This is the best I find right now and I need to go to bed. They retell the same anecdote that I referred to at the end of that piece.

Here is the relevant part:

Heath tells us some of his patients were given "self-stimulators" similar to the ones used by Old's rats. Whenever he felt the urge, the patient could push any of 3 or 4 buttons on the self-stimulator hooked to his belt. Each button was connected to an electrode implanted in a different part of his brain, and the device kept track of the number of times he stimulated each site. ... We ask Heath if human beings are as compulsive about pleasure as the rats of Old's laboratory that self-stimulated until they passed out. "No," he tells us. "People don't self-stimulate constantly -- as long as they're feeling good. Only when they're depressed does the stimulation trigger a big response. There are so many factors that play into a human being's pleasure response: your experience, your memory system, sensory cues..." he muses.

Though in the version I read several years ago the events were in a different order. And they were actually talking about this as a means to reach the happy equilibrium that Kaj is talking about, so they talked much more about the other subjects in the experiment. I had forgotten that Heath interfered with the gay guy after, because that was kind of downplayed.