Early starts and late finishes both reduce alertness and performance among short-haul airline pilots.

Flight crews are frequently required to work irregular schedules and, as a result, can experience sleep deficiency and fatigue. This study was conducted to determine whether perceived fatigue levels and objective performance varied by time of day, time awake, and prior night's sleep duration. Ninety-five pilots (86 male, 9 female) aged 33 years (±8) volunteered for the study. Participants completed a daily sleep diary, Samn-Perelli fatigue scale, and psychomotor vigilance task that were completed before and after each flight duty period and at the top-of-descent for each flight. Pilots experienced higher self-reported fatigue (EMM = 3.92, SE = 0.09, p < 0.001) and worse performance (Response speed: EMM = 4.27, SE = 0.08, p = 0.004) for late-finishing duties compared with early-starting duties (Samn-Perelli: EMM = 3.74, SE = 0.08; Response speed: EMM = 4.37, SE = 0.08), but had shorter sleep before early-starting duties (early: EMM = 6.94, SE = 0.10; late: EMM = 8.47, SE = 0.14, p < 0.001). However, pre-duty Samn-Perelli and response speed were worse (z = 4.18, p < 0.001; z = 3.05, p = 0.03; respectively) for early starts compared with late finishes (EMM = 2.74, SE = 0.19), while post-duty Samn-Perelli was worse for late finishes (EMM = 4.74, SE = 0.19) compared with early starts (EMM = 4.05, SE = 0.12). The results confirm that duty time has a strong influence on self-reported fatigue and performance. Thus, all flights that encroach on a biological night are targets for fatigue risk management oversight.

The relationship between workload, performance and fatigue in a short-haul airline.

The aim of this study was to determine the relationship between pilot workload, performance, subjective fatigue, sleep duration, number of sectors and flight duration during short-haul operations. Ninety pilots completed a NASA Task Load Index, Psychomotor Vigilance Task and a Samn-Perelli fatigue scale on top-of-descent of each flight and wore an activity monitor throughout the study. Weak, but significant, correlations were revealed between workload and all factors. Subjective fatigue, number of sectors and lapses were significant predictors of workload. Pilots reported higher workload when fatigue increased, the number of sectors were higher, and objective performance was worse.

Evaluation of a Psychomotor Vigilance Task for Touch Screen Devices.

OBJECTIVE: Our goals were to compare three techniques for performing a psychomotor vigilance task (PVT) on a touch screen device (fifth-generation iPod) and to determine the device latency. BACKGROUND: The PVT is a reaction-time test that is sensitive to sleep loss and circadian misalignment. Several PVT tests have been developed for touch screen devices, but unlike the standard PVT developed for laboratory use, these tests allow for touch responses to be recorded at any location on the device, with contact from any finger. In addition, touch screen devices exhibit latency in processing time between the touch response and the time registered by the device. METHOD: Thirteen participants completed a 5-min PVT on a touch screen device held in three positions (on a table with index finger, handheld portrait with index finger, handheld landscape with thumb). We compared reaction-time outcomes in each orientation condition using paired t tests. We recorded the first session using a high-speed video camera to determine the latency between the touch response and the documented response time. RESULTS: The participants had significantly faster reaction times in the landscape-oriented position using the thumb, compared with the portrait-oriented position using the index ( M = 224.13 and M = 244.26, p = .045). Using data from 1,241 unique touch events, we found a mean device latency of 68.53 ms that varied highly between individuals. CONCLUSION: Device orientation and device latency should be considered when using a touch screen version of a PVT. APPLICATION: Our findings apply to researchers administering touch screen versions of the PVT.

Adaptation and visual salience.

We examined how the salience of color is affected by adaptation to different color distributions. Observers searched for a color target on a dense background of distractors varying along different directions in color space. Prior adaptation to the backgrounds enhanced search on the same background while adaptation to orthogonal background directions slowed detection. Advantages of adaptation were seen for both contrast adaptation (to different color axes) and chromatic adaptation (to different mean chromaticities). Control experiments, including analyses of eye movements during the search, suggest that these aftereffects are unlikely to reflect simple learning or changes in search strategies on familiar backgrounds, and instead result from how adaptation alters the relative salience of the target and background colors. Comparable effects were observed along different axes in the chromatic plane or for axes defined by different combinations of luminance and chromatic contrast, consistent with visual search and adaptation mediated by multiple color mechanisms. Similar effects also occurred for color distributions characteristic of natural environments with strongly selective color gamuts. Our results are consistent with the hypothesis that adaptation may play an important functional role in highlighting the salience of novel stimuli by discounting ambient properties of the visual environment.