Robust Selectivity to Two-Object Images in Human Visual Cortex

We can recognize objects in complex images in a fraction of a second [1-3]. Neuronal responses in macaque areas V4 and inferior temporal cortex [4-15] to preferred stimuli are typically suppressed by the addition of other objects within the receptive field (see, however, [16, 17]). How can this suppression be reconciled with rapid visual recognition in complex scenes? Certain "special categories" could be unaffected by other objects [18], but this leaves the problem unsolved for other categories. Another possibility is that serial attentional shifts help ameliorate the problem of distractor objects [19-21]. Yet, psychophysical studies [1-3], scalp recordings [1], and neurophysiological recordings [14-16, 22-24] suggest that the initial sweep of visual processing contains a significant amount of information. We recorded intracranial field potentials in human visual cortex during presentation of flashes of two-object images. Visual selectivity from temporal cortex during the initial similar to 200 ms was largely robust to the presence of other objects. We could train linear decoders on the responses to isolated objects and decode information in two-object images. These observations are compatible with parallel, hierarchical, and feed-forward theories of rapid visual recognition [25] and may provide a neural substrate to begin to unravel rapid recognition in natural scenes.