In Lake Tanganyika in the heart of Africa, there lives an unusual species of fish, Haplochromis burtoni of the cichlid family. It is peculiar for having two varieties of male. One group of males is bright yellow or blue with black stripes around the eyes, while the other is a dull grey, similar in appearance to females of the species.

The main difference between them is that the colourful males are dominant, aggressive and territorial. They belong, as it were, to a kind of fish aristocracy and only they are allowed to fertilise the females. The grey males need to settle for a subordinate role, although their grey camouflage gives them better protection against predators.

This strict hierarchy in the African fish kingdom isn’t set in stone, though. Occasionally something almost miraculous happens. Within hours, a grey male serf may be able to transform himself into a colourful swaggering nobleman, should a vacancy open up as the result of a dominant male being killed.

Neuroscientist Ian Robertson tells this strange story of fish in his book The Winner Effect: How Power Affects Your Brain (Bloomsbury Publishing 2012). Robertson’s book is mainly about the effect of power on animal and human brains, but the author dedicates much of it to more general findings in modern science, such as the realisation that what goes on in our brain depends significantly on our environment.

The winner effect

Scientists researching animal behaviour through an experiment on mice noticed that a mouse, which had previously won a confrontation with a drugged competitor, also tended to defeat an unhandicapped competitor more often than a mouse with no previous victories. This phenomenon was dubbed the winner effect, and it means each victory increases the winner’s chances of winning the next battle.

This phenomenon isn’t found only in animals; it can also be noticed in humans, especially when they compete in sports. Additional testing, performed on other species besides mice, showed that winning increases testosterone levels and leads animals to put up a more aggressive fight.

Matthew Fuxjager of the University of Wisconsin studied the winner effect in even greater detail. He wanted to know what happened to the brain after a series of victories. By doing experiments on mice, he showed that winning increases the number of testosterone receptors in certain parts of the brain. This means that the same amount of testosterone has, in fact, a more significant effect on the animal’s behaviour.

He later made another exciting discovery. This increase in the number of receptors in the motivational part of the brain occurred only when the mouse won on home turf. When the victory was won on foreign territory, it had no effect on the number of receptors. Something similar was observed when studying addiction.

After the Vietnam War ended, American doctors noticed something unusual in returning veterans. Many soldiers and other military personnel had used heroin during their time in Vietnam, and many developed an addiction. But a large number suddenly felt no need for the drug on returning to the US. Their freedom from dependence on the drug contradicted everything scientists thought they knew about the biological mechanisms leading to heroin addiction. It seemed the servicemen had quite literally left their addiction behind them in the foreign warzone, or that it couldn’t follow them back to American soil.

The mystery of such locally limited addiction was solved by Stephen Siegel of McMaster University in Canada, in a study of drug addiction in rats. Just like humans, rats tend to develop a tolerance to a drug as doses increase in size. Siegel’s big discovery came when he created environment-specific rat addicts. He introduced rats to the drug in a specially coloured cage with a specific scent. When they developed a strong addiction, he injected them with a large control dose of heroin, but half of the rats received it in their usual cage, whereas the other half moved to a new environment.

The results were astonishing. The death rate due to heroin overdose was twice as high in the new environment as the death rate among rats that remained on “home turf”.

It is now known that the same principle applies to humans. Addicts who constantly take a drug after the same ritual in the same environment start to feel the effect of the drug even before they inject themselves with it. The mere prospect of receiving the next dose triggers the effect of the drug. But this “home turf effect” also causes the effect of the drug to lose its potency later on. Addicted users then require ever-larger doses to achieve the desired effect.

American soldiers who took heroin in faraway Asia, in a different climate, exposed to a very different way of life and the environmental shocks of a war zone, developed their addiction in that highly specific situation. When they returned to the U.S., they no longer encountered the elements that had triggered their addiction in Vietnam. Consequently, they didn’t have much difficulty letting go of their drug habit.

The colour does make a difference

The “home turf effect” is a fairly well-known phenomenon in sports, but other far more banal elements that tend to increase a team’s chances of winning are less well known and also less researched. When Russel Hill and Robert Barton of Durham University in England studied the results of the 2004 Olympic Games in Athens, they discovered that in some sports even the colour of the team’s jerseys can have a significant effect on the final result.

There was a rule in boxing and wrestling that one of the contestants needed to wear red and the other blue. When the two researchers compared the athletes’ results, they found that contestants wearing red kit won 62% of all fights. They noticed the same effect in football. In the 2004 Euro championship, the teams in red jerseys achieved better results.

The explanation they offered was a simple one. If we take a quick glance at someone who seems red in the face, we intuitively presume they are angry, whereas someone who is pale is considered frightened. Our brains spontaneously reach this conclusion without us giving it a much conscious thought. This interpretation seems to be mentally ingrained from times when we had to fight physically to survive.

In a given discipline or event, so little in terms of ability separates the very top athletes that the outcome of a contest will often be swung by the smallest of factors. The colour of the jerseys is one such factor. Red signifies domination, while blue implies subordination; and this has a subconscious effect on athletes. It can add or take away a decisive amount of energy or encouragement, and make the difference between winning and losing.