Optical Illusions

Judging from Twitter, most of my UK-based friends spent all of last night glued to the television news. Except, of course, for the idiots like me who spent it working. But today I caught up with some other TV, because there is a new series of the BBC’s science program, Horizon, just started, and the opening episode is well worth a dive into the iPlayer archives.

The program looks at the idea of color, how we perceive it, and what effect it has on us. Many of the findings may surprise you. For example, color influences not just our emotions, but also how awake we feel, and even our sense of the passage of time. Color perception is different for different people as well. For example, your ability to tell the difference between two colors depends heavily on how the language you speak divides up the spectrum into categories. That’s because as a child you learn to distinguish colors on the basis of the words you learn to describe them. And that’s fascinating because it means that our experience of art can be subjective on a very basic level.

Interestingly, our ability to perceive color is dependent on our expectations. So, for example, we will identify a banana as yellow under a range of different lighting conditions, but a patch of yellow paint has no such clues. That means that our brains are making up the color we see, based on their expectations of what we are looking at.

Color can also influence what we think we are seeing. In combat sports contestants are randomly allocated blue or red clothing. Experiments, including digitally altering the color of film, suggest that expert judges will tend to favor the contestant in red. Studies of sports at the Olympics suggest that in a close bout wearing red confers a significant advantage.

All of this is fascinating, but I can’t help but wonder if it is the tip of a very big iceberg. I have this sneaking suspicion that an awful lot of what we think that we see is influenced by our environment, and by our expectations of the things we are looking at.

For those of you who don’t have access to the iPlayer, there is an article about some of the issues raised during the program here.

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2 Responses to Optical Illusions

  1. Zander says:

    “That means that our brains are making up the color we see, based on their expectations of what we are looking at.”

    Um, if the programme actually stated that I think they were overstating the case. If someone tells me they’ve painted the living room a lovely shade of green, and I go in there and it’s pink, I will see pink and not green.

    I really find the persistence of this idea–that “we do not perceive what we think we perceive”–disturbing. Our senses were developed as survival mechanisms. I’m not versed in evolutionary biology, but it seems to me that senses that don’t convey an accurate picture, or even worse that show us what we expect to see rather than what’s there, would not be strong survival traits. The point about language is a good one, but the reasoning from it is doubtful, I think.

    • Cheryl says:

      I think you are mis-understanding the experiment here. No one is making a “power of suggestion” argument. We expect a banana to be yellow because we have seen hundreds, if not thousands, of bananas before and they are usually yellow. There’s no expectation of the color of living room walls. Also it wasn’t a case of the subjects being showed a blue banana and thinking it was yellow. They were shown a banana in poor lighting conditions where the color could not be discerned, and they assumed it was yellow. They did not make the same assumption about a patch of yellow paint under similar conditions.

      Also there’s a difference between “don’t convey an accurate picture” and “we do not perceive what we think we perceive”. What some of these experiments are showing is that what we think we perceive is a model of the world, and we don’t all have the same model. The utility of the model, particularly in the case of isolated populations, may be very dependent on circumstances. So for the Namibian tribe they found whose color spectrum is radically different from ours may have developed that spectrum because of local conditions, not in spite of them.

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