Poster D8, Wednesday, August 21, 2019, 5:15 – 7:00 pm, Restaurant Hall
The detection of repetition-based regularities from visual input at 6 months of age
Irene de la Cruz-Pavía1,2, Judit Gervain1,2, Iris Berent3;1Integrative Neuroscience and Cognition Center, CNRS, Paris, 2Integrative Neuroscience and Cognition Center, Université Paris Descartes, 3College of Science, Northeastern University, Boston
Infants’ ability to learn regularities related to repetitions in linguistic sequences (e.g. ABB: “wo fe fe”) has received considerable attention since Marcus et al.’s (1999) first showed that 7-month-olds can generalize different linguistic rules based on these patterns (e.g. ABB vs. ABA: “wo fe fe” vs. “wo fe wo”). But whether this capacity is specific to speech or whether it also extends to sign language is unclear (Rabagliati et al., 2012). Its neural correlates also remain only partly understood. We sought to answer two questions: Is the ability to learn repetition-based regularities found across linguistic modalities? If so, is it similar across all visual stimuli or is sign language processed differently than a non-linguistic visual analogue? We used NIRS to investigate whether 6-month-old infants, never exposed to sign language, were able to extract repetition-based regularities from visual stimuli. In Experiment 1, infants were presented with 6 sequences of two novel disyllabic signs in each block, for a total of seven blocks per condition, in two conditions: in the repetition condition (AA), the signs were identical, in the control conditions (AB), they were different. In Experiment 2, signs were replaced by visual analogues, matched for spatiotemporal properties. We measured infants’ brain responses in the bilateral temporal, parietal and frontal areas using a NIRx NIRScout system (Exp 1: 12 channels/hemisphere, Exp 2: 10 channels/hemisphere). Blocks with artifacts in the signal or when infants were not attending to the stimuli were discarded. We averaged responses across the remaining blocks of each condition. The results of cluster-based permutation tests show that infants discriminated between the AA and AB patterns in both experiments. Remarkably, though, the effect of repetition differed in the two experiments. While signs elicited greater activation to AA relative to AB sequences, visual analogs elicited the opposite pattern. When presented with sign, increased activation to AA sequences — as indexed by concentration changes of both oxy- and deoxyhemoglobin — was found in the bilateral fronto-temporal areas, involving the superior temporal and inferior temporal gyri, including Broca’s region. Spatial clusters included 3 channels in the LH and 4 channels in the RH (all p < 0.001). For the visual analogs, the greater responses to the AB sequences were found in the left fronto-temporo-parietal and the right temporal regions and were limited to changes of oxyhemoglobin concentration. Spatial clusters included 4 channels in the LH and two channels in the RH (all p < 0.001). These results suggest that the ability to extract repetition-based rules is general across language modalities, and that linguistic visual stimuli may be processed differently from other visual input. Corresponding author: i.berent@northeastern.edu - This research was funded by the National Science Foundation (NSF 1528411, PI Berent)
Themes: Development, Signed Language and Gesture
Method: Functional Imaging