Memory 2 - Encoding Failures

Question 1

What is sleep learning?

Answer 1

Simon & Emmons (1956):
- During sleep, pp’s hear questions and answers every 5 mins. Pp’s EEGs are recorded throughout the night to monitor their sleep. Subsequently they are asked the questions they heard overnight
- Overall performance is above change. Learning has occurred
Bruce, Evans, Fenwick & spencer (1970):
- Present material to sleeping subjects then awaken then immediately. No evidence for memory

Question 2

Learning while unconscious?

Answer 2

• The absence of learning about external events while asleep, doesn’t imply that we can’t remember internal events such as dreams, or that asleep itself might not play an important role in the consolidation of memories
  Levinson (1965): Memory during anaesthesia?
• 10 dental patients experience mock crisis during surgery (e.g. “her lips are blue, I’m gonna give a little more oxygen”)
• 1 month later patients were hypnotised
• 4 patients produced almost verbatim reports of the anaesthetist’s comments. 4 produced partial reports ad only 2 produced no recall at all under hypnosis

Question 3

Memory for events during anaesthesia?

Answer 3

• Some major problems with Levinson (1965):
  a) Serious ethical questions
  b) No control condition
  c) Suggestibility under hypnosis
  d) Experimenter not blind to hypothesis/ condition
  e) No measure of degree of anaesthesia
• Is the phenomenon possible? Potentially and it raises 2 issues:
  1. Anaesthesia may not be total
• Anaesthetic (hypnotic agent)
• Analgesic (removes pain)
• Muscle relaxant (allows surgery)
• Amnesic agent (prevents memory)
  2. Different tests of memory may reveal different evidence for memory from anaesthesia

Question 4

Explicit vs Implicit memory

Answer 4

• Explicit memory: requires conscious recollection of prior experiences
• Implicit memory: is knowledge revealed by tasks that don’t require reference to a specific episode
• Types of explicit memory tasks
  1. Free recall – pp attempts to remember target info without any assistance from the experimenter
  2. Cued recall – pp attempts to remember the target info in the presence of a specific cue
  3. Recognition – pp is presented with a stimulus and must decide whether it’s one that they were asked to remember

Question 5

Implicit memory from anaesthesia?

Answer 5

Iselin-Chaves et al (2005):
- Depth of anaesthesia carefully monitors using EEG bispectral index
- Pp’s listen to 2 lists of 20 words, each presented 25 times
- 1 word presented each 4 secs – 70 min of presentation
- Words are all 6 letters long, and each word shares a stem (first 3 letters) with at least 4 other words

Question 6

A method for scoring implicit memory

Answer 6

Jacoby (1991) Process Dissociation Procedure:
- Inclusion test – produce items from any source
- Exclusion test – only produce items that you didn’t study
- Scored as:
a) Inclusion = R + A (1-R) R is conscious recollection
b) Exclusion = A(1-R) A is unconscious or automatic memory
- Therefore R = inclusion – Exclusion

Question 7

We don’t remember what we don’t attend to

Answer 7

• Memory for Common Objects is often surprisingly poor
• ‘Weapon Focus’ (Loftus, 1979; Loftus, Loftus & Messo, 1987): Stress (during a crime) causes attention focusing such that only ‘central information’ is attended to (e.g. the attacker’s knife rather than face)
• Experimental demonstrations (e.g. Christianson & Loftus,1991): Change in attention (measured using eye tracking) in stressful situations is relatively easy to demonstrate

Question 8

Encoding failures conclusions

Answer 8

• Very little explicit information is encoded for free
• No evidence for sleep learning
• No evidence for explicit recall after complete anesthesia
• But some implicit learning may be possible without effort, even under light anesthesia
• Dramatic memory “failures” are easily observed for details that people have never attended to
• Attending to one type of information (e.g. central) can come at a cost to memory for other information (e.g. peripheral)
• Even successful encoding strategies in one domain do not automatically generalise to other domains