Rhythmic oscillations in the performance of a sustained attention task.

Attempts to sustain a narrow focus of attention over a long period of time are effortful and are punctuated by lapses. Most studies of sustained attention performance obscure the presence and pattern oflapses by reporting measures that are summed across the entire period of an individual's performance, or that are average scores for blocks of trials across many participants. In the present study we attempted to explore fluctuation in the attention of individual participants over the course of a vigilance task and to quantify its periodicity, if any exists.

Measures of variations in performance during a sustained attention task.

In this study the authors developed and explored measures of short-term variations in accuracy on a test of sustained attention, a departure from traditional measures of average performance over long periods. The study participants were normal young adults, actively engaged in a continuous performance test (CPT). Both correct (hits) and incorrect (misses) responses to CPT targets appeared to aggregate in runs (2 or more consecutive hits or misses).