PLEASE SCROLL DOWN FOR ARTICLE

This article was downloaded by: [Universita' di Trento]On: 14 April 2009Access details: Access Details: [subscription number 778410541]Publisher Psychology PressInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

Journal of Clinical and Experimental NeuropsychologyPublication details, including instructions for authors and subscription information:http://www.informaworld.com/smpp/title~content=t713657736

Ambiguous idiom comprehension in Alzheimer's diseaseCecilia Rassiga a; Federica Lucchelli b; Franca Crippa a; Costanza Papagno a

a University of Milan-Bicocca, Milan, Italy b Passirana di Rho, Alzheimer's Disease Centre, Milan, Italy

Online Publication Date: 01 May 2009

To cite this Article Rassiga, Cecilia, Lucchelli, Federica, Crippa, Franca and Papagno, Costanza(2009)'Ambiguous idiomcomprehension in Alzheimer's disease',Journal of Clinical and Experimental Neuropsychology,31:4,402 — 411

To link to this Article: DOI: 10.1080/13803390802220019

URL: http://dx.doi.org/10.1080/13803390802220019

Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf

This article may be used for research, teaching and private study purposes. Any substantial orsystematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply ordistribution in any form to anyone is expressly forbidden.

The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date. The accuracy of any instructions, formulae and drug dosesshould be independently verified with primary sources. The publisher shall not be liable for any loss,actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directlyor indirectly in connection with or arising out of the use of this material.

© 2008 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

http://www.psypress.com/jcen DOI: 10.1080/13803390802220019

JOURNAL OF CLINICAL AND EXPERIMENTAL NEUROPSYCHOLOGY2009, 31 (4), 402–411

NCEN Ambiguous idiom comprehension in Alzheimer’s disease

IDIOM COMPREHENSION IN AD Cecilia Rassiga,1 Federica Lucchelli,2 Franca Crippa,1 and Costanza Papagno1

1University of Milan-Bicocca, Milan, Italy2Alzheimer’s Disease Centre, Passirana di Rho, Milan, Italy

Ambiguous idiom comprehension was examined in 15 patients with mild probable Alzheimer’s disease (AD) bymeans of two tasks: a string-to-picture matching task and a string-to-word matching task. In the first, patientshad to choose among four pictures, while in the second they chose among four words. For both tasks the alternativeswere the picture/word corresponding to the figurative meaning, a semantic associate (picture/word) to the lastword of the idiom, and two unrelated alternatives, which were, in the case of words, an unrelated foil preservingthe semantic class and a literal continuation foil (a word that can follow the verb in that sentence), while in thecase of pictures the first was substituted by an unrealistic foil. The patients were also submitted to three language,one visuo-perceptual, and two executive tasks. Idiom comprehension was poor, particularly when the string-to-picture matching task was used, and correlated with executive tests. We confirm that linguistic and extralinguisticfactors must be taken into account to explain ambiguous idiom interpretation, and we underline the role of thetesting modality in the case of pathological populations.

Keywords: Figurative language; Idiom; Central executive; Stroop; Alzheimer’s disease.

INTRODUCTION

A peculiar aspect of linguistic communication isthe use of figurative expressions, which differ fromthe literal meaning of their component words;these expressions are, for example, proverbs,hyperboles, metaphors, and idioms. Two mainaspects concerning figurative language have beenstudied. While linguists have faced the problemrelated to the mechanisms involved in the interpre-tation of figurative language, neuropsychologistshave investigated its neural correlates. Both agreethat idioms, metaphors, proverbs, and so on donot constitute a homogeneous group. Idioms, inparticular, which are one of the most commonforms of figurative language (Gibbs, 1999), aretypically described as frozen phrases whose mean-ings are stipulated directly in a mental lexicon andcannot be derived from an analysis of the words’

typical meanings. However, the majority of idioms,in particular verbal idioms, are syntactically andsemantically processed and, accordingly, canundergo syntactic and semantic variations. There-fore, they vary as to their semantic transparency/opacity—that is, the ease by which the motivationfor their structure can be recovered (Nunberg, Sag,& Wasow, 1994): For instance, “to skate on thinice” evokes a potentially dangerous situation andtherefore can be defined as transparent. Idiomsvary as to their decomposability—that is, theextent to which the idiomatic interpretation can bemapped onto single constituents (Gibbs, Nayak, &Cutting, 1989) and also the degree to which theycan be syntactically transformed and still retaintheir idiomatic meaning (Gibbs & Gonzales, 1985).Finally, many idioms (known as “ambiguous”) canalso be assigned a literal plausible interpretation(e.g., “to break the ice”).

This study was supported in part by a FAR (Fondi di Ateneo per la Ricerca) grant and by PRIN (Progetti Ricerca di InteresseNazionale) grants to C.P.

Address correspondence to Federica Lucchelli, Alzheimer’s Disease Centre, Via Luigi Settembrini 1, 20017 Passirana di Rho, Milan,Italy (E-mail: flucch@libero.it).

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

IDIOM COMPREHENSION IN AD 403

Although neuropsychological studies on figurativelanguage comprehension in Alzheimer’s disease(AD) patients concern mainly metaphors, nonethelesssome information is also available for idioms.Kempler, Van Lancker, and Read (1988) examined29 patients with probable AD ranging from mild(Mini-Mental State Examination, MMSE, score 28)to severe (MMSE score 2), who were submittedto tests of word, idiom, proverb, and novel phrasecomprehension. AD patients were impaired ininterpreting abstract meanings as compared tocontrols: When faced with alternative interpreta-tions of familiar phrases, they chose concreteresponses, suggesting, in the authors’ opinion, thatthey were using lexical (single word), referentialmeaning to interpret the phrases.

In a recent study (Papagno, 2001), it was shownthat the decline of figurative language in AD patients,as assessed by means of an oral explanation task ofmetaphors and idioms, both ambiguous and non-ambiguous, decomposable and nondecomposable,frozen and unfrozen, was not an early symptomand occurred independently from literal languageimpairment. There were very few patients with animpairment of figurative language but normalpropositional language. In a further study (Papagno,Lucchelli, Muggia, & Rizzo, 2003), testing a specificclass of idioms—namely, nonambiguous opaqueidioms—by means of a sentence-to-picture matchingparadigm, AD patients with a mild degree ofcognitive decline (MMSE 16–22) proved to besignificantly impaired with respect to a comparisongroup, when they had to choose between twopictures, one representing the figurative interpretationand the other the literal one. However, the per-formance improved when the foil was substitutedwith a picture representing a situation described bya sentence that included only the last word of theidiom (for example, when the idiomatic expressionwas “to have a green thumb,” the alternative was aman hurting his thumb). When an oral explanationwas required, patients still produced several literalinterpretations, and their performance correlatedwith that on executive tasks. The literal interpreta-tion could have produced a Stroop effect, interferingwith the correct response, no matter whether theliteral interpretation was implausible. Therefore, itcould be hypothesized that rejecting the literalinterpretation of an ambiguous idiom (for whichthe literal interpretation is plausible) should beeven more difficult and should require a greaterinvolvement of the central executive.

The possibility of different processing and differentneural correlates for ambiguous and nonambiguousidioms is supported by a functional magnetic reso-nance imaging (fMRI) study in which an additional

right temporal lobe activation was found in thecase of ambiguous items in a relatedness decisiontask, as compared to nonambiguous items (Zempleni,Haverkort, Renken, & Stowe, 2007). However, thiscontrasts with a further fMRI study in which nodifference between ambiguous and nonambiguousidioms was reported in cortical activation duringa congruence judgment task (Romero Lauro,Tettamanti, Cappa, & Papagno, 2008). In addition,when ambiguous and nonambiguous idioms weretested in aphasic patients (Papagno & Caporali,2007) a double dissociation was found, suggestingthat these two types of idioms can be processeddifferently.

The aim of the present study was to investigatethe comprehension of a specific type of idiom—namely, ambiguous literally plausible idioms inAD. This type of expression has never been testedin these patients. As mentioned, in the case ofambiguous expressions, a literal interpretation isplausible and would represent a correct response;consequently this alternative was not included.In addition, since the testing modality has provedto be a significant factor in vascular patients(Papagno & Caporali, 2007; Tompkins, Boada, &McGarry, 1992), two testing modalities were used:a sentence-to-picture and a word-to-picture match-ing task. The rationale was that picture matchingcan underestimate the patients’ comprehension ofidioms (Papagno & Caporali, 2007), and converg-ing evidence, using different tasks, could strengthenthe results. Indeed, the idiomatic meaning does nothave a univocal representation as literal sentenceshave. Patients with impaired “flexibility” wouldreject pictures that do not match with their ownmental representation of that idiom. However, ifthey recognize the sentence as a figurative expres-sion, but they ignore its exact meaning, they shouldreject the semantic associate foil, too, since this isrelated to the literal/concrete interpretation: There-fore, a similar number of unrelated errors should beexpected. It has been suggested that adequate exec-utive functions are necessary to inhibit alternativeinterpretations: In fact, it was found that a suppres-sion of the literal interpretation of familiar nonam-biguous idioms was required in order to deriveidiomatic meaning (Papagno et al., 2003). On theother side, lexical-semantic deficits could impair asentence-to-word matching task simply because aword is not available and not because the patientignores the idiomatic expression.

It should be emphasized that our aim was notmerely to provide evidence of a significant impair-ment of idiom comprehension in AD patients.Rather, in view of the neuropsychological profileof this pathological population, we wanted to

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

404 RASSIGA ET AL.

investigate which components (linguistic andextralinguistic) are involved in this task in general.

Given these considerations, we examined:

• whether ambiguous idiom comprehension isimpaired;

• which type of error is more frequent;• whether a correlation exists between ambiguous

idiom and literal language performance;• which role executive functions play.

METHOD

Participants

A total of 15 patients (10 women and 5 men, meanage 75.5 ± 4.8 years; educational level 6.1 ± 2.3years) with a diagnosis of probable AD (McKhannet al., 1984) were selected on the basis of their per-formance on a test of screening for dementia (MilanOverall Dementia Assessment, MODA, Brazzelli,Capitani, Della Sala, Spinnler, & Zuffi, 1994). Onlypatients with a score over 63/100, which corre-sponds to a mild cognitive impairment (MMSE >17), were included in the study. Other criteria ofinclusion were: absence of previous neurologicaldiseases, absence of lesions on the computed tom-ography (CT) or MRI scan, a minimum of 3 yearsof education, and right-handedness. Demograph-ical and clinical data of the 15 AD patients arereported in Table 1. They all gave informed consentto participate in the study. A group of 15 neurolog-ically unimpaired healthy participants, matchedone by one to the patients for age, educationallevel, and gender, was also tested.

Materials

Patients were submitted to (a) two executive tasks:the Stroop test (Caffarra, Vezzadini, Dieci, Zonato,& Venneri, 2002) and the Pencil-and-Paper DualTask (Baddeley, Della Sala, Papagno, & Spinnler,1997); (b) three language tasks: the Token Test (DeRenzi & Faglioni, 1978), verbal fluency on semanticcue (a modified version of Novelli et al., 1986), andword auditory comprehension (Laiacona, Bar-barotto, Trivelli, & Capitani, 1993), and (c) twovisuo-perceptual tasks: the Street’s completion test(Spinnler & Tognoni, 1987) and the Line OrientationTest (Benton, Hamsher, Varney, & Spreen, 1983).

Experimental task

A total of 28 verbal ambiguous idioms wereselected (see Appendix). They were ambiguous inthat the string had both a figurative and a literalmeaning. In order to control for the semantictransparency of the idiom string, a rating studywas run, in which 35 language-unimpaired healthyparticipants were presented with the idiom list andwere asked to rate how easily the idiomatic mean-ing could be derived from the meaning of thewords forming each string. A score ranging from0 to 3 was assigned, where 0 meant “not at all” and3 “perfectly” (mean 1.19, range 0.49–1.96). We alsocontrolled for the plausibility of the literal meaningof the idiom string. The same 35 language-unimpaired participants were asked to rate theextent to which the literal meaning of the stringwas plausible. A score ranging from 0 (implausi-ble) to 3 (absolutely plausible) was assigned to each

TABLE 1 Demographical data of the 15 AD patients and matched controls

Patient GenderAge

(years)Education

(years) Control GenderAge

(years)Education

(years)

1. F 72 8 1. F 72 82. F 78 8 2. F 78 83. F 74 5 3. F 74 54. F 79 8 4. F 79 85. F 71 12 5. F 71 126. F 82 4 6. F 82 57. M 72 8 7. M 72 88. F 77 5 8. F 77 59. M 69 5 9. M 69 510. M 73 5 10. M 71 511. M 70 5 11. M 70 512. F 79 5 12. F 79 513. F 86 5 13. F 86 514. F 73 5 14. F 71 515. M 77 5 15. M 77 5

Note. AD = Alzheimer’s disease. M = male; F = female.

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

IDIOM COMPREHENSION IN AD 405

string (mean 1.98, range 0.13–3). Finally, they wereasked to rate the familiarity of each idiom stringwith a score of 0 (the idiom was unknown), 1(known but not sure about the meaning), 2 (famil-iar with a well-known meaning), or 3 (highly famil-iar); their familiarity ratings ranged from 1.15 to2.94 with a mean of 2.52.

Two tests were used. The first was a sentence-to-word matching task in which each idiomatic expres-sion was paired with four words matched in termsof length (mean number of characters 6.0, range 4–11) and written frequency (mean 10.4, range 2–26):The target word corresponded to the idiomaticinterpretation of the string (henceforth idiomatictarget; e.g., WINE, for “alzare il gomito,” “to raisethe elbow,” i.e., to drink too much); one foil wassemantically associated with the last constituentword of the idiom string (in the previous example,LEG); and two words were unrelated foils (TREE,BOX). Specifically, the first type of unrelated foilwas either an abstract or a concrete word depend-ing on the nature of the idiomatic target: The unre-lated foil was abstract if the idiomatic target wasabstract and concrete if the idiomatic target wasconcrete. A word was considered concrete based onthe availability of the word referent to sensoryexperience. The second type of unrelated foil was aword that could plausibly complete the verb in theverb phrase (BOX). Each idiom was presented in asyntactically simple sentence formed by a subjectfollowed by the idiom string (e.g., “He has raisedthe elbow”). The participants’ task was to point tothe word that matched the idiomatic meaning ofthe sentence: The examiner read the sentence fol-lowed by the four alternatives that were written oncards and remained in front of the patient until adecision was taken. For example, the examiner readthe sentence “He has raised the elbow,” and thenthe four alternatives (“wine, leg, box, tree”) werepresented. Participants were informed that theywould be read sentences commonly used in every-day conversation that had a nonliteral interpreta-tion. An example was provided to clarify that thestring had to be interpreted figuratively.

We tested the strength of the relationshipbetween (a) the semantically associate foil and literalmeaning of the string; and (b) the idiomatic targetand the idiomatic meaning of the idiom string. Tothis aim, 25 healthy participants were asked to ratethe specific relatedness of (a) and (b) on two 5-pointrating scales ranging from 0 (not at all related) to 5(perfectly related). Idiomatic targets were rated assignificantly more related to the idiom strings thansemantically associated targets were to the literalmeaning of the strings, 4.57 (range 3.68–4.92,SD 0.28) versus 1.61 (range 1–3.28, SD 0.67),

t(44) = 19.49, p < .00001, a result that might helpthe choice of an idiomatic target.

For the picture-matching task four line-drawingswere prepared: one corresponding to the figurativeinterpretation (for example in the case of to lift theelbow the drawing of a drunk person was pre-sented); a semantically associated foil, which wasdescribed by the verb of the idiom followed by asemantic associate (a dancer lifting his leg);a picture in which the verb was followed by a wordthat could normally follow that verb (a person lift-ing a box); and a picture in which the verb was fol-lowed by a word that made the sentenceimplausible (a man lifting a tree on his finger). Theabove example of the task is presented in Figure 1.

The tasks were performed in different sessions:In the first session, AD patients received the generalneuropsychological tests, while in the second sessionthey performed the idiom tasks. The order ofpresentation of the two idiomatic tasks was counter-balanced across participants.

RESULTS

The results of the 15 patients for the verbal, execut-ive, and visual tests are shown in Table 2, while theresults for the two idiom comprehension tasks arereported in Table 3 and Table 4. Word comprehen-sion and verbal fluency were minimally impaired. Asto the visuo-perceptual tasks, performance on theStreet completion test was normal in all patients,while the Line Orientation Judgment was mildlyimpaired in 3 patients.

In the sentence-to-picture matching task themean number of correct responses was 9.07 (32.35%,SD 4.80), while for the 15 healthy participants themean was equal to 15.93 (56.90%, SD 6.14). Errorswere predominantly semantic foils for both thepatients (64.43% of all errors) and the comparisongroup (68.50%). Unrelated errors of Type 1 (apicture described by a sentence in which the lastword of the idiom was substituted with a word thatcould plausibly follow the verb) did not differ fromType 2 errors (totally implausible) in patients,Type 1 = 16.90%, Type 2 = 18.66%, F(1, 14) = 0.42,p = .53, nor in comparison subjects, Type 1 =16.57%, Type 2 = 14.92%; F(1, 14) = 0.15, p = .71.

In the sentence-to-word matching task the meannumber of correct responses for the AD patientswas 17.73 (63.33%, SD 4.39), while in the case of thecomparison group it was 21.93 (78.35%, SD 4.23).Also in this case, errors were mainly semantic foilsfor patients (67.53% of all errors) and comparisonsubjects (59.34%). Unrelated errors were 22.73% ofType 1(abstract or concrete foils depending on the

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

406 RASSIGA ET AL.

target being abstract or concrete) and 9.74% of Type2 (a word that could follow the verb, but had norelation both with the literal and the idiomaticmeaning) in patients. The difference was significant,F(1, 14) = 9.12, p < .01, Cohen’s f = 0.81, while theydid not differ in the comparison group, Type 1 =20.88%, Type 2 = 19.78%; F(1, 14) = 0.028, p = .87.

Age proved to be the only significant confoundingfactor in modeling scores, F(2, 26) = 7.49, p = .003,

unlike gender, F(2, 23) = 1.39, p = .27, and years ofeducation, F(2, 23) = 0.132, p = .88. A multivariateanalysis of covariance (MANCOVA) model wastherefore tested, with the responses on the twomatching tasks as dependent variables, group asfactor, and age as covariate. Results showed thatthe difference in number of correct responses of boththe sentence-to-word and the sentence-to-picturematching tasks between AD and comparison

Figure 1. Example of the sentence-to-picture matching task.

TABLE 2 Alzheimer’s disease patients’ neuropsychological assessment

Patient MODA

Stroop

Dual task (%) Token test

Word comprehension

Semanticfluency

Street’s completion test

Benton lineorientation

Time (sec)

Errors

Cut-off (range) 89.1 (0–100) < 36.92 < 4.24 70.0 26.50 (0–36) 72 (0–80) 9.5 2.25 (0–14) 17 (0–30)

1. 85.3 55.50 11.50 95.0 29.75 78 5.6 7.50 242. 73.2 107.25 1.25 65.0 26.75 69 6.6 5.00 163. 72.4 100.75 8.25 82.3 29.75 73 4.9 5.75 224. 76.8 52.75 0.25 81.8 27.25 74 7.6 4.50 255. 79.7 97.75 3.25 67.0 29.25 80 10.7 4.50 236. 87.5 0.00 0.00 100.0 29.00 76 7.1 6.75 277. 89.2 36.50 0.50 86.3 33.50 76 7.2 7.25 278. 90.2 44.25 0.00 77.2 28.00 80 10.3 8.25 309. 88.2 44.00 1.50 74.1 30.50 77 9.1 7.50 1710. 78.6 85.75 13.25 70.4 28.75 77 9.0 4.75 1911. 82.3 101.75 7.25 58.3 23.25 77 7.1 4.75 1812. 79.1 9.75 19.00 83.3 32.75 79 6.7 5.75 1413. 67.2 0.00 12.75 87.7 28.50 66 4.6 4.75 1614. 83.9 44.25 1.25 97.1 33.25 80 6.7 7.75 2215. 77.0 41.75 0.00 92.0 33.00 70 6.1 2.25 27

Note. MODA = Milan Overall Dementia Assessment. Word comp. = Word comprehension.

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

IDIOM COMPREHENSION IN AD 407

subjects was highly significant, F(2, 26) = 5.87,p = .008, with a substantial effect size for each task(Cohen’s f = 0.66 and f = 0.84, respectively). Withrespect to the sentence-to-word matching task, the95% confidence interval for the difference betweengroups was equal to (0.98; 7.49), while for thesentence-to-picture task it was equal to (2.8; 10.6).

The performance on the sentence-to-wordmatching task correlated with that on the dual task(r = .569, p = .027), but neither with the severity ofcognitive decline as assessed by the MODA (r = .060,

p = .833) nor with the Stroop (r = –.24, p = .38).However, the performance on the Stroop corre-lated with the number of semantically relatederrors (i.e., the longer time to perform the Stroopwas related to more semantic errors with idioms;r = .59, p = .021). In light of such a correlationstructure, a causal model was adopted in order tomeasure how much each of the different independentabilities accounted for the AD performance. Dualtask proved to be the only predictor for the sentence-to-word matching task (b = 20.14, p = .027).

TABLE 3 Sentence-to-word matching task

Patient Ta SF D1 D2 Control Ta SF D1 D2

1. 18 6 1 3 1. 15 10 1 22. 14 8 4 2 2. 22 4 1 13. 13 11 3 1 3. 26 1 1 04. 22 5 0 1 4. 22 2 3 15. 19 8 1 0 5. 28 0 0 06. 23 2 2 1 6. 15 4 6 37. 13 8 6 1 7. 19 6 1 28. 23 3 2 0 8. 18 8 1 19. 12 9 5 2 9. 27 0 0 110. 16 7 3 2 10. 21 2 2 311. 12 13 2 1 11. 22 3 0 312. 16 8 3 1 12. 25 1 2 013. 21 6 1 0 13. 25 2 1 014. 25 3 0 0 14. 26 2 0 015. 19 7 2 0 15. 18 9 0 1

Mean 17.73 6.93 2.33 1.00 21.93 3.60 1.26 1.20SD 4.39 2.96 1.71 0.92 4.23 3.22 1.57 1.14

Note. Performance of AD (Alzheimer’s disease) patients and matched controls. Ta: target. SF: semantic foil. D1 (errors Type 1): foilpreserving the semantic class. D2 (errors Type 2): literal continuation foil.

TABLE 4 Sentence-to-picture matching task

Patient Ta SF D1 D2 Control Ta SF D1 D2

1. 11 14 0 3 1. 11 12 2 32. 2 17 4 5 2. 15 8 3 23. 6 13 3 6 3. 14 12 0 24. 9 9 5 5 4. 20 6 2 05. 18 5 3 2 5. 23 3 2 06. 7 14 2 5 6. 4 15 3 67. 5 16 4 3 7. 8 13 5 28. 20 4 3 1 8. 16 10 1 19. 8 13 3 4 9. 25 2 0 110. 10 11 2 5 10. 17 5 4 211. 12 12 2 2 11. 21 5 1 112. 6 16 4 2 12. 22 3 2 113. 6 14 5 3 13. 13 10 4 114. 10 10 5 3 14. 21 6 0 115. 6 15 3 4 15. 9 14 1 4

Mean 9.07 12.20 3.20 3.53 15.93 8.26 2.00 1.80SD 4.80 3.84 1.37 1.46 6.14 4.32 1.55 1.57

Note. Performance of AD (Alzheimer’s disease) patients and matched controls. Ta: target. SF: semantic foil. D1 (errors Type 1): foilpreserving the semantic class. D2 (errors Type 2): literal continuation foil.

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

408 RASSIGA ET AL.

The performance on the sentence-to-picturematching task correlated with verbal fluency (r =.705, p = .003), as well as with word comprehension(r = .671, p = .006). However, the correlation withverbal fluency was not significant (r = .50, p = .07)once the effect of word comprehension was partialedout. Conversely, no significant correlation wasfound with word comprehension, after removing theeffect of verbal fluency (r = .42, p = .13). All theseresults held even when variables were transformed inorder to stabilize their variance. It is, for instance,the case of count variables such as errors or correctanswers, transformed via a square root function.

Item analysis was performed by a repeated mea-sures analysis of variance (ANOVA). Results showeda significant difference between the word-to-sentenceand the picture-to-sentence matching tasks, both forthe target and for the semantic associate foil, inpatients and comparison subjects. With regard to thecorrect responses in the word-to-sentence matchingtask, the mean was significantly lower for patients(9.50) than for comparison subjects (11.75), F(1, 27)= 35.03, p < .001. Also in the case of the word-to-pic-ture matching task, the mean number of correctresponses was lower for patients (4.86) than for com-parison subjects (8.54), with a significant difference,F(1, 27) = 55.56, p < .001. As far as the semantic asso-ciate foil was concerned, the mean of semantic errorswas significantly higher for patients, both in theword-to-sentence (3.71 vs. 1.96), F(1, 27) = 18.194, p< .001, and in the sentence-to-picture matching task(6.54 vs. 4.43), F(1, 27) = 15.64, p < .001.

Moreover, performance in the sentence-to-wordmatching task was significantly better than thatin the sentence-to-picture matching task forboth groups, t(14) = 6.363, p = .000 and t(14) = 5.81,p = .000, for patients and comparison group,respectively. However, the correlation of the sentence-to-word with the sentence-to-picture matching taskis dramatically different between the two groups:While in the case of the comparison group it provesto be significant (r = .76, p = .001), this was not thecase for AD patients (r = .35, p = .20).

Familiarity did not correlate with the number ofcorrect responses in AD and in the comparisongroup, while the number of correct responsescorrelated with the goodness of the pictorial repre-sentation of the idioms (r = .53, p = .003).

DISCUSSION

The aim of the present study was to assess the com-prehension of ambiguous idioms in AD patients,by means of two different tasks. Adding to previousfindings (Papagno et al., 2003), it appears that AD

patients are impaired even with the easier categoryof ambiguous idioms and even when the task ismade easier than usual. Indeed, ambiguous idiomsproved to be a much easier category with respectto nonambiguous idioms in aphasic patients (seePapagno & Caporali, 2007). However, a signifi-cantly better performance was found in the sentence-to-word matching task. The type of task, therefore,had a significant effect on the participants’ per-formance. The result is consistent with that obtainedwith aphasic patients (Papagno & Caporali, 2007).It appears that the overt representation of the literalmeaning prompted the semantic associate response,suggesting that participants were unable to suppressthe literal interpretation when its explicit pictorialrepresentation was available.

A possible interpretation could be that thesetasks require the engagement of extensive extralin-guistic resources. Even if the semantic performanceof patients was still in the normal range (as checkedby means of word comprehension and verbalfluency), and the task was easier (two versions ofthe same task, one of which is much easier), none-theless AD patients were impaired. However, if theresults meant only that an extensive engagement ofextralinguistic resources is required, a correlationwith the degree of cognitive decline should befound, which was not the case.

Therefore, it seems clear that semantic deficitsalone and executive deficits alone cannot explainthe impairment of patients, but the two factorsshould be combined.

This means that, in general, people need bothsemantic resources and extralinguistic abilities inorder to understand idioms, even with the easiercategory of ambiguous idioms and with an easiertask. Neuroimaging studies, showing both a tem-poral and frontal activation in idiom processing,support this possibility (Romero Lauro et al., 2008;Zempleni et al., 2007).

Visuo-perceptual deficits could not be consid-ered responsible for the poor performance in thepicture-matching task, since the performance onthese tests was overall in the normal range and didnot correlate with the idiom task.

In the picture-matching task, a high variabilityemerged among AD patients but also among theelderly healthy participants. Some performed verypoorly, while others’ performance was almosterrorless. Unfortunately, the comparison groupwas not submitted to executive tests, but it can beargued that, since age proved to significantly affectperformance, and executive functions deterioratewith age (see Phillips, MacPherson, & Della Sala,2002, for a review), this variability would reflectdifferent executive performance even in normal

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

IDIOM COMPREHENSION IN AD 409

subjects. We can hypothesize that elderly peoplewith good executive functions perform well, whileelderly with less efficient executive functions per-form at a lower level. Although the hypothesisrequires further support, it is well known that agehas a significant effect on neurologically unim-paired subjects in many psychometric tasks. Thisalso holds true for idiom comprehension: In a sam-ple of 201 healthy 20- to 80-year-old individuals itwas found that performance significantly decreasedwith aging (Papagno et al., 2007). In the presentstudy, a relation between executive tasks and idiomcomprehension was found in the case of the sen-tence-to-word matching task. The correlationbetween the sentence-to-word matching task andthe dual task in the case of ambiguous idioms hasbeen found also in aphasic patients (Papagno &Caporali, 2007).

As far as errors are concerned, the most frequentlyproduced type was the semantically associated foil.This suggests that the literal interpretation remainsactive while the sentence is being processed andcannot be inhibited, even when the interference ofthe literal interpretation is minimized—that is,when the target word is semantically associatedwith the last constituent word and not with theglobal literal meaning of the string.

Although semantically based errors were evidentin both idiom tasks, it should be noted that all thepatients, with the exception of only one participant,were not significantly impaired at a word compre-hension level as well at a sentential level. The wrongchoice (literal/semantic associate) might be the out-come of an impairment at several levels. First, thepossibility that an associative mechanism mighthave contributed to this result exists, especiallybecause of the correlation between semantic errorsand Stroop performance, suggesting that an auto-matic association is not inhibited by the executivesystem, producing the semantically related answer.The AD patients’ degraded semantics can contrib-ute to this effect (Chertkow & Bub, 1990). Thechoice of AD patients seems to be influenced by alexical effect, and apparently no processing of thesentential meaning took place. An alternative inter-pretation could be a tendency to give concreteresponses to individual words resulting from thepremature choice of an interpretation, as found inproverbs by Burgess and Chiarello (1996) and byIakimova, Passerieux, and Hardy-Baylé (2006) inschizophrenic patients, whose common responsemode in a task of ambiguous idiom comprehensionwas the selection of responses relating to theconcrete meaning of a single word in the idiom.However, even if we cannot rule out the possibilitythat an associative mechanism may have contributed

to our results, especially because of the choice offoils that were semantically associated with the lastword of the idiomatic string, previous evidence(Papagno et al., 2003) suggests that the impairmentgoes far beyond a single-word level. In addition,unrelated errors of Type 1 (a word that could beabstract or concrete depending on the target seman-tic class) were significantly more frequent than Type2 errors in patients, suggesting that, at least in somecases, the patients processed the sentence andrejected the literal meaning, but the correct idio-matic one was not available. Finally, sententialprocessing was not impaired in AD patients, andthere is no reason to believe that AD patients (butalso the comparison subjects, who also producedsemantic errors) did not process the sentences.

A last comment concerns the lack of correlationbetween the two tasks in the AD patients, in con-trast with the significant correlation found in thecomparison subjects, and also in aphasic patientsusing nonambiguous idioms. A possible interpreta-tion could be that while aphasic patients with afocal vascular lesion are expected to have deficitsconfined to language, and the language impair-ment plays the same role in each test, AD patientsare impaired in different cognitive domains, and,since tests are multifactorial, this can result in anasymmetric, though pathological, performance inthe two idiom tasks.

All in all, this study shows that idiom compre-hension is a complex task, involving extralinguistic(executive) functions. This is in line with a tran-scranial magnetic stimulation (TMS) chronometricstudy (Fogliata et al., 2007), in which a selectiveimpairment in accuracy for idioms was foundwhen repetitive transcranial magnetic stimulation(rTMS) was applied to the prefrontal and temporalcortex 80 ms after picture presentation, but withrTMS continuing to affect performance after alonger time of 120 ms.

Original manuscript received 20 January 2008Revised manuscript accepted 21 May 2008

First published online 11 July 2008

REFERENCES

Baddeley, A. D., Della Sala, S., Papagno, C., & Spinnler, H.(1997). Dual-task performance in dysexecutive andnondysexecutive patients with a frontal lesion. Neu-ropsychology, 11, 187–194.

Benton, A. L., Hamsher, K., Varney, N. R., & Spreen, O.(1983). Contribution to neuropsychological assessment.New York: Oxford University Press.

Brazzelli, M., Capitani, E., Della Sala, S., Spinnler, H., &Zuffi, M. (1994). A neuropsychological instrumentadding to the description of patients with suspected

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

410 RASSIGA ET AL.

cortical dementia: The Milan Overall DementiaAssessment. Journal of Neurology, Neurosurgery andPsychiatry, 57, 1510–1517.

Burgess, C., & Chiarello, C. (1996). Neurocognitivemechanisms underlying metaphor comprehensionand other figurative language. Metaphor and SymbolicActivity, 11, 67–84.

Caffarra, P., Vezzadini, G., Dieci, F., Zonato, F., &Venneri, A. (2002). Una versione abbreviata del testdi Stroop: Dati normativi nella popolazione italiana[A shortened version of the Stroop test: Normativedata for the Italian population]. Nuova Rivista diNeurologia, 12, 111–115.

Cherktow, H., & Bub, D. (1990). Semantic memory lossin Alzheimer-type dementia. In M. Schwartz (Ed.),Modular deficits in Alzheimer-type dementia (pp.207–244). Cambridge, MA: MIT Press.

De Renzi, E., & Faglioni, P. (1978). Normative data andscreening power of a shortened version of the tokentest. Cortex, 14, 41–49.

Fogliata, A., Rizzo, S., Reati, F., Miniussi, C., Oliveri, M., &Papagno, C. (2007). The time course of idiom process-ing. Neuropsychologia, 45, 3215–3222.

Gibbs, R. (1999). Figurative language. In R. Wilson &F. Keil (Eds.), The MIT encyclopedia of the cognitivesciences (pp. 314–315). Cambridge, MA: MIT Press.

Gibbs, R. W., & Gonzales, G. P. (1985). Syntactic fro-zenness in processing and remembering idioms. Cog-nition, 20, 243–259.

Gibbs, R. W., Nayak, N. P., & Cutting, C. (1989). Howto kick the bucket and not decompose: Analyzabilityand idiom processing. Journal of Memory and Lan-guage, 28, 576–593.

Iakimova, G., Passerieux, C., & Hardy-Baylé, M. C.(2006). Interpretation of ambiguous idiomatic state-ments in schizophrenics and depressive patients. Evi-dence for common and differential cognitive patterns.Psychopathology, 39, 277–285.

Kempler, D., Van Lancker, D., & Read, S. (1988). Prov-erb and idiom comprehension in Alzheimer disease.Alzheimer Disease and Associated Disorders, 2, 38–49.

Laiacona, M., Barbarotto, R., Trivelli, C., & Capitani, E.(1993). Dissociazioni semantiche intercategoriali:Descrizione di una batteria standardizzata e datinormativi [Intercategory dissociations: Description andnormative data of a standardized battery]. Archivio diPsicologia, Neurologia e Psichiatria, 2, 209–248.

McKhann, G., Drachman, D., Folstein, M., Katzman,R., Price, D., & Stadlan, E. M. (1984). Clinicaldiagnosis of Alzheimer’s disease: Report of the

NINCDS-ADRDA Work Group under the auspicesof Department of Health and Human Services TaskForce on Alzheimer’s Disease. Neurology, 34, 939–944.

Novelli, G., Papagno, C., Capitani, E., Laiacona, M.,Vallar, G., & Cappa, S. F. (1986). Tre test clinici diricerca e produzione lessicale: Taratura su soggettinormali [Three clinical tests of lexical search andproduction: Standardization in normal subjects].Archivio di Neurologia, Psicologia e Psichiatria, 47,477–506.

Nunberg, G., Sag, I. A., & Wasow, T. (1994). Idioms.Language, 70, 491–538.

Papagno, C. (2001). Comprehension of metaphors andidioms in patients with Alzheimer’s disease: A longi-tudinal study. Brain, 124, 1450–1460.

Papagno, C., & Caporali, A. (2007). Testing idiom com-prehension in aphasic patients: The effects of taskand idiom type. Brain and Language, 100, 208–220.

Papagno, C., Caporali, A., Rizzo, S., Reati, F.,Morreale, L., & Venneri, A. (2007). La comprensionedi espressioni idiomatiche non ambigue: Taratura diun test di associazione frase-figura [Comprehensionof non ambiguous idioms: Standardization of asentence-to-picture matching test]. Giornale Italianodi Psicologia, 34, 1019–1039.

Papagno, C., Lucchelli, F., Muggia, S., & Rizzo, S.(2003). Idiom comprehension in Alzheimer’s dis-ease: The role of the central executive. Brain, 126,2419–2430.

Phillips, L. H., MacPherson, S. E. S., & Della Sala, S.(2002). Age, cognition and emotion: The role of ana-tomical segregation in the frontal lobes. In J. Grafman(Ed.), Handbook of neuropsychology (2nd ed., Vol. 7,pp. 73–97). Amsterdam: Elsevier.

Romero Lauro, L. J., Tettamanti, M., Cappa, S. F., &Papagno, C. (2008). Idiom comprehension: A pre-frontal task? Cerebral Cortex, 18, 162–170.

Spinnler, H., & Tognoni, G. (1987). Standardizzazione etaratura italiana di test neuropsicologici [Italianstandardization and normative data of neuropsycho-logical tests]. The Italian Journal of Neurological Sci-ences, 8(Suppl. 6).

Tompkins, C. A., Boada, R., & McGarry, K. (1992).The access and processing of familiar idioms bybrain-damaged and normally aging adults. Journal ofSpeech and Hearing Research, 35, 626–637.

Zempleni, M. Z., Haverkort, M., Renken, R., & Stowe,L. A. (2007). Evidence for bilateral involvement inidiom comprehension: An fMRI study. NeuroImage,34, 1280–1291.

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009

IDIOM COMPREHENSION IN AD 411

APPENDIX

List of idiomatic expressionsPlausibility of the literal meaning (range = 0–3)

Expression Plausibility

Alzare il gomito (to lift the elbow, to drink too much) 2.75Vuotare il sacco (to empty the sack, to confess something) 2.78Sputare il rospo (to spit the toad, to reveal a secret) 0.75Vedere le stelle (to see the stars, to experience a pain) 3.0Essere al verde (to be at the green, to be broke) 0.13Prendere la porta (to take the door, to go away) 1.75Levare le tende (to remove the tents, to leave) 2.44Perdere la testa (to lose the head, to get mad) 0.38Avere il pollice verde (to have a green thumb) 0.70Prendere un granchio (to take a crab, to make an error) 2.70Tirare la cinghia (to pull the belt, to be poor) 2.90Perdere il filo (to lose the thread, to get lost) 1.90Cambiare pagina (to change page, to change your own life) 2.75Mettersi le mani nei capelli (to put the hands in the hair, to be in despair) 2.85Tagliare la corda (to cut the rope, to escape) 2.85Scendere a rotta di collo (to go down breaking the neck, to behave riskily) 0.35Avere le mani bucate (to have holes in the hands, to spend too much) 0.35Saltare la mosca al naso (to jump the fly on the nose, to get angry) 0.60Mettere la pulce nell’orecchio (to put the flea in the ear, to suggest something) 0.75Avere carta bianca (to have white paper, to be free of taking decisions) 2.10Alzare i tacchi (to lift the heels, to go away abruptly) 2.45Attaccare un bottone (to attach a button, to speak too much) 2.95Stringere i denti (to tighten the teeth, to strongly pursue a goal) 2.55Gettare la spugna (to throw the sponge, to throw in the towel) 2.60Rompere il ghiaccio (to break the ice) 2.80Mangiarsi il fegato (to eat the liver, to eat one’s heart out) 2.0Chiudere un occhio (to shut an eye, with one’s eye shut) 3.0Perdere la bussola (to lose the compass, to lose one’s bearings) 2.50

Downloaded By: [Universita' di Trento] At: 07:41 14 April 2009