Implicit And Explicit Memory Tests Directed Forgetting Effect

Over the past 30 years, directed forgetting effect has been one of the most robust findings in the memory literature. On basis of cost-benefit principal, the directed forgetting is to give subjects certain materials, some of which must be remembered and others of which must be forgotten. If the marks of remembered items are superior to the forgotten ones, there exists directed forgetting effect. The research methods of the effect are the word method and the list method, of which the former is used comprehensively. Several theories have been developed to explain the directed forgetting effect, the most prominent of which is the set differentiation and selective rehearsal theory. The explanation of the theory is that there are two systems of remembering and forgetting in human brain, and forgetful clues make them separate, and remembering items are rehearsed further.The directed forgetting effect has been well established in many researches using traditional tasks (explicit memory tests). However, the effect on implicit tests appear to be less clear and discrepant. According to the transfer appropriate processing framework advanced by Roediger and colleagues to explain the dissociation between implicit and explicit memory tests, the good or bad memory scores are determined by the equality or similarity of retrieving and encoding processing .If they are equal, the transfer will appear, and or else the phenomenon will disappear. The potential retrieving operation variable affects the two tests, which at the same time facilitates the research of directed forgetting. Especially Macleod ( 1989 ) observed the predominant effect of directed forgetting in word-fragment completion and lexical decision task. But the phenomenon cannot be explained by the rehearsal theory, therefore another theory -retrieval inhibition, which is a prohibitive process of obstructing the items recovery when items are retrieved, that is to say, the forgetful instruction prohibits the items retrieving and makes the forgetful items retrieved more difficult than remembered items, became popular . However, in the research of Paller (1990) and Basden( 1993 ), directed forgetting hardly affected implicit tests, and the explanation of retrieving prohibition was limited, which was necessary to be tested.To our knowledge, there are very few contrastive research on the directed forgetting on explicit and implicit memory tests. Thus, many factors are worth further exploration. The aim in this thesis is to investigate the effect of retention on the performance on memory tests so as to test the retrieval hypothesis, the rehearsal theory and the retrieval prohibition theory.Three experiments were presented in this study. Experiment 1 investigate whether there are directed forgetting in recognition and preference decision by manipulating the instruction. In experiment 2, we continue to investigate the effect in the two tests above by using the retention variable. Based on the previous two experiments, experiment 3 used another implicit test, word-stem completion, and the explicit word-stem recall of it to explore the directed forgetting effect. In all three experiments, we used the Chinese characters as materials. And the experiment procedures were displayed on the computer in a standardized form.The experiment results showed: by use of word method, there were significant directed forgetting effects observed in recognition, word-stem recall, preference and word-stem completion. Regardless of the explicit and implicit memory test, directed forgetting effect was observed in retention. But the directed forgetting effects were observed on low frequency words. This complex pattern of results is not consistent with previous study. We analyzed the theoretical implications broadly and deeply. In conjunction with previous research results, we come to a tentative conclusion that subjective selectively rehearsal the remembering items intentionally, but the forgetful items are prohibited by use of word method, in other words, rehearsal and retrieval play a key role i...