Fig. 3: The strong relationship between ERP voltage following reward feedback and PE values was comparable between humans (left) and rats (right).

Linear regression revealed a strong positive correlation between ERP voltage during the reward positivity (RewP) period and PE value in both humans (A) and rats (B). Data reflect average regression coefficient values. We then predicted the ERP response based on several fixed PE values (PE = 0.3, blue dashed line; PE = 0.6, blue solid line; PE = −0.3, red dashed line; PE = −0.6, red solid line) and showed that the predicted ERP was more negative or positive when the PE value was negative or positive, respectively, in both humans (C) and rats (D). These effects only emerged during the RewP period and were nearly identical to the actual ERP voltages when split between high (PE > 0.5; blue solid line) and low PE (PE < −0.5; red solid line) values in both humans (E) and rats (F). Data reflect grand average ERP traces.