Nakanishi Daisuke, Kameda Tatsuya, Shinada Mizuho
Department of Behavioral Science, Faculty of Letters, Hokkaido University, Kita-ku, Sapporo, 060-0810.
Shinrigaku Kenkyu. 2003 Apr;74(1):27-35. doi: 10.4992/jjpsy.74.27.
Social learning is an effective mechanism to reduce uncertainty about environmental knowledge, helping individuals adopt an adaptive behavior in the environment at small cost. Although this is evident for learning about temporally stable targets (e.g., acquiring avoidance of toxic foods culturally), the functional value of social learning in a temporally unstable environment is less clear; knowledge acquired by social learning may be outdated. This paper addressed adaptive values of social learning in a non-stationary environment empirically. When individual learning about the non-stationary environment is costly, a hawk-dove-game-like equilibrium is expected to emerge in the population, where members who engage in costly individual learning and members who skip the information search and free-ride on other members' search efforts coexist at a stable ratio. Such a "producer-scrounger" structure should qualify effectiveness of social/cultural learning severely, especially "conformity bias" when using social information (Boyd & Richerson, 1985). We tested these predictions by an experiment implementing a non-stationary uncertain environment in a laboratory. The results supported our thesis. Implications of these findings and some future directions were discussed.
社会学习是一种有效的机制，可减少环境知识的不确定性，帮助个体以低成本在环境中采取适应性行为。虽然这在学习时间上稳定的目标（例如，在文化上习得避免食用有毒食物）方面很明显，但社会学习在时间不稳定的环境中的功能价值尚不清楚；通过社会学习获得的知识可能会过时。本文通过实证研究探讨了社会学习在非平稳环境中的适应性价值。当个体学习非平稳环境的成本很高时，预计种群中会出现类似鹰鸽博弈的均衡，即进行高成本个体学习的成员与跳过信息搜索并搭其他成员搜索努力便车的成员以稳定比例共存。这样一种“生产者-寄生者”结构应该会严重限制社会/文化学习的有效性，尤其是在使用社会信息时的“从众偏差”（博伊德和里克尔森，1985）。我们通过在实验室中实施非平稳不确定环境的实验来检验这些预测。结果支持了我们的论点。讨论了这些发现的意义和一些未来方向。
