Lovibond Peter E, Been Sara-Lee, Mitchell Chris J, Bouton Mark E, Frohardt Russell
School of Psychology, University of New South Wales, Sydney, Australia.
Mem Cognit. 2003 Jan;31(1):133-42. doi: 10.3758/bf03196088.
When two causes for a given effect are simultaneously presented, it is natural to expect an effect of greater magnitude. However many laboratory tasks preclude such an additivity rule by imposing a ceiling on effect magnitude-for example, by using a binary outcome. Under these conditions, a compound of two causal cues cannot be distinguished from a compound of one causal cue and one noncausal cue. Two experiments tested the effect of additivity on cue competition. Significant but weak forward blocking and no backward blocking were observed in a conventional "allergy" causal judgment task. Explicit pretraining of magnitude additivity produced strong and significant forward and backward blocking. Additivity pretraining was found to be unnecessary for another cue competition effect, release from overshadowing, which does not logically depend on additivity. The results confirm that blocking is constrained when effect magnitude is constrained and provide support for an inferential account of cue competition.
当针对某一特定效应同时呈现两种原因时，人们自然会预期会产生更大程度的效应。然而，许多实验室任务通过对效应大小设置上限（例如，使用二元结果）排除了这种可加性规则。在这些条件下，两个因果线索的组合无法与一个因果线索和一个非因果线索的组合区分开来。两项实验测试了可加性对线索竞争的影响。在传统的“过敏”因果判断任务中，观察到显著但较弱的正向阻断，且未观察到反向阻断。对大小可加性进行明确的预训练产生了强烈且显著的正向和反向阻断。研究发现，对于另一种线索竞争效应——遮蔽解除，可加性预训练并非必要，因为遮蔽解除在逻辑上并不依赖于可加性。结果证实，当效应大小受到限制时，阻断也会受到限制，并为线索竞争的推理解释提供了支持。
