投资决策进化心理学的研究：预期的私人资金分配和父母对子女的差异性精力投入

Evolutionary Psychology of Investment Decisions: Expected Allocation of Personal Money and Differential Parental Investment in Sons and Daughters

投资决策的进化心理学研究着眼于辨认人类获得进化适应的特定环境中经常出现的典型性风险，探寻为了应对这些风险而进化出的信息处理机制，并验证现时的社会因素和个体因素对这些心理机制的激活或抑制作用。在研究一中，被试预测了与自己同龄的男人或女人如何分配一笔中彩的奖金给自己和其他可能的受益人。研究发现：（1）钱数的分配大体由亲缘关系的疏密程度决定；（2）两性被试都假想男性比女性更慷慨，但实际上男性表现得更自利；（3）女性被试预测男性中奖人的金钱分配比男性被试预测女性中奖人的金钱分配更为准确；（4）女性被试的受益人更多，分享的社会范围更广。研究二探讨了父母对子女投入精力的不同取决于家庭的相对财富而非绝对财富的进化心理学假说。用哺乳与否和生育间隔期为测量指标，研究结果显示：（1）家庭实际收入影响父母对子女的总投入；（2）与邻里家庭相比，父母对于自己家庭相对收入的认知影响了对子女有别的差异性精力投入。基于男性普遍在财富和生育数量上比女性有更大的变异度，投资儿子比投资女儿更具博弈性。两项研究表明，人类的理性决策既受限于社会关系又适应于相对的财富状况。

This paper reports experimental and field studies of risky investment. Evolution by natural selection should have equipped humans with a kith-and-kin rationality for investment decisions while sexual selection entailed a higher expectation for investments from a man than from a woman. In Study 1， participants estimated how a typical man or woman in the same age cohort would allocate lottery money to self and other possible recipients. The results showed that (1) the degree of kith-and-kin relatedness largely determined the amount of investment. (2) An imagined typical man was more generous than an imagined woman. However， male participants were more selfish than female participants. (3) Women were more accurate in estimating the other sex’s investment distribution than men. (4) Women invested in more recipients， thus had a larger scope of social sharing. Study 2 tested the evolutionary psychological hypothesis that differential parental investment in sons and daughters would be affected by the family’s relative rather than absolute wealth. Using breastfeeding and interbirth interval as the measurements of parental investment， the results showed that (1) real household income affected overall amount of parental investment irrespective of the sex of a child; and (2) relative wealth perceived by parents against their neighborhood households affected differential investment in sons versus daughters. Parental investment in sons is viewed as a riskier prospect than investment in daughters since men have a universally higher variance in wealth and reproduction than women. The two studies suggest that human decision rationality is bounded by social relations and adapted to relative wealth conditions.