Abstract
We recently demonstrated (VSS 2003) that the presentation of novel, unexpected stimuli in an RSVP leads to a profound but extremely short-lived perceptual deficit in detecting a subsequently presented target. The lifespan of this impairment, lasting about 3 trials, suggests that it represents a new and distinct form of attentional deficit to explicit perception, named Surprise Blindness (SB). Here, we used functional magnetic resonance imaging to localize the neural circuits involved in SB. For each of the forty trials, subjects (n=30) searched for a single target letter in an RSVP of distractor letters, with each letter presented for 100ms. Six of the trials included the presentation of an ‘oddball’ face occurring 330ms prior to the presentation of the target. As expected, subjects were profoundly impaired in detecting the target when it occurred after an oddball, and this perceptual deficit vanished by the 4th oddball presentation. A network of lateral frontal cortex and temporo-parietal junction areas not only showed activation for each oddball, but the amplitude of this activation decreased markedly over the first few oddball presentations, in accordance with the group behavioral performance. This decrease was not simply due to sensory adaptation or priming, since the fusiform gyrus's response to each face was constant across all oddball presentations. These imaging results corroborate ERP studies showing a decaying response to successive novel stimuli in a parieto-frontal network. They also suggest that the activation of this neural network with oddball presentations may transiently impair subjects' ability to consciously perceive subsequent visual events.
Supported by NSF Grant BCS-0094992.