Table 1.
Clinical data.
Table 2.
Demographic and behavioral data.
Figure 1.
Successive screenshots displayed in one trial are shown from left to right, with durations in ms. Neutral or arousing pictures (with positive or negative valence) were shown prior to physical effort exertion. Effort was cued by simultaneously showing the amount of money at stake, materialized as coin images (1 cent, 10 cents or 1 euro), and a graduated scale in which a cursor represented the force exerted on the handgrip. Subjects knew that the top of the scale corresponded to the monetary incentive, such that the more they squeezed the handgrip, the more money they would win. After force production, subjects rated the extent of their effort by positioning a cursor on an analog scale. The final screen informed subjects about the cumulative total of monetary earnings.
Figure 2.
Histograms show the effects of the main independent factors (incentive and arousal levels) on the main dependent variables (grip force, effort rating). Grip force is expressed as a percentage of the highest measure. Effort ratings were divided by the actual force produced on a trial-by-trial basis. Error bars are ± inter-subjects standard errors of the mean. * Significant difference (paired t-test, P<0.05), between negative and neutral picture and between 0.01€ and 1€ in the task. NS = non significant.
Figure 3.
Each point is a healthy subject (empty circle) or a depressed patient (filled circle). Graphs show difference scores for incentive (1€ - 0.01€) versus arousal (emotional - neutral) effects on force production and effort rating. Grip force and skin conductance is expressed as a percentage of the highest measure. Effort ratings were divided by the actual force produced on a trial-by-trial basis.