title: Reaction time for object categorization is predicted by representational distance.
abstract: How does the brain translate an internal representation of an object into a decision about the object's category? Recent studies have uncovered the structure of object representations in inferior temporal cortex (IT) using multivariate pattern analysis methods. These studies have shown that representations of individual object exemplars in IT occupy distinct locations in a high-dimensional activation space, with object exemplar representations clustering into distinguishable regions based on category (e.g., animate vs. inanimate objects). In this study, we hypothesized that a representational boundary between category representations in this activation space also constitutes a decision boundary for categorization. We show that behavioral RTs for categorizing objects are well described by our activation space hypothesis. Interpreted in terms of classical and contemporary models of decision-making, our results suggest that the process of settling on an internal representation of a stimulus is itself partially constitutive of decision-making for object categorization.
authors.affiliation: Macquarie University, Sydney, Australia.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Carlson
authors.forename: J Brendan
authors.initials: JB
authors.lastname: Ritchie
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Kriegeskorte
authors.forename: Samir
authors.initials: S
authors.lastname: Durvasula
authors.forename: Junsheng
authors.initials: J
authors.lastname: Ma
mesh_terms: D003657:Decision Making / Q000502:physiology; D004215:Distance Perception / Q000502:physiology*; D005544:Forecasting; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D011930:Reaction Time / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*