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Vigilance, or sustained attention, typically requires observers to monitor many signals for infrequent critical signals over extended periods of time (Warm, 2003). Infrequent signals, otherwise known as critical signals, are presented differently in some manner and less frequently than the more common and frequent neutral signals. Critical signals typically indicate impending danger that requires immediate action to be made by an observer. Past research posits that sustained attention during a vigilance task declines for some time and is most likely caused by mindlessness, or a withdrawal of attention from the monitoring task (Robertson et al., 1997). The present research investigated the ability of participants to detect changes in visual stimuli and the confidence in their ability to accurately identify critical signals. Participants were presented with sets of stimuli containing four arrows in a circle facing the same clockwise or counter-clockwise direction. Participants responded to the critical signal in the set, which was when one arrow faced the direction opposite to the other three. Participants were queried about their confidence in the accuracy of their detections after all critical and an equal number of neutral signals. Our expectation is consistent with the typical decline in attention over time; that is, confidence will also diminish as the vigilance task continues. The results of the present study can be applied to any situation requiring sustained monitoring of informational displays. For example, pilots and technicians are required to monitor streams of visual and auditory stimuli for prolonged periods of time where the consequence of not detecting a critical signal could be catastrophic. Understanding more about vigilance processes can help avoid disaster.

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Project Designation

Independent Research

Primary Advisor

Susan T. Davis

Primary Advisor's Department



Stander Symposium poster

Detecting Critical Signals in Sustained Visual Attention Tasks Using Simulated Radar Screens