In two studies, participants performed a switching task, and we provided to only half of them feedback on goal progress (how much of the task still remains). Importantly, this feedback did not inform participants on how well they performed. We found that participants in the feedback condition achieved a higher asymptotic level of performance, reported less fatigue and took shorter breaks between blocks compared to the control condition. These results suggest that asymptotic level of performance reflects not only ability (as is commonly assumed in the literature) but also motivation. We suggest that when people know when a focal task would end, they invest more effort in it because foregoing other activities becomes less costly (i.e., opportunity cost of engaging in the focal activity decreases) and because knowing when a task would end frees the actor from the need to conserve effort. These results suggest a simple, effective and costless way to improve cognitive performance that may be applied in educational and organizational settings.
