Ever find yourself sitting down at the computer just for a second to find out what other movie you saw that actress in, only to look up and realize the search has led to an hour of Googling?
Our internal sense of time is believed to be controlled by the dopamine system. People with hyperactivity disorder have a shortage of dopamine in their brains, which a recent study suggests may be at the root of the problem. For them even small stretches of time seem to drag. An article by Nicholas Carr in the Atlantic last year, “Is Google Making Us Stupid?” speculates that our constant Internet scrolling is remodeling our brains to make it nearly impossible for us to give sustained attention to a long piece of writing. Like the lab rats, we keep hitting “enter” to get our next fix.
University of Michigan professor of psychology Kent Berridge has spent more than two decades figuring out how the brain experiences pleasure. Like Panksepp, he, too, has come to the conclusion that what James Olds' rats were stimulating was not their reward center. In a series of experiments, he and other researchers have been able to tease apart that the mammalian brain has separate systems for what Berridge calls wanting and liking.
Wanting is Berridge's equivalent for Panksepp's seeking system. It is the liking system that Berridge believes is the brain's reward center. When we experience pleasure, it is our own opioid system, rather than our dopamine system, that is being stimulated. This is why the opiate drugs induce a kind of blissful stupor so different from the animating effect of cocaine and amphetamines. Wanting and liking are complementary. The former catalyzes us to action; the latter brings us to a satisfied pause. Seeking needs to be turned off, if even for a little while, so that the system does not run in an endless loop. When we get the object of our desire (be it a Twinkie or a sexual partner), we engage in consummatory acts that Panksepp says reduce arousal in the brain and temporarily, at least, inhibit our urge to seek.
But our brains are designed to more easily be stimulated than satisfied. “The brain seems to be more stingy with mechanisms for pleasure than for desire,” Berridge has said. This makes evolutionary sense. Creatures that lack motivation, that find it easy to slip into oblivious rapture, are likely to lead short (if happy) lives. So nature imbued us with an unquenchable drive to discover, to explore. Stanford University neuroscientist Brian Knutson has been putting people in MRI scanners and looking inside their brains as they play an investing game. He has consistently found that the pictures inside our skulls show that the possibility of a payoff is much more stimulating than actually getting one.