Arshad Qadeer, Nigmatullina Yuliya, Siddiqui Shuaib, Franka Mustafa, Mediratta Saniya, Ramachandaran Sanjeev, Lobo Rhannon, Malhotra Paresh A, Roberts R E, Bronstein Adolfo M
Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom.
J Neurophysiol. 2017 Dec 1;118(6):3007-3013. doi: 10.1152/jn.00372.2017. Epub 2017 Sep 13.
Over the past decade neuroscientific research has attempted to probe the neurobiological underpinnings of human prosocial decision making. Such research has almost ubiquitously employed tasks such as the dictator game or similar variations (i.e., ultimatum game). Considering the explicit numerical nature of such tasks, it is surprising that the influence of numerical cognition on decision making during task performance remains unknown. While performing these tasks, participants typically tend to anchor on a 50:50 split that necessitates an explicit numerical judgement (i.e., number-pair bisection). Accordingly, we hypothesize that the decision-making process during the dictator game recruits overlapping cognitive processes to those known to be engaged during number-pair bisection. We observed that biases in numerical magnitude allocation correlated with the formulation of decisions during the dictator game. That is, intrinsic biases toward smaller numerical magnitudes were associated with the formulation of less favorable decisions, whereas biases toward larger magnitudes were associated with more favorable choices. We proceeded to corroborate this relationship by subliminally and systematically inducing biases in numerical magnitude toward either higher or lower numbers using a visuo-vestibular stimulation paradigm. Such subliminal alterations in numerical magnitude allocation led to proportional and corresponding changes to an individual's decision making during the dictator game. Critically, no relationship was observed between neither intrinsic nor induced biases in numerical magnitude on decision making when assessed using a nonnumerical-based prosocial questionnaire. Our findings demonstrate numerical influences on decisions formulated during the dictator game and highlight the necessity to control for confounds associated with numerical cognition in human decision-making paradigms. We demonstrate that intrinsic biases in numerical magnitude can directly predict the amount of money donated by an individual to an anonymous stranger during the dictator game. Furthermore, subliminally inducing perceptual biases in numerical-magnitude allocation can actively drive prosocial choices in the corresponding direction. Our findings provide evidence for numerical influences on decision making during performance of the dictator game. Accordingly, without the implementation of an adequate control for numerical influences, the dictator game and other tasks with an inherent numerical component (i.e., ultimatum game) should be employed with caution in the assessment of human behavior.
在过去十年中，神经科学研究一直试图探究人类亲社会决策的神经生物学基础。此类研究几乎普遍采用独裁者博弈或类似变体任务（即最后通牒博弈）。鉴于此类任务具有明确的数字性质，令人惊讶的是，数字认知在任务执行过程中对决策的影响仍不明确。在执行这些任务时，参与者通常倾向于以50:50的分配为锚点，这需要进行明确的数字判断（即数字对平分）。因此，我们假设独裁者博弈中的决策过程会调用与数字对平分过程中已知参与的认知过程重叠的认知过程。我们观察到，数字大小分配中的偏差与独裁者博弈中的决策制定相关。也就是说，对较小数字大小的内在偏差与不太有利的决策制定相关，而对较大数字大小的偏差与更有利的选择相关。我们通过使用视觉 - 前庭刺激范式，下意识地、系统地向较高或较低数字诱导数字大小偏差，从而证实了这种关系。数字大小分配中的这种下意识改变导致了独裁者博弈中个体决策的成比例且相应的变化。至关重要的是，当使用基于非数字的亲社会问卷进行评估时，未观察到数字大小的内在偏差或诱导偏差与决策之间的关系。我们的研究结果表明数字对独裁者博弈中做出的决策有影响，并强调在人类决策范式中控制与数字认知相关的混杂因素的必要性。我们证明数字大小的内在偏差可以直接预测个体在独裁者博弈中向匿名陌生人捐赠的金钱数量。此外，下意识地在数字大小分配中诱导感知偏差可以积极地推动亲社会选择朝着相应方向发展。我们的研究结果为数字对独裁者博弈执行过程中的决策影响提供了证据。因此，如果不充分控制数字影响，在评估人类行为时应谨慎使用独裁者博弈和其他具有内在数字成分的任务（即最后通牒博弈）。
