The figure illustrates the entire behavioral data set (19 mice). Each panel illustrates one behavioral measure, each row represents one mouse, and each data point represents one session. Relative value and steepness were obtained from Equation 1; side bias, choice hysteresis and direction hysteresis were obtained from Equations 2-4. Labels on the left indicate for each mouse the strain and the relevant experiment. Asterisks indicate the two mice (M39 and M53) trained in the flipped version of the task. Importantly, the measures obtained for these mice were comparable to those obtained for the other animals. For mice participating in optical inactivation experiments, only trials without stimulation (stimOFF) were included in this figure. (a) Relative value. Averaging across sessions and across animals, we obtained mean(ρ)=2.39 ± 1.01 (mean ± SD). (b) Steepness. Averaging across sessions and across animals, we obtained mean(η)=1.19 ± 0.41 (mean ± SD). (c) Side bias. On any given session, choices could present a side bias, although the direction changed across sessions and across animals. Seven animals presented a consistent bias (p<0.01, t test). Of them, four preferred right and three preferred left, indicating that side biases were not imposed by the experimental apparatus. Averaged across the population, the side bias was rather modest (mean(ε)=0.08 ± 0.04, mean ± SEM). (d) Choice hysteresis. Only one animal presented a consistent effect (p<0.01, t test). Averaged across the population, choice hysteresis was modest (mean(ξ) = –0.08 ± 0.01, mean ± SEM). (e) Direction hysteresis. Six animals presented a consistent effect (p<0.01, t test). For one of them the effect was negative. Averaged across the population, direction hysteresis was significant but fairly modest (θ = 0.15 ± 0.02, mean ± SEM).