Date of Award




Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Psychology


Cognitive Psychology

Content Description

1 online resource (viii, 73 pages) : illustrations (some color)

Dissertation/Thesis Chair

James H. Neely

Committee Members

Jeanette Altarriba, Heather Sheridan


mediator effectiveness hypothesis, mediator shift hypothesis, paired-associate learning, testing effect, Paired-association learning, Recall, Testing

Subject Categories

Cognitive Psychology


The testing effect (TE) is the robust finding that testing on previously studied material leads to better long-term retention as compared to restudying that material (Roediger & Karpicke, 2006b). Pyc and Rawson (2010) proposed the Mediator Effectiveness Hypothesis (MEH) as an explanation for the TE in paired-associate learning, The MEH states that review testing on cue-target word pairs strengthens semantic/associative mediators, which helps participants recall targets to their cues on a later test. Pyc and Rawson found support for the MEH with Swahili-English word pairs and explicit mediation instructions, using the most rigorous test of the MEH. Other researchers have claimed support for the MEH with semantically related English word pairs and spontaneous mediation conditions (e.g., Carpenter, 2011), but they did not use the most rigorous test of the MEH. Using the most rigorous test with spontaneous mediation conditions and unrelated English word pairs for which semantic mediation and phonological mediation strategies should have been especially beneficial, the results of the current Experiments 1 and 2 failed to support the MEH. When semantic/associative or phonological mediation was explicitly encouraged in Experiments 3a and 3b, respectively, the MEH was supported only for phonological mediation. This was also the case for Pyc and Rawson’s (2012) Mediator Shift Hypothesis in that for phonological mediation, the tested group was more likely to shift mediators than the restudy group and particularly so after target recall failures on the immediately preceding test.