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The first study, completed in the summer of 2007, was administered via the Internet. Each participant logged onto a website with an anonymous ID number and a password of their choosing. Every session began with a set of questions about the stress and call volume for the shift. Participants were then guided through a set of two of cognitive tasks targeting four specific facets of cognitive functioning.
The first of these games was based on the card game commonly known as “Concentration” in which pairs of matching cards are placed face down and are turned over two at a time, with the goal of matching all pairs of cards in as few turns as possible. The study’s computerized version used photos of fire equipment concealed behind virtual tiles. This task provided a measure of spatial orientation and memory for location, as well as the degree to which similar items were confused with one another.
The second game used a visual search task in which participants were asked to rapidly search an array of colored letters for a particular letter of a particular color. This provided a measure of the speed with which the target could be found, as well as a measure of the number of “false alarms” that were made when the target was not present in the array. This task also measured two of the most important cognitive abilities of a municipal firefighter (according to the U.S. Department of Labor; see http://www.occupationalinfo.org/onet/63008a.html): response orientation – “the ability to choose quickly and correctly between two or more movements in response to two or more signals” – and flexibility of closure – “the ability to identify or detect a known pattern (a figure, object, word, or sound) that is hidden in other distracting material.”
Nineteen firefighters at six stations participated in at least six sessions of data collection each, which provided sufficient data to control for practice effects. Results clearly indicated that the overall time needed to detect targets in the visual search task increased with increasing call volumes. Specifically, after 10 calls, participants typically slowed down by one-fifth of a second or more. Notably, however, there was not a statistically significant increase in the number of false alarms with increasing call volumes. This suggests that participants who had experienced a higher number of calls – and were therefore more likely to be cognitively fatigued – slowed down in their response times in order to maintain consistently high accuracy. This shows a situational awareness and an ability to compensate for fatigue that is commendable and makes the best of a bad situation.
The “Concentration” game produced trends in the same direction, though the declines in memory were not statistically significant (likely due to the small sample size). It should be noted, however, that compared to similar studies using introductory psychology students at Arizona State University, college students did perform significantly worse on this task when they were tired (i.e., when tasks were performed in the evening prior to going to sleep), which suggests that firefighters were able to resist the effects of cognitive fatigue better than many in the general population. This pilot study motivated the team to pursue a second, more controlled study in the late winter and spring of 2008.
The second study featured two different cognitive tasks designed to target a wider array of requisite on-the-job abilities. In the first task, participants were shown an image of a building with 12 windows. Six of these windows were lighted, indicating that they were potentially occupied. After four seconds, all the lights went out (mimicking the power cut in the scenario that opened this article). Participants were then asked to recall which of the windows were potentially occupied. This provided measures of spatial and response orientation, as well as selective spatial attention and response time.