The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human

I’m not saying these questions are unimportant; in fact, it’s best to be aware of them right up front. But we have to be careful not to give up the whole enterprise just because we cannot yet provide complete answers to every quandary. On the contrary, we should be pleased that the process of trying to discover aesthetic universals has thrown up these questions we are forced to confront.

Abhorrence of Coincidences

When I was a ten-year-old schoolboy in Bangkok, Thailand, I had a wonderful art teacher named Mrs. Vanit. During a class assignment, we were asked to produce landscapes, and I produced a painting that looked a bit like Figure 8.2a—a palm tree growing between two hills.

Mrs. Vanit frowned as she looked at the picture and said, “Rama, you should put the palm tree a bit off to one side, not exactly between the hills.”

I protested, “But Mrs. Vanit, surely there’s nothing logically impossible about this scene. Maybe the tree is growing in such a way that its trunk coincides exactly with the V between the hills. So why do you say the picture is wrong?”

FIGURE 8.2 Two hills with a tree in the middle. (a) The brain dislikes unique vantage points and (b) prefers generic ones.

“Rama, you can’t have coincidences in pictures,” said Mrs. Vanit.

The truth was neither Mrs. Vanit nor I knew the answer to my question at that time. I now realize that my drawing illustrates one of the most important laws in aesthetic perception: the abhorrence of coincidences.

Imagine that Figure 8.2a depicts a real visual scene. Look carefully and you’ll realize that in real life, you could only see the scene in Figure 8.2a from one vantage point, whereas you could see the one in Figure 8.2b from any number of vantage points. One viewpoint is unique and one is generic. As a class, images like the one in Figure 8.2b are much more common. So Figure 8.2a is—to use a phrase introduced by Horace Barlow—“a suspicious coincidence.” And your brain always tries to find a plausible alternate, generic interpretation to avoid the coincidence. In this case it doesn’t find one and so the image isn’t pleasing.

Now let’s look at a case where a coincidence does have an interpretation. Figure 8.3 shows the famous illusory triangle described by Italian psychologist Gaetano Kanizsa. There really isn’t a triangle. It’s just three black Pac-Man-like figures facing one another. But you perceive an opaque white triangle whose three corners partially occlude three black circular discs. Your brain says (in effect), “What’s the likelihood that these three Pac-Men are lined up exactly like this simply by chance? It’s too much of a suspicious coincidence. A more plausible explanation is that it depicts an opaque white triangle occluding three black discs.” Indeed, you can almost hallucinate the edges of the triangle. So in this case your visual system has found a way of explaining the coincidence (eliminating it, you might say) by coming up with an interpretation that feels good. But in the case of the tree centered in the valley, your brain struggles to find an interpretation of the coincidence and is frustrated because there isn’t one.

FIGURE 8.3 Three black discs with pie-shaped wedges removed from them: The brain prefers to see this arrangement as an opaque white triangle whose corners partially occlude circular discs.

Orderliness

The law of what I loosely call “orderliness,” or regularity, is clearly important in art and design, especially the latter. Again, this principle is so obvious that it’s hard to talk about it without sounding banal, but a discussion of visual aesthetics is not complete without it. I will lump a number of principles under this category which have in common an abhorrence for deviation from expectations (for instance, the preference for rectilinearity and parallel edges and for the use of repetitive motifs in carpets). I will touch on these only briefly because many art historians, like Ernst Gombrich and Rudolf Arnheim, have already discussed them extensively.