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Charles C.-F. Or, Joan Liu-Shuang, Bruno Rossion; Spatiotemporal dynamics of view-sensitive and view-invariant face identity processing. Journal of Vision 2017;17(10):262. doi: https://doi.org/10.1167/17.10.262.
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© ARVO (1962-2015); The Authors (2016-present)
The ability to extract the identity of faces across substantial variations in angular head orientation is critical for face recognition, yet the underlying neural mechanism is not well understood. Using a validated paradigm with fast periodic visual stimulation in electroencephalography (EEG; Liu-Shuang, Norcia, & Rossion, 2014, Neuropsychologia), we investigated the tuning function of face identity perception in 20 observers across 7 ranges of viewpoint variations: 0° (no change), ±15°, ±30°, ±45°, ±60°, ±75°, ±90°. In each 60-s stimulation sequence, images of one single face identity, randomly chosen from our stimulus set, were displayed successively at a rapid rate of F = 6 Hz (6 images/s), interleaved with different face identities at fixed intervals of every 7th face (F/7 Hz = 0.86 Hz). Critically, at every stimulation cycle, faces varied randomly both in viewpoint within a predefined range (e.g. in the ±45° condition, faces were shown between -45° and +45° in steps of 5°) and in size between 80% and 120%. Periodic EEG responses at 6 Hz captured general visual processing of the face stimuli, while those at 0.86 Hz and harmonics captured face individualisation. All observers showed significant face individualisation responses, peaking over bilateral occipito-temporal regions. These responses decreased linearly with increasing viewpoint variations (responses decreased by > 50% between 0° and ±90° conditions), suggesting reduced face identity discrimination. Analysing the face individualisation response in the time-domain revealed a dissociation between an early (~200–300 ms) view-sensitive response and a later (~300–600 ms) view-invariant response, both peaking over the same bilateral occipito-temporal regions. These findings suggest two separate view-based face recognition processes, where an initial reduced ability to discriminate face identities due to viewpoint variations is complemented partly by a later, high-level view-invariant process.
Meeting abstract presented at VSS 2017
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