Neurophysiological correlates of face gender processing in humans

Event-related potentials (ERPs) were recorded while subjects were involved in three gender-processing tasks based on human faces and on human hands. In one condition all stimuli were only of one gender, preventing any gender discrimination. In a second condition, faces (or hands) of men and women were intermixed but the gender was irrelevant for the subject's task; hence gender discrimination was assumed to be incidental. In the third condition, the task required explicit gender discrimination; gender processing was therefore assumed to be intentional. Gender processing had no effect on the occipito-temporal negative potential at approximately 170 ms after stimulation (N170 component of the ERP), suggesting that the neural mechanisms involved in the structural encoding of faces are different from those involved in the extraction of gender-related facial features. In contrast, incidental and intentional processing of face (but not hand) gender affected the ERPs between 145 and 185 ms from stimulus onset at more anterior scalp locations. This effect was interpreted as evidence for the direct visual processing of faces as described in Bruce and Young's model [Bruce, V. & Young, A. (1986) Br. J. Psychol., 77, 305-327]. Additional gender discrimination effects were observed for both faces and hands at mid-parietal sites around 45-85 ms latency, in the incidental task only. This difference was tentatively assumed to reflect an early mechanism of coarse visual categorization. Finally, intentional (but not incidental) gender processing affected the ERPs during a later epoch starting from approximately 200 ms and ending at approximately 250 ms for faces, and approximately 350 ms for hands. This later effect might be related to attention-based gender categorization or to a more general categorization activity.

Development of auditory cognition in 5- to 10-year-old children: Focus on speech-in-babble-noise perception

Speech-in-noise perception is consistently reported to be impaired in learning disorders, which stresses the importance of documenting its developmental course in young children. In this cross-sectional study, ninety children (41 females, 5.5-11.6 years old) and nineteen normal-hearing adults (15 females, 20-30 years old) were tested with a newly developed closed-set speech perception in babble-noise test, combining two levels of phonological difficulty and two noise levels. Results showed that speech-in-babble-noise perception takes a definite maturation step around 7 years of age (d = 1.17, grade effect) and is not mature at 10 years of age when compared to young adults (d = 0.94, group effect). Developmental trajectories of both accuracy and response times were evaluated, with influences of psycholinguistic factors, to foster the development of adequate screening tests.