Warm light in a cold environment enhances subjective comfort without improving cognitive performance: A...

Area of Science:

• Environmental Psychology
• Human Factors Engineering
• Physiological Psychology

Background:

• Prior research suggests light color temperature and thermal conditions influence human physiology and performance.
• Empirical evidence on the interplay between lighting and thermal environments is limited and inconsistent.

Purpose of the Study:

• To investigate how correlated color temperature (CCT) of indoor light modulates subjective comfort, cognitive performance, and autonomic nervous system (ANS) activity.
• To examine these effects under both cool (20 °C) and warm (28 °C) thermal conditions.

Main Methods:

• A study involving 36 participants exposed to different CCTs (2700 K vs. 6500 K) and thermal environments (20 °C vs. 28 °C).
• Utilized a multi-measurement approach assessing subjective comfort, cognitive performance (Go/No-go, PVT, 2-back, CMST), and ANS activity (heart rate, heart rate variability).

Main Results:

• Under cooler conditions (20 °C), warmer light (2700 K) enhanced visual comfort but decreased accuracy in response inhibition tasks.
• No significant interactions between CCT and thermal environment were found for psychomotor vigilance, working memory, or cognitive flexibility.
• Both higher CCT and higher temperatures increased heart rate and decreased heart rate variability, though not consistently linked to performance.

Conclusions:

• Lighting and thermal environments exhibit cross-modal compensatory effects on subjective sensations.
• These environments exert parallel modulatory influences on thermophysiology and cognitive performance.
• Findings highlight complex interactions between light and thermal cues influencing human responses.