Abstract
Scene gist is recognized within a single fixation. However, it is unknown whether gist recognition varies over space, specifically central versus peripheral vision, and over time, within a fixation. A related issue is whether attentional focus affects scene gist recognition (Evans & Triesman, 2005; Li, et al., 2001).
Previous research (Larson & Loschky, 2008) showed that both central and peripheral information can produce equal scene gist recognition, provided there is roughly twice as much area in the periphery. However, those studies did not vary processing time (through masking) or manipulate attention.
Methods: Scenes contained information only in a central circular region (the “window”), or blocked that central region (the “scotoma”) and only contained information in the periphery. These conditions were perfectly divided by a critical radius, such that both window and scotoma images produced equal gist accuracy when unmasked (i.e., unlimited processing time). Images and masks were presented for 24 ms each, with two SOAs (24 or 84 ms), and a no-mask condition. Central fixation was ensured by using an eyetracker and an algorithm requiring fixation. We manipulated the focus of attention by randomly interleaving trials of an alternate task, in which subjects had to discriminate a small briefly flashed “E” or “3” at fixation for 20% of trials (20% E/3 task, 80% gist recognition task).
Results: There was an interaction between central versus peripheral information and SOA. At the shortest SOA, central information produced better gist recognition than peripheral information. Unlimited processing time produced equal performance for central and peripheral information, as predicted based on use of the critical radius.
Conclusion: When attention is focused at the center of vision, centrally presented information is preferred early in processing, though with unlimited processing time, gist is equally processed in central or peripheral vision. Thus, gist recognition was influenced by attention.