Size-based selection in rapid serial visual presentation

Several recent studies [Farell, B., & Pelli, D. (1993). Can we attend to large and small at the same time? Vision Research, 33, 2757-72; Shih, S., & Sperling, G. (1996). Is there feature-based attentional selection in visual search? Journal of Experimental Psychology: Human Perception and Performance, 22, 758-79] have found that visual selection based on the size of stimuli is impossible when the stimuli are presented in rapid succession in overlapping positions (RSVP paradigm). In the present study effective size-based selection is demonstrated in several conditions with RSVP stimuli. Attention to specific size is highly efficient when stimuli are presented in a single location (at fixation point) and may be possible also with a few (2-4) locations. When overlapping small and large characters are presented without abrupt onsets, then selection by size is effective at least over six locations. The results are explained by certain mandatory properties of spatial attention.