Abstract
Priming of Pop-out (PoP) refers to the observation that participants are quicker to orient to a pop-out item if the color of the current pop-out stimulus is the same as the color of the pop-out stimulus on the preceding trial. Lee, Mozer & Vecera (2009) asked whether priming of pop-out was due to the momentary storage of the target color’s representation in Visual Short-Term Memory (VSTM) from one trial to the next. They loaded VSTM with four colored items and reasoned that if PoP is dependent on VSTM retaining target color information, then over-loading VSTM with these colors should wipe out PoP. Across four experiments, they consistently found that VSTM load was unrelated to PoP. Across three experiments, here we examined whether PoP is dependent on spatial VSTM resources, inspired by the findings that serial search is not affected by feature- but only spatial-VSTM load (Woodman & Luck, 2004). In Experiment 1, we compared feature- and spatial-VSTM load. We replicated the results of Lee et al.: feature-VSTM load had no effect on PoP. However, PoP was significantly reduced under spatial-VSTM load. In Experiment 2, we manipulated the amount of load (1 vs. 4 in feature-VSTM; 2 vs. 4 in Spatial-VSTM). Feature load had no effect on PoP. In contrast, the magnitude of PoP decreased with increased spatial load. In Experiment 3, we varied set size (3 vs. 12) in the PoP task: RTs decreased with larger set size and PoP decreased in magnitude. Importantly, the effect of set size did not interact with the effect of spatial-VSTM load in PoP. The results suggest that the degree to which a pop-out stimulus can direct attention unto itself is critically dependent on availability of resources in spatial VSTM, challenging current theories of parallel search and attentional guidance.
Meeting abstract presented at VSS 2013