Shedding light on being good

When walking alone at night, I’d rather walk on a street with good street lamps than a dark one. How about you?

Instinctively, I believe that bad things are less likely to happen on a well-lit street.

U.S. Supreme Court justice Louis Brandeis once wrote, "Sunlight is said to be the best of disinfectants; electric light the most efficient policeman.” He said this to illustrate the good that government transparency can do, but it draws on the same observation about the physical world: that increased light and visibility lead to better behavior.

There is a long tradition of metaphorically linking darkness and evil, light and goodness. Metaphorical relationships often come about through abstraction from more concrete experiences, suggesting an underlying link between light and goodness in our physical experience. 

When it’s light, we can see each other. It’s hard to sneak up on someone in broad daylight. If we do something bad or embarrassing, others will see it and judge us or laugh at us (we fear). Perhaps we’re more self-conscious, and as a result try to act in a way that others can’t fault. In the dark, we’re freer to do as we like. If we break a rule or do something improper, we’re less likely to be seen or identified. But the same holds for others, too. Walking down a dark alley, we fear those who might be hiding in the shadows. 

A few years ago, I was excited to come across evidence of this effect in the physical world — people are more likely to lie and act selfishly in the dark (we’ll look at this study in detail below). But since then, I’ve seen conflicting results, with some studies showing that people behave better towards each other in the light, and some showing that darkness fosters better behavior.

What gives? 

Inspired by yet another new paper to come out on this topic a couple of months ago, I thought I’d dig in and try to make sense of the mess. If you follow along, I think you’ll see that there are many potential applications to use lighting to impact our patterns of thoughts and behaviors, from rule-following, to healthy eating, to creativity.

Deviance in the dark

In a creepy 1970s study titled “Deviance in the Dark,” which I doubt would pass ethics review today, participants, who were mostly students, were individually led into a testing room which eventually held eight people. Approximately half were male and half female.

For some of these groups of eight, the room they went into was pitch dark. Only a tiny dot of red above the doorway illuminated the way to the exit.

Participants were told: “You will be left in the chamber for no more than an hour with some other people. There are no rules as to what you should do together. At the end of the time period, you will each be escorted from the room alone, and will subsequently depart from the experimental site alone. There will be no opportunity to meet the other participants.” This set-up meant that in addition to being in the dark, everyone was anonymous, too. They would never learn the identifies of the others in the room.

The researchers used infrared cameras to monitor the behaviors of the participants in the dark room and also asked everyone about their experience after they came out.

In another condition, the researchers left the lights on in the room, so that they could compare people's behavior in the dark and in the light.

The differences in behaviors and experience were stark. 

People came into the light room, found a place to sit that wasn’t too close to anybody else, and sat there for the remainder of the experiment. The group held a steady conversation from the beginning to the end of the hour. No one tried to touch other people (cause how weird would that be?).

In the dark room, people reported feeling tense and nervous at first. They moved around a lot. But things changed quickly. Talking stopped almost entirely within half an hour. Almost 90% of people touched another person on purpose. Around half hugged someone. One person wrote at the end of the experience: “I felt I had made some friends. In fact, I missed them.” Most volunteered to return to the room without getting paid to be part of a study. If you want to create a cult-like environment, you need look no further than this study for inspiration.

Image source, annotations added. Anonymous strangers in a dark room behaved very differently from ones in a light room.

A third condition was dark but not anonymous. Participants were told they would meet each other after their shared time in the dark room. This changed the experience for the worse—much worse. People reported feeling panicky. They were less likely to move around or introduce themselves to others or to hug. They were more likely to feel bored.

In a dark and anonymous environment, likely more extreme than what most of us have ever experienced, social norms were abandoned, and people felt like they were free to do things they would not under other circumstances. 

What about environments that are less extreme — less dark and less anonymous?

Deal with it

Sometimes, being in a dark environment can instead make us act like selfish jerks.

In one study, researchers compared people’s likelihood of cheating to get more money if they were in a dim or a bright room. Participants were each given a sheet of 20 math problems and told that they could keep $0.50 from a pile of $10 for each one they solved correctly in 5 minutes (which was too little time to solve all 20). They were asked to return the rest of the money in an envelope along with a collection slip that appeared to have no identifying information (but, sike! There was a code on the sheet that allowed researchers to match up the envelope with a particular sheet of math problems). Everyone overstated how well they performed. But people in the bright room only overstated their performance a little bit. Those in the dark room overstated their performance by a LOT — almost 60%.

Outside of changes in the ambient light environment, wearing sunglasses can also give us the impression that our surroundings are darker. And wearing sunglasses can also make us act like selfish jerks.

Image source. Deal with it.

In another experiment, participants were asked to wear either sunglasses or clear glasses (with no prescription) and then played a dictator game with another person ostensibly in another room. In this game, one person is the dictator, and one person the recipient. The participants were always the dictators. Each dictator had $6 to divide up between themselves and the recipient. The recipient could accept or reject the offer, but it made no difference to the dictator - the dictator always kept whatever money they didn’t offer to the other person.

Again, no one was perfect. People tended to keep a bit more money for themselves. Those wearing clear glasses shared almost equally, giving $2.71 out of the $6 pool to the recipient. But those wearing sunglasses only shared $1.81, which was significantly less than the $3 we’d expect if they were sharing equally.

In a final experiment, the researchers tested whether wearing sunglasses changed how people felt. People in sunglasses reported feeling more anonymous than those wearing clear glasses (e.g., endorsing items like “my choice went unnoticed during the study” — as if!), even though the shades made not one bit of difference in reality.

Light and goodness

While dim light can make people act selfishly, the flip side is that bright light can increase positive, pro-social behavior. 

One study replicated the dictator game findings described above using room lighting (vs. sunglasses) and also tested the effect of lighting on honesty. Participants were either in a dim room, a medium-brightness room, or a bright room. The bright room “dictators” shared more money than those in the medium-brightness room, and those in dimly lit room shared the least. After participants played the game, they were given an envelope with their payment and asked to make sure they received the payment they deserved. But each person was given additional, undeserved money in the envelope. Who fessed up? 

Honesty followed the same pattern as room brightness: those in the well-lit room were most likely to be honest (85% of people returned the extra cash), those in the medium-brightness room were medium-honest (70% returned the extra cash), and those in the dimly lit room were least likely to be honest (52% returned the extra cash).

In another experiment, the same dim, medium-brightness, and bright conditions were used to test the effect of lighting on charitable giving. After the experimental session seemingly wrapped up and participants were paid, they were told that the lab was collecting charity donations and that they could drop off a donation in a box by the door before leaving. Participants were left alone, so no one could directly observe their actions. Room brightness affected the donation amounts: those in the bright room donated the most, those in the medium-brightness room donated a medium amount, and those in the dim room donated the least.

In a final experiment, the researchers directly tested whether bright lighting affects people’s desire to be act morally. Participants, who were in a bright room or a medium-bright room, were asked to visualize someone who embodied a list of positive moral characteristics and to rate how much they wanted to be like this person. Under bright lights, participants aspired to be more moral — to be caring, compassionate, fair, helpful, honest, and kind.

At the end of the experimental session, participants’ actual desire to embody these traits was tested. They were asked whether they would like to volunteer their time to help out with a truly thankless task: coding the researcher’s data. 

Participants in the bright room volunteered to code more data than those in the medium-bright room (7.6 vs. 5.6 data sheets). In addition, the extent to which participants desired to act morally explained the relationship between lighting condition and volunteering. This suggests that bright light increased participants' desire to act morally, which in turn led them to help out when someone needed their help.

Why does bright light make us want to act better?

The key reasons might be increased self-awareness and inhibition of responses that don’t fit our view of our (good) selves. 

Bright light acts as a signal that we might be observed by others, leading to a heightened state of self-awareness. In one study, participants, who were either in a bright or dim room, completed measures of three types of self-awareness: 1) public self-awareness (e.g., “Right now I am concerned about what other people think of me”), 2) private self-awareness (e.g., “Right now I am conscious of my inner feelings), and 3) awareness of the immediate environment (e.g., “Right now I am keenly aware of everything in my environment).

Bright light only increased public self-awareness, and had no effect on private self-awareness or awareness of the environment. This suggests that in bright light conditions, we suddenly become keenly aware of how we might be seen and judged by others. 

If we’re afraid of being judged, we best follow the rules that society has laid out for us. There’s evidence that bright light influences rule-following, too. Another experiment tested whether people preferred to act in a way that was in line with rules (“I like to follow definite rules or directions”) or their own ideas and strategies (e.g., "When making decisions, I tend to rely on my own ideas”) under bright or dim lighting conditions. In bright light, people reported wanting to follow the rules, and in dim light, they preferred to follow their own ideas.

If you’re more aware of how others are seeing you, then you should also be more controlled and reflective in your actions. In another experiment, participants wore either sunglasses or clear glasses and listed their current desires and duties. They also rated how important each desire and duty was. Everyone wrote down more desires than duties, but this ratio was higher for those wearing sunglasses. People wearing sunglasses also thought their desires were more important than people wearing clear glasses. Another point for the 'sunglasses can make you act like a selfish jerk' theory.

Application to the design of spaces

Bright light is good if you want to encourage rule-following and self-control, while dim light encourages people to do what they want. The pitch black room from the Deviance in the Dark study described above is an extreme example of a “doing what you want” environment.

People seem to instinctively know this. When left to their own devices, people select brighter light for activities that require more self-awareness and self-control. For example, people prefer bright light for activities like working or studying, and dimmer light for activities that don’t require self-control, like taking a break, listening to music, or eating. People also prefer brighter lights in public places, where they will likely have to make a good impression (e.g., office or classroom), than in private places (e.g., bedroom or family room).

A lot of bad habits (overeating, smoking, impulse spending, gambling, etc.) are hard to break because they require override the “doing what you want” mode. Might lighting have an effect? There’s some evidence in line with this idea. For example, a field study varying the brightness of chain restaurants found that customers tended to choose more unhealthy food when the lighting was dim, ordering 39% more calories per person. In a more extreme case, among people trying to constrain their eating, those who preferred dimmer lighting tended to binge eat more. So brighter light might help to control our food impulses.

Image source. People tended to choose unhealthy choices in dimly light restaurants. 

Maybe even thinking of bright light could do some good. 

In one study, participants, some of whom were smokers and some who were not, recalled a time when they were in a bright or dark place. They then completed a task that tested their automatic impulse toward or away from smoking-related images (e.g., a picture of someone holding a cigarette, a cigarette next to an ashtray, etc.). For non-smokers, thinking of a bright or dark place made no difference: they had an automatic impulse away form smoking-related images. But for smokers, those who had previously recalled being in a dark place showed a higher smoking impulse. 

Image source, annotations added. Smokers who recalled being in a dark place had a higher smoking impulse.

Creativity

A more positive outcome of the freedom from constraints we experience in dim light is that it can help with a certain type of creativity, which requires looser and riskier thinking to find low-probability connections between ideas.

In one study, participants tried to solve insight problems in a dark or bright room, and they also rated how free from constraints they felt in the environment.

Here’s an example of one of these insight problems:

A window washer was cleaning the windows of a high rise building when he slipped and fell off a sixty-foot ladder onto the concrete sidewalk below. Incredibly he did not injure himself in any way. How was this possible? 

(Don’t know? See the answer)

Participants solved more insight problems in the dark room than in the bright room. And they also felt freer from constraints in the dark room. The effect of perceived freedom explained the relationship between room brightness and problems solved, suggesting that the dim light caused people to feel freer, which allowed them to solve these problems more easily.

But creativity isn’t just coming up with wacky ideas. They have to be good wacky ideas. And evaluating ideas' quality and feasibility requires logical thinking. In another experiment, participants were tested both on creative idea generation and logical reasoning in a bright or dark room. People had more original, creative ideas (as measured by a task where they got to draw aliens) in the dark room, but performed better on the reasoning task in the bright room.

A space for creative thinking—at least the kind of creative thinking that requires low-probability associations between ideas—would ideally combine two different kinds of environments. One, a dark, freeing space (e.g., a dark, soft lounge area) to help people come up with really out-there ideas, and two, a bright space in which people could evaluate their ideas, reason about their consequences, and build on them (e.g., a well-lit whiteboard room).

I or we?

While most studies have found that bright light increases helpful, pro-social behavior, a few have found the opposite effect. This discrepancy might have to do with whether people see themselves as independent or interdependent (also called individualistic vs. collectivistic) when they experience the lighting condition. 

The reasoning goes like this. Bright light makes you more self-aware. If you tend to think of yourself in relation to other people (i.e., if you are interdependent), then this self-awareness should cause you to try to help others. But if you tend to see yourself as completely separate from other people (i.e., you are independent), then this self-awareness should cause you to remember that all that matters is you, and to act more selfishly.

A recent study tested this idea directly.

Cultures vary in how independent or interdependent they are. The researchers tested whether bright and dim lighting would have different effects on people from Germany, who tend to be very independent, and Canada, who tend to less independent. After participants ostensibly finished the experimental tasks, they were paid and given the chance to make a donation to charity. Participants from Canada donated more money in the bright condition, while participants from Germany donated more money in the dim condition. 

This finding suggests that bright environments might be less effective at promoting pro-social behavior in highly independent populations (e.g., Germany, Norway, Finland). But, no fear, you can also use behavioral nudges to promote an interdependent mindset in those who are independent.

In another experiment, the researchers induced either an independent or interdependent mindset in a highly independent population—American college students—by asking them to write about enjoying life (independent mindset) or enjoying relationships with family and friends (interdependent mindset). Participants were once again given the chance to donate some of their earnings to charity. Those who were induced to have an interdependent mindset donated more money under a bright condition than a dim condition, with a weaker opposite effect for those induced to have an independent mindset. It turns out that if we think about others, most of us are not selfish jerks in the dark after all.

If you are creating an environment to encourage an independent population to be good and to follow the rules, perhaps combining behavioral nudges could help. These days, I’m thinking bright light and a sign along the lines of "protect your friends and family, stay six feet apart."

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