Perceived structure and the maintenance of attention

It was hypothesized that people can attain complex, hierarchically organized structures for incoming task-relevant information; that the boundaries between the units of information highest in the hierarchy constitute major breaks in the processing and integration of information; and that these major “breakpoints” are times when people are especially vulnerable to distraction. Subjects were trained to perceive formally defined structures in sequences of stimuli. After training, subjects performed a continuous prediction/classification task, using the same sequences of stimuli. Distractors were present during some stimulus events, occurring at each level of the unit hierarchy. Subjects’ response times increased as unit level increased and in the presence of distraction. However, the major hypothesis was not confirmed: The effect of distraction did not vary with unit level. An alternative to this hypothesis is discussed, as well as limitations of the present test.