Université de Strasbourg, Strasbourg, France.
Laboratoire de Recherche en Gestion et Economie, EM Strasbourg Business School, Université de Strasbourg, Strasbourg, France.
Philos Trans R Soc Lond B Biol Sci. 2021 Mar;376(1819):20190672. doi: 10.1098/rstb.2019.0672. Epub 2021 Jan 11.
Decision outcomes in unpredictable environments may not have exact known probabilities. Yet the predictability level of outcomes matters in decisions, and animals, including humans, generally avoid ambiguous options. Managing ambiguity may be more challenging and requires stronger cognitive skills than decision-making under risk, where decisions involve known probabilities. Here we compare decision-making in capuchins, macaques, orangutans, gorillas, chimpanzees and bonobos in risky and ambiguous contexts. Subjects were shown lotteries (a tray of potential rewards, some large, some small) and could gamble a medium-sized food item to obtain one of the displayed rewards. The odds of winning and losing varied and were accessible in the risky context (all rewards were visible) or partially available in the ambiguous context (some rewards were covered). In the latter case, the level of information varied from fully ambiguous (individuals could not guess what was under the covers) to predictable (individuals could guess). None of the species avoided gambling in ambiguous lotteries and gambling rates were high if at least two large rewards were visible. Capuchins and bonobos ignored the covered items and gorillas and macaques took the presence of potential rewards into account, but only chimpanzees and orangutans could consistently build correct expectations about the size of the covered rewards. Chimpanzees and orangutans combined decision rules according to the number of large visible rewards and the level of predictability, a process resembling conditional probabilities assessment in humans. Despite a low sample size, this is the first evidence in non-human primates that a combination of several rules can underlie choices made in an unpredictable environment. Our finding that non-human primates can deal with the uncertainty of an outcome when exchanging one food item for another is a key element to the understanding of the evolutionary origins of economic behaviour. This article is part of the theme issue 'Existence and prevalence of economic behaviours among non-human primates'.
在不可预测的环境下，决策结果可能没有确切的已知概率。然而，结果的可预测性水平在决策中很重要，动物，包括人类，通常会避免模棱两可的选择。与风险决策相比，管理模糊性可能更具挑战性，需要更强的认知技能，因为风险决策涉及已知的概率。在这里，我们比较了卷尾猴、猕猴、猩猩、大猩猩、黑猩猩和倭黑猩猩在风险和模糊情境下的决策行为。实验对象会看到彩票（一托盘潜在的奖励，有些大，有些小），可以用一个中等大小的食物来赌一个显示的奖励。赢和输的概率在风险情境下是变化的并且是可获得的（所有的奖励都是可见的），或者在模糊情境下是部分可获得的（一些奖励是被覆盖的）。在后一种情况下，信息的水平从完全模糊（个体无法猜测覆盖物下是什么）到可预测（个体可以猜测）不等。没有一种物种会避免在模糊彩票上下注，如果至少有两个大的奖励是可见的，那么下注的比例就很高。卷尾猴和倭黑猩猩忽略了被覆盖的物品，大猩猩和猕猴考虑了潜在奖励的存在，但只有黑猩猩和猩猩能够始终如一地对覆盖奖励的大小做出正确的期望。黑猩猩和猩猩根据可见的大奖励数量和可预测性水平来组合决策规则，这一过程类似于人类对条件概率的评估。尽管样本量较小，但这是首次在非人类灵长类动物中证明，在不可预测的环境下，几种规则的组合可以作为选择的基础。我们的发现表明，非人类灵长类动物可以在用一种食物换取另一种食物时应对结果的不确定性，这是理解经济行为进化起源的关键因素。本文是主题为“非人类灵长类动物的经济行为的存在和普遍性”的一部分。
