Episodic memory illusions: Suggestibility

• Def.: suggestibility

individual’s tendency to incorporate misleading info from external sources into personal recollections from episodic memory

[external sources; e.g., other people’s oral or written statements, pictures, films]

Episodic memory illusions: Suggestibility

• groundbreaking research by E. Loftus on suggestibility in memory:

demonstration of misinformation effectwhen people who witness an event are later exposed to new and misleading info about it, their recollections often become distorted

• classic experiment with slides showingsituation that leads to car accident (Loftus, Miller, & Burns, 1978)

Misinformation effect

Misinformation effect

• even with short delay less accurate memory after misleading info

• with delay (i.e. fading of original memory), higher susceptibility to memory errors

Misinformation effectFurther research questions

• How can the effect best be explained?

actual memory impairment (over-writing)

versus

demand characteristics of situation (compliance)

• related question:

Do subjects really remember misleading info as original? (i.e. is it truly memory illusion?)

Or can they keep sources apart if asked directly?

Misinformation effectFurther research

• research by Lindsay & Johnson addresses nature of errors

change of questions at time of memory testing:

+ simple recognition vs source monitoring question

Did you see info in slide? Did you see info in slide, read it, both, or

neither? ->more memory errors with recognition

than with source monitoring questions

-> suggests when demand characteristics are changed and source info is emphasized, people make less errors

BUT some errors occur even on source questions

-> suggests that some but not all errors reflect actual mis-remembering (illusions)

Misinformation effectFurther research

• further support that subjects cannot always resist memory illusions:

research by Lindsay with Jacoby’s opposition procedure in combination with misleading post-event info

‘Recall info from original slides!’‘Try to avoid all info provided afterwards; it was incorrect!’

-> some illusions occur despite subjects actively trying trying to avoid them

Misinformation effectFurther research

• general research outcome:

memory errors after suggestive misleading info can reflect both demand characteristics and actual illusions

under some conditions misleading info can impair people’s ability to remember what they witnessed and lead them to believe that they witnessed things they did not

• Legal issue: false confessions

after coerced interrogations, do people sometimes falsely confess a crime they did not commit, while actually believing in their own confession (i.e. having memory illusion for crime)?

-> yes, in extreme cases ‘memory distrust syndrome’(e.g. due to intoxication at event or if

person believes she could have repressed it)

-> demand characteristics of social situation also play role

SuggestibilityCan it even effect memory for our own

actions?

• study by Kassin & Kiechel (1996) on evoking false confession of unwanted action (no crime) in psychology lab setting

+ involves deception presumed goal: measuring reaction time in

typing+ involves confederate

+ try to type as fast the words you hear from other subject (confederate) but avoid to hit ‘ALT’ key+ after 1 min fake crash of computer; accusation that subject erroneously pressed ‘ALT’ key

SuggestibilityCan it even effect memory for our own

actions?

• study by Kassin & Kiechel (1996)

+ two variables manipulated in study:

- fast or slow typing speed- confederate acts as false witness of

presumed error or not + three different types of behaviour examined:

- compliance: willingness to sign form

admitting error- internalization: comments to other person

on what happened- confubulation: provision of details on how

error occurred

SuggestibilityCan it even effect memory for our own

actions?

Results from study by Kassin & Kiechel

No witness

Witness

Slow pace

Fast pace

Slow pace

Fast pace

Compliance 35 65 89 100

Internalization 0 12 44 65

Confabulation 0 0 6 35

percentage of subjects showing various behaviours

-> false witness report can induce false confessions with person believing in his/her own guilt (memory illusion)

Childhood amnesia / infantile amnesia

• observed in all healthy individuals-> no acquired brain damage involved

despite the acknowledged importance of the first 3 years of life in shaping the cognitive capacities and personality of human adults, almost no reportable memories are retained from this period

Childhood amnesia: How can it be studied?

• different research approaches:

(1) study of earliest childhood memory reported“what is the first episode of your life

you can recall?”

(2) study of childhood events with known date of occurrence

“ what do you remember about your youngest sibling’s birth?”

(3) examination of temporal distribution of memories across life-span in relation to cue words

“ describe a distinct episode that has to do with a dog”

Childhood amnesia: How can it be studied?

• study by Howes et al. (1993) of earliest childhood memory reported in undergraduate students

Negative affect

Positive affect

No info on emotion

Other people’s emotion

n(800) 441 151 220 38

% 55.1 18.9 27.5 4.8

-> most memories contain emotionally salient info-> average age at episode (memory acquisition):

3.07 for female3.40 for males

Childhood amnesia: How can it be studied?

• study by Howes et al. (1993) of earliest childhood memory reported in undergraduate students

All Partial

No info avail.

Distorted

Difference (unclear whether distorted)

Disconfirmed

n(800) 92 411 171 103 18 5

% 11.5

51.4 21.4 12.9 2.25 0.63

-> data suggest generally high accuracy for gist

e.g. see example from paper

verification through other person present in episode:

Childhood amnesia: How can it be studied? •study by Usher & Neisser (1993) of childhood events with known date of occurrenceearliest memory: 2 – 3 years

Childhood amnesia: How can it be studied?

• study by Rubin & Schulkind (1997) of childhood events in response to cue words

Explanations of childhood amnesia

• many explanations suggested in literature

• term ‘infantile amnesia’ introduced by Freud:‘it is impossible to avoid a suspicion that the beginnings of sexual life which are included in that period have provided the motive for its being forgotten – that is forgetting, in fact, is an outcome of repression’

• modern theories: psychology: linked to qualitative changes in cognitive abilities as children develop into preschool years

neuroscience: linked to major changes in brain development (maturation of hippocampus and frontal lobes)

-> both are not mutually exclusive!

Relevant background to explain childhood amnesia

• general consensus: infants and toddlers have ability to encode and acquire event-specific information

e.g. research by Rovee-Collier

long lasting memory for kicking of mobile in early childhood

more than 2 weeks in 6 month olds

unclear: nature of memory; likely not episodic but implicit

• further demonstrations of early memory capacities:

+ 2 year olds can express memory through

spontaneous ‘delayed imitation’

+ 2.5 year olds show retention of unique laboratory procedure (reaching in dark for sounding object) from single 20 min session acquired at age 7 month -> again likely implicit memory at work

+ toddler’s spontaneous (limited) talking at age 2 – 3 years reveals memory for episodes that happened 6 months earlier-> perhaps first truly episodic recollections?

Relevant background to explain childhood amnesia

Explanations of childhood amnesia

• what else is special in cognitive development between age 2 and 3:

+ emergence of self-concept (organizing function for episodic memory)+ emergence of theory of mind (perspective taking)+ emergence of language and critical conceptual

knowledge: - distinction between you/me, I/me

- use of past-tense+ emergence of social interactions based on telling of past episodes (personal stories)

-> likely all related to emergence of episodic memory

-> popular theory: childhood amnesia occurs due to lack of episodic memory abilities before age 2 – 3

Explanations of childhood amnesia

• problems with explanations that link childhood amnesia to emergence of specific new cognitive abilities at age 2-3

-> evidence only indirect-> no demonstration of causal link in retrospective research-> difficult even to determine how to test different

explanations (i.e., emergence of what specific cognitive function is critical) against each other

-> longitudinal studies most promising to provide deeper understanding