Is object-based attention mandatory or under strategic control? In an adapted spatial cuing paradigm, participants focused initially on a central arrow cue that was part of a perceptual group (Experiment 1) or a uniformly connected object (Experiment 2), encompassing one of the potential target locations. The cue always pointed to an opposite,…

The influence of frequency of occurrence of a visual stimulus on encoding processes is investigated, to discover what mechanisms allow cognitive processes to modify perceptual processes. Six experiments are described and the results are discussed. (MH)

A sample lacking variance was judged less probable than a variable sample and a sample representing the upper half of the population was judged less likely than one representing both. As range and mean approached an ideal, samples appeared more probable. A hierarchical model of sample cues seems appropriate. (CPT)