“…Studies which relate changes in the electroencephalogram with vigilance have generally shown that deterioration in performance is associated with increased theta and decreased alpha intensity (Carriero, 1977;Gale et al, 1977;Kornfield and Beatty, 1977;O'Hanlon and Beatty, 1977), although Townsend andJohnson (1979) andO'Hanlon and have indicated that beta activity is also altered. These changes reflect decreased cortical arousal which is likely to occur during long monotonous tasks requiring sustained attention (Belyavin and Wright, 1987).…”