Székely, MarcellMichael, John2023-07-242023-07-242023-07-031747-021810.1177/17470218231183963https://hdl.handle.net/20.500.14018/14055Effort perception is a crucial capacity underpinning characteristically human forms of sociality, allowing us to learn about others’ mental states and about the value of opportunities afforded by our environment, and supporting our ability to cooperate efficiently and fairly. Despite the crucial importance and prevalence of effort perception, little is known about the mechanisms underpinning it. Across two online experiments (N = 462), we tested whether adults estimate others’ cognitive effort costs by tracking perceptible properties of movement such as path length, time, and speed. The results showed that only time had a consistent effect on effort perception, that is, participants rated longer time as more effortful. Taken together, our results suggest that within the context of our task—observing an agent deciphering a captcha—people rely on the time of others’ actions to estimate their cognitive effort costs.engCC BY 4.0https://creativecommons.org/licenses/by/4.0/Social cognitionEffort perceptionEffortJoint actionNaive utility calculusJournal article1747-022610.1177/17470218231183963