A two-step task commonly used to study people's decision-making behaviors does not appear to be effective for training people to rely more on goal-oriented behaviors and less on habitual behaviors. Elmar Grosskurth of Inselspital University Hospital Bern, Switzerland, and colleagues present these findings in PLOS Computational Biology.
Some psychiatric disorders, such as addiction and obsessive-compulsive disorder, heavily rely on habitual behaviors at the expense of goal-oriented behaviors. Many studies have used a two-step experimental approach to investigate these behaviors. In the new study, Grosskurth and colleagues tested whether the two-step task could also be used to train people to engage in more goal-oriented strategies. Such a training would be beneficial for the above-mentioned psychiatric disorders to reduce habitual behaviors and enhance goal-directed decisions.
The researchers recruited 33 healthy participants who each completed 1005 trials of the two-step task over five weeks. In the first step of each trial, the participant chose between two different shapes on a computer screen. That choice was associated with a probability that influenced whether one or another of two new pairs of shapes now appeared. The participant then chose a shape from the second pair and received a small monetary reward or not, depending on their choice.
As usual for the two-step task, the participants showed a mix of goal-directed versus habitual behaviors in making their choices. However, analysis of their choices across five weeks of intensive training suggests that the training had no effect on goal-directed or habitual behavior, nor on the balance between the two. Neuroimaging of brain circuits thought to underlie these behaviors supported these findings, showing that the training did not affect brain activity.
"Our findings suggest that the two-step task in its current form has methodological drawbacks which are not suitable for training purposes," says Lisa Holper, the senior author of the study. This result was observed in healthy people and may be different under psychiatric conditions.
The authors suggest that future work could focus on developing a more sophisticated version of the two-step task that could be used for psychiatric patients to train goal-directed behaviors while reducing habitual behavior.
Peer-reviewed; Experimental study; People
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Citation: Grosskurth ED, Bach DR, Economides M, Huys QJM, Holper L (2019) No substantial change in the balance between model-free and model-based control via training on the two-step task. PLoS Comput Biol 15(11): e1007443. https:/
Funding: The authors received no specific funding for this work.
Competing Interests: The authors have declared that no competing interests exist.