Dimension intertrial and cueing effects in localization: support for pre-attentively weighted one-route models of saliency.

There are several alternative accounts of dimensional intertrial and cueing effects in singleton feature search tasks. Some accounts assume that these effects arise at post-selective processing stages; dual-route accounts assume them to be perceptual in nature, but coming into play only in non-spatial tasks (e.g., detection but not localization). By contrast, the Dimension Weighting Account (DWA) assumes dimensional effects to arise at pre-attentive processing stages of spatial as well as non-spatial tasks. The data available are ambiguous, permitting no clear-cut choice among these accounts. Therefore, the present study examined for early effects of dimensional weighting in a spatial task, the presence of which is only predicted by the DWA and not by post-selective or dual-route accounts. Salience is known to saturate for high feature contrast and long presentation times. Consequently, with lower bottom-up salience that still permits efficient search, dimensional weights would produce a greater modulation--if present at all. Thus, we examined localization accuracy under brief-presentation conditions in Experiment 1, and localization speed under conditions of low versus high feature contrast in Experiment 2. Both experiments revealed significant dimension intertrial and cueing effects. This strongly argues against dual-route accounts and strengthens evidence for a pre-attentive origin of these effects.