Josette Serres

Pupil diameter measurement errors as a function of gaze direction in corneal reflection eyetrackers

Pupil dilation is a useful, noninvasive technique for measuring the change in cognitive load. Since it is implicit and nonverbal, it is particularly useful with preverbal or nonverbal participants. In cognitive psychology, pupil dilation is most often measured by corneal reflection eye-tracking devices. The present study investigates the effect of gaze position on pupil size estimation by three common eye-tracking systems. The task consisted of a simple object pursuit situation, as a sphere rotated around the display screen. Systematic errors of pupil size estimation were found with all three systems. Implications for task-elicited pupillometry, especially for gaze-contingent studies such as object tracking or reading, are discussed.

Motor anticipation failure in infants with autism: a retrospective analysis of feeding situations

Previous studies on autism have shown a lack of motor anticipation in children and adults with autism. As part of a programme of research into early detection of autism, we focussed on an everyday situation: spoon-feeding. We hypothesize that an anticipation deficit may be found very early on by observing whether the baby opens his or her mouth in anticipation of the spoon’s approach. The study is based on a retrospective analysis from family home movies. Observation of infants later diagnosed with autism or an autism spectrum disorder (ASD) (n = 13) and infants with typical development (n = 14) between 4 and 6 months old show that the autism/ASD group has an early anticipation deficit.

Development of lexical–semantic language system:N400 priming effect for spoken words in 18- and 24-month old children

Our aim was to investigate whether developing language system, as measured by a priming task for spoken words, is organized by semantic categories. Event-related potentials (ERPs) were recorded during a priming task for spoken words in 18- and 24-month-old monolingual French learning children. Spoken word pairs were either semantically related (e.g., train-bike) or unrelated (e.g., chicken-bike). The results showed that the N400-like priming effect occurred in 24-month-olds over the right parietal-occipital recording sites. In 18-month-olds the effect was observed similarly to 24-month-olds only in those children with higher word production ability. The results suggest that words are categorically organized in the mental lexicon of children at the age of 2 years and even earlier in children with a high vocabulary.

A Consonant/Vowel Asymmetry in Word-form Processing: Evidence in Childhood and in Adulthood

In the literature, consonants have been proposed to be more important than vowels in lexical activation and access processes. However, despite a large body of evidence in the infant and adult literature, a recent study revealed a disappearance of the bias in newly learned words over the preschool years (Havy, Bertoncini, & Nazzi, 2011). As a first explanation of this developmental change, one might consider that the bias initially applies to all lexical processes to progressively narrow down its influence to specific cognitive and lexical mechanisms. Alternatively, the task used to address this question in Havy et al. (2011) might not have been sensitive enough to capture the bias in new-word learning from a certain age. The aim of the present study was to evaluate the extent to which the pattern observed over this period of development resulted from a lack of sensitivity of the task or from a real disappearance of the consonant bias during word learning. To address this issue, we designed two experiments evaluating the strength of the consonant bias during word learning in preschoolers and adults in ‘congruent’ versus ‘incongruent’ situations. Both experiments tested the recognition of a target object among two objects with similar names. In the congruent situation, the proposed target corresponded to one of the items presented. In the incongruent situation, the target differed from one of the items by a consonant and from the other by a vowel. Both experiments revealed the existence of a consonant bias in childhood and in adulthood. There was no difference between onset and coda processing in the congruent situation, but there was a slight advantage in adulthood for the first congruent information perceived in the incongruent situation.

On the importance of being bilingual: Word stress processing in a context of segmental variability

French-learning infants have language-specific difficulties in processing lexical stress due to the lack of lexical stress in French. These difficulties in discriminating between words with stress-initial (trochaic) and stress-final (iambic) patterns emerge by 10months of age in the easier context of low variability (using a single item pronounced with a trochaic pattern vs. an iambic pattern) as well as in the more challenging context of high segmental variability (using lists of segmentally different trochaic and iambic items). These findings raise the question of stress pattern perception in simultaneous bilinguals learning French and a second language using stress at the lexical level. Bijeljac-Babic, Serres, Höhle, and Nazzi (2012) established that at 10 months of age, in the simpler context of low variability, such bilinguals have better stress discrimination abilities than French-learning monolinguals. The current study explored whether this advantage extends to the more challenging context of high segmental variability. Results first establish stress pattern discrimination in a group of bilingual 10-month-olds learning French and one language with (variable) lexical stress, but not in French-learning 10-month-old monolinguals. Second, discrimination in bilinguals appeared not to be affected by the language balance of the infants, suggesting that sensitivity to stress patterns might be maintained in these bilingual infants provided that they hear at least 30% of a language with lexical stress.

Narrowing perceptual sensitivity to the native language in infancy: exogenous influences on developmental timing

The infancy literature situates the perceptual narrowing of speech sounds at around 10 months of age, but little is known about the mechanisms that influence individual differences in this developmental milestone. We hypothesized that such differences might in part be explained by characteristics of mother-child interaction. Infant sensitivity to syllables from their native tongue was compared longitudinally to sensitivity to non-native phonemes, at 6 months and again at 10 months. We replicated previous findings that at the group level, both 6- and 10- month-olds were able to discriminate contrasts in their native language, but only 6-month-olds succeeded in discriminating contrasts in the non-native language. However, when discrimination was assessed for separate groups on the basis of mother-child interaction—a ‘high contingency group’ and a ‘moderate contingency’ group—the vast majority of infants in both groups showed the expected developmental pattern by 10 months, but only infants in the ‘high contingency’ group showed early specialization for their native phonemes by failing to discriminate non-native contrasts at 6-months. The findings suggest that the quality of mother-child interaction is one of the exogenous factors influencing the timing of infant specialization for speech processing.

Constraints on the Timing of Infant Cognitive Change: Domain-Specific or Domain-General?

Most studies of infant cognition focus on group data from single domains. Yet, without the multidomain testing of the same infants longitudinally, such data cannot be used to evaluate whether the timing of cognitive change occurs in a domain-general or a domain-specific way. We present the results of a longitudinal study pooling data from three European laboratories set up identically. Over 100 healthy, monolingual infants each underwent multi-domain testing at 6 and again at 10 months in six experimental tasks (speech processing, face processing, and action/event processing), as well as a videotaped 3-minute recording of mother/infant dyads in a play session with an identical set of toys. Previous research examined the effects of maternal sensitivity only on general intelligence measures, but our approach is novel in that it assessed dyadic effects on specific cognitive domains, attempting to pinpoint in finer detail the effects of mother-infant dyadic interaction on the timing of cognitive change. Our findings highlight the importance of a multi-domain approach, in that unlike the assumptions drawn from cross-sectional data, our longitudinal study yielded different developmental timing across domains within the same infants. Our results also highlight a crucial difference: at the group level 6- and 10-month-olds display the expected effects found in previous research, but when re-analysed according to mother-child interaction ratings, the quality of dyadic interaction style turned out to subtly foster or delay development in domainspecific and age-specific ways, contributing to the range of individual differences in timing that we observe in cognitive development over the first year of life.

Understanding goal-directed human actions and physical causality: The role of mother-infant interaction

This study addresses the relation between early cognitive development and mother-infant interaction. Infants at the age of 6 and 10 months recruited from labs in three European countries--Germany, Great Britain, and France--were tested on two cognitive tasks: understanding of goal-directed human action and physical causality. Mother-infant interaction was assessed with the CARE-Index. In the goal-directed action task, the overall sample of the 6-month olds did not yet reliably discriminate between an object-change and a path-change trial while a subsample of infants of modestly controlling mothers did. All infants at 10 months of age showed discrimination. In the physical causality task, the overall sample of the 6-month olds did not yet reliably discriminate between an expected and an unexpected launching event. At 10 months of age, the overall sample showed discrimination, due to the major subsample of infants of highly sensitive mothers. Our findings support the view that exogenous factors influence cognitive development within a particular time window, in highly specific ways, depending on the age of the subjects, the cognitive domain, and the quality of mother-infant interaction.