Testosterone administration makes you worse at poker

Testosterone is a steroid hormone from the androgen group and is found in humans and other vertebrates. In humans and other mammals, testosterone is secreted primarily by the testicles of males and, to a lesser extent, the ovaries of females. Small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.

Studies show that, depending on situation and person factors (1, 2), testosterone can increase cooperation and fairness in economic interactions (3, 4). Testosterone administration furthermore has increased generosity in the Trust Game (5), and the hormone decreased lying in a private game of dice (6). These findings suggest that testosterone increases concerns for social reputation (2, 3, 4, 5), and that the hormone does not motivate for status seeking through either greedy or deceitful strategies (7, 8, 9). However, concerns for status and resources remain hard to disentangle in humans as they are intrinsically intertwined (5). Therefore, in a new study (10) republished corrected on February 25, 2016, Goetz S. M. et al. investigated the effects of testosterone administration on behavior in a paradigm wherein concerns for status and resources uniquely collide: a two-person poker game developed by Von Neumann and Morgenstern (11). They performed a placebo-controlled single-dose testosterone administration in young women, who played a game of bluff poker wherein concerns for status and resources collide. The profit-maximizing strategy in this game is to mislead the other players by bluffing randomly (independent of strength of the hand), thus also when holding very poor cards (cold bluffing). The profit-maximizing strategy also dictates the players in this poker game to never call the other players’ bluffs. For reputable-status seeking these materialistic strategies are disadvantageous; firstly, being caught cold bluffing damages one’s reputation by revealing deceptive intent, and secondly, not calling the other players’ bluffs signals submission in blindly tolerating deception. Here they’ve shown that testosterone administration in this game of bluff poker significantly reduces random bluffing, as well as cold bluffing, while significantly increasing calling. Their data suggest that testosterone in humans primarily motivates for reputable-status seeking, even when this elicits behaviors that are economically disadvantageous.

In sum, their data shows that after testosterone administration, compared to placebo, subjects bluff less randomly; their bluffing is more dependent on the strength of their hand. Bluffing under the influence of testosterone becomes thus more predictable and hence easier to foresee by the opponent. This is especially caused by subjects bluffing significantly less with very weak cards after testosterone administration; in the cold bluffing range. Both the reduction in random, as well as cold bluffing signifies a greater deviation from the game’s profit-maximizing strategy (11). Bluffing should be unpredictable and occur over the whole range, and thus also with a very weak hand.

If testosterone in humans encourages dominance behavior in ways corresponding to other animals, the hormone should not increase cheating behavior, but instead improve reputation building and cheater detection. Indeed, there is evidence in humans that dishonest, treacherous behavior is associated with low testosterone levels (12). Additionally, administration of testosterone has shown to induce reputable and honest behaviors in human males and females. Reputation is slowly earned and quickly lost, and cheating may seriously compromise one’s reputation and one’s chances of benefiting from future cooperation. Increases in prosocial behaviour observed in testosterone administration studies in humans may therefore serve reputation building, and mutually beneficial cooperation.

They’ve also shown that testosterone administration caused subjects to call the bluffs of the opponents more in the poker game, and these data provide powerful corroborating evidence for testosterone’s proposed role in reputable-status seeking in humans. The frequency of calling increased after testosterone administration in this poker game, wherein the profit-maximizing strategy in Bluff Poker is to never call (11). Note that this profit-maximizing strategy, to always fold and never call the other players’ bluff, clearly is a submissive policy, as the player passively allows the other player to deceive and make profit through these cheats. Their prior research has repeatedly demonstrated that humans with exogenously increased, or endogenously high testosterone levels automatically and robustly avoid the display of submission signals.


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