Expertise Training with Novel Objects Leads to Left-Lateralized Facelike Electrophysiological Responses

Abstract

Scalp event-related potentials (ERPs) in humans indicate that face and object processing differ approximately 170 ms following stimulus presentation, at the point of the N170 occipitotemporal component. The N170 is delayed 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 and novel objects (Greebles) were recorded in 10 participants before and after 2 weeks of expertise training with Greebles. The N170 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 electrophysiological face-inversion effect extend to visually homogeneous nonface object categories, at least in the left hemisphere, but only when such mechanisms are recruited by expertise.

Visual expertise with nonface objects leads to competition with the early perceptual processing of faces in the human occipitotemporal cortex

“…However, given the current debate about the specificity of the face N170 response (25)(26)(27)(28), our goal was to study the mechanisms involved in processing faces that could be recruited by visual expertise. Furthermore, any effect on N170 in response to objects of expertise under the conditions of concurrent stimulation created here may be difficult to interpret.…”

“…Thus, results from fMRI do not address whether the face-like effects associated with visual expertise for nonface objects occur during initial visual categorization and in the same time frame as those effects elicited by faces, that is, at Ϸ150 ms after stimulus onset (12,21,22). In support of the view that the processing of faces shares similar temporal characteristics with the processing of nonface objects, it has recently been found that the human scalp N170 is larger in response to birds, dogs, or cars in experts within each of these categories (23,24) and that the N170 displays a face-like inversion effect after Ϸ10 h of expertise training with novel nonface objects (25).…”

“…However, in contrast to previous studies (23,25), we focused on the N170 in response to faces. We reasoned that if visual expertise with nonface object categories recruits early face-related visual processes, then the N170 in response to faces should be attenuated (i.e., reduced in amplitude) in the presence of another object for which the observer is an expert.…”

Normal acquisition of expertise with greebles in two cases of acquired prosopagnosia

“…Furthermore, unlike studies of real-world object expertise (1,7), studies with greebles allow participants to be tested before and after training. Several studies have reported that greeble training elicited perceptual (2,14) and neural (15,16) effects similar to the effects characteristic of face processing (but see refs. 17-18 for contrary evidence with greebles and novel nongreeble objects).…”

It's a word: Early electrophysiological response to the character likeness of pictographs

“…Moreover, extensive training with novel objects (e.g., greebles) would lead to a stronger N170 response to the trained objects (Rossion, Gauthier, Goffaux, Tarr, & Crommelinck, 2002;Scott, Tanaka, Sheinberg, & Curran, 2006). Given such evidence, the visual word-specific N170 has been argued to reflect the human brain's expertise in reading visual words as a result of years of reading experience.…”