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. 2020 Jun 16;9:e54014. doi: 10.7554/eLife.54014

Figure 2. Phasic arousal reduces both conservative and liberal choice biases.

(A) Auditory yes/no (forced choice) tone-in-noise detection task. Schematic sequence of events during a trial. Subjects reported the presence or absence of a faint signal (pure tone; green band) embedded in noise (see 'Materials and methods'). (B) A separate batch of subjects performed the same task, but the signal now occurred in 30% of trials (‘rare’ condition) or in 70% trials (‘frequent’ condition). (C) Overall sensitivity and bias in rare and frequent conditions. (D) Task-evoked pupil response (solid line) and its derivative (dashed) in the equal (top), rare (middle) and frequent (bottom) signal occurrence conditions. Gray window, interval for extracting task-evoked pupil response measures; black bar, significant pupil derivative (p<0.05, cluster-corrected one-sample t-test). (E) Relationship between pupil response and choice bias in the equal (top), rare (middle) and frequent (bottom) signal occurrence conditions. For the biased signal occurrence conditions, we used three pupil-defined bins because there were fewer trials per individual (less than 500) than in the previous data sets (more than 500; see 'Materials and methods'). (F) As panel (E), but for mean RT and perceptual sensitivity. (D–F) Group average (N = 24; N = 15; N = 15); shading or error bars = s.e.m. Solid lines show linear or quadratic fits to binned data (linear fits are shown where first-order fit was superior to constant fit; quadratic fits are shown where second-order fit was superior to first-order fit). Blue ‘X’s, predictions from the ‘full’ drift diffusion model (see Figure 4 and associated text); p-values, mixed linear modeling.

Figure 2.

Figure 2—figure supplement 1. Additional analyses of data from auditory yes/no detection tasks.

Figure 2—figure supplement 1.

(A) Left: individual task-evoked pupil response for yes choices in the go/no-go task, plotted against individual pupil response for yes choices in the yes/no (forced choice) task. Data points are from individual subjects. Right: as left, but for no choices. Correlation was assessed by Pearson’s correlation coefficient. A leverage analysis verified that the reported correlations are not driven by outliers. (B) RT distributions in the equal (top), rare (middle) and frequent (bottom) signal occurrence conditions. Green window, included RTs (range, 0.5–2.5 s). (C) Pupil response time for three pupil-derivative-defined bins in the equal (top), rare (middle) and frequent (bottom) signal occurrence conditions. Group average (N = 24; N = 15; N = 15); shading shows s.e.m. (D) Left: trial-by-trail relationship between task-evoked pupil response and pre-trial baseline pupil size for example subjects in the equal (top), rare (middle) and frequent (bottom) signal occurrence conditions. Data points represent single trials. Right: correlation coefficient of the same relationship separately for each subject. Data points are single subjects; green dots highlight significant correlations (p<0.05).