Figure 3.

Net value analysis, stimulus-locked data. A, Heat map showing significant ERP activity correlated with net value, in conjunction with significant responses to stimulus value (red) and effort cost (green) alone. By definition, net value should reflect the overlap (yellow) of the stimulus value and effort cost activity. The data reveal an early window of activity associated with effort cost and a later window correlated with stimulus value (white dashed boxes) but relatively little overlap between the two factors. B, Cluster analysis of stimulus value, effort cost, and net value. Collapsing over scalp locations, this visualization further supports the distinction between activity correlated with effort cost early (e.g., 100–250 ms after stimulus) and stimulus value later (450–650 ms after stimulus), while finding only a few clusters associated with the overlap of these factors in the 450–600 ms time window (gray box). C, Source localization of net value, effort cost, and stimulus value from 450 to 600 ms after stimulus, FWE-corrected p < 0.01. Inset, Spherical masks based on peak coordinates from three fMRI studies [blue, Plassmann et al. (2007); magenta, Hare et al. (2009); cyan, Litt et al. (2010)], 6 mm radius.