Reward expectation yields distinct effects on sensory processing and decision making in the human brain
Fig 5
Space-specific, but not choice-specific, reward expectation biases microsaccades and reaction times spatially.
A. (Top) Microsaccade rate (MSC) toward the FX (solid line) and VR (dashed line) sides, respectively, for the “VR > FX” reward contingency in the space-specific reward expectation session (data averaged across n = 24 participants). x-axis: time relative to stimulus onset. Shading (orange and gray): s.e.m. for MSC traces (FX and VR sides, respectively). Gray horizontal bar: time epoch for quantifying MSC rates. Black horizontal overline: temporal clusters with significant differences in MSC rates (p < 0.05). (Bottom) Same as in the top panel, but for the “VR < FX” reward contingency. Inset: Microsaccade traces of horizontal (solid lines) and vertical (dashed lines) gaze positions, for an exemplar participant (SI Methods). B. Microsaccade bias induced by reward contingency change (ΔMSC = MSCVR > FX – MSCVR < FX) toward the FX and VR sides in the space-specific reward expectation session. Other conventions are the same as in Fig 2A. Asterisks: statistical significance levels assessed with a Wilcoxon signed rank test (***p < 0.001, **p < 0.01, *p < 0.05, n.s.: not significant). (C–D). Same as in panels (A–B) and inset, but showing MSC rates, sample traces and bias for the “liberal” and “conservative” reward contingencies in the choice-specific reward expectation sessions. E. (Top) Distribution of reaction times (RT) for correct responses on the FX (deep shading fill) and VR (unfilled) sides for the “VR > FX” reward contingency in the space-specific reward expectation session (data averaged across n = 24 participants). Light shading: region of overlap. Solid and dashed vertical lines: RT medians for the FX and VR sides, respectively. (Bottom) Same as in the top panel, but for the “VR < FX” reward contingency. F. Same as in panel B, but showing reward-induced modulation of reaction times (ΔRT = RTVR > FX – RTVR < FX) in the space-specific reward expectation session. Other conventions are the same as in panel B. (G–H). Same as in panels (E–F), but showing RTs and their modulation for the “liberal” and “conservative” reward contingency conditions in the choice-specific reward expectation sessions. Data are available at https://doi.org/10.6084/m9.figshare.25966015 [34].