Bottom-up attention capture with distractor and target singletons defined in the same (color) dimension is not a matter of feature uncertainty

In visual search, attention capture by an irrelevant color-singleton distractor in another feature dimension than the target is dependent on whether or not the distractor changes its feature: Capture is present if the irrelevant color distractor can take on different features across trials, but absent if the distractor takes on only one feature throughout all trials. This influence could be due to down-weighting of the entire color map. Here we tested whether a similar effect could also be brought about by down-weighting of specific color channels within the same maps. We investigated whether a similar dependence of capture on color certainty might hold true if the distractor were defined in the same (color) dimension as the target. At odds with this possibility, in the first and third blocks—in which feature uncertainty was absent—an irrelevant distractor of a certain color captured attention. In addition, in a second block, varying the distractor color created feature uncertainty, but this did not increase capture. Repeating the exact same procedure with the same participants after one week confirmed the stability of the results. The present study showed that a color distractor presented in the same (color) dimension as the target captures attention independent of feature uncertainty. Thus, the down-weighting of single irrelevant color channels within the same feature map used for target search is not a matter of feature uncertainty.

Attention capture is temporally stable: Evidence from mixed-model correlations

Studies on domain-specific expertise in visual attention, on its cognitive enhancement, or its pathology require individually reliable measurement of visual attention. Yet, the reliability of the most widely used reaction time (RT) differences measuring visual attention is in doubt or unknown. Therefore, we used novel methods of analyses based on linear mixed models (LMMs) and tested the temporal stability, as one index of reliability, of three attentional RT effects in the popular additional-singleton research protocol: (1) bottom-up, (2) top-down, and (3) memory-driven (intertrial priming) influences on attention capture effects. Participants searched for a target having one specific color in most (Exp. 1) or all (Exp. 2) trials. Together with the target, in half (Exp. 1) or two thirds (Exp. 2) of the trials, a distractor was presented that stood out by the target's (Exp. 1) or a target-similar (Exp. 2) color, therefore matching a top-down search set, or by a different color, capturing attention in a bottom-up way. Also, matching distractors were primed or unprimed by the target color of the preceding trial. We analyzed all three attention capture effects in manual and target fixation RTs at two different times, separated by one (Exp. 1 and 2) or four weeks (only in Exp. 1). Random slope correlations of LMMs and standard correlation coefficients computed on individual participants' effect scores showed that RT capture effects were in general temporally stable for both time intervals and dependent variables. These results demonstrate the test-retest reliability necessary for looking at individual differences of attentional RT effects.