Gambling in rhesus macaques (Macaca mulatta): The effect of cues signaling risky choice outcomes

Abstract

Preference for a larger-variable “risky” option over a smaller-reliable “safe” option often depends upon the likelihood that the risky option will deliver a sufficiently sized reward to have an equivalent or superior expected value. However, preference for the risky option has been shown to increase under conditions where informative stimuli signaling the outcome of a risky choice is included between the choice and the outcome (e.g., Zentall & Stagner, 2011) and this risk-prone preference persists even when the risky option has a lower expected value than the alternative safe option. In the present study, rhesus macaques chose between a risky option and a safe option across two experimental phases to determine whether the outcome signal affected the degree of preference for the risky option. Overall, six out of seven macaques showed a greater preference for the risky option in the signaled condition than in the unsignaled condition. The macaques’ risky choices were sensitive to the expected value of the risky option and the signaled condition produced a general increase in risky choices independently of the expected value of the risky outcome. Overall, these results are consistent with those obtained with other animals, and this may relate to a process where animals show a biased preference for “good news”. This process may model some of the relevant factors that explain the psychology of gambling in humans.

Human and pigeon suboptimal choice

“…Since Kendall's (1974) initial demonstration, suboptimal choice has been extensively studied in pigeons (see McDevitt et al, 2016 andZentall, 2016b), and has been observed in monkeys (e.g., Blanchard, Hayden, & Bromberg-Martin, 2015;Bromberg-Martin & Hikosaka, 2009;Smith, Beran, & Young, 2017) and starlings (e.g., Vasconcelos, Monteiro, & Kacelnik, 2015). The procedure has also been used with rats, but the results have been less consistent (e.g., Mazur, 2007;Trujano & Orduna, 2015; but see Cunningham & Shahan, 2019).…”

The description-experience gap: a challenge for the neuroeconomics of decision-making under uncertainty

“…Indeed, rhesus macaques exhibit robust risk-seeking behaviour in the gain domain [81][82][83][84][85][86][87][88][89][90]. Risk-seeking attitudes have also been reported in the loss domain [91]. Risk-seeking behaviour in experience-based studies can be computationally explained by an increased sensitivity to positive (compared to negative) prediction errors ('positivity' bias) as the one generally documented in humans (Box 1) [67,92,93].…”

Human Choice Predicted by Obtained Reinforcers, Not by Reinforcement Predictors

“…Past research has demonstrated preference for an alternative which produces stimuli that signal the future presence or absence of reinforcement over an alternative which does not produce reinforcement-predictive stimuli. This preference has been found in multiple species, including capuchins, rhesus macaques, pigeons, and rats ( Roper and Zentall, 1999 ; Smith et al, 2017 ; Cunningham and Shahan, 2019 ; Smith and Beran, 2020 ). For example, when Roper and Zentall (1999) presented a choice between two alternatives which produced reinforcement equally 50% of the time, pigeons’ choices were more frequently allocated to the alternative which provided reinforcement-predictive stimuli (see Figure 1A ).…”

“…When a similar study was conducted with rhesus macaques, subjects were more likely to choose a risky option which gave reinforcement less often if the outcomes were signaled ( Smith et al, 2017 ). That is, with experience, macaques chose suboptimally more often if stimuli predictive of reinforcement outcomes followed those choices.…”

“…This choice preference has been found multiple times in pigeons ( Stagner and Zentall, 2010 ; Zentall and Stagner, 2011 ; Laude et al, 2014 ) and has been likened to gambling behavior demonstrated by humans ( Zentall, 2014 , 2016 ). The present experiments used a similarly structured task to examine adult human preferences for reinforcement predictors and compared findings to choice behavior demonstrated by children ( Lalli et al, 2000 ), monkeys ( Smith et al, 2017 ; Smith and Beran, 2020 ), dogs ( Jackson et al, 2020 ), rats ( Chow et al, 2017 ; Cunningham and Shahan, 2019 ; Jackson et al, 2020 ), and pigeons ( Roper and Zentall, 1999 ; Stagner and Zentall, 2010 ). In Experiment 1, adult human participants showed no preference for reinforcement predictors.…”