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Inf1: Introduction to Cognitive Science

Lecture 21: Recall, forgetting, and eyewitness misidentification

Alyssa Alcorn, Helen Pain and Henry Thompson& Richard Shillcock

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Today’s goals

Look at retrieval and recall

Look at forgetting

Look at memory research and eye witness misidentification of crime suspects

In next week's tutorial: semantic memory and a review of other memory topics

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Course texts

Memory (Baddeley, Eysenck, & Anderson, 2009). Recent textbooks on Cognitive Pschology are likely to contain similar information.

http://www.scholarpedia.org/article/Category:Memory

Bahrick H. P., Bahrick L. E., Bahrick A. S., Bahrick P. E. (1993). Maintenance of foreign language vocabulary and the spacing effect. Psychological Science, 4, 316-321.

Ebbinghaus, H. (1885). Memory: A contribution to experimental psychology. (translated 1913). http://psychclassics.yorku.ca/Ebbinghaus/index.htm

Readings

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You can watch a demonstration of witnessing a crime and trying to idenitfy the perpetrator at:

http://www.open.edu/openlearn/body-mind/psychology/misidentification-can-you-identify-the-criminal

A criminal act

To be continued ...

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Remembering stored information

We need to be able to retrieve information from memory whenever it is useful, bringing it to conscious awareness.

Cued recall (“What’s this person’s name?) versus free recall (“Write down all the words from the list”).

In free recall there are typically effects of the original order of the items.

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Primacy and recency effects in free recall

The primacy effect: the first items in a list tend to be better recalled.

The recency effect: the last items in a list tend to be recalled well. A “filler task”, such as counting aloud between hearing the items and recall them, can eliminate this effect.

Items in the middle of a list are generally recalled worst.

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Primacy and recency effects in free recall

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Why do we sometimes failto retrieve information?

In forgetting, is information ever really completely lost?

In motivated forgetting, we can consciously try to forget something.

Forgetting can be adaptive. It can represent optimization of the memory system.

Failure to forget can be maladaptive.

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Forgetting over time

For most organisms forgetting increases over time.

Hermann Ebbinghaus (1885) hid a list of nonsense syllables in his desk, experimenting on his own memory.

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Ebbinghaus’s experimentNonsense syllables (lev, bup, ...) have little content.

He learned 169 lists of 13 nonsense syllables.

He then re-learned each list after varying time intervals, from several minutes up to one month later.

He used the amount of time required to re-learn each list as a measure of how much was forgotten.

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The Ebbinghaus forgetting curve

Ebbinghaus's basic results show that forgetting is not linear over time, but closer to a logarithmic curve.

A lot is forgotten very soon after learning, then the rate of forgetting slows down and eventually almost stabilizes.

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The Ebbinghaus forgetting curve

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Application to second-language learning

Bahrick (1984) tested retention for foreign language grammar, reading comprehension, recall and recognition vocabulary.

587 participants who studied Spanish 1 – 50 years previously.

He gathered information about their level of original training and their grades, their use of spoken and written Spanish language (i.e. rehearsal) since training.

Their memory showed exponential decline in retention for the first 3-6 years, then stable retention for up to 30 years.

Such results suggest that there is some level of memory “permastore” affected by original training, but not by subsequent rehearsal.

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Application to second-language learning

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Eyewitness identification and misidentification

Memory research is of particular interest in forensic psychology.

Unfortunately, eyewitness testimony is subject to error and distortions both during and after the event.

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A criminal act (continued)

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Eye witness reliability

77% of a set of 200 wrongful convictions had some component of eyewitness misidentification in the original verdicts.

Asking witnesses leading questions distorts their behaviour.

Allowing witnesses to pick the closest match from a group of suspects, as opposed to judging each in a sequential presentation, can lead to misidentification.

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Eyewitness unreliability can stem from distorting or interfering with information when it is retrieved.

However, the witness’s attentional biases, emotional state,and age may play a role, along with change blindness and presuppositions about the world.

Change blindness, presupposition, and expectations are aspects of optimal cognition, but may impair recognition, retrieval, and reconstruction.

Witnesses may focus on weapons; they may attend less to out-group members, defined by age and ethnicity.

Eye witness reliability

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Expectations about the world can affect interpretation, encoding, and retrieval.

Bartlett (1932) developed a theory of reconstructing the details of an event by relying on schemas to supplement data about what was actually observed.

Schemas are scripts or groups of facts about situations, locations, and events; e.g. going to the bank.

Schemas are stored as related information in long-term memory and appear to be accessed as a whole. This is optimal for real life, but not for reliable eyewitness evidence.

Schemas

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Tuckey and Brewer (2003) report a study in which “eyewitnesses” to a simulated bank robbery interpreted ambiguous gender information according to their schema about bank robbers.

Bank robbers should be male and wear dark clothing and/or a disguise.

Schemas

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Does stored information retain traces of its origins, or is it amodal?

The DRM paradigm shows that visual field can affect the nature of a word used to search a memory experience (Bellamy & Shillcock, 2007).

We do seem to retain detailed traces of spoken words (which demonstrably affect speaking performace) (Goldinger & Azuma, 2004)

Abstractionist versus episodic storage

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How to identify something materially involved in memory?

Circadian rhythms and sleep seem to affect consolidation (see Gaskell et al.).

Challenges in memory research