The pleasure of "maybe": both tease and terrorist exert control by fostering uncertainty in their targets

Natural History, Sept, 2003 by Robert M. Sapolsky

Then there was the summer Jonathan spent unsuccessfully wooing Rebecca. Both were savanna baboons living in the Serengeti Plains in East Africa, part of a troop I've been studying intermittently for twenty-five years. Jonathan was a gangly juvenile that had recently joined the troop; Rebecca was the confident young daughter of one of the highest-ranking matriarchs. Jonathan had taken one look at Rebecca and developed a god-awful male baboon crush that had him loping around after her wherever she went.

What he was probably after was to get her to groom him, or maybe even to coax her into something more intimate. What he was willing to settle for was a chance to groom her. But Rebecca was having none of it; she hardly acknowledged his existence. Whenever she'd sit down in the shade, or hang out with some friends, there was Jonathan, eager to groom her--and almost invariably getting the cold, fur-covered shoulder.

By all logic, such spectacular lack of success should have made Jonathan give up, or, as a psychologist might put it, should have caused "the behavior to extinguish." But eventually Rebecca became a little less resistant, and then, every so often, perhaps once a week, she gave in to his dogged devotion and let him groom her. Once she even groomed him back for a few distracted seconds, leaving him in baboonish ecstasy.

And that was all it took. Aglow from these crumbs of attention, poor Jonathan would redouble his efforts for the next few days.

The whole soap opera frustrated me enormously. I was working alone out in the middle of nowhere, probably badly in need of some "social grooming" myself, and clearly identifying with Jonathan. I sublimated Jonathan's predicament into grand orations in my head: "Here are the primate roots of our magnificent human capacity for gratification postponement. Here, in this pathetic dork of a baboon and his willingness to keep trying again and again despite a pitiful success rate, is the key to human greatness. Here is the suitor who keeps up a fifty-year courtship, the obsessive who spends a decade constructing a life-size replica of Elvis out of bottle caps. Here's all of us who forwent immediate pleasure in order to get good grades in order to get into a good college in order to get a good job in order to get into the nursing home of our choice."

What is it that gives us the power to do the harder thing, to be disciplined and opt for delayed gratification? And why is the rare, intermittent reward, the hint that you might win the lottery, so compelling? Two recent studies--one published in the journal Nature, the other in the journal Science--go a long way toward explaining these mysteries. But before considering those reports, it's worth taking brief tour through some parts of the brain that play a key role in the story.

The starting point of the tour is the frontal cortex, a region that takes up a much larger proportion of the primate brain than it does in other animals. The frontal cortex plays a big role in executive control, delayed gratification, and long-term planning. It does so by keeping the limbic system in check, primarily through neural projections that can release an inhibitory neurotransmitter into that deeper, more ancient brain system that specializes in emotion and impulsivity. Furthermore, the frontal cortex excels at resisting stimulating inputs from the limbic system: "Screw studying for the exam; run amok instead."

People with tight, regimented, "repressive" personalities have elevated metabolic rates in the frontal cortex, whereas sociopaths have lower-than-normal ones. If a person's frontal cortex is accidentally destroyed, he or she becomes a "frontal" patient--sexually disinhibited, hyperaggressive, socially inappropriate. With all that going for it, the frontal cortex is the closest thing we have to a neural basis for the superego.

But just what is it that gives the frontal cortex the backbone to ignore the siren call of the limbic system? There has long been evidence that a projection or conduit into the frontal cortex from a brain region called the ventral tegmentum plays a major role. This conduit serves as a Doctor Feel-good, dispensing doses of dopamine, a nourotransmitter closely associated with pleasure. Drugs such as cocaine increase the dopamine signal along this pathway, which is one reason they are so popular. Animals rigged up to get an electrical charge through the ventral tegmentum will work like maniacs, pressing levers, forgoing every-earthly pleasure offered to them, in order to get the stimulus.

So when is dopamine released? For a long time the answer seemed obvious: right after getting something highly desirable, a reward. Suppose you've implanted electrodes in a monkey's brain that enable you to monitor when the dopamine pathway gets activated. Sure enough, if you give the monkey some great reward from out of nowhere, you'll see a burst of activity: dopamine bathing the monkey's frontal cortex.

But in a series of studies in the mid-1990s, Wolfram Schultz, a neuroscientist then at the University of Fribourg in Switzerland, did some critical studies that threw that simple picture into disarray. Schultz trained monkeys to perform simple tasks to gain a reward. For example, if an animal pressed the correct lever, after a few seconds' delay it would get a bit of some desirable food. There was one special condition: a light would come on, signaling to the monkey that it could now begin its task. One might predict that the dopaminergic pathway would be activated after that food reward was received. But that's not what happened. The activity peaked right after the light came on, before the monkey performed its task.