A low dimensional manifold of human exploratory behavior reveals opposing roles for apathy and anxiety

The question of whether to explore for new rewards or to exploit one's knowledge to gain known rewards is a fundamental problem for all animals, including humans. This balance is modulated by subjective states of anxiety and apathy, which, although they would seem to be incompatible with each other, often co-occur psychiatrically. Here, we report a latent structure underlying sequential exploration and exploitation strategies on a decision task, which reveals separate decision patterns aligned to anxiety and apathy. 1001 participants in a gender-balanced sample completed a three-armed restless bandit task along with psychiatric symptom surveys. Using advances in dimensionality reduction methods, we found that the decision sequences reduced to a low-dimensional manifold. The axes of this manifold explained individual differences in the balance between states of exploration and exploitation and the stability of those states, as determined by a statistical mechanics model of exploration-exploitation dynamics. Position along the balance axis was correlated with opposing symptoms of behavioral apathy and anxiety, while position along the stability axis was correlated with the level of emotional apathy. This work provides a basis for using behavioral manifolds to reveal relationships between behavioral dynamics and affective states, with important implications for behavioral measurement approaches to neuropsychiatric conditions. ### Competing Interest Statement The authors have declared no competing interest.