Directorate of Learning Disability Services, Abertawe Bro Morgannwg University Health Board, Bridgend, UK.
J Intellect Disabil Res. 2010 Apr;54(4):380-91. doi: 10.1111/j.1365-2788.2010.01260.x. Epub 2010 Feb 25.
An assessment of mental capacity includes an evaluation of the ability to 'weigh up' information, but how to do this is uncertain. We have previously used a laboratory decision-making task, temporal discounting, which involves a trade-off between the value and the delay of expected rewards. Participants with intellectual disabilities (ID) showed very little evidence of 'weighing up' of information: only a third of participants showed consistent temporal discounting performance, and when present, consistent performance was usually impulsive; and the ability to perform consistently was more strongly related to executive functioning than to IQ. The aim of the present study was to replicate these observations and extend them to a more realistic financial decision-making task.
We administered a temporal discounting task and a financial decision-making task, as well as tests of executive functioning and IQ, to 20 participants who attended day services for people with learning disabilities (mean Full-Scale IQ = 59), and to 10 staff members.
Performance in both decision-making tasks was related more strongly to executive functioning than to IQ. In both tasks, decisions by service users were made largely on the basis of a single item of information: there was very little evidence in either task that information from two sources was being 'weighed'.
The results suggest that difficulty in 'weighing up' information may be a general problem for people with ID, pointing to a need for psycho-educational remediation strategies to address this issue. The importance of executive functioning in decision-making by people with ID is not recognized in the legal test for mental capacity, which in practice includes a possibly irrelevant IQ criterion.
对心理能力的评估包括对“权衡”信息的能力的评估，但如何做到这一点尚不确定。我们之前使用了实验室决策任务，即时间折扣，它涉及到预期奖励的价值和延迟之间的权衡。智障人士（ID）的参与者几乎没有表现出“权衡”信息的迹象：只有三分之一的参与者表现出一致的时间折扣表现，而当存在时，一致的表现通常是冲动的；并且执行功能与 IQ 相比，能够一致地执行的能力更强。本研究的目的是复制这些观察结果，并将其扩展到更现实的财务决策任务中。
我们向 20 名参加智障人士日间服务的参与者（平均全量表智商= 59）以及 10 名工作人员进行了时间折扣任务和财务决策任务，以及执行功能和智商测试。
两项决策任务的表现与执行功能的关系比与智商的关系更密切。在两项任务中，服务用户的决策主要基于一条信息：在两项任务中，几乎没有证据表明两个来源的信息正在“权衡”。
这些结果表明，“权衡”信息的困难可能是 ID 患者的普遍问题，这表明需要进行心理教育矫正策略来解决这个问题。在精神能力的法律测试中，执行功能在 ID 患者的决策中的重要性没有得到认识，该测试实际上包含了一个可能不相关的智商标准。
