Exploring auditory sustained attention in dynamic environments

A vigilance decrement refers to striking decline in human performance over time that occurs when completing a monotonous task with infrequent targets. Its classic pattern can be behaviourally expressed by an increase in the number of misses and/or reaction times on correct responses over time on the task. Usually with static stimuli, the effect of a vigilance decrement has been well documented in the visual modality, such that more frequent targets result in better sustained attention compared with infrequent targets. In the auditory modality, however, there has been less focus on vigilance. This thesis presents a new measure of auditory sustained attention, the auditory Multiple Object Monitoring (aMOM) task, where participants are required to continuously monitor for targets at varying rates of occurrence (target frequency hereafter). The task is designed to simulate critical features of dynamic real-life environments in abstraction, as presented in sounds of different timbres, sounds comprising/lacking pitch changes and sounds overlapping in time. We then used the aMOM task to assess auditory sustained attention under two conditions different in target frequency (low at ~ 12% vs high at ~ 50%). Our Bayesian analyses showed that we observed a partial vigilance decrement in the auditory modality when the target frequency was relatively low. The results on participants’ reaction times were similar to the documented pattern of a vigilance decrement, but the findings on miss rates were unclear. Although the results for miss rates were inconclusive, the increased correct reaction times over time suggest that a vigilance decrement may occur in the auditory modality as well as in vision. The aMOM task also provides a tool for further examining fundamental cognitive mechanisms that underpins auditory sustained attention.