Fig. 7: Only STZ-treated mice previously tested on the gradual schedule are uniquely insensitive to sunk costs.

a–c Sunk cost analysis of staying behavior in the wait zone, demonstrated using all mice. a The likelihood of staying in the wait zone and earning a reward (e.g., not quit) is plotted as a function of time left in the countdown along the x-axis and time already spent waiting orthogonally in color. Note the black 0 s time spent curve represents animals having just entered the wait zone from the offer zone. Inset vertical dashed gray line illustrates an example analysis point comparing three sunk cost conditions originating from different starting offers but matched at 10 s left. Data from a dimensioned reduced in b collapsing across time left, instead highlighting the grand mean of each time spent sunk cost condition (color and x-axis). Insets depict data from curves in a are collapsed into the observed (sunk condition) and control (0 s condition) lines. Difference between curves in b are plotted in c in order to summarize the envelope of the overall effect of time already spent on escalating the commitment of staying in the wait zone. Horizontal dashed line represents 0. d Sensitivity to sunk costs plotted across the entire Restaurant Row paradigm where the delta curve in c is plotted as vertical slices in d with time already spent along the y-axis and heatmap representing magnitude. Note no sensitivity to sunk costs until after transitioning to the 1–30 s epoch in all mice, and never in STZ-gradual mice. Delta curves collapsed across the entire 1–30 s epoch for e stepwise or f gradual schedules. Dashed gray box highlights peak differences. g Peaks from e to f for all groups. h Peaks split by flavor ranking. Shading/error bars represent ±1 SEM.