The makers of slot machines know what they are doing to keep patrons betting. Lights and sounds accompanying a win trigger something so deep in our brains, it can even addict rats to gambling. The process appears to be driven by a single component of the dopamine pathway, and blocking one dopamine receptor gets rats clean.
Dr. Catharine Winstanley of the University of British Columbia created a “rat casino,” where she taught rats to choose between buttons that sometimes deliver sugary treats. Some options provided small, probable returns; others seldom paid off, but offered a bigger win when they did. Losing meant being locked out of the game for a period of time. The system was designed for the low-risk, small return option to always beat the high-risk choice if both were repeated enough times.
The rats learned fast, and most preferred safe options, rather than banking on long odds bets to produce a sweet life. Winstanley then tried to alter the trials to make the rats behave more like problem gamblers. One such effort involved adding flashing lights and sounds accompanying a win, mimicking gambling venues' poker machines.
"It seemed, at the time, like a stupid thing to do, because it didn't seem like adding lights and sound would have much of an impact. But when we ran the study, the effect was enormous," Winstanley said in a statement. Rats, as nocturnal animals with very different lifestyles to our own, might be expected to respond differently to bright lights, but it seems the appeal runs deep in our evolutionary history.
Rats whose wins were accompanied with sound and motion were significantly more likely to chase rare big wins, rather than the boring but safe option chosen by their siblings who got treats without a sound and light show. "Anyone who's ever designed a casino game or played a gambling game will tell you that of course sound and light cues keep you more engaged, but now we can show it scientifically," Winstanley said.
The rodents' enthusiasm for high-risk options appears to be connected to the D3 dopamine receptor. In the Journal of Neuroscience, Winstanley reports that when a D3 agonist was used, triggering the D3 receptors, the rats became more likely to chase the big wins. “A D3 antagonist had the opposite effects,” the paper reports, but “only on the cued task.” In other words, blocking the D3 pathway did not change the behavior of the minority of rats who preferred to back long shots even without the lights and sound.
"This brain receptor is also really important to drug addiction, so our findings help support the idea that risky behavior across different vices might have a common biological cause," said Michael Barrus, Winstanley's Ph.D. student and the paper's lead author.
The findings may encourage regulation of casino environments, as well as spur research into whether D3 antagonists can help gambling addicts beat their habits.