Daniel Gaonac'h

Neuropsychological assessment of executive functions in women: effects of age and education.

The cognitive processes underlying age-related alterations in tests assumed to reflect frontal lobe functions were investigated with a card sorting test and an alternate semantic fluency task. The tests were administered to 133 healthy women belonging to 3 age groups (range=50-92 years) classed according to 2 education levels. The results revealed a negative association between total word fluency and perseveration in the sorting test. Aging similarly affected performance in both education groups in some components of the tasks (atypical word fluency and sensitivity to distraction). However, aging did not affect performance to the same extent in each education group in other components (particularly those reflecting switching abilities and strategies). This quasi-experimental approach provides useful tools to identify specific processing mechanisms underlying executive functions in normal aging.

Working memory and error detection in texts: what are the roles of the central executive and the phonological loop?

Subjects performed a text error detection task, either alone or in conjunction with a secondary task aimed at specifically hindering the functioning of either the central executive in working memory or of the phonological loop. We focused on the decline in detection performance as a function of the type of error to be detected (typographical, orthographic, or semantic/syntactic) and the processing span required for detection (one word, several words within the same clause, or several clauses). The results showed that the central executive in working memory is involved in detecting semantic/syntactic errors and in detecting orthographic ones, but not in detecting typographical errors. Moreover, the degree of involvement increases with the processing span. The phonological loop is involved in detection whenever processing above the word level is required. As observed in many studies, these results suggest that the difficulty subjects have detecting semantic errors as compared to other types of errors is due to the heavier working memory load: maintenance of the phonological representation and greater involvement of the central executive.

When a missing verb makes a French sentence more acceptable

Using an off-line complexity judgement task, Gibson and Thomas (1999) demonstrated that people found sentences with double centre-embedded relative clauses as easy to understand when the second verb phrase (VP) was omitted as when there were the three required verb phrases. This paper reports a self-paced reading experiment testing this syntactic illusion in French language. The results showed that readers rated the sentences where the second VP was omitted as easier to understand than the grammatical versions, even though the reading time of the last VP was longer for the ungrammatical version. The overall results support theories predicting that the sentence acceptability rating can be enhanced when a syntactically required word with an excessive integration cost is removed. The results are consistent with resource-based theories of sentence processing.

The effect of noun animacy on the processing of unambiguous sentences: Evidence from French relative clauses

Two experiments, one using self-paced reading and one using eye tracking, investigated the influence of noun animacy on the processing of subject relative (SR) clauses, object relative (OR) clauses, and object relative clauses with stylistic inversion (OR–SI) in French. Each sentence type was presented in two versions: either with an animate relative clause (RC) subject and an inanimate object (AS/IO), or with an inanimate RC subject and an animate object (IS/AO). There was an interaction between the RC structure and noun animacy. The advantage of SR sentences over OR and OR–SI sentences disappeared in AS/IO sentences. The interaction between animacy and structure occurred in self-paced reading times and in total fixation times on the RCs, but not in first-pass reading times. The results are consistent with a late interaction between animacy and structural processing during parsing and provide data relevant to several models of parsing.

Adjustments of task-set control processes: Effect of task switch frequency on task-mixing and task-switching costs

The present study tested the hypothesis that task-switch frequency triggers adjustments of task-set control processes. A mixed-task condition where task switches are frequent should promote flexibility—thus improving task-switch performance—whereas a condition where task repetitions are more expected should favour stability—thus improving task-repeat performance. In two experiments, participants performed single-task and mixed-task blocks. In mixed-task blocks, tasks varied randomly on a trial-by-trial basis. For half of the mixed-task blocks, the frequency with which the task changed was 25%, for the other half, it was 50%. Overall, depending on the task-switch frequency, performance on both task-repeat and task-switch trials was modified. Switch cost was reduced and task-repeat performance was altered by the increase in switch probability. This study demonstrates context-sensitive adjustments of task-set control processes. These results further support the view that mixing cost reflects sustained and endogenous components of cognitive control.

The effect of noun phrase type on working memory saturation during sentence comprehension

Double centre-embedded structures such as “the rat the cat the boy chased ate was brown” seem ungrammatical to many human subjects. Using an offline complexity judgement task, Gibson and Thomas (1999) demonstrated that people found such sentences no more difficult to understand when the second verb phrase (VP) was omitted, relative to a condition where all the required VPs were present. According to the Syntactic Prediction Locality Theory (SPLT; Gibson, 1998), this syntactic illusion is determined by the high working memory cost associated with the integration of the second VP. This cost could be reduced by replacing the third noun phrase (the boy) by a pronoun, making the reader more sensitive to the omission of the second VP. This hypothesis was tested in two experiments using French sentences. Both experiments confirmed the syntactic illusion when the second VP was not a pronoun. The second experiment measured the reading times of the VPs and showed that the pronoun induced a longer reading time of the final VP when the second VP was omitted. The overall results indicate a condition under which human subjects could process the most complex part of a sentence with more than one embedded relative clause. The overall results are consistent with most of the hypotheses derived from the SPLT although offline complexity judgements could not be the most sensitive measure to test some of these hypotheses.

Word-list learning and short-term memory

Abstract Ss had to learn (free recall) 15 words in 21 trials. In the even trials, eight new words, varying from one even trial to the next, were presented, according to the groups of Ss, (1) before, (2) after, (3) among the 15 constant words. The purpose of the experiment was to determine the recall variation of new words as a function of the learning of constant words, in the view of the dualist theories, according to which learning makes possible the transfer from STM to LTM, thus discharging STM. The results show that the appearance of new words strongly inhibits the learning and the structuration of the constant words, particularly for groups 1 and 3. The recency effect also makes a better recall of the new words, provided that the constant words structuration should become strong enough.

Le rôle de la similarité des informations en mémoire de travail dans le traitement des phrases grammaticalement très complexes

La syntaxe des langues naturelles est caracterisee par la possibilite d’une recursivite, permettant d’ajouter une proposition enchâssee a l’interieur d’une proposition de meme type. Cependant, une phrase contenant deux propositions relatives enchâssees centralement semble tres difficile a comprendre. Cette difficulte pourrait refleter la restriction d’une capacite de calcul impliquee dans le traitement des phrases. Pour verifier dans quelle mesure cette restriction est liee a la limitation de la memoire de travail, nous avons realise deux experiences ou les participants devaient maintenir des mots tout en traitant des phrases a double enchâssement. Nous avons manipule un facteur affectant la memoire de travail : la similarite entre informations maintenues et informations traitees. Pour les phrases a double enchâssement, le maintien de mots similaires etait plus difficile que le maintien de mots differents. Cet effet n’etait pas constate pour des phrases plus courtes et jugees moins complexes par les lecteurs. Ce resultat etait reproduit dans une seconde experience ou la duree de retention de la charge etait equivalente pour les phrases jugees simples et pour les phrases a double enchâssement. Les resultats confirment le role des ressources de memoire de travail dans le traitement des phrases a double enchâssement.