Holistic processing as measured in the composite task does not always go with right hemisphere processing in face perception

Abstract

Holistic processing has long been considered as a property of right hemisphere processing. Nevertheless, a counterexample was recently found: Chinese character recognition expertise is associated with reduced holistic processing (as measured in the composite task) and increased right hemisphere lateralization (as indicated by a left-side bias in character perception), revealing that they may be separate processes. Through computational modeling, in which we implemented a theory of hemispheric asymmetry in perception that posits a low spatial frequency bias in the right hemisphere and a high spatial frequency bias in the left hemisphere, we showed that when the face recognition task relied purely on featural information, there was a negative correlation between holistic processing and right hemisphere lateralization. In contrast, when the task relied purely on configural information, there was a positive correlation between holistic processing and right hemisphere lateralization. In another simulation with real face images, which naturally embed both featural and configural changes, we observed no correlation between holistic processing and right hemisphere lateralization. This result was replicated behaviorally with human participants. Together, these results suggest that holistic processing (as measured in the composite task) and right hemisphere lateralization are separate processes that can be influenced differentially by task requirements.