| Large variations in the magnitude of attentional capture have been evidenced across a wide range of studies (Burnham, 2007), but the precise nature of these variations is unknown. For example, such variations may reflect variations in the percentage of trials on which capture occurs, or variation in the amount of resources being allocated to a stimulus on a given trial. The present study used a modified spatial cueing task to address two related issues. The first experiment explored the hypothesis that the magnitude of attentional capture varies systematically as a function of cue-target similarity. Targets of a particular color were preceded by uninformative peripheral cues consisting of varying "percentages" of the target color. As predicted, the magnitude of attentional capture varied directly with the similarity between cue and target. The second experiment explored whether reduced magnitude of capture in a 50% target color condition reflects a mixture of trials in which attention is fully captured or not captured at all. Mixture analyses, consisting of a multinomial maximum likelihood mixture (MMLM) analysis and an analysis of variability, were conducted on obtained reaction time distributions. Although the MMLM analysis was inconclusive, the variability analysis proved inconsistent with a mixture model. |
