FIGURE 7.7 Dancing stone nymph from Rajasthan, India, eleventh century. Does it stimulate mirror neurons?
The relevance of the peak-shift law to caricatures and to the human body is obvious, but how about other kinds of art?2 Can we even begin to approach Van Gogh, Rodin, Gustav Klimt, Henry Moore, or Picasso? What can neuroscience tell us about abstract and semiabstract art? This is where most theories of art either fail or start invoking culture, but I’d like to suggest that we don’t really need to. The important clue to understanding these so-called higher art forms comes from a very unexpected source: ethology, the science of animal behavior, in particular, from the work of the Nobel Prize–winning biologist Nikolaas Tinbergen, who did his pioneering work on seagulls in the 1950s.
Tinbergen studied herring gulls, common on both the English and American coasts. The mother gull has a prominent red spot on her long yellow beak. The gull chick, soon after it hatches from the egg, begs for food by pecking vigorously on the red spot on the mother’s beak. The mother then regurgitates half-digested food into her chick’s gaping mouth. Tinbergen asked himself a very simple question: How does the chick recognize its mom? Why doesn’t it beg for food from any animal that’s passing by?
Tinbergen found that to elicit this begging behavior in the chick you don’t really need a mother seagull. When he waved a disembodied beak in front of the chick, it pecked at the red spot just as vigorously, begging the beak- wielding human for food. The chick’s behavior—confusing a human adult for a mother seagull—might seem silly, but it isn’t. Remember, vision evolved to discover and respond to objects (recognize them, dodge them, eat them, catch them, or mate with them) quickly and reliably by doing as little work as needed for the job at hand—taking short- cuts where necessary to minimize computational load. Through millions of years of accumulated evolutionary wisdom, the gull chick’s brain has learned that the only time it will see a long yellow thing with a red spot on the end is when there’s a mom attached to it at the other end. After all, in nature the chick is never likely to encounter a mutant pig with a beak or a malicious ethologist waving around a fake beak. So the chick’s brain can take advantage of this statistical redundancy in nature and the equation “long thing with red spot = mom” gets hardwired into its brain.
In fact Tinbergen found that you don’t even need a beak; you can just have a rectangular strip of cardboard with a red dot on the end, and the chick will beg for food equally vigorously. This happens because the chick brain’s visual machinery isn’t perfect; it’s wired up in such a way that it has a high enough hit rate in detecting mom to survive and leave offspring. So you can readily fool these neurons by providing a visual stimulus that approximates the original (just as a key doesn’t have to be absolutely perfect to fit a cheap lock; it can be rusty or slightly corroded.)
But the best was yet to come. To his amazement, Tinbergen found that if he had a very long thick stick with three red stripes on the end, the chick goes berserk, pecking at it much more intensely than at a real beak. It actually prefers this strange pattern, which bears almost no resemblance to the original! Tinbergen doesn’t tell us why this happens, but it’s almost as though the chick had stumbled on a superbeak (Figure 7.8).
FIGURE 7.8 The gull chick pecks at a disembodied beak or, a stick with a spot that is a reasonable approximation of the beak given the limits of sophistication of visual processing. Paradoxically, a stick with three red stripes is even more effective than a real beak; it is an ultranormal stimulus.
Why could such a thing happen? We really don’t know the “alphabet” of visual perception, whether in gulls or humans. Obviously, neurons in the visual centers of the gull’s brain (which have fancy Latin names like nucleus rotundum, hyperstriatum, and ectostriatum) are not optimally functioning machines; they are merely wired up in such a way that they can detect beaks, and therefore mothers, reliably enough. Survival is the only thing evolution cares about. The neuron may have a rule like “the more red outline the better,” so if you show it a long skinny stick with three stripes, the cell actually likes it even more! This is related to the peak-shift effect on rats mentioned earlier, except for one key difference: in the case of the rat responding to the skinnier rectangle, it’s perfectly obvious what rule the animal has learned and what you are amplifying. But in the case of the seagull, the stick with three stripes is hardly an exaggerated version of a real beak; it isn’t clear at all what rule you are tapping into or amplifying. The heightened response to the striped beak may be an inadvertent consequence of the way the cells are wired up rather than the deployment of a rule with an obvious function.
We need a new name for this type of stimulus, so I’ll call it an “ultranormal” stimulus (to distinguish it from “supernormal,” a phrase that already exists). The response to an ultranormal stimulus pattern (such as the three- striped beak) cannot be predicted from looking at the original (the single-spot beak). You could predict the response—at least in theory—if you knew in detail the functional logic of the circuitry in the chick’s brain that allows the rapid, efficient detection of beaks. You could then devise patterns that actually excite these neurons even more effectively than the original stimulus, so the chick’s brain goes “Wow! What a sexy beak!” Or you might be able to discover the ultranormal stimulus by trial and error, stumbling on it as Tinbergen did.
This brings me to my punch line about semiabstract or even abstract art for which no adequate theory has been proposed so far. Imagine that seagulls had an art gallery. They would hang this long thin stick with three stripes on the wall. They would call it a Picasso, worship it, fetishize it, and pay millions of dollars for it, while all the time wondering why they are turned on by it so much, even though (and this is the key point) it doesn’t resemble anything in their world. I suggest this is exactly what human art connoisseurs are doing when they look at or purchase abstract works of art; they are behaving exactly like the gull chicks.
By trial and error, intuition or genius, human artists like Picasso or Henry Moore have discovered the human brain’s equivalent of the seagull brain’s stick with three stripes. They are tapping into the figural primitives of our perceptual grammar and creating ultranormal stimuli that more powerfully excite certain visual neurons in our brains as opposed to realistic-looking images. This is the essence of abstract art. It may sound like a highly reductionist, oversimplified view of art, but bear in mind that I’m not saying that’s
The same principle may apply to impressionist art—a Van Gogh or a Monet canvas. In Chapter 2, I noted that visual space is organized in the brain so that spatially adjacent points are mapped one-to-one onto adjacent points on the cortex. Moreover, out of the thirty or so areas in the human brain, a few—especially V4—are devoted primarily to color. But in the color area, wavelengths adjacent in an abstract “color space” are mapped onto adjacent points in the brain even when they are not near each other in external space. Perhaps Monet and Van Gogh were introducing peak shifts in abstract color space rather than “form space,” even deliberately smudging form when required. A black-and-white Monet is an oxymoron.
This principle of ultranormal stimuli may be relevant not just to art but to other quirks of aesthetic preference as well, like whom you are attracted to. Each of us carries templates for members of the opposite sex (such as your mother or father, or your first really sizzling amorous encounter), and maybe those whom you find inexplicably and disproportionately attractive later in life are ultranormal versions of these early prototypes. So the next time you are unaccountably—even perversely—attracted to someone who is not beautiful in any obvious sense, don’t jump to the conclusion that it’s just pheromones or “the right chemistry.” Consider the possibility that she (or he) is an ultranormal version of the gender you’re attracted to buried deep in your unconscious. It’s a strange thought that human life is built on such quicksand, governed largely by vagaries and accidental encounters from the past, even though we take such great pride in our aesthetic sensibilities and freedom of choice. On this one point I am in
