiveness, demonstrated by hyperactive-distractible behavior, faulty tactile perception and defensive responses to tactile stimuli; ( d ) deficit of integration of the two sides of the body, identified by difficulty in right-left discrimination, avoidance in crossing the mid-line, and incoordinate bilateral hand movements; ( e ) deficit of visual figure-ground discrimination.

T h e increasing recognition of the role of perception in the development of cognitive and motor abilities focuses attention on the necessity of building a theoretical structure to explain the nanire of percepmal-motor dysfunction, thereby providing a basis for treatment procedures. Purpose of the Study

The research reported here was designed to discover and demonstrate relationships among the different kinds of sensory perception, motor activity, laterality, and selected areas of cognitive function. The sensory modalities to which the study was limited were vision, touch, and proprioception. Language functions were excluded. I t was hypothesized ( a ) that factors of perceptual-motor function would emerge from R - and Q-technique factor analyses of data obtained from sample populations of children with and without suspecced perceprual dysfunction, and ( b ) that factors derived from data gathered from the sample p o p ~ ~ l a t i o n with suspected perceptual deficits would differ from those factors appearing from 'This investigation was supported in part by a PHS Research Grant MH 06878-01 from the National Institute of Mental Health, Public Health Service. 'Associate Professor, University of Southern California. The author takes pleasure in thank- ing Edward Levonian, Ph.D. for his valuable aid with the statistical analysis of the data and to Jean Pennucci, 0. T. R., for her assistance with the project. The Western Data Process- ing Center, University of California at Los Angeles was utilized for computational services. Appreciation also is extended ro the many institutions whose cooperation facilitated the con- duct of the srudy. Especially helpful were the Dubnoff School for Educational Therapy, Kennedy Child Study Center, Los Angeles Child Guidance Clinic, Los Angeles City Schools, Pasadena City Schools, Pilgrim Day School, San Gabriel Elementary School District, and Scherick's South Bay School.

336 A. J. AYRES

a similar analysis of data acquired from a comparable group chosen without reference to perceptual skill. Backgrozlnd of the Problem

During the past several decades, isolated perceptual deficits in children have been described in the literature; more recent snidies have been characterized by attempts at associating two or more areas of perceptual dysfunction. Gallagher (1957) found definite relationships among a small number of perceptual and intellectual skills in a limited number of brain-injured mentally retarded children. The Binet mental age had a particularly high correlation with all scores on tests of perceptual and cognitive abilicy except direct learning. After thorough testing of finger agnosia and right-left disorientation, Benton (1959b) concluded that these adaptive deficits tend to occur together, along with a variety of other perceptual deficits, these being specific expressions of more pervasive impairment. In a later study of the Gerstmann syndrome in individuals incurring cerebral disease or damage in adulthood, Benton (1961) found that correlations between any two elements of the syndrome (finger localization, wricing, calculation, right-left orientation) were no higher than between any one of the elements and praxis, reading, or visual memory. The highest correlation (+.62) was between right-left orientation and finger localization and calciilation. The mean correlation between any two syndrome elements was +.48; between a syndrome element and one not of the syndrome the mean was +.52. Benton's data failed to support the existence of the Gerstmann syndrome. Kinsbourne and Warrington ( 1763 ) recently reported the presence of a developmental Gerstmann syndrome in seven children. I n addition to the four syndrome behavioral dimensions, constructional apraxia and dyslexia were found. The authors, in fact, felt that the syndrome was most fully manifested in the child who was retarded in reading and spelling. It is clear that Kinsbourne and Warrington interpreted the Gerstmann syndrome in a manner different from Benton.

A direction of psychological development which links performance on several different types of figure-ground perception with a specific type of personaliry structure has been described by Witkin and associates ( 1762 ) . They identified two major preferences for perceiving, based largely on response co figure-ground tasks.

In a group of cerebral palsied individuals, Cobrink (1959) found that those with more severe motor involvemenc scored more poorly on tests of figure-ground discrimination. T h e results were construed to support the hypothesis that degree of perceptual deficit reflected extent of cerebral damage. Thac such a simple explanation is not adequate is suggested by the study of Abercrombie, et al. ( 1964) of physically handicapped children. Perceptual and intellecmaI impairment was found to be virtually unrelated to degree of motor handicap or somatic sensory loss, even in brain-damaged Ss. Cerebral palsied children with spasticiry, how-

PERCEPTUAL-MOTOR DYSFUNCTION IN CHILDREN 337

ever, showed significantly greater perceptual dysfunction than athetoid Ss and other Ss with motor involvement. Furthermore, it was quite clear from their study that a child could show impairment on one test but not another.

A significant relationship between teacher ratings of classroom adjustment and scores on the Frostig visual perception test (Frostig, el al., 1963) was interpreted as supporting the idea that perceptual development is a sensitive indicator of a child's over-all developmental status between the ages of 3 and 7.

A strong relationship between sensori-motor activity and cognition is assumed and implied by the empirical work of such clinicians as Kephart (1960) , Getman (1962 ), Harmon (1957) , and Delacnto (1963 ). Strauss and Werner (1938) reported that children with arithmetic disability made more errors on a test of finger agnosia than did children without arithmetic disability. Benton and associates (1951) failed to find a similar relationship in a snidy of both normal and subnormal children.

T h e question of relation of laterality functions has intrigued investigators and clinicians for many years. Delacato (1963) is representative of the strong adherents to the belief in the clinical significance of mixed eye-hand dominance in individuals with speech and reading problems. Zangwill (1960) is among those who have made systematic observations leading to the conviction that cerebral dominance, with emphasis on degree of cerebral specialization or lateralization, plays a critical role in language functions. In spite of enthusiastic endorse- ment of various theorems, the significance of right-left hemisphere dominance and agreement between eye and hand dominance in perceptual, cognitive, and motor functions has remained, essentially, unresolved.

Factor analyses seemingly have not been applied previously to the identification of basic areas of percepmal-motor dysfunccion. The closest exception was within Gallagher's study (1957) , where correlations of scores o n a number of tests including intelligence, language, quantitative and perceptual ability and per- sonality factors were subjected to factor analysis. Factors were determined for both familial and brain-injured mentally retarded children. From both groups emerged a factor of general mental growth, which accounted for a large propor- tion of the total variance. The second factor for the brain-injured group related to poor perceptual ability, but in the familial group the second factor was general language development. N o further interpretation of the factors was attempted.

A study by Myers and associates ( 1962 ) compared factors in normal children with a mental age of 6. Using tests of visual perception, hand-eye coordination, language functions, and reasoning, the investigators distinguished four major ability factors common to both the retarded and non-retarded groups: ( a ) hand-eye psychomotor, ( b ) perceptual-speed, ( c ) linguistic, and ( d ) reasoning or spatial reasoning. The retarded group showed a simpler factorial strucrure with higher intercorrelations between test scores, while the normal group demonstrated more clearly differentiated mental development.

A. J. AYRES

Although ascertaining affinities between and among perceptual dimensions may lead to clarification of their nature, just as significant to the development of theoretical strucnlre is the identification of independence among some areas of perception. Frostig and co-workers (1961a) reasoned that five areas of perceptual-motor function, uiz., eye-motor coordination, figure-ground perception, form constancy, position in space, and spatial relations, could be disrurbed independently in children. Later (Frostig, el al., 1963a) the hypothesis was supported by obtaining low intercorrelations among tests of the five areas administered to cliil- dren of early school years. Frostig concluded that the five areas of visual perception developed relatively independently of each other. In a sample of cerebral- palsied children, Cruickshank and collaborators (1957) found unexpectedly low relationships between tasks involving tactile, kinesthetic, and visual perception tests which emphasized f igure-gro~~nd discrimination.

The literature is harmonious with the proposal of existence of natural associative bonds between and among many dimensions of perceptual-motor function, cognition, and laterality. The lack of consistency among reported results suggests that the degree of association may be dependent upon the nature of the population under study. At the same time, determination of relative independence of perceptual parameters augurs against the existence of one amorphous perceptual-motor ability or one rype of dysfunction. That associations among behavioral dimensions might form constellations of function or dysfunction has received some slight support from reported studies, while the possibility of constellations of performance differentiating abnormal groups has received only a hint. It appears that the next most logical step to be taken in the development of knowledge of percepmal-motor dysfunction is the investigation of possible patterns of perceptual-motor function and dysfunction and the relative independence of their manifestation.

METHOD A battery of perceptual-motor tests was given individually to each member

of two separate groups of children, one group selected on the basis of suspected perceptual deficits, especially as reflected in learning problems, and the other group chosen to represent the "normal" or average school population, without reference to behavior or academic performance. The scores of each group were in- tercorrelated and then subjected to R-technique analysis. Correlations between scores for the group with suspected dysfunction were subjected to Q-technique factor analysis. The data were gathered between August, 1962, and July, 1963. Subjects

The 100 children who conlprised the group with suspected dysfunction were selected from regular public schools-which comprised about 50% of the group -and from special schools and medical centers. The major criteria for selection were ( a ) teachers' reports of difficulty in learning, especially comparatively

PERCEPTUAL-MOTOR DYSFUNCTION IN CHILDREN 3 39

greater difficulty wich reading, writing, or arithmetic than with oral language or social studies, ( b ) additional observations by teachers of clu~nsiness, hyperactiviry and distractabilicy, and ( c ) lower scores on performance or perceptual than on verbal subtests of intelligence tests. Psychological tests and/or reports were available for assessing possible perceptual deficits in approximately 70 of the children with si~spected dysfunction. Another requirement for the group was a verbal intelligence qootient above 70. In 6 8 Ss intelligence quotients, based on various types of tests, were available and used to determine the adequacy of verbal intelligence as well as to estimate the mean intelligence of the dysfunction group. Ss on whom quotients were not available (mainly the younger children) were judged either by a psychologist or teacher or by the academic grades to have intelligence quotients within the normal range. Many of the children were preliterate. The use of a single screening device was avoided for fear of biasing the selection of Ss through preconceived ideas of perceptual dysfunction. Effort was extended to include every possible type of perceptual-motor dysfunction which might exist in children of 6 or 7 yr. of age outside the cerebral palsied or mentally retarded populations. N o child carried a medical diagnosis of cerebral palsy.

The mean IQ of the dysfunction Ss, based on 6 8 cases and on verbal scores only when possible, was 96.97, wich a. standard deviation of 14.05 and a range from 71 to 139. The mean chronological age was 84.1 mo., wich a standard deviation of 7.3 and a range from 70 to 96 mo., a coverage of 26 mo. There were 69 males and 3 1 females in the dysfunction group. Tile control group of 50 children was chosen to match the dysfunction group on mean, variance, and range of mental age and on sex. The estimated mean mental age of the dysfunction group was 81.48 mo.; the mean chronological age of the control Ss was 81.50 mo. The standard deviation of age of the control Ss was 7.5 and the range was 68 to 95 mo., a coverage of 27 mo. The g r o ~ ~ p i n c l ~ ~ d e d 35 males and 15 females, chosen from public and private schools and child care centers on the basis of parental occupation so as to represent proportionately the working population of the United States and thus, presumably, representing also the normal range of intelligence. On completion of the study, comparison of the mean scores of the control group with the normative data of the two standardized tests used suggested a few months immaturity of visual perception in the control Ss. All 150 Ss lived within the metropolitan Los Angeles area. T h e Test Battery

The tests which were adrniniscered to Ss are described below, numbered to facilitate reference to them in the tables. All estimates of reliability reported are based on scores of the dysfunction group only, unless otherwise indicated. Where tests were split in half for use of either the K~~der-Richardson or Rulon formula, the division was made in such a manner as to avoid comparing performance of one side of the body with the other side.

340 A. J. AYRES

( 1 ) Southern California Motor Acczdracy Test ( Ayres, 1964a) .-The child was required to draw a pencil line over a curved printed line. Each hand per- formed half the test. The score was derived from the degree of accuracy of the pencil line and the time of execution. Escablishrnent of test score reliability on the present population was not feasible. A previous estimate of reliability of the scores when administered to persons with neuromuscular pathology was .94, determined by a rho correlation of scores on two separate trials.

( 2 ) Graphic skill.-The task involved drawing, from a copy, a vertical line, horizontal line, circle, crossed lines, and a rectangle with diagonal lines connecting opposite corners. Drawings were rated 1 through 9, based on the following criteria: recognizability of figures, presence vs omission of figures, accuracy of figures, relative size and spacing of figures, tendency to mark-over, irregularity of line, and hesitancy vs assurance of lines. A n estimate of the reliability of the scores was .89, established by Pearson product-moment correlation of scores obtained by two separate scorers on the first 71 tests administered in this study.

( 3 ) Kinesthetic nzemory.-With the working area hidden from view, the child was asked to place a stylus on a spot to which his hand, holding the stylus, previously had been passively taken. A score was determined by how close the child came to the goal. Eight samples of behavior were taken and scored on degree of accuracy. Using the Rulon method of estimating reliability from scores on two halves of the test (Guilford, 1956) , a coefficient of .78 was obtained.

( 4 ) Localization of tactile stimz~li."The test ascertained the degree of accuracy with which a child could indicate wich his finger tip at what part on his forearm or hand he had been touched with a pencil used by the examiner. Vision was occluded. The estimate of reliability of scores (Rulon formula) was .99.

( 5 ) Eye pursuit.:'-Voluntary control of eye movement was the essence o f this test, the scores of which had an estimated reliability of .82. using the Kuder- Richardson Formula 2 1, corrected for length by the Spearman-Brown formula.

( 6 ) Skin designs."After the examiner drew a simple design on the back of the child's hand, the child was asked to draw the same design wich his finger on the back of the examiner's hand. Using the Rulon formula, reliability of scores was estimated at 36.

( 7 ) Manual perception of form.-The task r e q ~ ~ i r e d idencification of common objects or wooden geometric forms held in the hand and hidden from sight. The objects were identified verbally; the forms were identified by pointing to a chart of forms at which the child looked. Slow responses were penalized. Re- liability of scores (Rulon) was estimated to be .65.

(8) Standing balance I.3-The test score was dependent upon the length of time S could stand on one foot, eyes open. T h e reliability of scores (Rulon) was 39. T e s t protocols and items, described in detail in Document No. 8179, may be obtained by remitting $2.50 for photocopies or $1.75 for 35-mm. microfilm from the AD1 Auxiliary Publications Project, Photoduplication Service, Library of Congress, Washington 25, D. C .

PERCEPTUAL-MOTOR DYSFUNCTION IN CHILDREN 34 1

( 9 ) Stafzdifzg balafzce 11.''-The test was a replication of No. 8 with eyes closed instead of open.

( 10) Visz~al perception of verticality.-Using a piece of apparatus which eliminated visual cues to verticality, S adjusted a rod to his perceived visual vertical. Reliability of scores of the dysfunction population was not estimated. Pre- v i o ~ ~ s use (Sleeper, 1962) of the instrument with a population manifesting central nervous system dysfunction reported an uncorrected split-half reliability coefficient of 96 .

( 11 ) Marianne Frostig: Eye-motor Coordinatio?z.-This and the other Fros- tig tests were subtests of the Marianne Frostig Developmental Test of Visual Per- ception (Frostig, Lefever, & Whittlesey, 1961b). The eye-motor test required S to draw a line between two points, the score depending upon the accuracy of the line.

( 1 2 ) Marianne Frostig Figure-ground.-S drew around geometric forms which were superimposed or placed on a shaded background.

( 13) Marianne Frostig: Form Constancy.-The test involved the identification of circles and squares in a variety of visual contexts. Minimal motor activity was required.

( 14) Marianne Frostig: Position in Space.-S differentiated mirror images from exact likenesses by pointing to his choice of figures.

( 15) Marianne Frostig: Spatial Relations.-The task required copying with a pencil patterns superimposed on a constellation of dots.

( 16) Ayres Space Test.-S selected a block to fit a formboard on the basis of perception of position in space and visualization of rotation of objects in space. The short form which included only odd items was used, the score being prorated accordingly. Minimal motor activity was involved; response time as well as accuracy entered into the scoring. Reliabilities of scores reported (Ayres, 1962) on the 6- and 7-yr.-old children on which this test was originally standardized were .96 and .94, respectively.

(17) Hands test.-Plastic models of the hands were presented in different spatial orientations to S for right or left identification. Scoring was based on accuracy and speed of response.

( 18) Motor planning: gross."-S was judged on the quickness and accuracy with which he could duplicate a posture assumed by the examiner. Internal consistency reliability (Rulon) was estimated to be .47.

( 19) Right-left discriminario?z.:'-The task required identification of right and left on both examinee and examiner. Attention is drawn to the fact that many of the items required crossing the mid-line of the body. Reliability (Rulon) was estimated to be .81.

(20) Finger identification."-S was required to identify fingers touched by examiner. Rulon reliability was estimated to be .78.

( 2 1 ) Slrength of unilateral hand dominance."-Strength of hand preference

342 A. J. AYRES

was determined by frequency with which one hand was used for common tasks. ( 2 2 ) Degree of agreement between eye and hand domina?zce."The extent

to w h ~ c h homologous eye and hand preference were demonscrated was the basis for this test. A limitation in the nanire of scoring the test lay in the fact that S who was strongly right-handed and left-eyed, or the opposite, received a much poorer score than the one who had established neither eye nor hand dominance. For this reason and others, following the factor analyses results were rescored for analysis with nonparametric statistics.

( 2 3 ) Body v i s a a l i z a t i o n . ~ S was required to respond to verbal questions regarding the spatial relations of the body. The Rulon estimate of reliability of .64 reflects low internal consistency of the test.

( 2 4 ) Crossing the mid-line of the body."-The test attempted to evaluate the tendency to avoid crossing the mid-line of the body with the hands.

( 2 5 ) Perception of joint nzovement.-With S's arm resting on a kines- thesiometer and vision occluded, the child was asked to indicate when his arm was moved by the examiner. The score was determined by the number of degrees of excursion before motion was perceived. Many of the children with suspected dysfunction had much difficulty in grasping the concept involved in the test, quite possibly because they had very poor perception of joinc motion. In these cases, objectivity in scoring was severely diminished and prevented the collection of pre- cise data necessary for estimating reliability.

( 2 6 ) Fine motor planning: wire-grommet device.:'-The instrument involved consisted of a twisted wire held in both hands by handles a t each end. By continuously changing the spatial orientation, a rubber grommet was manipulated from one handle to the other. Three devices, of graded complexity, were used, the score resulting from the time taken by S to maneuver the grommet from one end to the other.

( 2 7 ) Fine motor planning: string ,winding.-The task involved winding a heavy string, making a figure eight, around two bolts set 3 in. apart in a piece of plywood. The score was based on the number of figure eights completed within a given period of time on two separate attempts. Since estimate of reliability would have had to be based on an infeasible test-retest procedure, reliability was nor computed for either fine motor planning test.

(28) Two-point tactile discrimination."-The standard test of two-point discrimination was administered using the two points on a sewing gauge. Rulon reliability was estimated at .99, which is spurious, due to the nature of scoring procedures.

( 2 9 ) Two simultaneoz~s tactile stimuli."Using a protocol based on that of Swanson (1957) and apparently developed originally by Bender and associates ( 1954; Fink, 1953) , the degree to which S could simultaneously perceive two tactile stimuli applied to hand and/or cheek was ascertained. T h e Rulon reliability was estimated at 36.


( 3 0 ) Sz~perimposed figures.-Simple outline drawings of common objects, superi~nposed on each other and occasionally embedded in s~~per f luous lines, were identified by S. The tesc design resembled that described by Teuber (1950) and Ghent ( 1956). Response time entered into scoring. Estimate of reliability (K~tder-Richardson corrected for length by Spearman-Brown formula) was 38.

( 3 1 ) Gestalt completion.-Using the same objects as in tesc No. 30, tesc icems were designed after Street's ( 1931) original Gestalt Test, to be identified by S. Scoring was based on accuracy and speed of response. Corrected splic-half estimate of reliability was 3 9 .

( 3 2 ) T ime and rhythwz."-The child was asked to beac ouc a rhythm wich one or taro hands as demonstrated by the examiner. The estimated reliability of scores (Rulon) was .90.

( 33 ) Number co?zcepts.-The Pacific State Hospital Number Concept Test (Shotwell, Dingman, e( Tarjan, 1956) used by permission of the senior auchor, was utilized for evaluating number concepts. The icems involved counting of objects, identifying numbers and coins, making numbers on paper with pencil on command, and addition and subtraction problems. One item required discriminating between similar objects of different weights and one item involved recognition of a triangle among geometric forms.

( 3 4 ) Freedom from tactile defensive behavior.-Tactile defensive behavior referred to responses indicating physical and emotional discomfort and a desire to escape the situation when tactile stimuli were imposed by the examiner during the tests of tactile perception. The child who made no efforc to avoid che tactile tesc and whose affect or activicy did not change during these tests was given a racing of "4." One or two comlnents or actions indicating a desire to escape (e.g., "I'm thirsty.") or discomfort (e.g., wiggling or saying "Are we nearly through?") during cactile tests designated a score of "3." A rating of "2" was given when several escapist or discomfort reaccions, especially with mild feeling, were elicited with tactile stim~ili. When scrong feeling (e.g., "I hace this game!") and much motor activity resulced from cactile cesting, the rating was "1." N o estimate of reliability of the raced scores was made.

( 3 5 ) Freedom from hyperactive and distrctclible behavior.-As with Vari- able 34, the behavioral dimension was rated by the examiner on a 4-point scale, a racing of "4" given lechargism and "3" to behavior manifesting an average amount of verbal and motor activity. A rating of "2" indicated more than normal amount of skeletal movement and verbosity; a rating of "1" denoced hyperactivity and the cendency co respond to stimuli not relevant to the test sinlacion with alertness and focusing of attention on them. Since the behavior determining the degree of hyperactivity and distractibility was observed during the entire testing period, it included the period of tactile tescing, resulting i n some difficulty in independence of measurements from Variable 34. N o estimate of reliability of the rated scores was made.

344 A. J. AYRES

Disc~inzination Value of means of Tes t Scores Most of the tests discriminated well between the dysfunction and control

groups, as shown by the mean scores and the significance of difference (critical

TABLE 1 MEANS A N D STANDARD DEVIATIONS OF TEST SCORES OF DYSFUNCTION A N D CONTROL GROUPS, WITH SIGNIFICANCE OF DIFFERENCE BETWEEN MEANS

Tesr Dysfunction Group Control Group CR* M SD M SD

1 431.6 55.4 463.3 15.6 5.29 7 - 5.6 1.6 6.2 .9 2.63 3 34.2 10.8 38.9 9.3 2.77 4 372.0 47.1 394.1 36.7 3.13 5 6.4 2.5 8.7 1.6 7.03 6 17.0 6.0 20.3 2.5 4.72 7 10.6 2.9 11.7 1.6 3.17 8 66.9 66.0 119.0 69.4 4.37 9 13.7 14.6 21.1 15.8 2.73

10 37.5 10.8 37.8 7.0 .19 11 10.3 4.0 13.3 3.2 4.85 12 4.7 2.4 6.5 2.2 4.00 13 5.2 4.5 7.6 4.3 3.17 14 4.8 1.5 5.7 1.3 3.87 15 3.7 2.2 5.5 1.4 5.99 16 26.2 7.7 35.7 8.0 6.32 17 10.9 4.9 15.0 4.4 5.18 18 11.7 3.6 15.6 1.9 8.39 19 9.0 4.8 11.7 4.9 3.18 20 22.4 5.7 29.8 5.2 7.91 21 5.5 2.1 6.1 1.7 1.94 22 10.5 5.1 11.2 5.3 .72 23 15.7 4.3 20.6 3.7 7.18 2 4 9.1 2.7 10.0 2.1 2.28 25 113.7 55.7 149.7 30.8 5.04 26 56.0 18.5 68.7 5.4 6.31 2 7 8.3 5.8 11.7 4.6 3.82 2 8 32.5 10.9 38.0 4.1 4.40 29 26.7 5.9 30.0 2.3 4.91 30 13.0 4.1 15.7 2.2 5.17 31 12.0 4.3 15.2 2.9 5.39 3 2 14.8 4.2 17.2 1.6 5.04 3 3 66.1 14.7 81.5 11.6 6.92 34 3.3 1.0 3.9 0.4 5.45 35 2.6 0.8 2.9 0.4 3.56 36 84.1 7.3 81.5 7.6 2.00

+A critical ratio of 1.96 is required at P.46 and 2.58 at P.au.


ratios) between means in Table 1. Those tests showing poor discriminative properties were perception of verticality (Var. 1 0 ) and degree of agreement between eye and hand dominance (Var. 22 ) . The test of unilateral hand dominance (Var. 21) approached but did not reach the statistical differentiation between means of scores.

Associations A m o n g the Variables Strong, positive, and usually statistically s ignif icant~orrelat ions were dem-

onstrated among scores derived from the dysfunction group (Table 2, p. 347) . The degree to which scores on all other tests predicted a score on a given test is reflected in the R>olumn, i.e., the squared multiple correlations becween a given variable and all other variables. A notable exception to the observation of strong bonds among all behavioral dimensions was found with Variable 22, degree of agreement between eye and hand dominance, which correlated significantly (and negatively) with only one variable, the discrimination of two tactile stimuli. The role of chance in producing a few significant correlations must not be overlooked. A second exception was Variable 21, strength of unilateral hand dominance. This variable, however, did demonstrate staristically significant positive linkage with three other variables, each concerned with an ocular or visual function. In the control group, association among the variables was considerably less in extent and less frequently statistically significant. R-technique Factor Analyses

Using the IBM 7090 computer, intercorrelations among the 35 test scores plus age were subjected to an orthogonal rotation factor analysis. The correlation matrix was modified by insertion in the diagonal of the squared multiple correlation coefficients. Factors were extracted by the principal components method, the number of factors rotated being equal to the number of eigenvalues greater than zero. Rationale supporting the extraction of this number of factors has been given by Cattell ( 1958) , Guttman ( 1954), and Thurstone ( 1947). Extracted factors were rotated by rhe Kaiser varimax criterion (1958) .

In the group with suspected dysfunction, 23 rotated factors emerged, as shown on the left in Table 3 ( p. 348, cf. 26 in Table 3 for the control group). Factor loadings under .30 were omitted from the table, which eliminated the last four factors from presentation. The algebraic signs of the loadings on Factors B, E, G, H, J, N, 0, Q, R, and S were reversed. The eigenvalues for the 19 factors were 13.90, 1.87, 1.71, 1.12, .95, .87, .75, .65, .59, .56, .46, .40, .36, .31, .27, .18, .17, .14, .12. Perusal of the matrix suggests that most of the variance was accounted for by six major factors (A, C, E, H, K, and L ) , five of which were inter-

'For 98 df an + of .20 is required if p = .05; an r of .26 is required if # = .01. W i t h 48 df, r of .27 is significant ar p < .05 and .36 at p < . O l .

346 A. J. AYRES

pretable as hypothesized behavioral correlates of patterns of neurological dysfunction. Unrotated factors are shown in Table 4 on pp. 350 and 351.

A comparable analysis of the intercorrelations among scores of the control group yielded 27 factors, the first 26 of which are shown on the right in Table 3. The algebraic signs of the loadings were reversed on Factors A, C, F, G, H, K, M, N, 0 , R, S, T, U, and W. The eigenvalues for the factors were 8.26, 2.51, 2.07, 1.77, 1.58, 1.45, 1.38, 1.27, 1.15, 1.00, .89, 35, .76, 67, 62, .51, .50, .41, .39, .33, 29, 26, .19, .IS, .09, .07. Unrotated factors are in Table 5 (pp . 352-353). Factors o n the whole, were not comparable to the major factors emerging from the dysfunction group. One exception to the dissimilarity was the appearance of Factors I and K which seem related to Factor L, figure-ground discrimination, of the dysfunction group. The second exception was the presence of Factor E in the control group with similar high loading of body balance as in Factor H in the dysfunction group. I n addition, some of the singlets were repeated. Factor A, accounting for most of the variance in the control group, appeared to be one of general perceptual-motor and cognitive ability, with the highest loadings on Variables 15 (Fros- tig Space Relations), 18 (gross motor planning), 33 (number concepts), and 12 (Frostig Figure-Ground). Inspection of the remaining factors in the matrix did not lead to meaningful interpretations.

-

A third R-technique factor analysis of the intercorrelations of scores of the combined dysfunction and control groups yielded, essentially but less clearly, the same major factors as did the dysfunction group alone. One exception was the emergence of a factor appearing to reflect somatic perception and the motor skills directly associated with them. Standing balance did not load on this factor.

Descriptive titles proposed for the five major factors emerging from the dysfunction group were expressed as the following syndromes: ( a ) Factor A = apraxia, ( b ) Factor C = perceptilal dysfunction: form and position in two- dimensional space, ( c ) Factor E = tactile defensiveness, ( d ) Factor K = deficit of integration of function of the two sides of the body, and ( e ) Factor L = perceptual dysfunction: visual figure-ground discrimination. Q-technique Factor Analysis

In a search for identification of natural cli~sters of Ss best deinonstrating the factors emerging from the analysis of scores of the dysfunction group, the data were subjected to Q-technique factor analysis. T o meet the requirements of the analytic process, the group of 100 Ss was divided into four groups of 25 with approximately equal means and standard deviations. The resultant factors were far less clear than those produced by the R-technique analysis. Heaviest reliance for interpretation was placed on inspection of the ipsative standard scores, which indicated that few, if any, Ss showed deficits i n one pattern (factor) only. The substantial relationship between variables in the dysfunction group supports the observation chat disability in one area is apt to be associated with disability in other

PERCEPTUAL-hlOTOR DYSFUNCTION IN CHILI

TABLE 2 I INTERCORRELATIONS OF TESTS: DYSFUNCTION GROUP ( U P P E R RIGHT) AND C NTROL GROUP (LOWER LEFT)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16 17 18 19 20 24 22 23 24 25 26 27 28 29 30 31 32

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 2 3 24 25 26 2 7 28 29 30 3 1 32 3 3 34 3 5 3 6 -

Note

R2 78 73 74 58 65 87 55 56 57 53 78 24 52 36 47 80 01 27 51 51 7 6 02 21 03 41 8 1 39 21 19 26 68 -03 05 29 -02 -13 8 5 19 44 26 27 37 84 37 28 32 19 35 85 09 20 20 -10 15 65 13 13 -12 09 -03 84 39 57 39 13 26 87 37 52 51 09 14 80 18 15 19 -12 27 8 3 26 30 34 05 21 88 38 35 37 10 27 87 12 30 40 31 31 75 -04 04 -01 12 04 82 38 27 33 19 25 72 -22 07 03 14 02 9 1 15 -02 14 31 12 65 02 -01 -15 -10 -02

16 04 17 12 14 69 14 29 34 30 10 81 79 28 40 26 02 30 67 01 -15 11 -02 -10 80 -01 31 17 08 17 7 7 46 25 08 26 34 68 10 -04 08 -12 -01 89 18 29 23 25 22 8 1 17 -05 06 -07 13 80 10 06 28 13 37 77 07 18 23 -15 -06 87 50 28 36 19 35 7 8 14 17 39 02 40 7 7 39 13 15 -09 05 7 6 30 28 35 03 41

.-Decimals have been omitted.

w m w r . m N N N N N


areas. Nevertheless, using the patterns of ipsative standard scores, Ss showing the clearest cases of the major syndromes were selected to test additional hypotheses. Eye and Hand Dominance

In both the dysfunction and the control groups, the scores on tests of agreement of eye-hand dominance and strength of unilateral hand dominance tended not to share their variance with the other variables, including each other. They require separate consideration. In each of the factor matrices of the two groups, the variable appeared as a singlet, but in the matrix of the total group, right-left discrimination and strength of hand dominance held loadings of .49 and .53, respectively, on the same factor. Eye pursuit, with a loading of 3 4 , was the only other variable showing much saturation with the factor. In the total group, the degree of agreement between eye and hand dominance appeared as a singlet.

Laterality functions d o not lend themselves easily to analysis by parametric statistics. This fact, plus the large amount of interest shown in the possible role of various aspects of cerebral dominance, led to the searching for possible associations through additional scatistical analyses. T o accomplish this objective, Ss were grouped according to different criteria. The frequency distribution of handedness and strong mixed or homologo~~s eye-hand dominance was determined for the grouped Ss (cf. Table 6 , p. 354). Inspection of the relative frequencies of the two laterality dimensions among the groups of Ss best representing four of the major syndromes failed to suggest any likelihood of relationships between laterality functions and clinical syndromes. Chi square tests of possible differences in frequency of mixed vs homologous eye-hand dominance in dysfunction vs control Ss indicated all differences were well within the realm of chance occurrence. Likewise, neither handedness nor eye-hand dominance differentiated statistically the higher 40% from the lower 40% of the dysfunction group. And, the X' of 4.59 resulting from testing the d~fferences in frequencies of handedness between the dysfunction and control groups only approached statistical significance. Number Concepts

From the correlation matrix it is evident that a substantial relationship is held between skill in number concepcs and perceptual-motor functions, excepting those of laterality. Stronger associations were found in the dysfunction group than in the control group, although in this latter group definite ties were shown between number concepts and space relations, form perception, eye-motor skill, body visualization, and finger localization. The number concept variable appeared as a singlet in addition to loading on the general ability factor in the factor matrix derived from the control group. In the dysfunction group, number concepts showed closer affiliation with specific perceptual-motor symptom constellations. Particularly evident were identification with the syndromes of perceptual deficit of form and space and with deficit of integration of the two sides of the body.

A. J. AYRES

- u m + b ~ m m ~ ~ ~ m m w O r - m - W 0 ~ 0 0 0 0 0 0 0 0 0 0 0 - 0 0 0 0 I I I I I I I I m w ~ w m m m w o m w - m r n o w a a 0 0 0 0 0 0 0 0 0 - 0 0 0 0 - 0 0 0

I I I I l l I I

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I I I I I I I I I I m r n w ~ w + o d o m - ~ m m w w m m O O O ~ O - - O O O - O - - O - O O

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~ + + O O m O ~ O O - O ~ O O O O O ~ I I I I I I I I I G ,

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n m m m + m r n m ~ w ~ o r - r - m m w m O O N O N O ~ ~ ~ N O ~ V ~ ~ ~ N N I I I I I

m v w ~ - h i - m ~ m m v r - w m w m o m ~ ~ 0 ~ 0 0 + m m ~ + ~ - 0 ~ 0 0

I I I l l I 4 ~ n ~ + m m v m ~ n w ~ b o r n w m m w ~ r . w w m w w ~ W w r - w m r - ~ v r -

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TABLE 4 (Cont'd) FACTORS (UNROTATED) : DYSFUNCTION GROUP W m

Tests Factors 5? A B C D E F G H I J K L M N O P Q R S

19 36 06 -11 34 -06 35 04 08 08 -20 15 14 -04 15 -12 06 -06 -01 01 8 ?=

20 68 32 -12 21 18 -02 06 01 10 15 07 -06 -11 -12 10 07 08 -03 -11 21 17 29 -08 -13 -03 32 10 -16 23 -21 04 -04 12 -08 03 -09 09 02 -09

E 22 -10 -01 -04 -07 05 2 3 - 3 3 - 0 9 1 5 - 0 9 - 3 1 - 0 2 - 0 8 - 1 1 07 1 1 - 0 7 0 5 - 0 2 3 23 38 02 09 49 14 -08 -09 -06 01 -01 -12 11 20 -06 08 -10 07 02 -03 24 56 02 -12 36 -13 03 -02 -18 06 -06 -12 02 -06 08 -16 -10 -02 02 -05 U 25 50 15 -18 -02 -06 -12 09 00 -15 -26 01 -25 -16 11 22 -04 07 08 03 V) < 26 70 11 -03 -08 36 11 07 02 15 15 05 03 09 13 02 07 -09 -09 00 c" 27 76 -03 -02 00 03 -07 -08 -10 09 -03 16 -27 -02 -12 -12 -06 -08 05 -03 28 74 32 04 04 -15 -01 08 -09 -13 20 04 -08 19 04 -05 00 -07 -01 07

z 29 71 32 -15 11 00 -23 -13 09 17 -08 -11 15-12 07 0 8 - 0 7 07-06 13 2 30 76 -24 -08 00 -06 -18 33 06 01 00 -24 00 01 -10 -05 01 -06 00 -07 Z 31 61 -36 -07 -07 -18 -27 18 20 17 -11 -08 09 15 04 03 01 -05 02 -01 2 32 71 -03 -22 27 -01 02 33 -01 -01 02 03 -02 -11 -05 07 02 -11 05 -01 n 33 69 -36 21 25 -03 19 -15 -04 -15 -08 05 -04 09 08 10 08 -03 -01 03 34 71 28 -20 04 -32 -08 -12 09 -07 06 01 -06 -03 -01 -02 02 02 -16 -06

E 35 52 35 -26 -12 - 4 2 - 0 2 -24 11 02 16 -01 -05 08 05 -04 07 02 11 00 36 13 -62 -15 -02 04 02 -12 23 15 01 07 -19 07 13 03 06 12 -02 -07

i Z

Note.-Decimals have been omitted.

A. J. AYRES

n w o m m o m m ~ ~ m a ~ ~ w ~ o - 3 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 I I I I I 1 I 4 m n m m + - v b m m m w m m m m m 3 0 0 0 4 4 4 0 0 c 0 0 0 0 0 0 0 0 I I I I l l I 1 3 m w m o w + + m m m w ~ r n o w - ~ 3 0 0 0 0 y y - 0 0 0 0 0 0 + - 0 0

I I I I I ~ - m r n O O - N ~ N W O u N O O ~ + 3 d 0 0 0 N N 0 0 0 0 d 0 0 0 + 0 0 I I I I I I I I n m N N w m w + m m m o w - m - N m 3 0 N 0 0 0 0 0 0 0 0 0 0 0 ~ - 0 0 I I I I b w m m r n m r - O W - W m m r - W r - Q m > 0 0 + 0 + 0 d 0 0 0 0 0 0 0 d 0 0 I I I I I 3 r n - m - m w m - w o ~ + m + ~ ~ m ~ ~ - O N ~ O O O O N - O - - O O O

I I I I I I I I I I I 1 I - 0 - O V m O l . W r - m W + V m N W W ~ + - N + - O m o 0 0 0 N 0 0 0 + I I I I I ? I * m u + - m N w w N m m m m O N m O - - 0 0 - 0 0 0 - 0 0 - ~ 0 ~ 0 N O I I I I I I I I n W O ~ w m w ~ w w m m w O m m W 0 - ~ - + 0 0 0 0 0 0 + 0 0 - 0 0 - + I I I I I I n m - v w m w w w - m o o m u r - m w 3 - 0 0 0 0 0 0 - m - 0 N 0 - 0 0 - I I I I I I I I I I ~ w - O w m + r . J w P - b w w m - O - 3 + 0 + - 0 + + O N O

~ m b m u o w w m - ~ - r n m c o - w + 3 0 0 0 N 0 + 0 0 N O - - O O N O N ~ I I I I I I 1 I n

m m w r - ~ + m m v m m m m o o r n m m ~ + ~ - ~ o o O - N - m N O N - - + N X

I I I I ' I I 1 g e w m w ~ m w m ~ m ~ b o m w w - N ~ + N + 0 0 ~ + N ~ ~ . . ~ 0 0 0 + + ~

I l I I I l l = m m m - e o r - m - m r - m v + ~ c o ~ m w . S - 0 - 0 - N - 0 0 0 0 - ~ N - N O O ~ I I I I I I I

d ~ N ~ 0 0 e d + N 0 - + 0 - 0 0 - I I I I I I I I I I I

m U m m m - + m m W w w W m m m ~ m N + ~ - - N N y - y y o 4 y T N y ? I I

m m m m a w w m o + w m m 0 - + ~ + o m - r n w - m o o - - O N - 0 - - - I I I I I I I

~ ~ f i m ~ W C O N W P V Q V P W C 3 O O 0 0 0 + 0 0 I 4 4 7 " 4 7 4 7 4 " Y 0

V w W b b m W m d O m V d b m + m d m + o w m - ~ o + - o - ~ O - I I 1 1 1 1 1 1 1 9 - 7

~ o w m ~ w m ~ r n w m ~ m o ~ ~ o m O - N O N N O V ~ ~ + - - - 0 0 - + I I I I I I I l l I

~ m m m - m m w m o r - m m v r - - m W m O N + v N 0 0 m + 0 0 + - 0 0 0 0

I I I I I I I I I I I I I o m - e r - m m - ~ - o r - m m o m ~ ~ - - N ~ ~ o o o N ~ ~ ~ ~ ~ ~ N - - N o N I l l I

+ d m + m ~ m m w ~ b w m u w + W W o + ~ m O m m C d ~ O - O

I I I I 4 O T T 4 w ~ m m m w r - o r - ~ m u r - m m f i ~ m 7 3 C Y T 7 3 Y T y Y ' T C Y ' T Y T Y

+ ~ m ~ m w b m m O - ~ m - T m Q r - C O 3 3 3 3 - - 3 3 -

TABLE 5 (Cont'd) FACTORS (UNROTATED) : CONTROL GROUP eel

m

Tests Factors z A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

20 -47 -52 34 04 -04 -11 -05 14 15 27 -01 -13 04 -16 07 07 -29 04 10 07 14 -08 02 06 -04 -04

$ 19 -06 -15 32 -10 -01 46 01 -17 -30 29 -18 -02 01 20 -15 -16 05 14 -01 -13 -08 05 01 05 02 -03 > 2 1 17 30 02 21 -14 13 03 10-35 47 -15 -03 12 -17 -06 10 04 09 10 -09 07 -05 -04 00 00 04 i 22 -28 23 09 40 -19 13 -25 15 11 23 21 -24 -03 20 05 02 -05 -02 -13 04 -07 11 05 -09 -07 06 E( 23 -58 -19 11 -33 -16 17 23 -06 -02 -12 -03 13 18 06 -20 - 0 5 -15 -06 10 08 -12 20 00 -09 -09 -01 2 24 - 4 9 35 -28 04 -30 16 11 -05 07 -13 -34 -19 -09 06 11 -05 -08 -02 -01 11 -02 08 -01 03 13 -01 U

* 25 -03 -35 19 -13 -05 -38 33 -09 10 19 -26 09 -04 -06 -09 -17 14 -15 -03 03 08 -02 17 -02 06 06 26 - 4 3 01 -14 -25 42 -04 24 30 -13 23 00 06 -17 02 25 08 -05 -04 14 06 -08 06 -01 -16 05 02 2 27 - 4 9 -23 13 46 10 -07 15 12 -11 08 -11 02 02 09 -02 -05 32 -09 -10 18 00 02 -02 -04 -08 -07 5 28 -14 -13 17 -21 -06 -09 -59 -04 02 -04 -25 26 09 -17 -03 16 07 03 05 -05 -14 08 05 -01 -01 03 5 29 -47 -50 -33 -08 -23 19 08 06 04 03 -26 -30 08 02 06 08 07 04 06 02 -12 -17 -03 -04 -01 -03 30 -25 42 48 23 24 -27 15 15 07 00 -18 00 -12 20 03 03 -01 03 03 -05 -10 02 -01 08 00 05 31 -34 26 34 15 30 24 -14 -19 31 -02 -14 18 -10 20 -09 -07 -16 03 17 13 05 -13 -04 00 01 -04 2 32 -23 64 13 -17 -19 05 09 11 -24 13 16 -05 05 -13 -10 01 -08 -28 00 01 -02 -06 07 09 00 -07 n 33 -76 -07 26 12 -08 01 04 -20 -19 -10 16 -08 09 -09 -13 -01 -12 -05 -04 05 -13 -15 -06 -07 09 11 % 34 - 4 8 03 -12 -06 -09 21 23 -53 -04 -02 07 -05 -01 13 04 29 07 -11 00 03 14 05 07 08 -02 02 6 35 -12 -20 -48 37 -30 -30 -08 -07 19 20 -02 -03 -18 14 -20 02 -09 07 06 -09 01 07 03 00 03 -01 36 -58 22 -12 07 31 -03 -02 -24 05 19 07 06 -06 -24 -22 19 06 11 -05 06 07 10 -03 -13 06 -07

No~e.-Decimals have been omitted.

A. J. AYRES

TABLE 6 HANDEDNESS AND AGREEMENT OF EYE-HAND DOMINANCE AMONG SS

BY VARIOUS CATEGORIES

Category N R L A Eye-hand Dominance Strong Strong Mixed Homol.

Clinical Syndrome Apraxia Perceptual Dysfunction: Form and Space Deficit of Functional Integration

of Sides of Body Perceptual Dysfunction: Figure-ground

Degree of Dysfunction Highest Standard Scores Lowest Standard Scores

Dysfunction vs Control Group Dysfunction Group Controls

Note.--R = Right-handed (Scores of +4 to +8), L = Left-handed (Scores of -4 to -8), A = Adominant (Scores of -3 to + 3 ) . Strong eye-hand dominance determined by rest scores of - t 5 or greater on both eye and hand dominance tests, agreement of algebraic signs indicating homologous dominance and disagreement indicating mixed dominance. Ss with weak eye or hand dominance excluded from two right-hand columns.

D ~ s c u s s r o ~ AND CONCLUSIONS Because knowledge of perceptual-motor disability is in its early, descriptive

stages and because its s~~bcle nature has been the source of difficulties in building theories of perceptual-motor development, considerable structure has been imposed on the findings. Attention is called to the fact that this strucnlre is considered provisional and will need to be modified as additional scientific data be- come available.

The factor analytic structure leads to postulating the existence of five major patterns of perceptual dysfunction. Future investigations may well reveal a larger number. The fact that four of the five identifiable major factors emerging from analysis of the scores of the dysfunction group did not appear in the factor matrix of the control group leads to the hypothesis that those factors were not due to normal developmental processes but to underlying deficits in specific mechanisms of integration, resulting in symptom complexes. The fifth factor, which appeared on both matrices, was identifiable as figure-ground perception, a behavioral parameter long considered vulnerable to central nervous system dysfunction. These two facts served as a basis for simplifying reference to the patterns of dysfunction as clinical syndromes. Attention is called to the fact that the syndromes do not reflect inherent categorizations based on individual sensory modalities but seem, to some degree, to be expressive of rather specific mechanisms by which


intersensory and (sometimes) motor information is coordinated to enable development of perceptual-motor functions. Developmental Apravia

The fact that Factor A tended to load the greatest constellation of variables suggests that a large number of tests of this disorder were included in the test battery, thus yielding the clearest definition of the factor. The descriptive title was chosen on the basis of high loading of Variable 1 (eye-hand accuracy), 2 6 (motor planning using the grommet-wire device), and 18 (gross motor planning). Since all Ss in the dysfunction group were young children and presumably had had perceptual-motor difficulty from an early age, "developmental apraxia" might be a more accurate term. Finger identification (Var. 2 0 ) is a definite part of the syndrome.

Of particular interest are the significant loadings of every test of tactile perception (Vars. 4, G, 7, 28, and 2 9 ) , suggesting that praxis is strongly dependent upon perception of tactile stimuli. The substantial relationship between finger identification and tactile perception tests seems to indicate that finger gnosis is partly a matter of identifying location of tactile stimulus. T h e mutual appearance of finger agnosia and deficit in motor planning on the same factor is in accord with the theorem, arising from several sources, that finger dyspraxia is associated with finger agnosia. Benton (1959a) , for example, found a significant correlation in a group of normal children between finger localization and motor tasks involving movement of individual fingers in reference to each other. Both finger agnosia and apraxia may stem, partially, from a common etiological factor-a dis- ordered tactile system.

Rather unexpectedly, kinesthesia carried a much lower loading on the factor, with kinesthetic memory (Var. 3 ) being .30 and perception of joint movement (Var. 25) showing no significant saturation. The diffici~lties encountered in evaluating perception of joint movement may have influenced this variable's appearance as a singlet in the analysis. Attention also is drawn to the fact that graphic skills (Var. 2 ) loaded on the apraxia factor to a barely significant degree. T h e common practice of including drawing of geometric forms in the training o f children with percepnial deficits may have reduced the validity of this test item as an indicator of percepmal-motor dysfunction.

The slight loading of the eye-pursuit test on the factor favors the conjecnlre that the poor control over voluntary oailar movement as assessed in the snidy is related to apraxia.

Benton (1951) found the concept of the body scheme "vague and ill-defined." These research data d o not add appreciable clarification, but it seems that one aspect of body-scheme is the neurological substrate of which praxis is the behavioral or motor manifestation. If this is the case, then tactile impulses form the major sensory source for the development of the body scheme. Another

356 A. J. AYRES

aspect of body scheme may be found i n the integration of function of the two sides of the body, which is discussed below. The development of the body scheme is considered to be dependent upon organization of past experience rather than upon concomitant sensory information. The present findings show comparability with the concept, for the test which best represented apraxia (fine mocor planning: wire) provided little tactile stimulation relevant to what was primarily a visual-motor planning cask. The constellation of the syndrome militates against the specificity of the finger scheme as separate from the body scheme in these children. Percepfz~al Dysf i~nct ion: Form and Posilio?~ in Two-dimensional Space

This factor ( C ) , which also loaded a considerable number of variables, was best represented by the Frostig s~lbtests of Form Constancy and Space Relations (Vars. 13, 1 5 ) , both tests of visual perception. Kinesthecic memory (Var. 3 ) was most highly saturated with chis factor, as also was manual perception of form (Var. 7 ) . While the latter test did involve a visual component, secondary to the tactile, the former test did not. The factor is interpreted to include tactile and kinesthetic perception of form and position in two-dimensional space as well as visual perception. The strong cohesiveness among the behavioral parameters reflecting perception in the three different sensory modalities may be quite significant in terms of postulating development of visual percepcion. The finding is a n indirect argument for the theory that visual perception arises partly out of motor activity which gives rise to somatic sensation.

Abercrombie and associates ( 1964) came to a different conclusion regarding the significance of mocor activity and visual perception in their physically handicapped Ss. Finding that physically handicapped children without brain damage and cerebral palsied children with athetosis scored significantly better on perceptual tests than did cerebral palsied children with spasticity, the authors concluded that deprivation of spatial experience resulting from a motor handicap could not be responsible for disorders of visual perception. Furthermore, the study failed to find an association between perceptual or intelligence scores and somatic sensory loss. Differences in these findings with those of the current sntdy may be attributed to different conceptual orientations. Somatic sensation was measured by very different operations in the two smdies. In the Abercrombie smdy, the somatic sensory involvement found in the spastics' involved upper extremities was apparently not considered to relate significantly to their perceptual disorder. Finally, it is probable that lack of movement imposed by a handicap is not critical to visual perceptual development but the inability to attribute adequate meaning to the somatic stimuli arising from existing movement is important to the development of visual perception.

Graphic skill (Var. 2 ) , while not a good indicator of percepn~al dysfunction in form and space, is slightly more indicative of this factor than of apraxia, very


likely because of the emphasis on form. The perception of verticality (Var. 1 0 ) has a relatively significant loading on this factor and a lesser one on apraxia. This fact, coupled with the substantial correlation of scores on perception of verticality with scores on kinesthetic and tactile tests invites entertainment of the conjecture that visual appreciation of verticality in this age group is dependent, to a certain extent, upon the same neurological processes as are tactile and kinesthetic perception. Contrary to expectations, the perception of verticality failed to show strong association wich one-legged standing balance. These findings concur with those of Sleeper (1962) who found the perception of verticality in cerebral palsied individuals unrelated ( r = .08) to body balance but linked with performance on the Ayres Space Test ( Y = .47, p < .01) .

The question of why percepcion of joint movement (Var. 2 5 ) failed to be represented on this factor remains unanswered. Although not a test with which reliable results are easily obtained in children who have, at best, a poor concept of movement, the test discriminated well between the dysfunction and control groups. Could it be that the difference in the physiological processes involved in perception of joint movement and position accounts for the difference in their appearance in the factor matrix? Tactile Defensivenes~

Factor E, most clearly delineated by hyperactive-distractible behavior, has been interpreted as a previously unrecognized syndrome characterized by deficit in tactile percepcion, a defensive response to certain types of tactile stimulation (Var. 34) and hyperactive behavior (Var. 3 5 ) . Attention is directed to the fact that hyperactive-distractible behavior, a rather frequent concomitant of perceptual-motor dysfunction, appeared with significant loading on Factor E only, suggesting that, in this group, disinhibited behavior could be linked especially with one particular pattern of neurological dysfunction. A theoretical rationale for the existence of the syndrome of tactile defensiveness has been developed and presented elsewhere (Ayres, 1964b). D e f i c i ~ of Integrution of Function of the T w o Sides of the Body

The emergence of Factor K, along with the findings of other investigators, may evenrually contribute to a theoretical system of considerable heuristic value. Although the number of variables which loaded on the factor is limited, their con- figuration plus inspection of the correlation matrix provides some insight into possible inherent linkage between isolated symptoms observed over the past cen- tury. Of the dimensions of behavior tested, the ability of the child to discriminate between the right and left sides of the body (Var. 1 9 ) most clearly evaluates the status of the symptom complex. The tendency of a child to cross or avoid crossing the mid-line of the body wich his hand (Var. 24) was the next best indicator. The appearance of the test of time and rhythm (Var. 32) wich a low loading on the factor adds clarification to the nanlre of the syndrome. Two-thirds of the

358 A. J. AYRES

items of the time and rhythm test required accurate and carefully timed reciprocal interaction of the two upper extremities. Interitem correlations of scores of the dysfunction group suggest natural relationships between right-left discrimination and tactile and motor functions. However, in the control group, the only correlations approaching significance were with strength of hand dominance and body visualization. Rather surprisingly, visual tests of a type of right-left discrimination, as in the items of the Frostig test of position in space or the Ayres Space Test seem unrelated to perception of the right and left sides of the body.

These findings are not inconsistent with Benton's ( 1959b) conclusion that the right-left gradient of the body scheme, on its most elementary level, is a function of somasthesia and motor integration. Benton suggested a probably decisive role of proprioceptive innervation in the development of right-left discrimination. Contrary to his premise, the tests designed to evaluate kinesthesis failed to load on the same factor as right-left discrimination. The correlations between right-left discrimination and each of the two kinesthetic variables also lacked statistical significance. I n the dysfunction group, the relationship of kinesthesis with crossing the mid-line was low but significant. When considered along with the substantial correlation between body balance and crossing the mid-line, there seems to be some basis for proprioceptive linkage with the syndrome. The data point toward a closer relationship of right-left discrimination with tactile and possibly vestibular than with kinesthetic perception. In view of the limitations inherent in evaluating kinescher~c functions, these findings sho~ild not be considered ir- reversible.

N o evidence was found in the research data to support the supposition that the degree of right-left discrimination was significantly related to symbolic language function in children, which Benton feels is necessary for discrimination be- yond an elementary level. The data, however, did not provide an adequate test of such an hypothesis. T h e sample population may have been at what Benton would consider an elementary level. T h e age and degree of neurological integration of any group probably are important factors in investigating right-left orientation.

Considering the small sample of behavior tapped by the test of crossing the mid-line, the test scores yielded an unexpected amount of information. That some brain-injured individuals have a tendency to avoid crossing the mid-line in activity has long been reported in the literature. Its relationship to sensorimotor function is expressed in the significant correlations with tactile perception and body balance in the dysfunction group and with tactile perception in the control group.

Inspection of the operations forming the basis for quantification of behavior for analysis may shed possible insight into the nature of the syndrome. Some of the items of che finger identification test, which was substantially related to crossing the mid-line, required that the child identify a finger on the opposite hand or o n the analogous hand of the examiner, which would be on the opposite side of the child's indicated hand. Introduction of a task involving the relationship of


the two sides of the body may have introduced an element common to the test for crossing the mid-line. On the other hand, both parameters may be linked with tactile functions or a complex neurological mechanism not yet understood.

Similarly, the greatest degree of association of the scores on crossing the mid- line with any of the tests of visual perception was with Frostig's test of space relations, in which the child was required to look on one side of the page and repro- duce a line on the other side. W h e n the page was centered in front of the child, the left side of the body space was interacting visually with the right side. Visual impulses from the left part of the field of vision course to the right hemisphere while the left hemisphere primarily directs the copying by the right hand. Warn- ings, however, are directed against acceptance of a mere heuristic explanation, however attractive. Froscig's space relations test was particularly sensitive to what might be a common element in most perceptual-motor dysfunction. The common element may account for the correlation.

Occasional reference is found in the literature to difficulty in ocular movement across the mid-line. Whi le the degree of association between tests of crossing the mid-line and eye pursuits was low but significant in both the dysfunction and control groups, the association of right-left discrimination with eye pursuits in the dysfunction group was greater. I t is not unreasonable to conjecture that some aspects of ocular movement are partially dependent upon the same neurophysiological mechanism as the other dimensions of behavior reflected in this syndrome.

The above observations have led to concepnializing this pattern of deficits as encompassing more than difficulty in crossing the mid-line or in identifying right and left sides of the body. There seems to be a basic defect suggestive of lack of interhemispheral integration. The cencrencephalic system of Penfield ( Penfield & Roberts, 1959) may be pertinent to the syndrome. The system, located in the brain stem, was hypothesized as a "coordinating mechanism that makes possible appropriate employment of various parcs of the brain." Penfield reasons that there must be a place in which activity of both hemispheres is summarized and fused, making conscious planning possible.

Inspection of the pattern of ipsative standard scores used with the Q-technique factor analysis suggests that a considerable number of children whose main difficulty appeared to lie in the syndrome of lack of integration of function of the sides of the body also scored low on tests loading on the facror of perception of form and space, an association not necessarily reflected in the correlation matrix. There may be an inherent relationship between the two types of disorder, although the only direct statistical support comes from the loading of number concepts on both of the factors.

Although reading was not a behavioral element under study in this research, a few comments about possible relationships may suBes t new directions for seeking understanding of reading disorders. An invariable right-left disorientation in

360 A. J. AYRES

children with dyslexia has been reported by Gooddy and Reinhold (1961) who found it reflected in telling time, mirror reversal of letters, and the right-left orientation of doors. Frequently attendant to the symptom array were trouble wich ll~athematical symbols, mixed dominance, and lack of establishment of handedness. The authors suggest, as a causal factor, failure to establish asymlnetry of function, of which handedness, writing, and reading are the outcome.

Assuming that crawling and creeping enhance integration of the two sides of the body through sensorimotor activity, the use of the basic quadrupedal ambu- lation patterns to enhance perceptual-motor integration may have its basis in the mechanism of integration reflected in this syndrome. Further, assuming that some reading disorders result from perceptual dysfunction, the use of creeping as an aid to learning to read, as reported by Delacato (1963), may have a neurological basis related to the mechanism underlying these research observations. Caution must be used, however, in accepting a convenient heuristic explanation of what is undoubtedly a very complicated process.

Factor L, identified by its two best representatives, superimposed figures and Gestalt completion (Vats. 30 and 31) , is identified as ability to discriminate foreground from background. Operationally, the Gestalt completion test seems to involve organizing visual stimuli into a whole, pulling them into a foreground. The superimposed figures cest required separating a part our from a whole, or forcing a figure and ground relationship onto competing visual stimuli. Coeffi- cients of the scores on the two tests with the other perceptual-motor tests suggest that figure-ground perception is linked almost as closely to somesthecic and motor processes as visual functions. The substantial relationship with tactile perception is noteworthy. The high multiple correlation ( R = 9 2 ) between scores on the test of superimposed figures and all other test scores leads to reasoning that the test is particularly sensitive to neurophysiological dysfunction basic to much of the percepmal-motor domain.

I t is noteworthy that visual figure-ground perception emerged as an independent factor as well as appearing linked wich apraxia. There may be a neurophysiological mechanism specifically responsible for figure-ground perception. This mechanism may be v~llnerable to dysfunction in a manner similar to that which underlies apmxia.

The emergence of the figure-ground factor in the control group factor analysis may bear some significance, perhaps to the effect that the ability may be expressive of a discrete area of normal development. The higher loading of the age-related Gestalt function on the factor in the control group matrix attests to this interpretation. The greater discriminative value (as judged by the critical ratio) of the Gestalt cest was likely a function of its greater difficulty and not a matter of sensitivity to neuropathology. The superimposed figures test did not discriminate well among the better Ss in the dysfunction group. Identifying


superimposed or embedded figures is probably a better detector of neurological dysfunction than is perception of the Gestalt figures. Factor H

Difficulty is encountered in recognition of the essential identity of the neurophysiological process behind the bare statistical numbers loading on Factor H in the dysfunction group and its counterpart, E, in the control group. It is clear that the main identity is one-legged standing balance, whether eyes are open or closed. Its appearance in the control group, where figure-ground discrimination shared a low loading as opposed to motor planning in the dysfunction group, suggests chat the factor may be expressive of a normal developmental process rather than, or in addition to, a dimension of neurological dysfunction. This interpretation is supported by the fact that standing balance (Var. 8) was more closely linked with age in the dysfunction group than was any other variable excepting Gestalt completion. In the control group, standing balance showed an even higher association with age, exceeded only by scores o n the Frostig Figure-Ground subtest. T h e multiple Rs of both standing balance I and I1 in both groups suggest a close inter- relation of this aspect of development to all areas of perceptual-motor performance.

Inspection of those Ss who, from the Q-technique factor analysis, appeared to reflect Factor H led to the conjecture that Ss with poor standing balance were apt also to show deficits associated wich one of the identifiable clinical syndromes described above.

The original theoretical framework anticipated that the two standing balance variables woi~ld enhance the understanding of the vestibular system in perceptual- motor development. It is not illogical to interpret the high multiple correlation of standing balance wich all other variables as a pervasive influence of the vestibular system. A safer interpretation is that standing balance results from a com- posite of many neurophysiological mechanisms and hence is a fair representative of degree of total neurological integration. Another fact to be taken into consideration is that no cerebral palsied were included in the sample. Disorders of the vestibular system may have resulted in neuromuscular symptoms leading to a diagnosis resulting in exclusion from the study of Ss with perceptual dysfunction associated with the vestibular system. The investigation of the role of the vestibular system in perception may require a different research approach.

In spite of the fact that standing balance requires little cortical direction, it is of value as an indicator of perceprual-motor dysfunction, although the strong de- terminant of age must be considered. Irrespective of its diagnostic value, deficit in standing balance and those variables also saturated with the same factor are probably not worthy of syndrome status without further evidence. The Remainder of Emerging Factors

A considerable number of the variables remained factorially aloof, appearing

362 A. J. AYRES

as singlets or doublets in the factor matrix of the dysfunction group. Factor B is clearly an age factor and is of interest largely because age did not carry a loading on any of the other factors. Likewise, sex, included in a preliminary analysis, demonstrated such low correlations with any of the other variables that it was removed from the analysis to simplify the factor structure.

A common test of body scheme disturbance in ad~llts involves visualizing the spatial relations of the body on a verbal command, as in Variable 23. As the major identifier of Factor D, it may reflect a general intellectual ability. The variable showed low saturation wich the general ability factor of the control group. Scores on the test carried a significant ( .42) correlation with scores on a test of identification of parts of the body, a test which was part of the original test battery but was omitted from the study when a preliminary analysis indicated a strong dependence upon verbal skill. However, the significant correlation between body visualization and most of the variables of somatic perception suggests test performance was partially dependent upon somesthesia.

Perception of joint movement ( a singlet on Factor J ) is also a puzzle, largely because the theoretical framework led to the anticipation of the loading of this basic sensory modality on one of the major factors. The answer may lie partly in difficulty in test administration. The fact that the cest discriminated well between the dysfunction and control groups speaks in favor of further investigation of the role of this type of perception.

Factor N does not lend itself to interpretation. Factor 0 indicates only that the hands test tended not to share variance wich other factors, nor did it do so in the control group. Factor P seems to represent some kind of eye-hand interrela- tionship.

The role of visualization of rotation of objects in space probably accounted for the appearance of the Ayres Space Test as a singlet in Factor Q, for no other tests in the battery evaluated this ability. The test's discriminating properties relative to the dysfunction and control groups and the appearance on the Q-technique factor analysis of a small group of children whose main problem seemed to be on this cest suggests the advisability of a further look at visualization of movement of objects in space as a discrete type of perceptual dysfunction. Laterality Functions

The failure of the variable "degree of agreement between eye and hand dominance" to manifest strong associative bonds with any of the other variables suggests that it is not related to perceprual-motor dysfunction as measured in this study. These results, of course, do not preclude the possibility of the establishment of relationships between this variable and other dimensions of behavior, such as language functions, or in different populations, or under different opera- tional procedures for dominance.

The findings in relation to right- or left-hand preference also fail to supply


any support to theorems regarding the relationship of the variable to the percepmal-motor functions under investigation.

Of the laterality functions studied, strength of unilateral hand preference, re- gardless of whether right or left, appeared to be most closely linked to perceptual- motor functions. The degree to which strength of hand dominance correlated with the other variables suggests that the behavioral parameter is related to functions of the eye and to manual dexterity; however, these data certainly d o not provide cogent evidence to that effect.

T h e one finding which lends support to Benton's (1959b) hypothesis thac right-left discrimination is associated with strength of hand dominance was found in the appearance of the two variables on the same factor in the analysis of all 150 Ss as one group.

I n addition to ascertaining the strength of hand dominance, the test battery originally included a measurement of the strength of body-laterality, determined by the sum of strength of unilateral hand, eye, and foot preference. Since the measurement was not experimentally independent of the test of strength of unilateral hand preference or degree of agreement between eye and hand dominance, it was excluded from the factor analysis. The correlations between strength of unilateral body dominance and all other variables gave some information of value, however. While strength of unilateral hand dominance demonstrated something in common with the other variables, strength of lateralization of the body showed n o significant relationship whatever. If strength of lateralization is linked with perceptual-motor function, i t is likely limited to that of hand dominance. Number Concepts

The results of this study are not inharmonious with the frequent attempts as reported in the literanire to relate mathematical skill to perceptual-motor functions. The strong and comprehensive relationship of that type among Ss with suspected dysfunction was particularly noteworthy, leading to the thesis that this cognitive function is especially jeopardized by perceptual deficits. The data augur for both a pervasive handicap as well as some specific connections. The most obvious association is that with visual form perception. Distinguishing between a "2" and a "3" is analogous to distinguishing between a rectangle and a square. The spatial element of performance on number concepts may lie in the dependence upon spatial sequences and arrangements of objects used by the child and instructor in forming the elementary concepts central to understanding number relationships.

Danger lies in seeking only direct, external association between perception and numerical learning as just illustrated. There is no self-evident explanation for the appearance of number concepts as part of the symptom array reflecting integration of interhemispheral function. I t may be thac the presence of this symptom complex provides particular interference in the development of cognitive processes.

3 64 A. J. AYRES

The classical question of relationship between finger agnosia and arithmeti- cal ability, then, seems to be a part of the premise chat perceptual-motor development in general undergirds this academic skill. Finger identification is one of the becter indicacors of level of perceptual-motor funccions. It is quite conceiv- able, though, that in children wich or without niinor perceptual deficits, other factors i~nderlying cognitive functions may be stronger determinants of academic attainment.

OVERVIEW The study was designed to discover and demonstrate relationships among the

different kinds of sensory perception, motor activity, laterality, and selected areas of cognitive funccion. The sensory modalities under study were vision, tooch, and proprioception. Langoage processes were excluded. I t was hypothesized ( a ) that factors of percepmal-motor function would emerge from R- and Q-technique factor analyses of data obtained from sample populations of children with and without suspected perceptual dysfunction, and ( b ) that factors derived from data gathered from a sample population with suspected perceptual deficits would differ from those appearing from analysis of data from a matched group chosen without reference to perceptual skill. The illtimate objective of the search for a taxonomical categorization was to provide empirical data for the building of a theoretical structure to explain the nature of perceptual-motor dysfunction, thereby providing a basis for treatment procedures. Method

A battery of 35 perceptual-motor tests was given individually to each member of two separate groups of children, one group selected on the basis of suspected or known percepnial deficits, especially as reflected in learning difficulty, and the ocher group chosen from the "regular" public and private schools without reference to behavior or academic performance. T h e tests evaluated the following areas of function: eye-hand coordination, graphic skills, visual perception, kinesthetic perception, tactile functions, ocular control, finger identification, one- legged standing balance, gross and fine motor planning, right-left discrimination, strength of unilateral hand dominance, degree of agreement between eye and hand dominance, crossing the mid-line of the body, time and rhythm, number concepts, tactile defensive behavior, and hyperactive distractible behavior.

The 69 males and 31 females who comprised the group wich suspected perceptual dysfunction were selected from regular and special schools and medical centers. A requisite for inclusion in the group was a verbal intelligence quotient above 70. T h e estimated mean IQ of the dysfunction group was 96.97; the mean age was 84.1 mo. with a standard deviation of 7.3 mo. The control group of 50 children was chosen to approximate the dysfunction group on mean, variance, and range of mental age, on sex, and on the basis of parental occupation to proportionately represent the working population of the United States.


Using the IBM 7090 computer, intercorrelations between the 35 test scores plus age were subjected to an R-technique orthogonal rotation factor analysis. Analyses were made of the data from the dysfunction group alone, from the control g r o ~ ~ p alone, and from the total group of 150. The data from the dysfunction group were also subjected to Q-technique analysis. The frequency distribution of handedness and strong mixed or hornologoi~s eye-hand dominance was determined for the control and dysfunction Ss as well as for those Ss who showed natural clusters best representing the major syndromes, as determined by the data from the Q-technique analysis. The significance of differences of frequencies was determined with application of the ~"esc. Resz~lts and Discz~ssion

For the dysfunction group, 23 factors emerged from the R-technique analysis. Six factors accounted for most of the variance; five of the six were interpretable as hypothesized behavioral correlates of patterns of neurological dysfunction. The factor matrix derived from scores of the control group did not, for the most part, yield faccors comparable to the major ones emerging From the dysfunction group, and those thac did emerge appeared to have little theoretical impor- tance, suggesting that the factors derived from the dysfunction group reflected symptom complexes or clinical syndromes. From the factor matrix based on all 150 Ss emerged factors similar to those derived from the dysfunction group, but the factors were less clearly defined. I t is hypothesized for heuristic purposes that the patterns appearing as factors in the dysfunction group were not due to normal developmental processes, bot to underlying deficits in specific mechanisms of in- tegra tion.

Major clinical syndromes.-The five interpretable patterns of percepmal- motor dysfunction (based on dysfunction group data only) , their descriptions, and their proposed means of identification follow.

Developmental apmxia: The first factor to emerge tended to load quite a consrellation of variables, especially those designed co evaluate motor planning and eye-hand accuracy. Also appearing on the factor were finger identification and all tests of tactile perception, suggesting a strong relation berween praxis and tactile functions. Kinesthetic perception demonstrated a much lower saturation with the factor than did tests of tactile functions. The loading of eye pursuit on the factor favors the conjecture thac poor control over voluntary ocular movement is related to apraxia.

Perceplaal dysfz~nciion, form and position in two-dimen~ional space: This factor, which also loaded a considerable number of variables, was best represented by visual tests of form constancy and space relations. The appearance of tests of manual perception of form and kinesthetic perception on the factor leads to interpretation of the factor as including tactile, kinesthetic, and visual perception of form and position in space.

366 A. J. AYRES

Tactile defensivenes.r: Most clearly represented by hyperactive, distractible behavior, this factor was interpreted as a previously unrecognized syndrome characterized by deficit i n tactile perception, a defensive response to certain types of tactile stimulation, and hyperactive behavior. T h e fact that hyperactive behavior appeared wich significant loading on only one factor suggests that, in this group, disinhibited behavior might be linked with one particular neurological mechanism.

Deficit of integration of fnnction of the two sides of the body: The ability of the child to discriminate between the right and left sides of the body best identified the syndrome. Freedom from avoidance i n crossing the mid-line of the body wich the hand was the next best indicator. The nanlre of the dysfunction received some clarification froin a low but definite saturation of the factor on the test of time and rhythm, which required temporal interaction of the two sides of the body without crossing the mid-line. The pattern of behavioral dimensions suggests they are the correlates of diminished interhemispheral integration. Cor- relations among the variables pointed toward some affiliation with tactile functions.

Perceptual dysfn?zction, visual figure-ground discrimina~ion: This symptom complex was best represented by the ability to identify superimposed figures. T h e Gestalt completion test was also heavily saturated with the factor. Correla- tions of the scores of the two tests with other perceptual-motor tests suggest that figure-ground perception is linked almost as closely with somesthetic and motor processes as wich visual functions. The mutuality may lie in dependence of many behavioral parameters upon the discriminative functions of the non-specific processes of the reticular formation and the thalamus.

In addition to the five identifiable syndromes, a sixth factor accounting for an amount of variance worthy of consideration could not be interpreted in a manner significant to understanding perceptual-motor dysfunction. The factor, best represented by one-legged standing balance, appeared in matrices of both dysfunction and control groups. Although standing balance appeared to reflect perceptual-motor ability, the factor seemed unworthy of syndrome status without further evidence.

Laterality fr~~zction~.-The x-esulting from testing the difference of frequency of mixed and homologous eye-hand dominance in the dysfunction vs control groups failed to reach significance. Similarly, the x-est of frequency differences of right- and left-handedness and lack of dominance in the same groups did not yield significant results. Inspection of the relative frequencies of scores on the two laterality tests among the groups of Ss best representing four of the major syndromes failed to suggest any likelihood of association between lateralicy functions and the symptom complexes. These results, accompanied by the fact that both laterality variables did not share their variance wich the other variables in the factor analyses strongly suggests that handedness and degree of homologo~is

PERCEPTUAL-MOTOR DYSFUNCTION IN CHILDR

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