Stress prompts habit behavior in humans

Area of Science:

• Neuroscience
• Behavioral Science
• Psychology

Background:

• Instrumental behavior is governed by goal-directed (action-outcome) and habitual (stimulus-response) processes.
• Distinct brain systems support these two types of learning.
• Previous research indicates stress influences memory systems, but its role in coordinating goal-directed and habit processes in learning was unclear.

Purpose of the Study:

• To investigate whether stress influences the balance between goal-directed and habit processes during instrumental learning in humans.
• To determine if stress promotes habit formation at the expense of goal-directed control.

Main Methods:

• Participants underwent a stress induction (socially evaluated cold pressor test) or a control condition.
• Trained on two instrumental actions linked to distinct food outcomes.
• One outcome was devalued post-training via satiety.
• Action-outcome contingency knowledge and performance were assessed during extinction.

Main Results:

• Stress exposure prior to training resulted in behavior that was insensitive to the devaluation of action outcomes, indicating a shift towards habit.
• Stress significantly reduced participants' explicit understanding of the action-outcome contingencies.
• These findings demonstrate stress promotes habit performance over goal-directed control.

Conclusions:

• Stress plays a critical role in promoting habitual behavior in instrumental learning.
• Stress impairs the goal-directed system, leading to less flexible, stimulus-driven actions.
• This study provides the first human evidence that stress shifts instrumental performance from goal-directed to habitual control.