Autonomic nervous system correlates to readiness state and negative outcome during visual discrimination tasks.

► Reaction time, IHR and SR responses were the main dependent variables. ► Independent variables were task difficulty, response accuracy and feedback fairness. ► RT increased with task difficulty while bradycardia predicted better performance. ► Discriminating identical stimuli prolonged SR responses. ► Both errors and unfair feedback elicited the largest and longest SR responses.