Figure 2.

Average response bias during an early (session 1–8), middle (session 9–16) and late block (session 17–24) of Pavlovian autoshaping training. Response bias was calculated for each session by subtracting CS-elicited port entries from lever-CS activations and dividing by the sum of CS-elicited port entries and lever-CS activations, and then averaging across eight sessions. Individual rats were categorized based on the late block as either sign-trackers (n = 19), intermediates (n = 16) and goal-trackers (n = 28). Shifted sign-trackers (n = 13) were identified as having response bias scores comparable to sign-trackers in the late block and comparable to goal-trackers in the early or middle block. Dashed lines indicate response bias score cut-offs (0.35 and −0.35) for phenotype categorization.