The relationship between theory of signal detection statistics d' and beta and 40-Hz EEG during performance on an auditory vigilance task

40-Hz electroencephalographic activity was first noted in rhinencephalic structures in animals during performance on learning tasks and during periods of "hypervigilance". More recently, it has been measured in humans during performance on a variety of cognitive tasks. It has been proposed that this neural activity represents "focused arousal", a functional component of attention, and a neural model of its production has been developed involving the ascending cholinergic reticular system (Sheer, 1984). This conception of 40-Hz EEG potentially has great- implications for both neural and psychological models of attention and memory. However, most of the studies involving human subjects have utilized tasks involving more complex cognitve features. In order to make an unambiguous statement of the relationship of 40-hz EEG to the attention process, it is necessary to utilize a task which does not involve more complex cognitive processes. This study attempted to look more specifically at the role of 40-Hz EEG in attention, through the utilization of an auditory vigilance task. A vigilance task is defined as any task on which performance decreases as a function of time on task, with this decline interpreted as an inability of the subject to sustain attention. An application of the Theory of Signal Detection to the vigilance paradigm provided two variables of interest: 1. d1, which is observer sensitivity and in the vigilance situation represents the ability to sustain attention, was the primary dependent measure; 2. Beta, which is observer response bias and sometimes accounts for the vigilance decrement, was monitored as a control variable. It was hypothesized that the level of 40-Hz EEG measured from the scalp would be correlated with d1, but not Beta during task performance. These expected results were not evidenced. An explanation of these findings is discussed, with an emphasis on the vigilance task parameters and the behavioral data.