Properties of Long-term Memory

• Very large capacity
• Organized according to meaningful relations
• The major cause of forgetting is interference
• Reconstructive

Principles of Long-term Memory

• Elaboration
• Encoding-Retrieval Match
• Massed vs. Distributed Practice

Encoding-Retrieval Match

• Encoding Specificity (ESP): Memory is better when the test context matches the study context.
• Transfer-Appropriate Processing (TAP): Memory is better when the mental processes engaged at test are the same as those engaged at the time of study.

Implications

• The characteristics of an exam should determine how you study:
• Essay: Practice recalling answers in response to test questions.
• Fill-in-the-blank: Recall names/terms in response to definitions.
• Multiple choice: Practice on other multiple choice questions.
• Study by quizzing yourself and being quizzed in the appropriate manner.
• Reading chapters preparing for the exam.

Massed vs. Distributed Practice

• Memory is better when material is studied a little bit at a time ("distributed") than when it is studied all at once ("massed").
• One researcher studied memory of Spanish vocabulary 8 years after learning. Distributed practice was TWICE as good as massed practice.

Forgetting

• A major cause of forgetting is interference.
• Two types:
• Retroactive interference
• Proactive interference

Retroactive Interference

• Newly learned material interferes with previously learned material.

Proactive Interference

• Previously learned material interferes with learning new material. E.g., "misconceptions."

Reconstructing the Past

Reconstructing the Past

• Not everything gets encoded.
• Not everything can be retrieved.
• We often reconstruct what has happened in the past from bits and pieces of true and false (!) information.

Implications: Eye-Witness Testimony

• One of the most credible sources of evidence in a trial.
• But accuracy is affected by
• Ethnicity of accuser & accused.
  • Errors are especially likely when ethnicity differs.
• Manner in which questions are asked.
  • Smashed, collided, bumped, hit, contacted
  • the broken headlight vs. a broken headlight

About how fast were the cars going when they ____ each other?

• smashed: 41 mph
• collided: 39 mph
• bumped: 38 mph
• hit: 34 mph
• contacted: 32 mph

Questions

• Male or female?
• Race?
• Height?
• Color of dress?
• Color of shoes?
• How long in the room?

Implications: Repressed Memories

• Basic assumption of some theories of personality & psychological disorder.
• People cope with traumatic events by repressing memories of them. If anxiety is removed, an accurate memory may return.
• Many psychotherapists use hypnosis and similar techniques to uncover repressed memories.
• Proponents claim that laboratory studies are artificial and deal with trivial memories.

Implications: Repressed Memories

• We know memory is reconstructive; it is not a video camera in the head.
• Almost all claims involve sexual abuse; no one has repressed memories of being in a concentration camp or in a war.
• There are no scientific studies documenting repressed memories.
• False memories can be "implanted."

Implications: Repressed Memories

• When should we be skeptical of claims of recovered memories?
• Memory is attributed to being in therapy.
• The recovered memories become more implausible over time.
• Therapist's diagnosis is made quickly.
• Hypnosis or guided imagery is used to recover the memory.

Implications: Repressed Memories

• When should recollections be trusted?
• Corroborating evidence.
• Signs of trauma at the time the abuse was supposed to have occurred.
• Spontaneous recall of the event without the aid of suggestive techniques.

Explicit vs. Implicit Memory

• Explicit Tasks:
• Recognition
• Recall
• Implicit Tasks:
• Word-fragment completion
• Repetition priming

Explicit Memory Tasks

• These tasks require you to try to remember a previous experience; effort is required and you may have a conscious awareness of remembering.

Implicit Memory Tasks

• Words that have been seen recently are generated more often to word fragments and named faster than words that have not been seen recently.
• These effects occur even though the person may not realize that he or she is being tested.
• You are not asked to try to remember a previous experience, and yet your performance may be affected by this experience.

Why is this important?

• Performance on explicit and implicit tasks seems to be independent.
• Damage to the hippocampus causes deficits in explicit but not implicit tasks ("H.M.").
• Damage to perceptual areas of the brain (e.g., occipital lobe) can cause deficits in implicit but not explicit tasks ("M.S.").
• There may be two long-term memory systems.

Summary

• Long-term memory is improved by elaboration, high similarity between encoding & retrieval conditions, distributed practice.
• Major cause of forgetting is interference.
• Memory is highly reconstructive.
• Two major types of memory tasks: Explicit & implicit.