The self-regulatory power of environmental lighting: The effect of illuminance and correlated color temperature

Abstract

Ambient lighting in particular, its brightness is known to affect cognitive activation and self-control, but research on lighting has reported mixed effects. Some studies have shown that brightness increases cognitive activation, whereas others have shown that darkness prompts cognitive activation. In this research, we attempted to reconcile those inconsistent findings by investigating how lighting's effects on cognition are affected by fluency the subjective experience of ease of processing information. We propose that the interaction between the brightness and the correlated color temperature (i.e., the warmth or coolness) of ambient lighting can make it either fluent, promoting cognitive activation, or disfluent, diminishing cognitive resources. Because self-controlled behaviors reflect the willful suppression of automatic responses, the exertion of self-control requires greater cognitive activation. Our results replicated prior findings on brightness by showing that warm bright light improved participants' self-control; however, that effect extended to cool dim lighting conditions as well. By contrast, self-control was weakened under cool bright lighting and warm dim lighting. Our results from four experiments demonstrate that those lighting conditions induce disfluency, leading to cognitive depletion and, consequently, lower self-control.