Neuroscience & Psychology Postgraduate Society Seminars

The discrete stages of face processing

The subjectively seamless nature of visual experience would intuitively suggest that the underlying representations of the visual world evolve continuously. However, there is an often considered, but not widely accepted, alternative suggesting that the brain builds visual representations across a number of distinct information processing epochs. To examine this claim, we developed a new method, based on Bubbles (Gosselin & Schyns, 2001), to relate the information processing states of the brain to its EEG oscillatory activity. We derived the sensitivity of an integrated brain signal, low frequency EEG oscillations, to facial features when observers resolved a variety of the tasks. In particular, we show that theta oscillations support discrete information processing epochs, corresponding to a modulated sensitivity of the brain to specific facial features. We reveal the integration of features over several epochs to forge specific visual representations for different face categorizations. These later epochs not only represent more facial features, but they also integrate information across hemi-fields (i.e. bilaterally rather than contra-laterally). The evidence of processing epochs reported here supports the idea that visual representations of faces evolve discretely in the brain.