因果信息和提示指导语对大学生贝叶斯推理的影响

The Influence of Causal Information and Prompt Instruction on College Students’ Bayesian Reasoning

基于三重加工心智模型,以大学生为被试,采用经典贝叶斯推理的文本范式,通过操纵自变量:因果信息(有或无)与提示指导语(提供或不提供),试图探讨激发反省心智,消解理性障碍的情况下,因果贝叶斯框架的作用机制。结果发现,因果信息显著提高了被试的推理正确率,改善了后验概率估计的准确性;提供指导语虽未提高推理正确率,但却降低了推理偏差,从而有效改善了贝叶斯推理表现。此外,在提供提示指导语的条件下,有无因果信息并无差异,表明因果信息的作用是有限的。

In daily life,it is common for people to meet problems like Bayesian reasoning which means updating already existed beliefs according to new evidence.Bayesian reasoning has been widely applied into various fields such as psychology,medical treatment,and business.However,despite the wide usage of Bayesian reasoning,individual performance is surprisingly poor,as manifested by previous laboratory studies.In order to improve the Bayesian inference capacity,many researchers have investigated solutions from various aspects(e.g.,data format,graphics assistance,and explicit nested set structure).One of the potential factors is causal information.Krynski and Tenenbaum(2007)proposed the causal Bayesian framework according to which reasoning processes consisted of three stages:model construction,parameter assignment and Bayesian inference.As to the"base-rate neglect",a common bias observed in Bayesian reasoning tasks,they further argued that,the false positive rate in conventional study materials could not be completely understood,which in turn resulted in incorrect model construction;In contrast,problems with causal information might promote constructing proper model.Unfortunately,subsequent studies could not reach an agreement on the validity of this assertion.These controversial results questioned the ability of causal information to help people make rational inference.Based on the"triple processing mind"model,the activation of introspective mind could suppress the intuitive beliefs(e.g.,the transpositional representation bias in Bayesian reasoning),and then help subjects think in a more rational way.Hence,if instructed to reason introspectively(through prompt instruction),Bayesian problems might be more easily to be solved.In consideration of the unstable effect of causal information and the triple processing mind model,causal information might help people construct correct model,but only intuitively,while prompt instruction could essentially facilitate rational process(including the correct modeling as a byproduct).Hence,this study assumes that,when participants receive both causal information and prompt instruction,compared with other situations(with the absence of causal information and/or prompt instruction),their performance would reach the highest.To test this hypothesis,138 undergraduates were recruited to take part in the 2(with or without causal information)×2(with or without prompt instruction)between-subjects experiment.The dependent variable was Bayesian reasoning performance,with 2 criteria:the correctness and the accuracy.The results were as follows:under the correctness criterion,most participants did not give the correct response,but there was a very strong evidence of the effect of causal information(χ^2(1)=10.90,p<.01,V=.28);For the accuracy criterion,the main effects of causal information(F(1,134)=6.06,p<.05,η^2=.04)and prompt instruction(F(1,134)=3.68,p<.05,η^2=.03)were both significant,meanwhile,the interaction also existed(F(1,134)=4.13,p<.05,η^2=.03).Based on these results,we come to 3 conclusions:(1)Providing causal information can significantly improve the reasoning correctness and the accuracy;(2)Even though the prompt instruction does not improve the reasoning correctness,it can increase the accuracy by reducing the reasoning deviation,thus effectively improve the Bayesian reasoning performance;(3)Once the prompt instruction is provided,causal information brings no more significant difference,which indicates that the effect of causal information is limited.