Phasic Not Tonic Pupillary Responses Vary With Auditory Vigilance Performance

ABSTRACT Pupillary movements were monitored as 11 university students listened to a series of 1K Hz 50‐msec tone bursts presented at 3.2‐sec intervals for a period of 48 min. Their task was to report target tones (‐3dB), which were presented randomly with a probability of 0.12. Under these conditions, monitoring performance deteriorated as a function of time on the task. This vigilance decrement was attributed to both a decrease in listener sensitivity and a conservative shift in decision criterion, as determined by a signal detection analysis. The amplitude of the phasic task‐evoked pupillary response reflected these changes in performance, decreasing significantly over time on the task. Tonic or baseline pupillary diameter exhibited no such relationship with performance. These results are interpreted in the context of an activation theory of attention that suggests that a common neurophysiological system mediates both intensive and sustained attentional processes.