Retrieval-induced forgetting with novel visual stimuli is retrieval-specific and strength- independent

Retrieval-induced forgetting (RIF) is the phenomenon whereby remembering a subset of learned items can reduce memory for other related items. There are two main explanations for this effect: the competition account and the inhibition account. Most research to date has favoured the inhibition account, though two potential confounds have been identified in the evidence for key predictions of the account: (1) Using binary measures of accuracy may make it difficult to detect correlations between the magnitude of RIF and the increase in recall for practised items that is predicted by the competition account (strength dependence), and (2) typical non-competitive restudy may be too weak a form of practice to elicit detectible RIF effects. The present study aimed to test these contentions by adapting the RIF paradigm to allow a more graded measurement of memory strength and a more active form of non-competitive practice. We trained participants (N = 87) to draw sets of novel shapes from memory, using colour as a category cue and overlaid patterns as individual item recall cues. Responses were graded based on the number of features present and items underwent retrieval practice, copying practice (as a more effective form of restudy), or no practice. The results demonstrated RIF in the retrieval practice condition, but no evidence of RIF in the restudy condition, despite a large memory gain for practised items, supporting the notion of retrieval specificity. There was no evidence of strength dependence in any condition. Our results are consistent with the forgetting in this experiment being driven by inhibition.