Animate Categories Show Higher Cross-Duration Representational Selectivity in Ventral Occipitotemporal Cortex Under...

Background: The human visual system can extract object-category information from extremely brief visual input, and animate categories often show behavioral advantages over inanimate categories in rapid categorization, visual search, and change-detection tasks. Motivated by these behavioral findings, the present study asked whether, at the representational level, animate categories elicit more category-selective neural patterns than inanimate categories in the ventral visual cortex under brief input. Methods: Using fMRI and correlation-based multivoxel pattern analysis (MVPA), we examined whether activity patterns elicited by animate categories in the ventral occipitotemporal cortex under a 33 ms brief-presentation condition corresponded more selectively to same-category patterns under a 500 ms extended-viewing condition than did patterns elicited by inanimate categories. During scanning, participants viewed animate and inanimate stimuli, each comprising four basic-level subcategories, and performed a noise-detection task that did not require explicit category judgments. Results: Across multiple ROI-definition strategies, animate categories showed significantly higher cross-duration category information than inanimate categories. This effect also remained significant after excluding the human-head category, which contained human-face information. Stimulus-level image-feature analyses further showed that within-category visual homogeneity explained part of the variance in cross-duration category information, particularly in the full stimulus set that included human heads. However, a composite visual homogeneity index derived from HOG, Gabor, and ResNet50 features did not fully account for the higher cross-duration category information observed for animate categories. Conclusions: Overall, these results suggest that, when visual input is highly limited, animate categories elicit VOTC multivoxel patterns that correspond more selectively to same-category patterns under extended viewing.