Wrapping the Brain Around Vigilance: Using Functional Near-Infrared Spectroscopy to Examine Theories of Vigilance
Vigilance is the ability to sustain attentional focus to detect rare and unpredictable critical events over a prolonged period of time. In operational contexts such as healthcare and aviation, maintaining vigilance is imperative to ensure safety and security. However, individuals are susceptible to a time-related decline in performance, known as the vigilance decrement. There are several major theories for why this vigilance decrement occurs. Resource theory argues that as a vigilance task is being performed, cognitive resources are depleting over time at a faster rate than at which those same resources can be replenished. By contrast, mind wandering theory states that the vigilance decrement occurs because vigilance tasks are monotonous and understimulating leading the individual to withdraw their attention from task and redirect it to task-unrelated thoughts. Finally, resource-control theory states failures of executive control results in cognitive resources being misappropriated from the task to mind wandering, leading to a performance decline. The aim of the current dissertation determined which theory most appropriately accounts for the vigilance decrement by employing functional near infrared spectroscopy (fNIRS) to measure neural activity in multiple regions responsible for vigilance and for mind wandering. Participants completed a vigilance task while wearing the fNIRS device. Results revealed that correct detections declined, and response times were slower with time on task (i.e., the vigilance decrement). Individuals also reported greater workload, higher distress, and loss of engagement after the vigilance task. For vigilance regions, neural activity increased over time on task for some areas, while activity decreased for other areas. For mind wandering regions, all areas showed increased activity over time. Taken together, the current findings suggest that increases in some vigilance regions may suggest a compensatory mechanism as other areas involved in vigilance struggle to meet task demands, as seen by trends showing declining activity over time. At the same time, increases in activity for mind wandering regions may represent a failure to meet those task demands since individuals are mind wandering instead of focusing on the task. The current findings have implications for each vigilance theory and how the vigilance decrement can be mitigated in operational contexts.
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