the psychology of learning and motivation - Percepts and Concepts ...

18 Henry L. Roediger et al.this material was related to the questions that had been answered on theinitial test. In the restudy condition, students read the answers but did notreceive a test. After 24 h, all the students returned to complete a final testcovering the entire passage. Results of the final test revealed that retentionof the nontested information was superior when students had taken a testrelative to conditions in which they restudied the material or in whichthey had no further exposure after study. Chan et al. concluded thattesting not only improves retention for information covered within a test,but also improves retention for nontested information, at least when thatinformation is related to the tested information.In contrast, other researchers have found that retrieving some informationmay actually lead to forgetting of other information, a findingtermed retrieval-induced forgetting (e.g., Anderson, Bjork, & Bjork,1994). In a typical retrieval-induced forgetting experiment, subjects firststudy words in categories and then take an initial test. For some categories,half of the items are repeatedly retrieved during the initial test; for othercategories, none of the items are retrieved during the initial test. Thegeneral finding is that the unpracticed items from the categories cued forretrieval practice are impaired on a later retention test relative to itemsfrom the nontested categories.Retrieval-induced facilitation and retrieval-induced forgetting areobviously contradictory findings. Consequently, Chan (2009) sought todifferentiate between conditions causing facilitation and conditions causingforgetting in these paradigms. In two experiments, he demonstratedthe importance of integration of the materials and the delay of the test forthe retrieval-induced facilitation and retrieval-induced forgetting effects.In his first experiment, subjects studied two prose passages; each passagewas presented one sentence at a time on the computer. During study,some subjects were given the sentences in a coherent order and were toldto integrate the information (the high integration condition). For anothergroup of subjects, the sentences within each paragraph were scrambled todisrupt integration of information during study (the low integrationcondition). Similar to the Chan et al. (2006) experiments, an initial testoccurred immediately after studying one of the passages, and subjectscompleted the same test twice in a row. Subjects completed the final testcovering material from both the passages 20 min or 24 h after the completionof the initial learning phase.Figure 5 depicts performance on the final test. Results reveal both aretrieval-induced facilitation effect (see the fourth pair of bars in Figure 5)and a retrieval-induced forgetting effect (see the first pair of bars inFigure 5) within the same experiment. This outcome demonstrates theimportance of both integration of materials and delay of the final test forthese effects. When subjects were instructed to integrate the informationduring study (i.e., the high integration condition) and the test was delayed