Shedding the Light on Decision Making

A bright sunny day in Vancouver. Source: Cindy Hu.

Here in Vancouver, it’s no secret that many are often in a more positive mood on a sunny day compared to a rainy day. In fact, published studies from as far back as the 1970s have linked bright sunny weather to outcomes associated with positive feelings; people report a higher well-being, tend to be more helpful, and display a greater optimism for the stock market. Meanwhile, based on an article which reviewed seasonal trends of suicide, depression-prone people become even more depressed. The article found that in over sixty of the eighty studies reviewed, suicides tend to peak in late spring and summer–when sunshine is more abundant. What was the answer behind these results? Well, researchers from the University of Toronto and Northwestern University have recently added new evidence to support these findings. The results of their study suggest that human emotion, whether positive or negative, is experienced more intensely under bright ambient light.

Chicken wings. Source.

In the study, participants were asked to rate several qualities on various number scales: the spiciness of chicken wings, aggressiveness of a fictional character, attractiveness of a woman, taste of two juices (orange juice and vegetable juice), and feelings towards certain words (eg. flower, smile, medicine, paper). The participants were assigned to either a bright-light or dimmed-light condition. In the bright-light condition, the room was brightly lit by fluorescent ceiling lights, while in the dimmed-light condition, the room was lit only by light from computer monitors. The room temperature was kept constant, and none of the participants knew the true purpose of the study.

Under bright light, participants rated the chicken wings as spicier, fictional character more aggressive, woman more attractive, consumed more of the favorable juice (orange juice), and felt better about positive words and worse about negative words. What was the theory behind these results–why are our initial emotional reactions to different kinds of stimulus intensified under bright light? According to the two researchers, bright light can increase perception of heat; in other words, bright light makes people feel warmer. This heat can, in turn, trigger a person’s emotional system and intensify their initial emotional response, whether positive or negative, to a stimulus.

Ceiling lights. Source.

How can these findings help us in the decision making process? Since the majority of everyday decisions seem to be made under bright light, researchers suggest that dimming down the lights may allow us to think more logically and therefore make more rational decisions. So the next time you make an important decision, have an emotional conversation, or settle a negotiation or argument, moving to conditions with dimmer lighting may help alleviate some unwanted emotions.

You can read the full published study here.

References: UToronto News.

– Cindy Hu