Blink Activity in a Discrimination Task as a Function of Stimulus Modality and Schedule of Presentation

ABSTRACT Eyeblink performance parameters were investigated in subjects engaged in a series of duration discrimination tasks differing in modality (visual vs. auditory) and presentation schedule (fixed vs. variable). Visual tasks were associated with slower blink rates and shorter blink durations than auditory tasks. Sensitivity measures suggested that this difference might be due, in part, to the greater difficulty of the visual tasks. Blink latency declined within and across tasks and was longer for target stimuli which were followed by responses. Since the target stimuli were the short duration stimuli, the latter effect could be a compound of two opposing effects. The first is related to the response, which tends to delay the blink on target trials, while the second, related to decision processes, would tend to increase latencies on nontarget trials. Schedule of stimulus presentation did not affect dependent measures as predicted. RT was unaffected by either of the experimental variables.