PSC 130 L07: False Memories

False memory on high association

• Study: list of high associates (e.g., tired, bed, rest) of nonstudied target items (e.g., sleep), then recall

• Found: high false recall rate (55%) and confident false recognitions

• → high confidence false memories are easy to create

Implanted childhood memories

• Study: ‘do you remember when…’ (2 memories and 1 implanted memory of being lost in a shopping mall)

• Found: false memories for implanted events

• → false memory in life-like situations

Implanted memories for committing a crime

• Study: Three 40 minute interviews over 3 weeks, asking subjects to report details of two remote memories (one was true and one was false) - true memories were identified from parent questionnaires, false items were either a crime (assault, theft) or not (accident, animal attack)
  Used standard police interview techniques (building rapport, social pressure, positive feedback)

• Found: No false memory reports on first day, but by week 3:
  70% believed the event occurred and recalled >=10 details

  10% believed the event occurred and recalled <10 details

• → standard interview methods can produce false memory for having committed a crime (false confessions)

Schema-related distortions in memory (NOT ON TEST)

• Study: reproducing pictures from memory over several days

• Found: very systematic distortions (leveling - loss of atypical details, and sharpening - adding typical details)

• → our general knowledge about the world (i.e., schema or script) leads to distortions in memory

Mandela effect

consistent false memories for specific icons in popular culture (related to schema-related distortions in memory)

• subjects are more likely to ‘misremember’ the manipulated version than the true version (seen in recall, recognition, long term memory, and short term memory)

• ‘sharpening’ (e.g., monkeys typically have tails) & leveling

Distorted flashbulb memories (salient/emotional events)

• Study: After the Challenger crash, they tested what people were doing 24 hours after the crash and 2 years after the crash

• Found: 40% of subjects reported dramatic distortions and were highly confident about their false memories

• → false memories can be very vivid

Are flashbulb memories different from other memories?

• Study: memory for 9/11 (flashbulb memories) and another salient everyday event

• Found: accuracy of flashbulb and everyday events decreased at the same rate, but subjects believed their flashbulb memories to be more accurate (high confidence)

• → flashbulb memories exhibit normal forgetting, but subjects believe that they are not forgotten

Confabulation

inaccurate memories ranging from subtle alternations to bizarre fabrications often associated with medial/orbital frontal damage (honest liars)

confabulators - people with medial/orbital frontal damage who has fabricated memories

False Recognition neuroimaging

• Study: recognition across repeated tests (‘was the item presented in this list already?’) - in confabulation patients & using fMRI in controls

• Found: confabulators exhibit inflated false recognition for recently encountered items as opposed to the control and the non-confabulating amnesics

  Control subjects exhibited medial/orbital frontal fMRI activity during presentation of test lures

• → A critical role for the medial/orbital frontal cortex in monitoring or inhibiting false memories

False Recognition neuroimaging - meta-analysis

• → orbital/medial frontal & medial frontal gyrus (simplify: medial PFC)

• left inferior parietal region

• → ???

• (note: L-parietal lesions do not impair LTM)

Why is it so easy to create false memories?

1. Reproductive Memory - accurate habitual repetition reproduction of material from memory (rarely occurs)

2. Reconstructive Memory - an active process of constructing what ‘must have’ happened (very common)

   
   → memory does not reflect the “playback” of recorded events, rather it reflects a reconstruction based on many past experiences, our knowledge of the world, and our expectations