Diffusion model parameters for data from Experiment 2.

Three parameters—distance to the upper boundary (a+; A/B), distance to the lower boundary (a-; C/D) and drift rate (v) were analysed for each tone. Change from baseline (control session) for a+ and a- was also calculated for the midpoint tone only to take into account individual differences in underlying bias. Data shown are averages for all probe sessions during that experimental period. (A) Changes in a+ in the restraint stress and social isolation (RS&SI) group compared to control group were unclear from the overall analysis of this measure. (B) However, during stress only, change from baseline in a+ was positive in the RS&SI group, and significantly larger compared to controls. (C) The effect of RS&SI on the a- was again unclear from the overall analysis. (D) During the post-stress period only, a positive change from baseline in a- was seen in the RS&SI group, and was also significantly larger compared to controls. (E) There was no difference in v between the RS&SI and control group during any stage of the manipulation. (F) Diagrammatic representation of diffusion model parameters for the control (dashed lines) and RS&SI group (solid lines) for the midpoint tone only for this manipulation. Illustrations are to scale representing mean values for each parameter, and are aligned to decision starting point (dotted line). Drift rate is scaled 5:1. Graph data represent mean ± SEM; n = 5 per group. Independent samples t-tests to compare groups: **p < 0.01, *p < 0.05; one-sample t-tests to compare to baseline: ##p < 0.01, #p < 0.05.