贝叶斯推理中的“自击中率参照抑制”

The Inhibition From Hit Rate Reference of Bayesian Reasoning

本文旨在研究贝叶斯推理中基础比率、击中率起作用的机制。通过设置肝炎情境、中彩情境的贝叶斯推理问题,同时操作基础比率和击中率的水平,考察449名大学生被试的概率估计情况。结果表明,总体上,贝叶斯推理中的基础比率和击中率均起作用,表现为后验概率估计值随基础比率水平的提高而增加,随击中率水平的提高而增加。然而,在低基础比率的中彩情境中,后验概率估计值先随击中率的增加而增加;之后却随击中率水平的继续提高而显著降低,出现"自击中率参照抑制"。这似乎说明,击中率在贝叶斯推理中并非一致地起作用,而可能与推理者的知识经验对击中率加工的调节有关。

The base rate and the hit rate are the two probabilistic information which play important roles in Bayesian reasoning. However,there are numerous different explanations for how the two probabilistic information function.New findings revealed this controversy was caused by speculators＇ different experiences.Thus,taking speculators experiences into consideration,the paper explored the mechanism of the integrated function of the base rate and the hit rate in Bayesian reasoning. Setting hepatitis and lottery as contexts,this research investigated 449 college students＇ posterior probability estimation by manipulating the levels of the base rate and the hit rate.Specifically,it applied three factors between a subjects design of 2（problem： hepatitis/ lottery）×2（base rate：high 70%/ low 1%）×3（hit rate：high 90%/moderate 55%/low 2%）,and the independent variable was the posterior probability estimation provided by the subjects. The results showed that overall,the base rate and the hit rate both played an important role in Bayesian reasoning.In other words,the posterior probability estimation rose with the promotion of the base rate level,as well as with the promotion of the hit rate level.However,in the lottery context with low base rate,as the hit rate level went up,at first the subjects＇ estimation increased, then decreased,so the＂inhibition from hit rate reference＂was tested.It indicates that the hit rate,which might be related with the modulation of subjects＇ knowledge and experience in hit rate processing,do not play a consistent role in Bayesian reasoning.That is to say,if the hit rate information is congruent with the speculator＇s experience,the speculator will process this hit rate information,so the posterior probability estimation will increase with the promotion of the hit rate level,then the hit level will contribute;while the processing of the hit rate information strongly conflicts with the speculator＇s cognitive schema,the awakening of the individual＇s cognitive alertness will suppress the hit rate information.Therefore with the increased hit rate level,the posterior probability estimation will decrease,and the weight of the hit rate＇s influence will greatly decrease.