The impact of physical effort on behavioural and neural computations guiding value-based choice Miriam Klein-Flügge University College London Choices in a natural environment involve different types of costs, such as physical effort, delay and uncertainty, which need to be incorporated into the representation of the value of potential rewards. Reward valuation is commonly characterized by subjective distortions of the true costs, such as for example the hyperbolic discounting of rewards over time, or the over-estimation of small probabilities. However, how physical effort influences choice behavior remains largely unclear, despite its relevance for understanding disorders such as apathy and depression, and a surged interest into its neural implementation. First, I will show that the cost of exerting physical effort in a value-based choice context is best accounted for by a model describing small reward devaluations for lower efforts, and steeper devaluations for higher efforts. Furthermore, effort discounting behaviour is clearly dissociated from delay discounting, consistent with findings at the neural level showing that partly separate neural networks implement effort- and delay-based choice. Second, using fMRI, I will show how physical effort is integrated into the representation of an option’s value, and then compared against alternative options. Unlike for other types of costs such as delay or uncertainty, chosen and unchosen values are not compared in vmPFC, but instead in a cingulate region known to connect to both limbic and motor structures. Connectivity analyses further highlight the role of this region in interacting with structures that enable the implementation of the choice.