Child Development, January/February 2002, Volume 73, Number 1, Pages 35–46
Who’s in the Mirror? Self–Other Discrimination in Specular Imagesby Four- and Nine-Month-Old Infants
Philippe Rochat and Tricia Striano
This research investigated the early determinants of self–other discrimination in infancy. Ninety-six 4- and9-month-old infants were placed facing a live image either of themselves or of another person (experimenter)mimicking them. The specular image was either contingent (on-line), or contingent with a 2-s delay. After afirst 1-min presentation, the video image of either the self or the other was suddenly frozen for 1 min (still-faceepisode). This was followed by a last minute of live presentation. From 4 months of age, infants appeared toperceive and act differentially when facing the specular image of themselves or the mimicking other. In gen-eral, infants tended to smile more, look more, and have more protracted first-look duration toward the mim-icking other compared with the self. Developmentally, 9-month-olds showed markedly more social initiativestoward the mimicking other compared with the self during the still–face episode. In all, these results indicatethat infants develop self–other discrimination in specular images long before mirror self–recognition, which istypically reported by the second year. Discrimination of the self from other is interpreted as a precursory abil-ity and a perceptual foundation of later conceptual self development.
INTRODUCTION
Seeing oneself in a mirror or in a live video projection isa significant and profoundly revealing psychologicalexperience. The way in which infants, children, andeven adults react and behave while contemplatingtheir specular image reveals not only how they con-strue their bodily self, but also how they might con-strue others in relation to themselves. Recognizingoneself in a specular image is more than overcomingthe sudden experience of spatial dislocation betweenthe proprioceptive and visual sense of one’s own body.It entails some synthesis of “coexistence with others”(Merleau-Ponty, 1964/1989, p. 140). In other words, itentails the realization that the specular image is stand-ing for the identified or conceptual self (i.e., “Me”), notsomebody else (Rochat, 2002). Self-recognition is therealization that one’s own specular image is nothingbut my one’s bodily self: the self as seen by others.
Questions remain as to what are the developmen-tal origins and determinants of self–other discrimina-tion in specular images. Much research documentsthe emergence of behaviors by 14 to 18 months thatindicate explicit self-awareness in mirrors or any otherreflecting surfaces. Self-referencing activities, self-labeling, and emotional expression of embarrassmentafter discovering some rouge on the face are typicallytaken as unambiguous signs of self-recognition, namelythat children begin to construe their specular imageas standing for their own body and how it appears toothers (Bertenthal & Fisher, 1978; Guillaume, 1926;Lewis & Brooks-Gunn, 1979; Zazzo, 1981). If such be-haviors express conceptual self-awareness, namely
the child’s construal that what is reflected in the spec-ular image is nobody else but Me, then how does thisconceptualization come about? Is it a sudden devel-opmental emergence or is it progressive? If it is pro-gressive, do infants already show some basic per-ceptual abilities in discriminating what pertains tothemselves and what pertains to others in specularimages, long before they manifest conceptual and ex-plicit self-awareness? Recent research seems to sup-port this concept.
From at least 3 months of age, when placed in frontof mirrors, infants tend to engage in long bouts ofself-exploration, observing their own movementsand seemingly enjoying the experience of visual–proprioceptive contingency afforded by mirrors. Theymanifest positive affect, including smiling, cooing,reaching for the part of the body reflected in the mir-ror, and often demonstrating sudden bursts of joyfulactivities (Amsterdam, 1972). There is some evidencethat from 3 months of age, when mirror reflections be-come potent objects of exploration, infants can dis-criminate whether they are looking at a mirror imageof themselves or that of a peer. Field (1979) observedthat 3-month-olds tended to look significantly moreat themselves in a mirror compared with when at-tending to another, noncontingent infant to whomthey smiled and vocalized more. Other research hasshown that young infants are responsive to particu-lar aspects of their own specular image. Placing 1- to
24-month-old infants in front of two mirrors that wereeither flat, blurred, or distorted, Schulman and Kap-lowitz (1976) showed that prior to 6 months of age, in-fants tended to look more often at the clear ratherthan the blurred image of themselves, and showedless interest in the distorted image compared with theflat nondistorted mirror image. Interestingly, Schul-man and Kaplowitz noted that compared with olderinfants, 1- to 6-month-olds were not yet showing com-plex behavior such as looking at a particular body part,followed by an immediate inspection of the body part’sreflection in the mirror.
Lewis and Brooks-Gunn (1979) have suggested thatwhat determines early specular image exploration isthe discovery by the young infant of the contingencybetween visual and proprioceptive feedback frombody movements (see also Guillaume, 1926; Wallon,1942/1970). This suggestion, however, does not ac-count for the observations of Schulman and Kaplowitz(1976), in which infants discriminated between spec-ular displays of themselves that were equally contin-gent, but spatially transformed. One possibility is thatin addition to visual–proprioceptive contingency,young infants might already be able to discriminatebetween specular images that are spatially more orless eccentric relative to what they calibrated of theirown body via direct visual exploration of limb move-ments. Another possibility is that experimentally trans-forming the specular image (e.g., blurred), aside frommaking it perceptually less salient, might also elimi-nate important features of the mirror reflection thatare potentially social in nature—in particular, eyecontact between self and specular image.
Papousek and Papousek (1974) introduced an ex-perimental paradigm based on video recordings ratherthan mirrors. They placed 5-month-olds in front of twodifferent video images presented side-by-side: oneof themselves and one of another infant. By measuringpreferential looking of the infant, this method allowedfor the assessment of what the infants discriminated be-tween the two video images. Papousek and Papousekreported that infants preferred to look at images of theself or at images of others that allowed for eye contact.Eye contact as a social factor appears to play a role indetermining the exploration of specular images, whetherthey are of the self or of another child. Both are appar-ently treated by the infant as social rather than self ob-jects. This apparent social treatment of the specularimage, whether it refers to the self or to another in-fant, might only hold for situations in which specularimages include faces and facial displays, however.Much research indicates that from birth, infants dem-onstrate particular attention to facelike displays andare capable, within hours after birth, of discriminat-
ing subtle differences among faces, depending on thefamiliarity of the faces (Walton, Bower, & Bower, 1992)or whether they have organized or disorganized inter-nal features (Fantz, 1963; Johnson & Morton, 1991). By 2months of age, the internal features of faces increas-ingly become focal aspects of infants’ visual scanningof faces (Haith, Bergman, & Moore, 1977); and as earlyas 3 to 5 months, infants appear remarkably sensitiveto eye contacts and eye direction in facial displays(Hains & Muir, 1996; Hood, Willen, & Driver, 1998).
Bahrick and Watson (1985) demonstrated the earlydetection of proprioceptive–visual contingency innonfacial images. In their study, infants were simulta-neously presented with either a noncontingent, prere-corded view of their own legs or the view of anotherbaby’s legs wearing identical booties. These viewswere presented on two adjacent TV screens for prefer-ential looking analysis. Bahrick and Watson showedthat 5-month-olds looked preferentially to the noncon-tingent view. They also observed this phenomenon in asituation in which an occluder prevented infants fromseeing their legs directly. Three-month-olds showedsplit preferences, looking much longer at either thecontingent or the noncontingent view. These findingsindicate that perceptual discrimination of own versussomeone else’s specular image does not rest solely onthe display of faces, but can also pertain to nonfacialparts of the body (i.e., moving legs). From 3 to 5months, young infants appear to be sensitive to visualand proprioceptive contingency in general, and not justto the contingency of eye contact, as suggested by pre-vious researchers who emphasized the social contextin which first discrimination between self and otherstakes place (Dixon, 1957; Papousek & Papousek, 1974).
Follow-up studies using the video paradigm intro-duced by Bahrick and Watson indicate that from 3months, infants are not only sensitive to the presenceor absence of temporal contingency between visualand proprioceptive feedback in specular images, butalso to the spatial calibration of their own bodilymovements that are reflected in these images. From 3months of age, infants are sensitive to a left–right re-versal of their own legs seen on-line on a TV screen(Rochat, 1998; Rochat & Morgan, 1995). Convergingobservations were made using a similar paradigmthat involved infants’ hands and arms instead of legs(Schmuckler, 1996).
In summary, existing research suggests that by 3 to 5months, infants are able to discriminate differences invisual–proprioceptive temporal contingency (Bahrick& Watson, 1985), changes in the spatial calibration ofvisual and proprioceptive feedback (Rochat & Mor-gan, 1995), as well as to the presence or absence of eyecontact (Papousek & Papousek, 1974) in the sponta-
Rochat and Striano 37
neous exploration of their own specular image. Thesefindings show that young infants are discriminant ofspatial, temporal, and configurational aspects of theirspecular image. They do not, however, demonstratethat infants construe the specular image as eitherstanding for themselves or someone else.
Recent studies began testing this issue more di-rectly by assessing infants’ differential responding toprerecorded (i.e., noncontingent) video views of theirown face or the face of another infant, controlling forage, gender, head posture, and clothing. Bahrick, Moss,and Fadil (1996) found that infants as young as 3months prefer to look at the dynamic video of anotherinfant’s face. Infants at this age appear to be able todiscriminate their own facial features, probably basedon previous mirror experience (Bahrick et al., 1996).The preferential looking at the display of the other infantsuggests that 3-month-olds might already construe theother infant as a putative social partner with whom toengage. This interpretation, however, is highly specula-tive, because aside from gazing, Bahrick et al. did notrecord any social responses, such as smiling, cooing, orother socially oriented behaviors. Their interpretationwas limited to the idea that infants probably learned todiscriminate and detect invariant feature characteristicsof their own face via previous mirror exposure.
Legerstee, Anderson, and Schaffer (1998) replicatedthe findings of Bahrick et al., providing further evi-dence that by 5 months, infants do differentiate be-tween the dynamic specular image of self, others, or apuppet. Such discrimination appears to hold in theauditory presentation of prerecorded sounds madeby a peer, an object, and the infants themselves. Ingeneral, infants show preference for social faces andsocial sounds. Interestingly, this preference is not re-stricted to gazing, but also to responses such as vocal-izing and smiling. Overall, Legerstee et al. showedthat from 5 months of age, infants attended to theirown face and voice as familiar and differentiated fromother social or nonsocial facial and auditory events. Ifthese findings confirm that by 5 months there is anearly perceptual discrimination between images andsounds reflecting either the self, others, or physical ob-jects (i.e., a puppet), it is still not clear whether such dis-crimination is purely perceptual or whether suchdiscrimination might also entail some early signs ofself-recognition, in the sense of a construal of the selfas differentiated from someone else. On the one hand,the discrimination reported by Bahrick et al. (1996)and Legerstee et al. (1998) could rest merely on differ-ential feature or vitality detection that more or lessmatches what infants might be familiar with whenfeeling their own body moving or visually exploringtheir own face in mirrors. On the other hand, this dis-
crimination might also entail higher categorization ofthe self as an entity differentiated from others.
Relevant to the developmental emergence of suchhigher processing are the observations of Meltzoffand Moore (1999) on infants’ ability to detect mirror-ing from a social partner. Infants were tested whilefacing two experimenters, one imitating systematicallythe action they performed on an object, as in a specularimage, and the other responding contingently butwithout any exact mirroring of the infant’s own action.The authors reported that by 14 months, infants be-gan to show clear signs of discrimination between thetwo social partners. By 9 months, infants were re-ported to spend more time looking at the imitatingrather than the contingent experimenter (Meltzoff &Moore, 1999). It is not clear, however, whether suchtendency might entail self-recognition in the action ofthe imitating experimenter.
The aim of the present research was to investigatefurther the emergence and determinants of self–other discrimination, by systematically manipulat-ing temporal and featural characteristics of on-linespecular (video) images. Two basic questions guidedthe research:
1. When do infants start to show signs of a dis-crimination between self and others in on-linespecular images?
2. What are the featural and temporal determi-nants of such discrimination?
To address these questions, both visual attention andinfants’ social responses to the specular image with var-ied featural characteristics (self versus experimenter) aswell as varied temporal characteristics (on-line versusdelayed contingency) were measured. To enhance theassessment of self–other discrimination, testing in eachcondition included a still-face period in which thespecular image became momentarily frozen. Past re-search indicates that from approximately 2 months ofage, infants react to a sudden still-face from a socialpartner with marked negative behaviors such as gazeaversion and diminished smiling (Toda & Fogel, 1993;Tronick, Als, Adamson, Wise, & Brazelton, 1978). Thisrobust phenomenon is typically considered as index-ing infants’ sensitivity to social contingency and earlysocial attunement as well as emerging social expecta-tions in face-to-face protoconversations (Muir & Hains,1993; Rochat & Striano, 1999; Trevarthen, 1979). Fur-thermore, by 7 to 9 months, infants begin to manifestclear attempts to re-engage a social partner who hasadopted a sudden still-face (Striano & Rochat, 1999).Such attempts are clearly social in nature, oriented to-ward changing the behavior of the social partner. Thus,in the context of the present research, such responses
38 Child Development
were considered as an index of infants’ construal ofthe specular image as standing for a social (nonself)partner with communicative intents. Our rationalewas that if infants manifested enhanced social re-engagement toward nonself compared with self spec-ular images (either on-line or delayed), this would fur-ther support self versus other discrimination.
In all, the present research added to previous inves-tigations that used prerecorded specular images (Bah-rick et al., 1996; Legerstee et al., 1998). It was specifi-cally designed to address the question of whether andwhen infants might treat an on-line specular image as asocial partner, or as referring to the self. In addition, theresearch was designed to assess more directly the pos-sible determinants of such discrimination in infancy.Infants were presented with on-line specular imageswhile temporal (simultaneous versus delayed visual–proprioceptive feedback) and featural aspects of thespecular image (image of the self versus the image of amimicking other) were covaried.
As a general working hypothesis, and in the con-text of the recent body of findings showing a majortransition in social–cognitive development at around9 months of age (Tomasello, 1995, 1999), we expectedthat 9-month-old infants would start demonstratingdifferential responding between self and an imitatingother. By this age, and not prior (i.e., 4 months), in-fants should begin to show reliable signs that they donot respond to their own image on the TV as if it wereanother infant, even when the image of the self is pre-sented with a temporal delay that might resemble thetime-lagged but synchronized turn-taking format ofearly social exchanges (Gergely & Watson, 1999; Stern,1985; Trevarthen, 1979). In addition to enhanced visualattention, when facing the imitating experimenteron the TV, infants were expected to manifest socialresponses — in particular, explicit attempts at so-cial re-engagement of the kind documented in9-month-olds during still-face episodes that inter-rupted normal face-to-face social exchanges (Striano &Rochat, 1999). Compared with the group of 9-month-olds, we expected 4-month-olds to respond to theirown image as if it were another infant. We expectedthem to show less explicit attempts at social re-engagement, however.
METHOD
Participants
Ninety-six healthy, term infants were tested andincluded in the final sample, divided equally into twoage groups: forty-eight 4- to 5-month-olds (referred toas the group of 4-month-olds;
range
�
110–150 days;
23 males, 25 females) and forty-eight 8- to 9-month-olds (referred to as the group of 9-month-olds;
range
�
240–289 days; 26 males, and 22 females). Fifty-oneadditional infants were tested but not included in thefinal sample: 49 for fussiness prior to completion oftesting and 2 for technical errors. The infants were re-cruited from a participant pool consisting of over 500infants born at the Northside Maternity hospital ofAtlanta, Georgia. Races were representative of theNortheastern Greater Atlanta population, predomi-nantly of Caucasian middle class.
Apparatus and Setup
Participants were seated on an upright infant seatplaced on a table and facing a black enclosure made ofa metal frame structure holding a 45
�
inclined one-way mirror that faced the infants (see Figure 1). A 50-cm TV monitor rested horizontally (facing down) ontop of the metal frame structure so as to project its im-age onto the mirror that faced the infants approxi-mately 1.5 m away. The TV image appeared to the in-fants as if it was seen on a regular monitor facing theinfants, with no particular inclination or deformation.The mirror technique was meant to allow for the pro-jection of an on-line image of self or of the experi-menter, with the possibility in both instances for pre-cise eye-to-eye contacts between the specular imageand its viewer (the same as viewing oneself in a frontaland parallel mirror). This technique was originally es-tablished by Murray and Trevarthen (1985) and laterused by Rochat, Neisser, and Marian (1998) to accountfor eye contacts as an important social variable fromthe outset of development (see Papousek & Papousek,1974; Symons, Hains, & Muir, 1998). A video camera,
Figure 1 Diagram of the experimental setup. Infants wereseated facing their own or the mimicking experimenter’s spec-ular image from a TV, which was reflected on a one-way mirrorplaced diagonally in a metal frame structure. A video camera,which was placed behind the one-way mirror, was invisible tothe infants and filmed them at eye height through the mirrorprojecting the TV image seen by the infants.
Rochat and Striano 39
which was placed behind the one-way mirror, was in-visible to the infants and filmed them at eye heightthrough the mirror projecting the TV image seen bythe infants. The mirror reflected to infants either anon-line view of themselves—including face, shoul-ders, and arms—recorded by the camera behind themirror (self condition), or the view of a female exper-imenter mimicking the infant on-line (other condi-tion), see Procedure and Design section below).
Figure 1 presents a diagram of the apparatus andsetup used in the self or in the other condition. Awhite curtain surrounded the infant and the framestructure holding the mirror. The TV and camerawere invisible to the infant who sat across from the45
�
-inclined mirror framed by a black curtain that hidthe faced-down TV as well as cables and other piecesof equipment. Infants could not kick or touch theframed mirror, or lean forward and look up directly atthe TV.
In the other condition, the experimenter wasplaced on the other side of the table, facing another,identical metal frame and one-way mirror apparatus.To mimic the infants, the experimenter viewed theon-line image of the infants as reflected in the mirror.Infants were simultaneously presented with the on-line specular image of the mimicking experimenterfilmed at eye height. The specular image of the mim-icking experimenter included face, shoulders, andarms, as in the self condition (see Figure 2). The exper-imenter was always the same person, trained tomimic on-line the infants’ slightest head, facial, arm,and trunk movements with comparable magnitude.Facial movements included mouth opening and emo-tional expressions such as smiling or frowning. Limbmovements were matched to appear on the ipsilateralside of the specular image relative to the infants. Inother words, the mimicking by the experimenter wasreflected in the same way the infants would see theirown actions on a mirror (left/right reversal).
In addition to the self or other condition, each infantwas tested with a mirror reflection of the TV that waseither on-line (on-line contingency) or delayed by 2 s(delayed contingency). In the delayed contingency sit-uation, prior to being projected onto the TV facing theinfant, the image was fed into a special effect broad-casting device (Primeimage Pipeline Video Delay SN5066), which allowed for short-term storage and ad-justable delayed output of on-line video recording. Inaddition, prior to being projected onto the TV, the im-age was also fed into a video mixer (Videonics mx-1NTSC), which allowed for the freezing of the record-ing of the current image at the push of a button. Thisdevice was used for the still-face episode in each ex-perimental condition (see Procedure section below).
For later coding, this device was also used for the syn-chronized recording of one final split image com-posed of the infant’s face recorded by the camera be-hind the one-way mirror, and the TV image (self/other in on-line or delayed contingency) projectedonto the mirror and seen by the infant.
Procedure and Design
Infants of each age group were further divided intofour equal experimental subgroups of 12 infants. Eachsubgroup was tested separately in one of four experi-mental conditions combining self versus other and thetwo types of video feedback contingency, respectively:
1. self condition with on-line contingency.2. self condition with delayed contingency.3. other condition with on-line contingency.4. other condition with delayed contingency.
Each experimental condition lasted a total of 3 mindivided into three successive 1-min episodes. Duringthe first minute, infants saw a view of either them-selves or the mimicking experimenter in either one ofthe two contingency conditions (on-line or delayed).Following this first minute of free interaction and ex-ploration, the video image projected onto the mirrorwas frozen for a second minute (still-face episode).Following the still-face episode, infants were tested
Figure 2 Example of own specular image (self condition) andspecular image of the mimicking experimenter (other condi-tion) viewed by infants in the current research.
40 Child Development
for a third and last minute of free interaction and ex-ploration of the dynamic mirror reflection. The three1-min episodes occurred with no interruption.
Coding and Analysis
Video recordings of the infant were coded separatelyby two naive observers using a computerized event re-corder. While viewing the on-line video recording ofthe infants’ frontal view and pressing on a particularkey of a computer corresponding to a specific behavior,observers activated a channel of the event recorder.Once coded, a program computed the cumulated oc-currences of a particular behavior and its proportion(percentage) over total trial time. First-look duration(see below), was measured directly on the printout ofthe computerized event recording, with .5-s precision (1cm long deflection of the signal on paper
�
1 s in dura-tion). The coding corresponded to the occurrence of thefollowing five behaviors that indexed infants’ visual at-tention (proportion in percentage of gazing at the spec-ular image and duration in seconds of first look at thespecular image) and infants’ social responding to thespecular image (proportion in percentage of smiling,vocalizing, and social re-engagement). These behaviorswere operationally defined as follows:
1. Visual attention:
Gazing
: Infant gaze oriented toward the specu-lar image.
First look
: First gazing bout oriented toward thespecular image from the onset of a presentationepisode.
2. Social responding:
Smiling
: Infants’ cheeks raised and sides of themouth raised up while gazing at the specularimage.
Vocalizing
: Positive (i.e., cooing) or neutral (i.e.,babbling) vocalization expressed while lookingat the specular image. Negative vocalizationsuch as fussing and crying were not included.
Re-engagement
: Clapping, banging, or reachingtoward the specular image while gazing at it.
Interobserver reliability measured on 20% of all testedinfants in every condition yielded
�
s on all measuresranging from .79 to .89.
RESULTS
Table 1 presents the means and standard deviation forthe visual attention measures (percentage of gazing andfirst-look duration) and social responding measures(percentage of smiling, vocalizing, and re-engagement
behaviors) as a function of age, condition, contingency,and episode.
Each dependent measure was analyzed by per-forming a 2 (age: 4 months versus 9 months)
�
2 (con-dition: self versus other)
�
2 (contingency: on-lineversus 2-s delayed)
�
3 (episode: first minute, still-face episode, third minute) mixed-design analysis ofvariance (ANOVA). In this design, episode was thewithin-subjects factor, and all other variables wereentered as between-subjects factors. The results of thevisual attention measures are reviewed first.
Visual Attention Measures
Gazing.
The ANOVA yielded a significant maineffect of age,
F
(1, 88)
�
9.43,
p
�
.003, with 4-month-olds tending overall to look significantly more at thespecular image, regardless of condition, contingency,or episode. The ANOVA also yielded a significant ep-isode main effect,
F
(2, 176)
�
23.01,
p
�
.001, with allinfants tending overall to look less during the still-face episode, regardless of age, condition, or contin-gency. More interesting, the ANOVA revealed a sig-nificant main effect of condition,
F
(1, 88)
�
5.34,
p
�
.023, whereby infants, regardless of age, contingency,or episode, tended to look significantly more at thespecular image when it reflected the mimicking othercompared with the self. The analysis also revealed acontingency main effect approaching significance,
F
(1, 88)
�
3.87,
p
�
.052. This effect rested on the factthat overall, infants tended to gaze more at the spec-ular image displaying on-line contingency.
First-look duration.
The ANOVA yielded a signifi-cant main effect of age,
F
(1, 88)
�
14.12,
p
�
.001, withyounger infants displaying, overall, a longer first-lookat the duration specular images. The analysis also re-vealed a significant condition main effect,
F
(1, 88)
�
5.13,
p
�
.026, with infants demonstrating a signifi-cantly longer first-look duration at the specular imagewhen it reflected the mimicking other rather than theself. In addition, the analysis yielded a significant ep-isode effect,
F
(2, 176)
�
4.93,
p
�
.008. This effect wasdue to a significant overall drop in first-look dura-tion during the still-face episode compared with thefirst and last minute of interaction. Futhermore, theANOVA revealed a marginally significant Condition
�
Contingency interaction,
F
(1, 88)
�
3.71,
p
�
.057, anda significant Condition
�
Contingency
�
Episode in-teraction,
F
(1, 176)
�
3.33,
p
�
.038. Analysis of thesimple effects of the latter three-way interaction indi-cated that in the other condition and Delayed contin-gency, infants showed more decline in first-look dura-tion during the still-face episode,
p
�
.05. Finally, theANOVA also yielded a significant Age
�
Condition
�
Rochat and Striano 41
Contingency interaction,
F
(1, 88)
�
6.71,
p
�
.001. Thisinteraction rested on the fact that the group of 4-month-olds in the on-line contingency tended to have amarkedly longer first-look duration at the specularimage of the other compared with the self,
p
�
.015.
Overall, the analysis of both gazing and first-look du-rations revealed that infants’ visual attention varied insignificant ways as a function of age and episode, butalso as a function of condition (self versus other) and thekind of contingency displayed in the specular image.
Table 1 Means for Each Dependent Measure as a Function of Age (4- and 9-Month-Olds), Condition (Self versus Other), Contin-gency (On-Line versus Delayed), and Episode
The ANOVA yielded a marginal main ef-fect of condition,
F
(1, 88)
�
3.77,
p
�
.055, with infantstending overall to smile more at the specular image ofthe mimicking other compared with the self (see Fig-ure 3A). The analysis also revealed a significant Age
�
Contingency interaction,
F
(1, 88)
�
4.05,
p
�
.047.Nine-month-olds tended to smile more in the delayedcompared with the on-line contingency condition;whereas 4-month-olds showed the reverse. No othersignificant main effects, nor any significant interac-tions were found.
Vocalizing.
The ANOVA yielded only a significantmain effect of condition,
F
(1, 88)
�
13.20,
p
�
.001,
whereby infants who faced their own specular image(self condition) tended to vocalize significantly morecompared with those who faced the specular image ofthe mimicking other (other condition, see Figure 3B).The analysis also yielded a close to significant Condi-tion
�
Contingency interaction,
F
(1, 88)
�
3.62,
p
�
.06. This marginal interaction rested on the fact thatinfants tended to vocalize more in the self conditionwhen the specular image displayed an on-line com-pared with a delayed contingency.
Re-engagement behavior:
The ANOVA yielded a sig-nificant main effect of age,
F
(1, 88)
�
17.864,
p
�
.001,with 9-month-old infants manifesting markedly morere-engagement behavior compared with the group of4-month-olds. The analysis also yielded a conditionmain effect,
F
(1, 88)
�
4.86,
p
�
.03, with infants man-ifesting significantly more re-engagement behavior inthe other compared with the self condition (see Figure3C). The analysis also yielded a significant Age
�
Contingency
�
Episode interaction,
F
(1, 88)
�
3.41,
p
�
.035. Analysis of simple effects revealed an Age
� Ep-isode interaction in the on-line contingency conditiononly, p � .032. In this latter condition, 4-month-oldstended to show increased re-engagement behaviorduring the second minute still-face episode, whereas9-month-olds showed a marked increase of such be-havior by the third minute of interaction.
DISCUSSION
The aim of the present research was to investigatethe emergence and determinants of self–other dis-crimination in specular images, manipulating tem-poral and featural characteristics. Two basic ques-tions guided the research: (1) When do infants beginto show signs of a discrimination between self andmimicking others in on-line specular images? and (2)What is the relative role of featural and temporal fac-tors in such discrimination?
Overall, the research indicated that by 4 months ofage, infants showed signs of self–other discrimina-tion in specular images. As a working hypothesis, wespeculated that 9-month-olds who begin to under-stand others as intentional agents of communication(Bates, Benigni, Bretherton, Camaioni, & Volterra,1979; Bruner, 1983; Tomasello, 1995) would perceivethe specular image of others as intentional and com-municative, and, hence, as socially more engagingcompared with the self. The present research pro-vides new evidence supporting this hypothesis. Italso provides more direct evidence supporting previ-ous findings from which it was inferred that by 5months, infants show signs of a discrimination be-tween the specular image of self and someone else
Figure 3 Average percentage of time (and SEs) that infantssmiled (A), vocalized (B), or manifested attempts to re-engage thespecular image (C), as a function of the two age groups (4- and9-month-olds) and two experimental conditions (self versus other).
Rochat and Striano 43
(i.e., the prerecorded view of another infant; see, e.g.,Barhrick & Watson, 1985; Schmuckler, 1996).
The analysis of behaviors indexing infants’ overallvisual attention to the various specular images (gaz-ing and first look) indicated that infants tended to payrelatively more visual attention to the specular imageof the other compared with the self. Both age groupsmanifested reliable visual discrimination and prefer-ence for the specular image that was potentially socialand communicative. Analysis of the social respond-ing measures provided convergent and more directsupport for this contention.
In general, infants at both ages displayed differen-tial smiling, vocalizing, and re-engagement toward thespecular image of the other compared with the self.They tended to smile and re-engage more in the othercondition, whereas they vocalized more in the self con-dition. The increased smiling and re-engagement be-haviors in the other condition clearly points to infants’enhanced social responding when facing the specularimage of the mimicking experimenter compared withthe self. Interpreting the reversed tendency with re-gard to vocalizing is less straighforward. The markedincrease of infants’ vocalizing while facing their ownspecular image corroborates what has previously beenreported by Legerstee et al. (1998) in 5-month-oldinfants. The reliable increase of vocalizing in the selfcondition could be part of self-exploration and the spon-taneous self-production of redundant visual, proprio-ceptive, and auditory stimulation afforded by their ownspecular image. An analogous interpretation is offeredby Legerstee et al. (1998). This interpretation is in reso-nance with Bahrick and Lickliter’s (2000) suggestionand empirical demonstration of a tendency by infants toconsolidate and maximize learning via increased redun-dancy of intermodal information.
Although both 4- and 9-month-olds expressed suchdiscrimination, some results indicate that they do so indifferent ways. In general, the older group of infantsdevoted reliably less time to exploring and giving afirst glance at the specular image in either the self orother condition. Between 4 and 9 months, visual mon-itoring becomes markedly more fleeting and lessprotracted, probably as part of documented changesin visual attention and performance—in particular, thedevelopment in the course of the first year of inhibitorymechanisms that reduce gazing inertia or attentional“stickiness” (Colombo & Mitchell, 1990; Johnson,1990; Ruff & Rothbart, 1996).
In accord with the rationale for our developmentalhypothesis, the data confirmed that by 9 months, in-fants developed a new propensity toward social initi-atives, attempting to re-engage a social partner (seealso Striano & Rochat, 1999). In general, 9-month-olds
tended to demonstrate more re-engagement behaviors(i.e., social initiatives) compared with 4-month-olds.However, both 4- and 9-month-olds tended to manifestgreater social re-engagement toward the specular im-age in the other compared with the self condition. Theanalysis points toward an age effect, with the impactof condition tending to be greater for older comparedwith younger infants (see Figure 3C). In general, thedifferential re-engagement behavior as a function ofcondition (cardinal main effect of the present analy-sis) is a clear expression of self–other discriminationin specular images. As suggested in the Introduction,re-engagement behavior can be construed as attemptsby infants to intitiate social responses and change the be-havior of a social partner (Striano & Rochat, 1999). In thecontext of the present research, we propose that such be-havior probably reflects an understanding of other’sspecular image as a social communicative partner.
Infants also demonstrated self–other discrimina-tion when one considers the other dependent mea-sures. Both 4- and 9-month-olds tended to smile more,look larger in general, and have more protracted first-look duration at the specular image in the other com-pared with the self condition.
Smiling and looking are the most common measuresof social monitoring and emotional regulation used indocumenting early social attunement of infants in face-to-face protoconversation (Rochat, Querido, & Striano,1999; Toda & Fogel, 1993; Tronick, Als, Adamson, Wise,& Brazelton, 1978). The self versus other condition effectregarding these measures demonstrates infants’ inclina-tion at both ages to be more socially engaged in interact-ing with the mimicking experimenter compared withtheir own specular image.
Considering that both 4- and 9-month-old infantsshowed self–other discrimination, questions remainas to what determines such discrimination. Our re-sults indicate that it is probably based on a complexcombination of featural, movement dynamic, andtemporal information. Infants at both ages showedsome evidence of being sensitive to all of these in theirdiscrimination.
Physical and dynamic features of what was re-flected in the specular image need to be considered asthe basis of the self–other discrimination expressedby the infants. Adult (specular other) and infant(specular self) did not look the same, and obviouslydid not move in exactly the same way. Although the ex-perimenter was trained to mimic the infant to the bestof her ability, the on-line mimicking could never per-fectly equate the copied facial and limb movements ofthe infant in amplitude, vitality, general dynamic, andtiming. It is thus reasonable to think that the self–other discrimination manifested by the infant was
44 Child Development
based primarily on a combination of featural and dy-namic information. On the one hand, infants could al-ready have some template featural representation oftheir own reflection in a mirror based on past experi-ence (see Bahrick et al., 1996; Legerstee et al., 1998). Onthe other hand, they could also have an intermodal(i.e., visual–proprioceptive) and dynamic sense oftheir own body reflected in the specular image. Thisdynamic sense of the body would be based on previ-ous visual–proprioceptive calibration arising fromearly self-exploration. Such calibration is evident ininfants as young as 3 months of age who showedsigns of discriminating on-line views of their ownbody on a TV, which violated familiar spatial arrange-ments of the directly perceived body (Rochat, 1998).Further research is needed to isolate the relative im-portance of featural detection and visual–propriocep-tive calibration as the basis of self–other discrimina-tion in specular images.
Because the mimicking experimenter could onlyapproximate the movements and gestures of the in-fants, she provided them with analogous but imper-fectly contingent behaviors, whether in the on-line ordelayed contingency condition. Considering that byat least 3 months infants are particularly interested inexploring imperfect contingency even when it comesfrom inanimate sources (Watson, 1979), it is feasiblethat an early preference for imperfect temporal con-tingency could be the basis of self–other discrimina-tion. Results regarding the re-engagement behaviorhowever, show that there is probably more than theinvolvement of an imperfect contingency detection,with infants perceiving the experimenter as a socialpartner with communicative intents.
Other results point to infants’ sensitivity to the tem-poral contingency displayed in the specular image(i.e., on-line versus 2-s delayed contingency). Self–other discrimination expressed in the analysis of visualattention (gazing and first look), as well as social re-sponding (i.e., vocalizing and re-engagement) tendedto depend on whether the specular image was on-lineor delayed. This dependence, however, was marginal.By manipulating the contingency variable, we ex-pected to find more evidence of its role as a determi-nant of self–other discrimination in the specular imageacross our measures. In fact, only one marginally sig-nificant condition-by-contingency interaction was ob-served, p � .057, for the measure of first-look duration.It may be that infants are not sensitive to delays smallerthan 2 s. Some have suggested that imperfect contin-gency detected by infants might begin with at least 3-sdelays (Watson, 1984, 1995). For adults, preliminarytesting with the apparatus demonstrated that a 2-sdelay in a specular image was highly noticeable. It is
feasible, however, that more delay is necessary for ananalogous discrimination by young infants.
In general, we observed what is typically re-ported in a still-face procedure. Infants at both 4 and9 months tended to decrease their overall proportionof gazing at the specular image during the still-faceepisode. This observation is consistent with previ-ous still-face experiments using live adults (Toda &Fogel, 1993; Tronick et al., 1978) or on-line specular(reflected video) images of the mother (Rochat et al.,1998). From 4 months, infants reacted to the specularstill-face in ways resembling those observed withthe sudden still-face of live adults. Interestingly, forthe gazing response, we found that when the specu-lar image had a 2-s delayed contingency, infantsoverall tended to look significantly less at the image,p � .052. The tendency toward greater visual atten-tion paid to the on-line compared with the delayedspecular image is difficult to interpret. One possibil-ity, however, is that the on-line specular image tendedto be viewed by the infant as more novel comparedwith the contingent but delayed visual feedback typ-ically characterizing familiar face-to-face exchanges(e.g., affective mirroring as depicted by Gergely &Watson, 1999).
In all, this research provides converging evidence,on the basis of multiple measures, that infants from 4months of age are able to discriminate between thespecular image of themselves and the specular imageof a mimicking other. This discrimination becomesparticularly evident by 9 months of age, when infantsdisplay a propensity toward social initiatives at thespecular image of the mimicking adult, apparentlyconstrued by the infant as a social partner who is dif-ferentiated from the self. This discrimination appearsto have multiple determinants, including featural anddynamic, as well as temporal dimensions.
Early self–other discrimination in specular imagescannot be equated to mirror self-recognition indexed,for example, by the passing of the rouge task. Signs ofsuch discrimination do not mean that infants from 4months actually recognize themselves or express con-ceptual self-awareness. Despite the fact that this dis-crimination is primarily perceptual, however, it is thefoundation from which children can eventually de-velop the conceptual and explicit sense of themselvesexpressed by the middle of the second year.
Our research confirms the idea that there is a longand probably continuous development from the earlyperceptual sense of one’s own body as differentiatedfrom the body of others, to the actual recognition andexplicit identification of the self in specular images.More research is needed to capture this development;in particular, the functional link between early self–
Rochat and Striano 45
other discrimination as demonstrated in the presentstudy, and later conceptual self-awareness.
ACKNOWLEDGMENTS
The authors wish to thank Rebecca Gauchman,Rebecca Messerli, Valerie Weisser, and Briarly Whitefor their help in running and coding this experiment.They are grateful to parents and infants for their par-ticipation. This research was supported in part by agrant No. SBR-9507773 from the National ScienceFoundation awarded to P. Rochat.
ADDRESSES AND AFFILIATIONS
Corresponding author: Philippe Rochat, Departmentof Psychology, Emory University, 532 North KilgoCircle, Atlanta, GA 30322; e-mail: [email protected] Striano is now at the Max Planck Institute forEvolutionary Anthropology in Leipzig, Germany.
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