Memory: Retention and Retrieval Thomas G. Bowers, Ph.D. 2001

What Is Memory? Some claim it is the exact neurological trace, even though it may not be obtained on attempts at recall Penfield (1959) has been cited for this view Provided electric stimulation directly to the brain while an individual was conscious

What Is Memory? Penfield Reports of relatively vivid, clear experiences Doubtful if this is truly memory, however

What Is Memory? Nelson (1971) While later material may be lost to recall, there appears to be a large gain in re- acquiring the information

Retention Functions Retention functions are highly predictable and orderly Dates back to Ebbinghaus studies Negatively accelerated curve

Retention Functions Wickelgren (1975) described a d’ function Measure of memory strength

Retention Functions Where T is time Can be transformed to linear curve

Retention Functions Where T is still time, and C is a constant C=10 a

Retention Functions D’ Time Most recall is represented by this type of curve, a negatively accelerated effect

Retention Functions Log of D’ Log of Time These curves represent a power function, and the pattern is described as the power law of forgetting

Retention Functions Wickelgren (1975) and associates demonstrated this effect Forgetting appears to be highly predictable and orderly Why should this be so?

Retention Functions Bahrick (1975) demonstrated a similar effect for long-term retention Also noted the impact of increased exposure Claimed later higher levels of drop off was related to physiological deterioration in old age

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 II. Inference theory Memories fade due to competing effects

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 Syllables Recalled Hours Sleep Waking

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 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 Hours Sleep Wake % Retent

II. Interference Notion It is hypothesized that competing cognitive demands account for forgetting

Interference Evidence Interference paradigm List learning inference Learn A-B Learn A-D Test A-B List learning control Learn A-B Learn C-D Test A-B

Interference Evidence Interference paradigm Results Non-interference yields better learning

Interference Notion - Types 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 % Recall Number of Lists Cued Recall Free Recall

III. Alternatives to Interference Theory Network theories may explain results better Activation of nodes or associative links There is evidence of elaboration and inferential reconstruction Tends to demonstrate semantically significant material

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 There have been some experimental demonstration of repression phenomenon Other explanations may be possible, however Some individuals have demonstrated later (a few days) superior recall of material thought to be subject to repression

Repression Parkin, Lewinsohn & Folkard (1982) Tested recall to neutral words (window, cow, tree) Tested recall to emotional words (quarrel, angry, fear) Superior memory on immediate recall for neutral words, but better delayed (7 days) recall of emotional words

Repression Parkin, Lewinsohn & Folkard (1982) ImmediateDelayed Emotional 24.1Emotional 21.1 Neutral 27.6Neutral 18.3

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

Hypnosis There is considerable research on hypnosis, mostly focused on therapeutic aspects Described as a relaxed state of narrowed awareness, with increased suggestibility Eg. Reading an interesting book

Hypnosis No evidence that hypnosis can enhance memory, although there may be a state dependent effect, and relaxed recall may also be helpful However, individuals are also more suggestible in this state Rate recall as more certain, but doubtful increase in accuracy

Repression There is 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