Face processing in congenitally deaf signers

Studies on face processing in congenitally deaf signers have revealed alterations at both the behavioural and neural levels. Nevertheless, a systematic assessment of different aspects of face processing in this population is lacking. We tested fourteen congenitally deaf signers and fourteen hearing controls, using fast periodic visual stimulation paradigms while the EEG was recorded. Three different levels of face processing were evaluated: 1) generic face categorization (faces within a sequence of objects); 2) individual face discrimination (different vs. identical unfamiliarfaces) and 3) emotional facial expression discrimination (expressive vs. neutral faces) The stimuli within each experiment were presented with 1.2 and 6 Hz. In Experiments 1 and 3 only deaf signers displayed a left lateralized hemispheric dominance of the SSR. In Experiment 2the deaf signers had a larger amplitude at frontal and central electrodes as compared to hearing participants, possibly suggesting a cross-modal activation of auditory cortices. Our results show that congenitally deaf signers exhibit distinct changes for different aspects of face processing.