Warmer Environments Increase Implicit Mental Workload Even If Learning Efficiency Is Enhanced.

Tsukasa Kimura,Noriko Takemura,Kazumitsu Shinohara,Hajime Nagahara,Hirokazu Kobori,Yuta Nakashima,Masayuki Numao

doi:10.3389/fpsyg.2020.00568

Abstract

Climate change is one of the most important issues for humanity. To defuse this problem, it is considered necessary to improve energy efficiency, make energy sources cleaner, and reduce energy consumption in urban areas. The Japanese government has recommended an air conditioner setting of 28°C in summer and 20°C in winter since 2005. The aim of this setting is to save energy by keeping room temperatures constant. However, it is unclear whether this is an appropriate temperature for workers and students. This study examined whether thermal environments influence task performance over time. To examine whether the relationship between task performance and thermal environments influences the psychological states of participants, we recorded their subjective rating of mental workload along with their working memory score, electroencephalogram (EEG), heart rate variability, skin conductance level (SCL), and tympanum temperature during the task and compared the results among different conditions. In this experiment, participants were asked to read some texts and answer questions related to those texts. Room temperature (18, 22, 25, or 29°C) and humidity (50%) were manipulated during the task and participants performed the task at these temperatures. The results of this study showed that the temporal cost of task and theta power of EEG, which is an index for concentration, decreased over time. However, subjective mental workload increased with time. Moreover, the low frequency to high frequency ratio and SCL increased with time and heat (25 and 29°C). These results suggest that mental workload, especially implicit mental workload, increases in warmer environments, even if learning efficiency is facilitated. This study indicates integrated evidence for relationships among task performance, psychological state, and thermal environment by analyzing behavioral, subjective, and physiological indexes multidirectionally.

Highlights

Climate change is one of the most important issues for humanity
Post hoc comparisons indicated that the reaction times of the fifth block were shorter than those of the other blocks
The present study aimed to investigate whether the thermal environment influences task performance over time and whether the relationship between task performance and thermal environment influences psychological states of participants

Summary

Introduction

Climate change is one of the most important issues for humanity This problem influences environmental destruction and pollution and infrastructure such as water and energy, health, production of food, and economic activity (e.g., Haines and Ebi, 2019). As part of the home and office conservation effort, fixed settings are recommended for room temperatures controlled by air conditioners. The Japanese government has recommended an air conditioner setting of 28◦C in summer and 20◦C in winter since 2005. These settings, called “COOLBIZ” and “WARMBIZ,” were decided according to the higher and lower limit to invoke cooling, set by the “Act on Maintenance of Sanitation in Buildings” (Ministry of Health Labour and Welfare, 1970). Even if “COOLBIZ” and “WARMBIZ” have been widely accepted in Japan so far, it is unclear whether they create an appropriate temperature for workers and students

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Discussion

Conclusion