Novel popout is an attention-based phenomenon: an ERP analysis

When observers are given a brief glimpse of a display containing one novel object and three repeated objects, they are often better able to report the location of the novel object than the location of any one of the repeated objects. The present study contrasted two interpretations of this "novel popout" effect. The attention-based interpretation suggests that the novel popout is an attentional phenomenon, occurring during the initial processing of the four-object display. The retrieval-based interpretation suggests that novel popout is due to differential processing occurring when observers are subsequently probed for the location of one of the objects in the display. ERP measures recorded while subjects performed the novel popout task revealed differences during the initial processing of the four-object display but not subsequent to the presentation of a localization probe. The findings are most consistent with the attention-based interpretation of novel popout, which suggests that attention is rapidly drawn to the novel object in an otherwise familiar display.