Vicarious trial-and-error is associated with the use of place-strategies in human virtual navigation

Studies of decision-making in rodents have demonstrated that vicarious trial-and-error (VTE) is an important behavioral index of deliberation, when animals search through and evaluate the available options before making a decision. In rodents, VTE is enhanced during the use of hippocampally-dependent place strategies, which may represent a type of model-based behavior. While some evidence exists for VTE-like behaviors in humans during navigation, it is unknown if VTE in humans is specifically associated place-strategies, as would be predicted for model-based behaviors. To address this gap, humans were tested in navigation tasks in symmetrical environments, which allowed for the use of probe trials to assess navigation strategies (place or response) or impose them directly. The use of place strategies (on probe trials and place-training) was associated with increases in measures of VTE (reorientations and pausing) especially at high-cost decision points, similar to results from rodent studies. In contrast, response-strategies were associated with the development of efficient, stereotyped trajectories (consistent with model-free learning). These results support the identification of place- and response-strategies in human navigation with model-based and model-free learning, respectively, and demonstrate that VTE is specifically related to the use of place-strategies.