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Detections, false responses, and response latencies were measured for subjects monitoring auditory signals (more‐intense noise pulses in a periodic‐noise pulse train) over a 1‐h period following administration of a stimulating drug (D‐amphetamine), an antiadrenergic tranquilizer (chlorpromazine), an anticholinergic tranquilizer (benactyzine), and a placebo. It was tentatively concluded that changes in performance over time following administration of the placebo could be explained in terms of shifts in subjects' criteria for responding and that, following administration of the tranquilizer, shifts both in effective sensitivity and response criteria were occurring. Following injection of D‐amphetamine, performance remained relatively constant throughout the monitoring period.

The size and form of the b-wave of the human electroretinogram are shown to be dependent on the duration as well as on the intensity (the term stimulus intensity as used in this paper refers to luminance specified in ft-L.) of the stimulating light. In determining the amplitude of submaximal b-waves, intensity and duration share equally until a certain critical duration is reached. Above this critical duration of about 100 msec in the dark-adapted eye, less under conditions of light-adaptation, amplitude is determined by intensity alone. The latency of the response, however, is determined without reference to the stimulus duration. It is interesting to note that a critical duration of just over 100 msec has also been reported from psychophysical studies of the dark-adapted eye in which visual threshold rather than electrical response criteria were used.