Memory and

1. Memory and its Influences Vaughan Bell vaughan@backspace.org

2. Outline • Memory Process • Encoding / storage / retrieval • Divisions of Memory • Sensory memory (very short term) • Short term / Working memory • Long Term • Procedural / Declarative • Semantic / Episodic • Memory Effects, Distortions and Disorders

3. Memory Functions • Encoding – the transformation of an event or perception into a memory trace. • Storage – the maintenance of the memory trace for later use. • Retrieval – the use of previously stored information for a current process. • In practice these effects can be quite difficult to separate. • E.g. ‘not remembering’ could result as a failure to any of these three processes.

4. Divisions of Memory • It is important to remember that the divisions in memory we will talk about are theoretical ones. • There is still a debate in some cases whether the different forms of memory models reflect distinct memory systems… • …or are simply different tasks or processes of the same system.

5. Sensory Memory • Our senses have some persistence in that a stimulus may still be experienced after it has ceased. • In 1740, Johann Andreas Segner attached a glowing coal to a spinning cartwheel and span the wheel until a complete circle was traced by the coal. • He calculated the speed of the wheel and estimated that the senses must continue experiencing the light from the coal for 100ms to allow this to happen.

6. Sensory Memory • Sperling (1960) tested a similar phenomena by briefly presenting groups of letters. • [Demonstration here] • Despite being unable to report the whole grid of letters, people can often report any arbitrary line after the whole grid has been presented. • Meaning the whole grid must be retained for a small amount of time. • Visual sensory memory is called iconic memory, the auditory equivalent is called echoic memory.

7. Short Term Memory • The best evidence for a distinction between long term memory and STM is from neuropsychology. • Scoville and Milner (1957) reported that Patient HM demonstrated normal short term verbal recall, as measured by a digit span task… • …but grossly impaired LTM, being unable to retain new information for more than a few minutes. • Shallice and Warrington (1970) reported the reverse in Patient KF, who could retain new information permanently but had a grossly impaired digit span.

8. Short Term Memory • Digits are only one sort of ‘thing’ that we can remember, but what determines a ‘thing’ ? • George Miller (1956) argued that we use ‘chunking’ to group information into units for verbal STM. • A chunk could be a single digit, or a word, or a meaningful number (e.g. 1969) or any integrated piece of information. • Miller demonstrated that we can, on average, retain 7 plus or minus 2 chunks in STM. • STM lasts far approximately 10 seconds (textbooks tend to say anything between 2 and 15).

9. Working Memory • Often we are manipulating information in STM to solve problems (e.g. mental arithmetic). • The ability to do STM manipulations is co-ordinated by what Baddeley and Hitch (1974) call the ‘central executive’. Central executive Visual spatial scratchpad Phonological loop

10. Working Memory • Baddeley’s model has been extended since its 1974 incarnation and the ‘executive system’ is now regarded in a far wider sense. • It seems to have a role in many skills (not just memory) that involve the co-ordination of cognitive resources or attention. • E.g. social interaction and abstract thinking. • It is particularly associated with the prefrontal cortex and damage to this area can produce particular memory pathologies. • Such as confabulation and over-recognition.

11. Long Term Memory • Previous accounts of LTM had considered it as a single store. • It has become increasingly apparent, largely from the effects of brain injury on memory that this is not the case. • Tulving (1983) made the distinction between three LTM components: • Semantic Memory • Episodic Memory • Procedural Memory

12. LTM Components • Semantic memoryis memory for ‘general knowledge of the world’, e.g. facts, names, places. • Recall from semantic memory does not necessarily involves recollection of the occasion when the information was first learnt. • e.g. what is the capital of France ? • Episodic memory is associated with the remembrance of our personally experienced past. • It is associated with a kind of conscious awareness that characterises the recollection of past happenings. • e.g. what happened on your 18th birthday ?

13. LTM Components • Procedural memory is for actions you have learnt to do by doing them. • It is characterised by unconscious automatic retrieval • e.g. riding a bike • Conditioning could also be classified as procedural memory. • It is more difficult to classify procedural memory by system or content. • Rather, certain forms of learning have procedural qualities.

14. Procedural vs Declarative • The philosopher Gilbert Ryle (1949) argued for a distinction between ‘knowing how’ and ‘knowing that’. • Cohen and Squire (1982) have argued that LTM can be understood purely in these terms. • They consider both episodic and semantic memory as a unitary system called declarative memory. • Literally, memory you can ‘declare’ or state as a proposition. • This argument is given some weight by amnesia studies.

15. Amnesia Studies • Anterograde amnesia is of particular interest, this is the inability to form new long term memories, with the spared ability to recall old ones • It be particularly striking after damage to the hippocampus or connected neural pathways. • In reality, damage that causes AA will also produce some retrograde amnesia, so some memories from before the insult will be lost. • With newer memories more likely to be lost than older ones (the ‘temporal gradient’).

16. Amnesia Studies • The links between different types of LTM have been investigated by studying amnesia. • e.g. if episodic and semantic memory are different systems, it is possible they may be individually impaired. In practice this is more difficult to find. • Gabrielli et al (1988) Amnesic Patient HM, who has no episodic memory, has only learnt 8 new words since amnesia inducing surgery. • Butters (1984) A similarly impaired Patient PZ showed an identical temporal gradient for semantic and episodic information.

17. Amnesia Studies • However, more recent studies (e.g. Kitchener et al, 1998) have shown word learning in an amnesic patient with no episodic recall. • Although the patients learning is not normal, it does support the division between episodic and semantic memory. • This is an area of ongoing debate !

18. Forgetting • This is a particularly import memory process. • A.R. Luria (1968) reported on S, a person with near perfect recall (as well as synaesthesia). • Unfortunately, S’s lack of forgetting caused him serious problems. • He could not block unwanted memories and often found he remembered things too exactly. • For example, when people changed their appearance he couldn’t recognise them as the same person.

19. Forgetting • Herman Ebbinghaus (1893) was first to study forgetting in any great detail. • He studied his ability to remember nonsense syllables (like TUV and DIL) over time. • He produced a forgetting curve that still holds to this day. • Demonstrating that we forget most information quickly and the rest remains fairly constantly.

20. Forgetting Curve • Ebbinghaus argued that forgetting was due to spontaneous decay and interference.

21. The Role of Context • The context in which we encode or retrieve memories can affect our memory performance. • Godden and Baddeley (1975) demonstrated this with divers. • They asked divers to learn 40 words either underwater or on dry land. • The words were recalled better when they were recalled in the same environment they were learnt in.

22. Schemas • Of course, our own knowledge and assumptions are also a context. • Frederick Bartlett’s (1932) famous War of the Ghosts study demonstrated that memory can be influenced by our past experience. • He called this past experience a schema, i.e. an internal model of how we expect a situation to be. • Bartlett showed we tend to mould ambiguous information into the schema during encoding and recall.

23. Encoding Specificity • Tulving (1972) argues that retrieval relies on matching retrieval cues to aspects of a stored memory trace. • He suggested the success is largely dependent on the amount of overlap between these two.

24. Encoding Specificity Demo • Write down the first line of: • Marvin Gaye’s “I Heard it Through the Grapevine” • Now do the same after listening to the intro. • Actual first line.

25. Encoding Specificity • According to encoding specificity theory, you should be more likely to remember the 1st line of the song after hearing the intro. • Because the more associated information we have the more likely we are to retrieve an associated memory. • However, this can sometimes cause false recall or distortions.

26. Wade et al (2003) • This study used digital image manipulation to place create fake photos of fictional events.

27. Wade et al (2003) • Using an interview based on a current procedures usedin abuse cases… • 50% of participants created complete or partial false memories. “But I’m still pretty certain it occurred when I was in form one (6th grade) at um the local school there . . . Um basically for $10 or something you could go up in a hot air balloon and go up about 20 odd meters . . . it would have been a Saturday and I think we went with, yeah, parents and, no it wasn’t, not my grandmother…” - extract from participant S.B.

28. Roediger and McDermott (1995) • Used a technique known as the Deese, Roediger and McDermott (DRM) paradigm. • [DRM demo here] • Both these studies demonstrate that memory can be easily fooled and manipulated. • And that our confidence in our memory is not necessarily a good measure of its accuracy.

29. Source Monitoring • Johnson (1988) - we establish the accuracy by using a source monitoring framework. • She argues we distinguish between perception, memories and belief using: • sensory detail • embeddedness in supporting memories, knowledge and belief • the absence of memory for, or consciousness of, the cognitive operations producing the mental event.

30. Source Monitoring • In other words, we infer the source of a memory by its properties. • This may suggest how the DRM paradigm and other false memory induction techniques work. • Research suggests that some people may be more liable to these sort of memory distortions.

31. Memory Distortion in Psychosis • Brebion et al (2002) reported source monitoring impairments in people with schizophrenia. • Such as intrusions, interference between tests, false recognition and source confusion. • These effects were positively correlated with positive symptoms. • And negatively correlated with negative symptoms. • Suggesting memory distortions may be a factor in delusions, hallucinations or thought disorder.

32. Clancy et al (2002) • These effects may also be present in people who are not mentally ill. • Clancy et al (2002) advertised for “people who may have been contacted or abducted by space aliens”. • Tested memory with the DRM paradigm. • ‘Abductees’ able to remember words from the original list as well as non-abductees • …but tended to show a higher rate of recall and recognition for words that were never read out.

33. Conclusions • Our understanding of memory is dependent on the tasks we use to measure and examine it. • We must be careful not to confuse the task with the natural organisation of memory. • If I find fruit pickers have a better memory for apples, it does not mean there is a special fruit memory system. • However, some divisions of memory seem to be well supported by a variety of sources, including healthy participants and brain injured patients.

34. Conclusions • There are influences on encoding, storage and retrieval that can cause memory distortions. • Memory distortions may be the basis of misperceptions from the trivial (misrecognising someone)… • …to the unsual (alien abduction beliefs)… • ...to the pathological (psychosis).