You May Not See as Much Colour as You Think You Do

You May Not See as Much Colour as You Think You Do
A participant views a partially desaturated scene in virtual reality. (Image: Michael A. Cohen, Thomas L. Botch, and Caroline E. Robertson, PNAS 2020)

If everything in your peripheral vision suddenly changed from colour to black and white, would you notice? There’s a good chance you wouldn’t — in a new study involving virtual reality, most people never realised that their surroundings had abruptly desaturated. The results add to a large body of research suggesting we often perceive much less of the world around us than we think we do.

In the study, published last week in PNAS, 160 participants freely explored scenes in virtual reality. They weren’t given any particular task, and the videos were complete with audio, including music and dialogue. For the first 7 seconds of each session, the scenes were in full colour. After that, though, all colour was removed from the periphery of the videos (the researchers used eye-tracking technology embedded in the headsets to ensure that colour only appeared directly where the participants were looking).

Fascinatingly, most people didn’t notice that much of the scene they were looking at had turned to black and white. When the researchers divulged the change after the experiment was over, the volunteers were shocked.

“Some people laugh, some people are kind of in denial. It’s really common to get phrases like, ‘wait, no way,’” Michael Cohen, a professor of neuroscience and psychology at Amherst College, told Gizmodo. “A lot of people were really taken aback. It’s a fun experiment to run, because there’s a lot of smiling and a lot of laughing once you do the reveal.”

The video below, made by the researchers, shows how the experiment worked:

The research team, which included Cohen, Dartmouth College psychology professor Caroline Robertson, and Dartmouth researcher Thomas Botch, tested out four different versions of the trial, each with increasingly shrinking areas of colour. In the most extreme trial, participants only saw a tiny circle of colour — and yet, 30% of them didn’t notice the desaturation at all. In the trial with the largest area left in colour, a whopping 83% were oblivious to the black-and-white periphery.

“We were very surprised by how big the effect was,” Cohen said. “We thought, everyone’s gonna notice this, but whatever, let’s try it anyway. And people were still not noticing.” He added, “It’s not a subtle thing at all.”

The results seem to be an example of a phenomenon called “inattentional blindness,” or when people fail to see something in their field of view because they didn’t pay attention to it. If you’ve ever been looking for your phone, only to finally find it sitting on top of your desk, you know what it’s like to not see something that’s clearly visible. Indeed, many other studies have found that people can fail to perceive seemingly obvious things happening right in front of them.

Are you thinking that you’d never miss something so conspicuous? It’s worth checking out perhaps the most famous study of inattentional blindness, published in 1999. Psychologists showed participants a video of people tossing basketballs and asked them to count the number of times the players in white passed the ball. If you’re not familiar with this experiment, go ahead and try it for yourself here — I’ll save the spoiler for after the video.

About half of viewers never notice that, partway through the video, a person in a gorilla costume strolls into the middle of the action and bangs their chest. Psychologists Daniel Simons and Christopher Chabris eventually won an Ig Nobel Prize, which honours researchers that “make people laugh, then think,” for this finding. A 2006 study replicated the experiment using eye-tracking technology, and, amazingly, many people did look directly at the gorilla but still didn’t consciously perceive it.

But what if people are warned ahead of time to look for anomalies? Cohen and his colleagues ran a second experiment, in which the same volunteers again explored scenes in virtual reality, but this time, they were told to press a button every time they saw the periphery switch to black and white. Even then, depending on how much of scene was desaturated, many people still didn’t notice the change.

Lester Loschky, a psychology professor at Kansas State University who wasn’t involved in the new research, told Gizmodo that the experiments were “very nicely done.” While virtual reality is of course not the same as real life, “it is the best way to test something close to real-world perception while still having tight control over the experimental stimuli,” said Loschky, who specialises in the study of visual perception and cognition.

Graphic: PNAS 2020 Graphic: PNAS 2020

He said the results line up with what scientists currently know about how people perceive changing scenes.

“There is actually a lot of research showing that people fail to notice things in their peripheral vision. Everyday experience is full of cases where people don’t notice things that were in plain sight but were in their visual periphery,” Loschky said. “Drivers talking on their mobile phones and looking at the car ahead of them often fail to notice other cars, motorcyclists, bicyclists, or pedestrians entering the roadway in their visual periphery. That has been shown in a large number of carefully controlled driving simulator experiments.”

It’s not that people can’t see changes in their peripheral vision; instead, they just aren’t aware of them. This sort of research has implications for the real world, including for how pilots are trained and how courts treat eyewitness testimony. “Perception is far from infallible, and it pays to be able and willing to question one’s own perceptions, because sometimes they are very wrong,” Loschky said.

If you want to go even deeper down this rabbit hole, there’s something called “inattentional blindness blindness” — basically, you don’t know how much you don’t see. Cohen recalled how baggage screeners will often overlook really obvious things, like guns or knives in suitcases. “They’ll later see what they missed and think, ‘How could I have not seen that?’”

Looking ahead to future research, Cohen and his colleagues want to study whether they can make other kinds of changes to scenes without people noticing, like scrambling the periphery or making it blurry.

If you can’t see things that are right in front of you, as research suggests, it’s worth wondering what else you’re missing. The reckless driver you need to watch out for, the favourite sweater you’re looking for, even the simple beauty of the place you live in could all be hidden in plain sight.