14The amount of mental effort we invest in a task is influenced by the reward we can expect if we 15 perform that task well. However, some of the rewards that have the greatest potential for driving 16 these efforts (e.g., jobs, grants) are partly determined by factors outside of one's control. In such 17 cases, effort has more limited efficacy for achieving one's desired outcome. We have proposed 18 that people integrate information about the expected reward and efficacy for effort to determine 19 the expected value of control, and then adjust their control (i.e. mental effort) allocation 20 accordingly. Here we test key predictions this makes about behavior and neural activity. We 21show that participants invest more control in a task when this control is more rewarding and 22 which people evaluate the potential rewards to expect for a certain control allocation, much less 41 is known about how they evaluate the efficacy of that control, nor how these two values are 42 integrated to determine how much control is invested. 43We have recently developed a model that formalizes the roles of evaluation, decision-44 making, and motivation in allocating and adjusting cognitive control 17,18 ( Fig.1). Our model 45 describes how cognitive control can be allocated based on the overall worth of executing 46 different types and amounts of control, which we refer to as their Expected Value of Control 47 (EVC). The EVC of a given control allocation is determined by the extent to which the costs that 48 would need to be incurred (mental effort) are outweighed by the benefits. Critically, these 49 4 benefits are a function of both the expected outcomes for reaching one's goal (reward, e.g., 50 money or praise) and the likelihood that this goal will be reached with a given investment of 51 control (efficacy) (Fig. 1A). The amount of control invested is predicted to increase 52 monotonically with a combination of these two incentive components (Fig. 1B). 53 54 Figure 1. The EVC model predicts that control should increase with expected reward and efficacy. 55 A. EVC model. Control intensity is chosen to optimize the trade-off between effort costs and payoff, 56 maximizing the expected value of control. The payoff of a given control signal is determined by the 57 expected reward and efficacy for a given control intensity. B. Increasing control signal intensity (x-axis) 58is associated with greater effort costs (red) but often leads to greater payoffs (blue). The EVC of a given 59 control intensity (purple) increases with expected payoff and decreases with expected costs, determining 60 the optimal (EVC-maximizing) amount of control to invest in a task (black arrows). The model predicts 61 that control should increase when reaching a goal is more rewarding (left) and when control is more 62 efficacious for reaching that goal (right).
64The EVC model integrates over and formalizes past theories that posit roles for 65 reward/utility and/or efficacy/controllability/agency in the motivation to engage in a particular 66 course of actio...