Data_Sheet_1_A Bayesian Modeling Approach to Examine the Role of Testosterone Administration on the Endowment Effect and Risk-Taking.pdf

Financial risk-taking and loss aversion are multifaceted phenomena that are the focus of neuroscience, psychology, and economics research. A growing number of studies highlighted the role of hormones (particularly of testosterone) on socio-economic decision-making. However, the effects of testosterone on risk-taking under framing and consumer-based choices and preferences are inconclusive. We investigated the effects of 100 mg testosterone administration on aspects of decision-making within the Prospect Theory framework which is the most used descriptive model of decision-making under risk. We assessed risk-taking under framing and the endowment effect (effect of possession) using Bayesian modeling. Forty men participated in this double-blind placebo-controlled fully-randomized cross-over experiment and performed two tasks. One was a risk-taking task with binary choices under positive and negative framing associated with different probabilities. In the second task participants had to bid money for hedonic and utilitarian items. We observed a significant increase in serum testosterone concentrations after transdermal application. Compared to placebo, testosterone administration increased risk-taking under the positive framing (very large effect size) and decreased under the negative framing (moderate to small). The sensitivity to gain was positive in each framing. Our model showed that decision-making is jointly influenced by testosterone and the trade-off between gains and losses. However, while the endowment effect was more pronounced for hedonic than for utilitarian items, the effect was independent of testosterone. The findings provide novel information on the complex modulatory role of testosterone on risk-taking within the framework of prospect theory and shed light on mechanisms of behavioral economic biases. The proposed models of effects of individual differences in testosterone on risk-taking could be used as predictive models for reference-depended behavior under positive and negative framing with low and high probabilities.

金融风险承担与损失厌恶是多维度的复杂现象，亦是神经科学、心理学与经济学研究的核心议题。越来越多的研究证实，激素（尤其是睾酮（testosterone））在社会经济决策中发挥着重要作用。但目前关于睾酮对框架效应下风险承担行为，以及消费者导向选择与偏好的影响尚未形成定论。本研究依托风险决策领域最常用的描述性模型——前景理论（Prospect Theory）框架，探究了100mg睾酮给药对决策行为多维度的影响。本研究采用贝叶斯建模（Bayesian modeling）方法，评估了框架效应下的风险承担行为与禀赋效应（即所有权效应）。本研究共招募40名男性受试者参与此项双盲安慰剂对照的完全随机交叉实验，受试者需完成两项任务：第一项为风险承担任务，受试者需在对应不同概率的正负框架下完成二元选择；第二项任务中，受试者需为享乐型与实用型商品出价。经皮给药后，受试者血清睾酮浓度出现显著升高。与安慰剂组相比，睾酮给药可提升正向框架下的风险承担水平（效应量极大），并降低负向框架下的风险承担水平（效应量中等偏小）。两种框架下，受试者对收益的敏感度均为正向。本研究构建的模型显示，决策行为同时受到睾酮水平与损益权衡的共同调控。不过，尽管享乐型商品的禀赋效应较实用型商品更为显著，但该效应与睾酮水平无关。本研究结果为前景理论框架下睾酮对风险承担行为的复杂调节作用提供了全新认知，并揭示了行为经济偏差的内在机制。本研究提出的睾酮个体差异对风险承担影响的模型，可作为不同概率下正负框架内参照依赖行为的预测模型。