Comfort, not temperature alone, is what moves performance
The clearest pattern across these studies is that performance tracks thermal comfort rather than the thermometer reading by itself. In one experiment with college students exposed to 23, 25, 27, and 30 °C, the best performance and the best comfort both occurred at a mean standard effective temperature of 27.2 °C, when occupants felt neutral to slightly cool; at that point total mood disturbance and mental workload were relatively low [1]. The same study reports that thermal comfort correlates with lower mood disturbance, lower mental workload, and higher performance, and vice versa [1].
A tropical study makes the same point from the opposite direction. Students felt warm at 27–30 °C, and their overall relative performance scores were about 7–8% lower in warm sensations than in cool, slightly cool, or neutral sensations [4]. But when elevated air velocity kept them comfortable at those same high temperatures, cognitive performance was not affected by the higher temperature or the moving air [4]. In other words, the temperature change mattered through the comfort it produced, not as a direct hit on the brain.
Warm discomfort taxes mood and mental workload
The studies point to a plausible route from discomfort to poorer performance: discomfort makes the task feel harder and the person feel worse. The 27.2 °C experiment found that the biggest changes in mood disturbance and mental workload appeared in warm environments, alongside the biggest performance changes [1]. That is consistent with a simple idea: when the body is struggling to shed heat, some mental capacity goes to managing the discomfort, leaving less for the task.
The tropical results fit this picture. Warm sensations were the only ones linked to lower cognitive scores, while cool and slightly cool sensations produced no negative effects [4]. The authors describe the warm-environment effect as a negative one on cognitive performance, but they also show it disappears when comfort is restored through air movement [4]. So the harm is not inevitable at high temperatures; it depends on whether the person can stay comfortable.
Motivation is the missing piece, not a proven moderator
None of these studies measured motivation, so they cannot say whether a highly motivated person would push through thermal discomfort or whether discomfort would drain the motivation needed to perform. The closest hint comes from a winter classroom study, which reports that uncomfortable cold was more detrimental to both performance and motivation than other short-term thermal experiences [5]. That is a suggestion that discomfort and motivation move together, not proof that motivation changes how much temperature affects performance.
What the evidence does support is that the comfort-performance link is strong enough to matter for design. Studies in classrooms and workplaces recommend temperature ranges chosen to balance comfort and performance rather than comfort alone, and they find that such ranges can differ substantially from standard comfort limits [2][3]. One workplace model reduced the preferred upper temperature limit by 3 °C below current standards while still balancing comfort and task performance, and saved about 10% energy within the desired range [2]. A classroom study similarly recommended an upper limit 5 °C lower than international standards for winter comfort and learning [3]. These are design recommendations, not tests of motivation, but they show that the comfort-performance trade-off is real and measurable.
Sources used in this answer
Exploring the influence of indoor temperature on thermal comfort and performance
In a controlled experiment with college students, the highest performance and thermal comfort occurred at a mean standard effective temperature of 27.2 °C, where mood disturbance and mental workload were relatively low, and thermal comfort correlated with lower mood disturbance, lower mental workload, and higher performance.
An adaptive indoor temperature control approach simultaneously improving thermal comfort and task performance
An adaptive indoor temperature control approach for workplaces balanced thermal comfort and task performance, recommended a preferred temperature range, and achieved about 9.98% energy savings while reducing the preferred upper temperature limit by 3 °C compared with current standards.
A holistic approach to the evaluation of the indoor temperature based on thermal comfort and learning performance
A classroom study established quantitative relationships between temperature, thermal comfort, and learning performance, and recommended temperature ranges that balance both, with an upper limit 5 °C lower than international standards for winter comfort and learning.
Effect of elevated air temperature and air velocity on thermal comfort and cognitive performance in the tropics
In tropical Singapore, students' cognitive performance was about 7–8% lower in warm sensations than in cooler or neutral sensations, but performance was not affected by elevated air temperature and air velocity when thermal comfort was maintained.
Experimental evaluation of short-term thermal experiences on students' thermal comfort and cognitive performance
In a simulated winter classroom, uncomfortable cold was reported to be more detrimental to both performance and motivation than other short-term thermal experiences.