ALLOCATING VISUAL-ATTENTION - TESTS OF A 2-PROCESS MODEL

Observers require less time to identify a visual target when its locat ion is cued in advance than when it is not cued, and the magnitude of the improvement depends on the validity of the cue. According to J. Jo nides's (1983) 2-process model, there exist 2 possible modes of attent ional readiness: a focused-attention mode and a diffuse-attention mode . Observers are assumed to enter the focused-attention mode on a propo rtion of trials that matches the validity of the cue and to enter the diffuse-attention mode on the remaining trials. The present experiment tested and rejected the response time mixture prediction of the 2-pro cess model. An instance of the class of 1-process models in which perc eptual objects are sampled in parallel according to, the validity of t he cue was evaluated. A stochastic simulation of the model yielded res ults that paralleled those of the experiment.