Experimental study demonstrating Desirable difficulties, after Bjork in the context of Retrieval practice.
Although substantial research has demonstrated the benefits of retrieval practice for pro- moting memory, very few studies have tested theoretical accounts of this effect. Across two experiments, we tested a hypothesis that follows from the desirable difficulty framework …, the retrieval effort hypothesis, which states that dif- ficult but successful retrievals are better for memory than easier successful retrievals. To test the hypothesis, we set up conditions under which retrieval during practice was suc- cessful but differentially difficult. Interstimulus interval (ISI) and criterion level (number of times items were required to be correctly retrieved) were manipulated to vary the dif- ficulty of retrieval. In support of the retrieval effort hypothesis, results indicated that ==as the difficulty of retrieval during practice increased, final test performance increased. Longer versus shorter ISIs led to more difficulty retrieving items, but higher levels of final test per- formance==. Additionally, as criterion level increased, retrieval was less difficult, and dimin- ishing returns for final test performance were observed.