Display size effects in visual search: analyses of reaction time distributions as mixtures.
In a reanalysis of data from Cousineau and Shiffrin (2004) and two new visual search experiments, we used a likelihood ratio test to examine the full distributions of reaction time (RT) for evidence that the display size effect is a mixture-type effect that occurs on only a proportion of trials, leaving RT in the remaining trials unaffected, as is predicted by serial self-terminating search models. Experiment 1 was a reanalysis of Cousineau and Shiffrin's data, for which a mixture effect had previously been established by a bimodal distribution of RTs, and the results confirmed that the likelihood ratio test could also detect this mixture. Experiment 2 applied the likelihood ratio test within a more standard visual search task with a relatively easy target/distractor discrimination, and Experiment 3 applied it within a target identification search task within the same types of stimuli. Neither of these experiments provided any evidence for the mixture-type display size effect predicted by serial self-terminating search models. Overall, these results suggest that serial self-terminating search models may generally be applicable only with relatively difficult target/distractor discriminations, and then only for some participants. In addition, they further illustrate the utility of analysing full RT distributions in addition to mean RT.
Reynolds
Ann
A
Department of Psychology, University of Otago, Dunedin, New Zealand. ann@psy.otago.ac.nz
Miller
Jeff
J
D001288:Attention; D004193:Discrimination Learning; D006801:Humans; D016013:Likelihood Functions; D009949:Orientation; D010364:Pattern Recognition, Visual; D011930:Reaction Time; D012858:Size Perception