Expertise training with novel objects leads to left-lateralized facelike electrophysiological responses

Scalp event-related potentials (ERPs) in humans indicate that face and object processing differ approximately 170 ms following stimulus presentation, (it the point of the N170 occipitotemporal component. The NI 70 is delalyed and enhanced to inverted faces but not to inverted objects. We tested whether this inversion effect reflects early mechanisms exclusive to faces or whether it generalizes to other stimuli as a function of visual expertise. ERPs to upright and inverted faces card novel objects (Greebles) were recorded in 10 participants before and after 2 weeks of expertise training with Greebles. The NI 70 component was observed for both faces and Greebles. The results are consistent with previous reports in that the N170 was delayed and enhanced for inverted faces at recording sites in both hemispheres, For Greebles. the same effect of inversion was observed only for experts, primarily in the left hemisphere. These results suggest that the mechanisms underlying the electrophysiologhal face-inversion effect extend to visually homogeneous nonface object categories, at least in the left hemisphere, but only when such mechanisins are recruited by expertise.