Exploring decoy effects on computerized task preferences in rhesus monkeys (Macaca mulatta).

Parrish, Audrey E.; Afrifa, Elyce; Beran, Michael J.

doi:10.26451/abc.05.02.06.2018

Cited by 6 publications

(3 citation statements)

References 20 publications

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“…A rst perceptual task by Parrish and colleagues (2015) found an attraction effect in macaques choosing among geometric gures. However, the following value-based study with the same species failed to replicate the effect (Parrish et al, 2018). Similar negative results have been reported in comparable studies on other primate species, such as capuchins monkeys (Cohen & Santos, 2017) or great apes (Sanchez-Amaro et al, 2019), choosing between different food options.…”

Section: Introductionsupporting

confidence: 74%

Real and Phantom Decoys in Capuchin Monkey (Sapajus spp.) Decision-Making

Marini,

Colaiuda,

Gastaldi

et al. 2023

Preprint

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Decision-making has been observed to be systematically affected by decoys, i.e., options that should be irrelevant, either because unavailable or because manifestly inferior to other alternatives, and yet shift preferences towards their target. Decoy effects have been extensively studied both in humans and in several other species; however, evidence in non-human primates remains scant and inconclusive. To address this gap, this study investigates how choices in capuchin monkeys (Sapajus spp.) are affected by two types of decoys: asymmetrically dominated decoys, i.e., options that are inferior to one of the other alternatives, and phantom decoys, i.e., unavailable options that are superior to another available alternative. After controlling for the subjective strength of initial preferences and the distance of each decoy from its target in attribute space, results demonstrate a systematic shift in capuchins’ preference towards the target of both asymmetrically dominated decoys (whether they are available or not) and phantom decoys, regardless of what options is being targeted by such decoys. This provides the most comprehensive evidence to date of decoy effects in non-human primates, with important theoretical and methodological implications for future comparative studies on context effects in decision-making.

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Section: Introductionsupporting

confidence: 74%

Real and Phantom Decoys in Capuchin Monkey (Sapajus spp.) Decision-Making

Marini,

Colaiuda,

Gastaldi

et al. 2023

Preprint

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“…These findings seemed to suggest that context effects emerge quickly and early in the decisional processes and are not limited to complex decision making (for a similar result in humans, see Trueblood et al 2013). However, in a following study using a computerized preference task (Parrish et al 2018), which entails a more cognitively complex decisional situation, rhesus macaques did not show any substantial evidence of attraction effects.…”

Section: Introductionmentioning

confidence: 78%

Context-effect bias in capuchin monkeys (Sapajus spp.): exploring decoy influences in a value-based food choice task

et al. 2022

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Decision making is known to be liable to several context effects. In particular, adding a seemingly irrelevant alternative (decoy) to a set of options can modify preferences: typically, by increasing choices towards whatever option clearly dominates the decoy (attraction effect), but occasionally also decreasing its appeal and generating a shift in the opposite direction (repulsion effect). Both types of decoy effects violate rational choice theory axioms and suggest dynamic processes of preference-formation, in which the value of each alternative is not determined a priori, but it is instead constructed by comparing options during the decision process. These effects are well documented, both in humans and in other species: e.g., amoebas, ants, honeybees, frogs, birds, cats, dogs. However, evidence of decoy effects in non-human primates remains surprisingly mixed. This study investigates decoy effects in capuchin monkeys (Sapajus spp.), manipulating time pressure across different conditions, to test whether such effects require time-consuming comparative processes among available alternatives. Whereas the time-dependent nature of decoy effects is a robust finding in the human literature, this is its first investigation in non-human animals. Our results show that capuchins exhibit an attraction effect with decoys targeting their preferred food, and that this effect disappears under time pressure; moreover, we observe preliminary evidence of a repulsion effect when decoys target instead the less-preferred food, possibly due to the larger distance between decoy and target in the attribute space. Taken together, these results provide valuable insight on the evolutionary roots of comparative decision making.

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“…For example, bees and 93 grey jays show decoy effects when choosing among artificial flowers and 94 tubes holding raisins, respectively [24]. But in primates, the only study 95 that has found a decoy effect used a perceptual discrimination task [25], 96 but the same monkeys do not show the effect when choosing among tasks 97 that vary in effort required [26]. Further, two studies using food choice 98 tasks, which are arguably most similar to the foraging experiments used 99 with bees and grey jays, found no evidence of this bias [19,27].…”

Section: Introduction 64mentioning

confidence: 99%

Capuchin monkeys (Sapajus [Cebus] apella) are more susceptible to contrast than to decoy and social context effects

Watzek¹,

Brosnan²

2020

Preprint

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42Theories of optimal decision-making typically assume that animals have 43 consistent preferences among options. In reality, economic behaviour in 44 humans and foraging behaviour in some animals is often susceptible to 45 choice-irrelevant factors such as inferior options or conspecifics' 46 outcomes, but the evidence for primate decision-making is mixed. Unlike 47 previous experiments, we assessed the relative magnitude of three context 48 effects. Using a food preference paradigm, we varied the number of cereal 49 pieces to determine how much a piece of food A was "worth" (50% 50 choice) to each of 13 capuchins. We predicted that monkeys would 51 devalue A in the contrast condition (when a higher-quality but 52 unattainable food was present) and overvalue it in the decoy condition 53(when a smaller version of A was a third option) and social condition 54(when A, if unchosen, was given to a partner). Capuchins were 4 times 55 less likely to choose A in the contrast condition, but 2 to 3 times more 56 likely to choose it in the decoy and social conditions. When carefully 57 accounting for initial preferences, we found that these primates, like 58 humans, are sensitive to context effects. This suggests that these biases are 59 evolved and impacts how we think about them in humans. 60 Keywords: decision-making bias, context dependence, decoy effect, 61 contrast effect, capuchin monkey, Sapajus [Cebus] apella 62 63

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Exploring decoy effects on computerized task preferences in rhesus monkeys (Macaca mulatta).

Cited by 6 publications

References 20 publications

Real and Phantom Decoys in Capuchin Monkey (Sapajus spp.) Decision-Making

Real and Phantom Decoys in Capuchin Monkey (Sapajus spp.) Decision-Making

Context-effect bias in capuchin monkeys (Sapajus spp.): exploring decoy influences in a value-based food choice task

Capuchin monkeys (Sapajus [Cebus] apella) are more susceptible to contrast than to decoy and social context effects

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