Chapter 6

Long-Term Memory: Structure

Some Questions to Consider

• How does damage to the brain affect the ability to remember what has happened in the past and the ability to form new memories of ongoing experiences?

• How are memories of personal experiences, like what you did last summer, different from memories for facts, like state capitols?

• How do the different types of memory interact in our everyday experience?

• How has memory loss been depicted in popular films?

Long-Term Memory

• “Archive” of information about past events and knowledge learned

• Works closely with working memory

Long-Term Memory

• Storage stretches from a few moments ago to as far back as one can remember

• More recent memories are more detailed

Long-Term Memory

• Korsakoff’s syndrome

– Result of chronic alcoholism

– Unable to form new long-term memories

– Anterograde amnesia

Double Dissociation

• Functioning STM but cannot form new LTM’s

– Clive Wearing

– H.M.

• Poor STM but functioning LTM

– K.F.

Caption: A double dissociation for STM and LTM

Serial Position

• Murdoch (1962)

• Read stimulus list, write down all words remembered

Serial Position Curve

• Memory better for stimuli presented at beginning

– Primacy effect

– More time to rehearse, more likely to enter LTM

Serial Position Curve

• Memory better for stimuli presented at end of list

– Recency effect

– Stimuli still in STM

Caption: Serial position curve (Murdoch, 1962). Notice that memory is better for words presented at the beginning of the list (primacy effect) and at the end (recency effect).

Coding in Long-Term Memory

• Predominant type: semantic coding

– Remember meaning, not exact wording

• Others: auditory, visual

Types of Long-Term Memory

• Implicit/non-declarative: unconscious memory– Procedural– Priming: previous experience changes response without

conscious awareness

• Explicit/declarative: unconscious memory – Episodic: personal events/episodes– Semantic: facts, knowledge

Caption: Long-term memory can be divided into declarative memory and implicit memory. We can also distinguish between two types of declarative memory, episodic and semantic. There are a number of different types of implicit memory. Two of the main types are repetition priming and procedural memory.

Types of Long-Term Memory

• Declarative: conscious recollection of events experienced and facts learned

– Episodic: memory for personal events

– Semantic: facts and knowledge

Types of Long-Term Memory

• Episodic involves mental time travel

– No guarantee of accuracy

• Semantic does not involve mental time travel

– General knowledge

• Episodic and semantic show a double dissociation

Separation of Episodic and Semantic Memories

• K.C. damaged hippocampus

– No episodic memory, cannot relive any events of his past

– Semantic memory intact, can remember general information about the past

Separation of Episodic and Semantic Memories

• Italian woman

– Impaired semantic memory

– Episodic memory for past events was preserved

Separation of Episodic and Semantic Memories

• Evidence from brain-imaging experiments that retrieving episodic and semantic memories activate different areas of the brain

Episodic and Semantic Memories

• Episodic can be lost, leaving only semantic

– Acquiring knowledge may start as episodic but then “fade” to semantic

• Semantic can be enhanced if associated with episodic

– Personal semantic memory: semantic memories that have personal significance

– Can influence what we experience (episodic) by determining what we attend to

Types of Long-Term Memory

• Implicit: memory that unconsciously influences behavior

– Repetition priming

– Procedural memory

– Classical conditioning

Repetition Priming

• Presentation of one stimulus affects performance on that stimulus when it is presented again

Repetition Priming

• Tulving (1982)

– Presented words and then fragments to be completed

– Participants completed many more primed words than new words

Implicit Memory

• Warrington and Weiskrantz (1968)

– Korsakoff’s syndrome patients

– Showed fragmented pictures, participant had to identify

Caption: Incomplete pictures developed by Gollin (1960) that were used by Warrington and Weiskrantz (1968) to study implicit memory in patients with amnesia. (Reprinted from Nature, London, 217, March 9, 1968, E. K. Warrington, & L. Weiskrantz, “New Method of Testing Long-Term Retention With Special Reference to Amnesic Patients,” pp. 972-974, Fig. 1. Copyright © 1968 with permission from Nature Publishing Group.

Caption: Results of Warrington and Weiskrantz’s (1968) experiment.

Implicit Memory in Everyday Experience

• Perfect and Askew (1994)

– Propaganda effect: more likely to rate statements read or heard before as being true

• Implications for advertisements

Implicit Memory: Procedural Memory

• Skill memory: memory for actions

• No memory of where or when learned

• Perform procedures without being consciously aware of how to do them

• People who cannot form new LTMs can still learn new skills (e.g., H.M.)

Implicit Memory: Classical Conditioning

• Pairing a neutral stimulus with a reflexive response