Habits Need Time: Evidence of Habit-like Behavior After Short Training Likely Reflects Failures in Habit Testing

Habits are stimulus-driven responses that are produced independently of the current outcome value. They enable efficient actions in familiar contexts while freeing up cognitive resources. Habits are expected to influence behavior after substantial experience, whereas limited training leaves behavior under goal-directed control. This transition from goal-directed to habitual control is well-documented in animal research but remains challenging to replicate in humans. Recent studies have suggested that human protocols are so effective at inducing habitual control that habits can appear even after short training, thereby masking the training effects. These studies typically test habits by reducing outcome value (e.g., food, through satiation) and report persistent habit-like behavior in minimally trained participants. Here, we propose an alternative explanation: we think that the devaluation protocol was ineffective for this subset of ‘habitual’ participants. To test this hypothesis, we conducted a pre-registered experiment using the same task but with monetary rewards instead of food, hypothesizing that money can be more effectively devalued and avoid the social issues associated with eating. We found no difference in habitual responses between short and extended training. In contrast to prior reports, most participants were sensitive to outcome devaluation. We further supported our hypothesis by reanalyzing previous datasets, finding that across all studies (including ours), participants showing more habit-like responses were those for whom the devaluation was less effective. We discuss the theoretical and methodological implications of these findings.