The Time Course of Natural Scene Perception with Reduced Attention Scene Perception with Reduced Attention Author Names and Affiliations

20 Attention is thought to impose an informational bottleneck on vision by selecting 21 particular information from visual scenes for enhanced processing. Behavioral 22 evidence suggests, however, that some scene information can be extracted even 23 when attention is directed elsewhere. Here, we investigated the neural correlates of 24 this ability by examining how attention affects electrophysiological markers of scene 25 perception. In two electro-encephalography (EEG) experiments, human subjects 26 categorized real-world scenes as man-made or natural (full attention condition) or 27 performed tasks on unrelated stimuli in the center or periphery of the scenes 28 (reduced attention conditions). Scene processing was examined in two ways: 29 traditional trial averaging was used to assess the presence of a categorical man30 made/natural distinction in event-related potentials (ERPs), while single-trial analyses 31 assessed whether EEG activity was modulated by scene statistics that are diagnostic 32 of naturalness of individual scenes. The results indicated that evoked activity up to 33 250 ms was unaffected by reduced attention, showing intact categorical differences 34 between man-made and natural scenes and strong modulations of single-trial activity 35 by scene statistics in all conditions. Thus, initial processing of both categorical and 36 individual scene information remained intact with reduced attention. Importantly, 37 however, attention did have profound effects on later evoked activity: full attention on 38 the scene resulted in prolonged man-made/natural differences, increased neural 39 sensitivity to scene statistics, and enhanced scene memory. These results show that 40 initial processing of real-world scene information is intact with diminished attention, 41 but that the depth of processing of this information does depend on attention. 42 43