NEW PAPER: Testosterone fluctuations and slot machine gambling

Congratulations to Mario Ferrari for his first CGR paper, based on his MA thesis, just published in the APA journal ‘Psychology of Addictive Behaviors’, on testosterone fluctuations and slot machine gambling: evidence for a ‘winner-loser’ effect?  We were interested in the classic finding that outcomes of social contests affect testosterone levels (i.e. the winners show an increase, the losers decrease). Would winning vs losing outcomes on 15 min real slot machine play have similar effect? In 113 males, we also looked at ‘anthropomorphism’ — the tendency to treat the slot machine as if a human opponent — as possibly regulating this effect. Mario used a sophisticated analysis technique (Hierarchical Linear Modelling) to analyze testosterone (& cortisol) changes over time. Unfortunately, the data did not support our hypotheses! Couple of interesting things that we did see. First, slot machine anthropomorphization did vary a lot even in novice gamblers, and seems to be a neglected cognitive distortion. Second, an exploratory finding was that game enjoyment & flow ratings actually predicted testosterone decreases. Third, we realized some of the difficulties with using real slot machines to ‘manipulate’ winning and losing: we can’t randomize these conditions, the winners win less than the losers lose (given the RTP), and we cannot control rare events like bonus features. Many thanks to Paula Brown and Michael Chan at BCIT for their help with the hormonal assays, and of course, the participants for taking part.

Ferrari MA, Chan M, Brown PN, Clark L. Slot machine gambling and testosterone: Evidence for a ‘winner-loser’ effect? Psychology of Addictive Behaviors 2018, 32: 961-971. doi: 10.1037/adb0000425