Abstract
Performance in a cognitive task domain can fluctuate broadly within an individual over time, often in relation to intrinsic neurophysiological states that change on various timescales. For example, attention and arousal can impact task performance on a relatively short timescale, but neurophysiological effects from chronic sleep loss and fatigue likely influence behavior and performance on a much broader timescale. We conducted a longitudinal 16 week study in which participants (n=15) returned biweekly (8 sessions) to perform a psychomotor vigilance task (PVT) with eye-tracking to investigate relationships between pupil diameter (tonic baseline and phasic event-related responses) and performance variables (response speed, lapse rate). Across the study period, we monitored naturalistic sleep patterns with daily sleep diaries and wrist actigraphy (Readiband SBV3) to estimate objective fatigue via effectiveness score using Sleep, Activity, Fatigue, and Task Effectiveness "SAFTE" model (Hursh et al., 2004). We examined pupillary predictors of fluctuations in biweekly performance, using correlation coefficients and linear mixed models to examine between-subjects and within-subjects effects. We found that within-subject variability of response speed and lapse rate across sessions was significantly associated with changes in both tonic and phasic features of pupil diameter. Experimental sessions showing a relatively faster mean response speed and correspondingly lower lapse rate (relative to the individual's mean) were associated with larger tonic pupil diameter, lower peak amplitude, and shorter latency of the mean phasic response. We used multivariate models to examine the influence of several sleep and fatigue-related variables on task performance. Within subjects, we found that lower effectiveness score (higher fatigue) was associated with slower response speed, higher lapse rate, and smaller tonic pupil diameter. These results reveal long-timescale relationships within individuals between the pupillary system and vigilance-related performance outcomes, with a modulating influence from natural variability in states related to sleep and fatigue.
Meeting abstract presented at VSS 2018