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.
Original language | English |
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Article number | 667 |
Number of pages | 14 |
Journal | Frontiers in Psychology |
Volume | 6 |
DOIs | |
Publication status | Published - 26 May 2015 |
Externally published | Yes |
Keywords
- EEG
- face processing
- visual system
- low-level vision
- high-level vision
- categorization
- FIGURE-GROUND ORGANIZATION
- TEXTURE SEGREGATION
- OBJECT RECOGNITION
- REVERSE HIERARCHIES
- CORTICAL ACTIVATION
- BINOCULAR-RIVALRY
- VISUAL-CORTEX
- FEEDFORWARD
- PERCEPTION
- POTENTIALS