The cost of regulating effort: Reward and difficulty cues with longer prediction horizons have a stronger impact on performance

Many theories on cognitive effort start from the assumption that cognitive effort can be expended at will, and flexibly up- or down-regulated depending on expected task demand and rewards. However, while effort regulation has been investigated across a wide range of incentive conditions, few investigated the cost of effort regulation itself. Here, we studied the effect of reward expectancy and task difficulty on effort expenditure in a perceptual decision-making task, and comparted cues with different prediction horizons between Experiment 1 (cueing the next trial, n = 45) and Experiment 2 (cueing the next six trials, n = 49). In Experiment 2, but not in Experiment 1, a high reward expectancy resulted in better accuracy on low difficulty trials, indicating that participants used the cue information only when it was valid for multiple trials in a row. Together, our results indicate that people experience a cost to effort regulation, and that lower adjustment frequency can compensate for this cost.