Transcript Forgetting
Forgetting Thomas G. Bowers, Ph.D. Penn State Harrisburg 2000 Does Forgetting Exist? While it appears obvious that forgetting exists, it is not clear how forgetting occurs – What is the process of forgetting? • 1. A decay of memory? • 2. A failure of retrieval? • 3. Problems in interference? Examples of Hypermnesia Short story - Borges (1964) “Funes the memorious” Could not forget anything memory like a garbage heap Examples of Hypermnesia Luria (1968) described the case of “S” Remembered everything - but on tests of intelligence, did not do well, because he was often distracted by rich details of memory Theoretical Accounts of Forgetting I. Decay theory – With the passage of time, memories fade or erode Decay Theory Testing the decay theory – Of course, memory for remote events is weak relative to recent events – Not a unique effect of decay however Decay Theory Testing the decay theory – It is also possible the reduction of remote memory is due to interference as well – In most studies (usually classical conditioning), the mere passive of time is a poor predictor of forgetting Decay Theory Testing the decay theory – Classical study by Jenkins and Dallenbach (1924) – Compared retention intervals under sleep and waking conditions, with intervals of 1, 2, 4, 8 hours – Nonsense syllable learning Decay Theory Sleep Syllables Recalled Waking Hours Decay Theory Braddeley and Hitch (1977) – Tested inference theory on rugby players recall of meaningful material (i.e. team names) Decay Theory Percent Recall Number of intervening games Decay Theory With the passage of time, memories fade or erode – Cells may die – Networks may evolve Decay Residual Benefit Decay Process Depends on a frequency effect Testing the decay notion – Contrast with the notion of interference – Forgetting occurs because new learning works against older learning – Actual passage of time is a poor predictor of forgetting Forgetting With Time Asleep Sleep % Retent Wake Hours II. Interference Notion Our exercises have demonstrated aspects of interference on short term memory – Can occur in serial learning or paired associate tasks Interference Notion Proactive interference – Learning that has come before can impact negatively if similar Retroactive interference – Learning that has come latter can impact negatively as well Why Does Interference Occur? Mechanisms – 1. Response competition • It does not appear that only intrusion errors account for interference • May instead be an interference or error in effort – 2. Unlearning must also occur • Similar to extinction Evidence Against Interference It was thought that interference could explain most or all forgetting However, some efforts questioned that idea – Cued recall versus free recall Cueing Eliminates Interference Cued Recall % Recall Free Recall Number of Lists III. Alternatives to Interference Theory Network theories may explain results better Activation of nodes or associative links Repression Freud’s theory claimed that the conscious mind was denied access, but that the memories were not erased Forgetting is thought to be selective in the service of the psyche “Slips”, or returns when dreaming, or fatigued Repression Processed by defenses as – 1. Displacement – 2. Sublimation – 3. Projection From this view, it is thought memories can be recovered – Hypermnesia can be demonstrated experimentally Repression There is some dispute and controversy about repression and recovered memories in therapy Recovered memories remain controversial Emotions and Memory We may expect to not remember unpleasant emotional events, but in fact we tend to recall dramatic experiences well Flashbulb effects - clarity about highly significant events Even so, memory is far from perfect Emotions and Memory It has been hypothesized that there is a narrowing of memory and attention during emotionally charged events Called the Easterbrook (1959) phenomenon For example, a witness to a crime may only recall the gun Emotion and Memory Emotion appears to have multiple effects on memory Emotional arousal may disorganize early memory and recall, although some elements may be very vivid Later recall may be enhanced by emotional arousal