Henri Etel Skinner^1,2, Tabitha Cook¹, Kamya Mahendru¹, Janani Aiyer¹, Barry Giesbrecht^1,2; ¹University of California Santa Barbara, ²Institute for Collaborative Biotechnologies

The vigilance decrement has been long characterized as a decline in performance and individuals continuously maintain attention to rarely occurring vigils. Often vigilance tasks rely upon detection rate to characterize this decline, but studies that measure false alarm rates are also able to compute signal detection metrics of sensitivity and criterion. One blindspot of these methods is that reliance on responses indicating a target is present makes them unable to disambiguate between true changes in decision making parameters (sensitivity and criterion) and failures to respond outside of these processes (e.g, due to lapses in responding or lapses in attention). Here subjects viewed a continuous stream of images each appearing for short (1640 ms, 90% of trials) or long (2040 ms, 10% trials) durations. Participants were instructed to make a short/long judgement for each trial. Results showed across time (~5 minute blocks), detection rate and false alarm rate (indexed by “long” responses) declined. Miss rate increased and correct rejection rate remained stable (both indexed by “short” responses). Criterion (c) increased over time (b = 0.0676, se = 0.0156, p < 0.001) while sensitivity (d’) did not change (b = -0.0224, se = 0.0198, p = 0.259). Lastly, while omission rate (failure to respond on any trial) also increased, this was not the driving force behind criterion shifts. These results suggest the driving factors for declines in detection rate appear to be conservative shifts in criterion. While the continuous nature of this task is different from standard vigilance tasks requiring rare responding and other sustained attention tasks requiring frequent responding and rare withholding (i.e., SART), it adds critical information to the study of sustained attention. Specifically the present results indicate declines in detection rate that are characteristic to the vigilance decrement can be driven primarily by shifts in criterion.

Acknowledgements: Research was sponsored by the U.S. Army Research Office and accomplished under cooperative agreement W911NF-19-2-0026 for the Institute for Collaborative Biotechnologies.