Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for controlling an agent. One of the methods includes sampling one or more index variables from a continuous space of possible index variables in accordance with a probability distribution over the continuous space; for each index variable: processing the index variable using a hypermodel, in accordance with values of a plurality of parameters of the hypermodel, to generate an output that specifies values of a plurality of parameters of an environment model; and generating an action selection output using the environment model in accordance with the values of the plurality of parameters of the environment model that are specified by the hypermodel output for the index variable; and selecting the action to be performed by the agent at the time step using the one or more action selection outputs for the one or more index variables.