title: Segmentation precedes face categorization under suboptimal conditions.
abstract: Both categorization and segmentation processes play a crucial role in face perception. However, the functional relation between these subprocesses is currently unclear. The present study investigates the temporal relation between segmentation-related and category-selective responses in the brain, using electroencephalography (EEG). Surface segmentation and category content were both manipulated using texture-defined objects, including faces. This allowed us to study brain activity related to segmentation and to categorization. In the main experiment, participants viewed texture-defined objects for a duration of 800 ms. EEG results revealed that segmentation-related responses precede category-selective responses. Three additional experiments revealed that the presence and timing of categorization depends on stimulus properties and presentation duration. Photographic objects were presented for a long and short (92 ms) duration and evoked fast category-selective responses in both cases. On the other hand, presentation of texture-defined objects for a short duration only evoked segmentation-related but no category-selective responses. Category-selective responses were much slower when evoked by texture-defined than by photographic objects. We suggest that in case of categorization of objects under suboptimal conditions, such as when low-level stimulus properties are not sufficient for fast object categorization, segmentation facilitates the slower categorization process.
authors.affiliation: Department of Experimental Psychology, Helmholtz Institute, Utrecht University Utrecht, Netherlands ; Department of Developmental Psychology, Utrecht University Utrecht, Netherlands.
authors.forename: Carlijn
authors.initials: C
authors.lastname: Van Den Boomen
authors.affiliation: Department of Experimental Psychology, Helmholtz Institute, Utrecht University Utrecht, Netherlands ; Department of Cognitive Psychology, Vrije Universiteit Amsterdam, Netherlands.
authors.forename: Johannes J
authors.initials: JJ
authors.lastname: Fahrenfort
authors.affiliation: Department of Experimental Psychology, Helmholtz Institute, Utrecht University Utrecht, Netherlands ; Department of Developmental Psychology, Utrecht University Utrecht, Netherlands ; Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen Nijmegen, Netherlands ; Centre for Language Studies, Radboud University Nijmegen Nijmegen, Netherlands.
authors.forename: Tineke M
authors.initials: TM
authors.lastname: Snijders
authors.affiliation: Department of Experimental Psychology, Helmholtz Institute, Utrecht University Utrecht, Netherlands ; Department of Developmental Psychology, Utrecht University Utrecht, Netherlands ; Department of Child and Adolescent Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Netherlands.
authors.forename: Chantal
authors.initials: C
authors.lastname: Kemner
keywords: EEG; categorization; face processing; high-level vision; low-level vision; visual system