van der Leer Leslie, McKay Ryan
a ARC Centre of Excellence in Cognition and its Disorders, Department of Psychology, Royal Holloway , University of London , Egham , TW20 0EX Surrey , UK.
Cogn Neuropsychiatry. 2014;19(3):257-67. doi: 10.1080/13546805.2013.861350. Epub 2013 Dec 6.
That delusional and delusion-prone individuals "jump to conclusions" on probabilistic reasoning tasks is a key finding in cognitive neuropsychiatry. Here we focused on a less frequently investigated aspect of "jumping to conclusions" (JTC): certainty judgments. We incorporated rigorous procedures from experimental economics to eliminate potential confounds of miscomprehension and motivation and systematically investigated the effect of incentives on task performance.
Low- and high-delusion-prone participants (n = 109) completed a series of computerised trials; on each trial, they were shown a black or a white fish, caught from one of the two lakes containing fish of both colours in complementary ratios. In the betting condition, participants were given £4 to distribute over the two lakes as they wished; in the control condition, participants simply provided an estimate of how probable each lake was. Deviations from Bayesian probabilities were investigated.
Whereas high-delusion-prone participants in both the control and betting conditions underestimated the Bayesian probabilities (i.e. were conservative), low-delusion-prone participants in the control condition underestimated but those in the betting condition provided accurate estimates. In the control condition, there was a trend for high-delusion-prone participants to give higher estimates than low-delusion-prone participants, which is consistent with previous reports of "jumping to conclusions" in delusion-prone participants. However, our findings in the betting condition, where high-delusion-prone participants provided lower estimates than low-delusion-prone participants (who were accurate), are inconsistent with the jumping-to-conclusions effect in both a relative and an absolute sense.
Our findings highlight the key role of task incentives and underscore the importance of comparing the responses of delusion-prone participants to an objective rational standard as well as to the responses of non-delusion-prone participants.
妄想及易产生妄想的个体在概率推理任务中“急于下结论”，这是认知神经精神病学的一项关键发现。在此，我们聚焦于“急于下结论”（JTC）中一个较少被研究的方面：确定性判断。我们采用了实验经济学中的严格程序，以消除误解和动机方面的潜在混淆因素，并系统地研究了激励措施对任务表现的影响。
低妄想倾向和高妄想倾向的参与者（n = 109）完成了一系列计算机化试验；在每次试验中，向他们展示一条黑色或白色的鱼，这些鱼是从两个湖里捕获的，两个湖里都有两种颜色的鱼，且比例互补。在投注条件下，参与者可获得4英镑，并可按自己的意愿在两个湖之间分配；在控制条件下，参与者只需估计每个湖的可能性。我们研究了与贝叶斯概率的偏差。
在控制条件和投注条件下，高妄想倾向的参与者都低估了贝叶斯概率（即较为保守），而在控制条件下，低妄想倾向的参与者低估了概率，但在投注条件下，他们提供了准确的估计。在控制条件下，高妄想倾向的参与者有给出比低妄想倾向参与者更高估计的趋势，这与之前关于易产生妄想的参与者“急于下结论”的报告一致。然而，我们在投注条件下的发现，即高妄想倾向的参与者提供的估计低于低妄想倾向的参与者（后者的估计是准确的），在相对和绝对意义上都与急于下结论效应不一致。
我们的发现凸显了任务激励的关键作用，并强调了将易产生妄想的参与者的反应与客观理性标准以及不易产生妄想的参与者的反应进行比较的重要性。
