On-task errors drive effort avoidance more than opportunity costs.

While trying to complete arduous tasks (e.g., emails, grading), our attention is often mired by the desire to disengage. Opportunity cost theories of mental effort argue that rather than our "sense of effort" being a cognitive limitation, it is an adaptive signal which repels us from unrewarding tasks toward worthwhile alternatives; in short, this signal ensures our cognitive resources are not spent on fruitless pursuits. The current work tests the primary predictions of the opportunity cost theory of effort: That our phenomenology during a cognitively demanding task (sense of effort and boredom), and subsequent on-task behavior (response times and accuracy), are affected by the value of the available alternatives. Over three experiments, manipulating both the extrinsic value (i.e., monetary reward) and intrinsic value of alternative tasks (i.e., how enjoyable the task is), we find no strong evidence in favor of opportunity cost theories. In Experiment 1, we observe no effect of the extrinsic value of an alternative on participants' subjective ratings or behavior during a primary task. In Experiments 2 and 3, while participants' subjective ratings of a primary task (e.g., sense of effort and boredom) may be affected by the intrinsic value of an alternative, we observe no commensurate changes in participants' performance, as measured by accuracy and response times. We explore the consequences of these results for theories of cognitive effort aversion and detail plausible alternative models, such as error aversion. (PsycInfo Database Record (c) 2025 APA, all rights reserved).