The brain science behind gambling with the debt ceiling
By David J. Linden, PhD
The opinions expressed are his own.
The debt ceiling debate is raging in Washington. But what’s going on in the minds of the politicians working on the seemingly intractable problem? Barack Obama, Mitch McConnell, John Boehner and Eric Cantor are all taking calculated risks — bets — that they can win the standoff and get more out of the deal than the other side can. Their strategies are rooted in their politicals beliefs and theories on how government should operate, but their tactics come from the part of the brain that covets social acceptance and individual rewards.
In this excerpt from his new book “The Compass of Pleasure,” (Viking Press, 2011) David Linden, a professor of neuroscience at The Johns Hopkins University School of Medicine, explains what happens in the brain when people calculate risk and reward in dollar terms. One basic conclusion: humans get caught up in the risky thrill of winning big, sometimes at the expense of correctly understanding what they have to lose. They also compare themselves with their competitors and derive satisfaction from outperforming them — something Linden says humans are simply hardwired to do.
The pleasure circuit in the brain evolved so that we would find food and water and sex rewarding and thereby survive, have children and propagate our genes. While money is not an ancient and intrinsic reward in the same way that food, water, and sex are, one could argue that it has come to represent the possibility of intrinsic rewards, and so activation of the pleasure circuit by money is not strictly arbitrary. Or it may be that we just like money for its own sake, no matter what it represents.
Hans Breiter and his coworkers addressed these issues in some clever in human brain scanning experiments. Initially each subject received an account containing $50 worth of credit. They were instructed that they were working with real money and that they would be paid the balance of their account in cash at the end of the experiment. In the brain scanner, they watched a video screen that showed one of three wheels, each of which was divided into three pie-shaped segments labeled with a monetary outcome. The “bad” wheel had only negative or neutral outcomes (-$6.00, -$1.50, or $0), an “intermediate” one had mixed results (+$2.50, -$1.50, $0), and a final “good” wheel primarily had rewards (+$10.00, +$2.50, $0). After a particular wheel type was presented on the screen, the subject would push a button that would initiate rotation of an animated pointer. The pointer would spin for about five seconds and then come to rest, seemingly randomly, on one of the three possible outcomes, where it would remain for five more seconds.
The design of this experiment makes it possible to measure brain activation during both an anticipation phase (while the pointer is spinning) and an outcome phase (after the pointer has stopped). Of course, the software running the pointer is controlled by the experimenters so that it can deliver all of the possible monetary outcomes in a balanced manner.
The main finding was that key regions of the brain’s pleasure circuit were activated during both the anticipation phase and the outcome phase, when the outcomes were positive. The anticipation phase responses were graded according to the possible outcome: There was greater activity while the “good” wheel’s pointer was spinning than when that of the “intermediate” or “bad” wheel. And finally, during the outcome phase with the “good” wheel, greatest activation was seen for the largest monetary rewards. Thus even anticipation and experience of an abstract reward, like money, can activate the human pleasure circuit—we’re hardwired to catch a buzz of gambling and to catch the biggest buzz when the most is at stake.
This experiment was also designed to test another hypothesis about monetary reward in gambling. Using a related task, Barbara Mellers and coworkers demonstrated that people regard a $0 outcome on the “good” wheel as a loss but a $0 outcome on the “bad” wheel as a win. If our minds were completely rational, we would value these outcomes the same way, but we don’t. We are influenced by the counterfactual possibility of “what might have been.” Was this irrational belief reflected in brain activation? The response strength to the $0 outcome on the “good” wheel was lower than that for the “bad” wheel. However, the responses to the $0 outcome on the “intermediate” wheel did not fall between the levels for the good and the bad $0 responses, as would be predicted. The theory that counterfactual comparison modulates brain pleasure circuit activation is therefore possible, but remains unproven.
Another irrational idea about gambling involves near misses. For example, if a horse one bets on to win comes in second, or if two of three reels on a slot machine’s payline match, it will be experienced as a near miss rather than as a loss. A number of experiments have manipulated near-miss frequency and have shown that near misses promote continued gambling. In fact, there appears to be an optimal frequency of near misses to maximally extend slot machine gambling—about 30 percent. Manufacturers of video slot machines are well aware of this effect and some have programmed their devices to increase the rate of near misses above random levels.
In games of pure chance, like craps or the lottery, gamblers have the same probability of winning whether or not they have a direct involvement in the process (such as buying the lottery ticket, or rolling the dice). Nonetheless, many studies have shown that gamblers will bet more and continue gambling longer if they do have a personal role in these fundamentally random events. In some cases, this even affects the style of the particular actions involved in the game . For example, craps players tend to throw the dice with less force when trying to roll low numbers.
While both the near-miss effect and the direct-involvement effect are seen in general populations, they are even more prevalent in gambling addicts. Considering these irrational aspects of gambling, Luke Clark and his colleagues at the University of Cambridge hypothesized that there would be significant activation of the pleasure circuit by near misses on a video slot machine and that this activation would be stronger on trials where the gambler had some personal control, as opposed to those presented exclusively by the computer. They placed forty subjects in a brain scanner and presented them with a simplified two-reel video slot machine in which one reel was fixed and the other spun. The position of the fixed reel was set by the subject on some trials and by the computer on others. Hits in which the two reels matched yielded a payout of 50 pence. Near misses were those trials in which the matching symbol of the spun reel came to rest either one row above or below the payline. Neither near misses nor full misses produced a payout. The computer was programmed to produce near misses on two out of six trials, hits on one out of six trials, and full misses on three out of six trials.
Before each trial the subject was asked, “How do you rate your chances of winning?” After each trial the subject was then asked, “How pleased are you with the result?” and “How much do you want to continue to play the game?” In confirmation of previous findings, personal control of the fixed reel increased both the subject’s estimation of his chances and his interest in continuing to play. Also, on winning trials, the “pleased with result” ratings were higher on the personal-control trials as compared with the computer-control trials. When compared to full misses, near misses were experienced as less pleasant but as stimulating the desire to continue to play, but only for those trials where the subject had personal control of the fixed reel.
When the brain scanning data were examined, there were two main findings. First, in all trials, near misses activated much of the same pleasure circuit regions as wins. Both results activated a key region called the the nucleus accumbens and another called the anterior insula. However, wins and personal-control trial near misses, but not computer-control trial near-misses, also activated another nearby region: the rostral anterior cingulate cortex. These results might help to explain some of the irrational behavior involving gambling: Activation of win-related regions by near-miss outcomes is somehow pleasurable and is more pleasurable when the subject has personal control. This pattern of brain activation could underlie the ability of near misses to promote continued gambling.
All of our behavior is embedded in a social context, and this social context powerfully influences our feelings and decisions. Even mild social rejection can activate the emotional pain centers in the anterior cingulate cortex. Does this mean that positive social interactions can activate pleasure centers as well?
One form of positive social interaction is acceptance—a positive evaluation of the self by others. Norihiro Sadato and his coworkers at the National Institute of Physiological Sciences in Japan have sought to delineate the brain regions activated by one’s “good reputation” and compare that to the activation pattern produced by monetary reward. The monetary reward task was like many we have discussed before: Subjects in a brain scanner chose one card of three on a video screen and received various monetary rewards. This produced a pattern of activation similar to that seen in previous studies. The strongest activations were produced by the largest rewards, and these occurred in a number of regions of the pleasure circuit and structures interconnected with the pleasure circuit, including the orbitofrontal cortex, the insula, the dorsal striatum, and the nucleus accumbens.
When the same subjects returned for a second day of testing, they took an extensive written personality survey and recorded a short video interview. Then they entered the scanner, where they received social feedback in the form of evaluations of their personality that had supposedly been prepared by a panel of four male and four female observers. To further the deception, they were shown photos of these observers and were told that they would meet them at the end of the experiment. The feedback took the form of a photo of the subject’s own face with a single-word descriptor underneath. Some of the descriptors were positive, such as “trustworthy” and “sincere,” while others were rather neutral, like “patient.” (All of these terms were actually in Japanese, not English.) Of course, these descriptors were all generated by the experimenters and presented in a randomized order. The main finding was that the most positive social reward descriptors activated portions of the pleasure circuit—most notably the nucleus accumbens and the dorsal striatum—that substantially overlapped with those activated in the monetary reward task. This finding suggests that there is, quite literally, a common neural currency for social and monetary reward.
In recent years, many social scientists have come to realize that social comparison can be in important factor in driving economic (and other) decisions of individuals. We evaluate our own economic circumstances and prospects not on some absolute scale, but rather in comparison to those of people around us. We already know that monetary reward can activate certain pleasure centers. If social comparison is indeed encoded in brain function, then it is reasonable to hypothesize that activation of pleasure centers should reflect socially relative rather than absolute levels of payout.
To address this issue, Armin Falk and his colleagues at the University of Bonn conducted an experiment in which nineteen pairs of subjects were monitored in side-by-side brain scanners. Each subject simultaneously performed a simple perceptual task: A field of dots was displayed on a video screen for 1.5 seconds, and immediately afterwards a number (such as “24”) was shown. The subject had to choose, using a rapid button press, whether the dot count was higher or lower than the number. After a short delay, a feedback screen informed the subject about his performance and that of the other subject along with respective monetary rewards give (e.g., He: 60 euros, You: 120 euros).
The subjects received a payout only if they solved the task correctly: If both subjects failed, no payout was given. If only one was correct, he received either 30 or 60 euros, while the other got nothing. However, when both solved the task correctly (which occurred about 66 percent of the time) the computer would assign rewards randomly, from 30 to 120 euros. Sometimes the subjects would get the same reward, sometimes the rewards would be mildly disparate, and other times they would be highly disparate. This experiment showed that social comparison strongly influences activation of reward centers in the brain. The nucleus accumbens was most strongly activated in those trials in which there was a significant difference between one subject’s monetary reward and that of the adjacent subject.
In other words, despite the biblical injunction of the Tenth Commandment, “Thou shalt not covet thy neighbor’s house/wife/slaves/ox/ass/plasma TV/Porsche/etc.,” we seem to be hardwired to compare our own experiences and circumstances to those around us.
For footnotes from this excerpt please visit the Compass of Pleasure website.