Recall,&forge6ng,&and& eyewitness&misiden-ﬁca-on&

March 23, 2012 Intro to Cognitive Science 1

Inf1: Intro to Cogni-ve Science

Recall, forge6ng, and eyewitness misiden-fica-on

Alyssa Alcorn, Helen Pain and Henry Thompson

1. Today we will cover:

1.  A short discussion of retrieval and recall (aka how to get the stored informa9on back out again)

2.  Forge>ng 3.  Memory research and eyewitness misiden9fica9on of crime

suspects

Next week's tutorial will discuss seman9c memory (plus reviewing other memory topics)

3/23/12 Intro to Cognitive Science 2

2. First, a criminal act

We will discuss eyewitness misiden9fica9on at the end of the lecture, but will begin today by witnessing a (staged) crime.

Please watch carefully. Just like a real witness, it may not be clear now what details will be relevant later.

Open University video with Professor Graham Pike to introduce topic of eyewitness misiden9fica9on

hNp://www.open.edu/openlearn/body-‐mind/psychology/misiden9fica9on-‐can-‐you-‐iden9fy-‐the-‐criminal

(first 50 seconds only)


3. “Remembering” stored informa-on Storing informa9on in memory is of very liNle use unless the

informa9on can be:

-‐ accessed again (retrieved or recalled) -‐ at an appropriate 9me (aka remembering)

Retrieval is the process of using one or more cues (in any modality) to recover a target memory, bringing the target memory or informa9on to conscious awareness

Recall is when a person must generate items from memory. This is effec1vely a search process.


3. “Remembering” stored informa-on Examples include:

•  Cued recall in which a cue prompts recovery of the target informa9on

–  Running into your friend’s flatmate (cue) and trying to remember their name (target)

– Memories invoked by senses and context – Was X in the pub last night?

•  Free recall, in which no cues are given. –  For example, an experiment which instructs “write down all the words you remember from the list you just studied”

– Who were all the people in the pub last night? Free-‐recall tasks are suscep9ble to sequencing effects -‐ the original

order of item presenta9on affects the likelihood of later recall. 3/23/12 Intro to Cognitive Science 5

4. Primacy and recency effects in free recall The primacy effect is that the first items presented in a list or

sequence tend to be beNer recalled than subsequent items

The recency effect is that the last items in a list or sequence tend to be recalled well. These may be eliminated by doing “filler tasks” (such as coun9ng) between hearing the items and recall.

Thus, items in the middle of a list are generally the least likely to be recalled.

The memory experiment described in the sta9s9cs lab was a free-‐recall task in which the lists of words to be recalled were designed to elicit “false” recall of an item not on the list

Par9cipant data exhibited both primacy and recency effects to some degree:


4. Primacy and recency effects in free recall


5. Why do we some-mes fail to retrieve informa-on? Forge<ng can be conceptualised as a failure of memory

retrieval, though it is difficult to determine whether informa9on is ever really “lost” completely.

Forge>ng or retrieval failure can be divided into two categories:

•  Incidental forge<ng or uninten9onal forge>ng (our everyday use of this word)

•  Mo1vated forge<ng, which includes both conscious, inten9onal forge>ng and uninten9onal forge>ng triggered by some mo9va9on. For example: –  Consciously deciding (or being told) to forget something

–  Limi9ng retrieval of some experience (usually a nega9ve one) as a form of emo1onal regula1on


5. Why do we some-mes fail to retrieve informa-on? In all of these forms, losing informa9on or failing to retrieve is actually beneficial and adap9ve for our cogni9on overall. It is a form of op9misa9on for the memory system.

-‐ We are most likely to be able to retrieve items and events that we need to recall, with less interference from rarely-‐needed or no longer needed items and cues.

-‐ We are not overburdened by recalling endless stressful, trauma9c, and nega9ve events


6. Forge6ng over -me

A fundamental rule for most organisms (that have been studied so far) is that forge6ng increases as -me progresses


In one of the earliest psychological studies (s9ll cited today!) Hermann Ebbinghaus (1885/ trans. 1913) used himself as a par9cipant to study memory for nonsense syllables over 9me

http://en.wikipedia.org/wiki/File:Ebbinghaus2.jpg

6. Forge6ng over -me

•  He chose nonsense syllables as the s9muli to be learned in an aNempt to make sure that the content did not affect his memory for it

•  In other words, that he would not form associa1ons between learned content and prior knowledge or images that could serve as cues

Ebbinghaus learned 169 lists of 13 nonsense syllables (like “LEV” and “BUP”)

•  He then re-‐learned each list aler varying 9me intervals, from several minutes later up to one month later.

•  He used the amount of 9me required to re-‐learn each list as a measure of how much was forgoNen.


7. The Ebbinghaus forge6ng curve

While our intui9ve sense might be that we keep forge>ng things fairly steadily over 9me, Ebbinghaus's (much-‐replicated) results show that this is not the case.

Forge>ng is not a linear rela9onship between 9me and content retained, but close to a logarithmic curve

•  This means that a lot is forgoNen very soon aler learning

•  Then the rate of forge>ng slows down and almost stabilises over a longer 9me


7. The Ebbinghaus forge6ng curve


8. Applying research to second-‐language learning In a long-‐term example with more naturalis9c content, Bahrick

(1984) tested reten9on for foreign language grammar, reading comprehension, recall and recogni9on vocabulary

•  587 par9cipants who studied Spanish 1 to 50 years previously •  Gathered addi9onal informa9on about their language learning

–  Level of original training, grades –  Use of spoken, wriNen Spanish language (rehearsal) since training

Memory showed exponen9al decline in reten9on for first 3-‐6 years, then stabilisa9on in reten9on for up to 30 years!

Results like this suggest that there is some level of memory “permastore” affected by original training, but NOT by subsequent rehearsal.


8. Applying research to second-‐language learning


9. Eyewitness iden-fica-on and misiden-fica-on One par9cular area of interest for applying memory research (and

where memory researchers may be contacted for an “expert opinion”) is in rela9on to crime.


As part of an inves9ga9on, a witness to the crime may be called on to provide informa9on about its circumstances and/or to iden9fy a perpetrator from a selec9on of suspects. Unfortunately... eyewitness tes9mony is subject to many errors and distor9ons both during and aler the event.

10. Open University Video (Graham Pike) hNp://www.open.edu/openlearn/body-‐mind/psychology/misiden9fica9on-‐can-‐you-‐

iden9fy-‐the-‐criminal (play from 0:50 to 2 minutes)

“Who thought witness was in first row (A, B, or C)? Second row?

Third row? No idea at all?”

(play rest of video)


11. Key points from the video Pike makes several points that suggest that eyewitness evidence

is really not very reliable.

e.g., 77% of a set of 200 cases overturned aler DNA appeal (i.e. wrongful convic9ons) had some component of eyewitness misiden9fica9on as a factor in the original verdicts.

Pike men9ons several factors contribu9ng to unreliable eyewitness accounts or iden9fica9ons, which crucially involve procedures and circumstances aaer the event

•  Use of leading police ques9ons with witnesses •  Presen9ng suspects as a group (simultaneous presenta9on)

rather than one-‐by-‐one (sequen9al presenta9on)

The following video explains more about factors influencing misiden9fica9on, including official procedures and also features of the witness, perpetrator, or event


12. Second video with Graham Pike hNp://www.open.edu/openlearn/body-‐mind/psychology/iden9fica9on-‐evidence


13. More reasons for unreliable iden-fica-ons The Memory textbook has an en9re chapter on eyewitness

tes9mony, and discusses various causes in some detail.

The issues of poten9ally poor police prac9ce discussed in the videos come down to the issue of distor1ng or interfering with informa9on when it is retrieved.

However, other processing factors may also play a role •  ANen9onal biases •  Witness characteris9cs and emo9onal state

–  A very young or very old witness tends to be less reliable –  An extremely frightened or stressed witness is also generally less reliable

•  Change blindness •  “Seeing what we expect to see” 3/23/12 Intro to Cognitive Science 20

14. Acen-onal biases in eyewitness misiden-fica-on To aAend to something means that we expend cogni9ve resources

on it and process its features more deeply.

May be suscep9ble to change blindness when items are not aNended, also unlikely to process and store much informa9on about unaNended or minimally aNended aspects of situa9on.

AAen1onal biases can mean that a witness is likely to aNend to and encode some aspects of a scene, event, or perpetrator at the expense of encoding others. For example:

•  The weapon focus effect: Witnesses may dispropor9onately focus on a weapon, if one is present during crime, and might not aNend to key details like a perpetrator's appearance.

•  Race and age biases: In-‐depth processing of in-‐group members + more superficial processing of out-‐group members mean may be harder to iden9fy a perpetrator who is dissimilar to the witness

(see Simons & Levin 1998 “door study”) 3/23/12 Intro to Cognitive Science 21

15. Seeing (and remembering) what we expect to see Expecta9ons about events can change how we interpret them,

and what we encode (and later can retrieve) about them.

BartleN (1932) developed a theory of recalling informa9on as consis9ng largely of reconstruc-ng the details of the event, using not only what was actually observed, but also “packages” of knowledge called schemas.

•  These are scripts or groups of facts about situa9ons, loca9ons, and events

– What happens when we go to bank – What bank robberies and bank robbers are like

– What criminals are like

•  They are stored as related informa9on in long-‐term memory and appear to be accessed as a whole package


15. Seeing (and remembering) what we expect to see

Schemas can lead us to form expecta-ons about events and may systema-cally influence our recall. Thus, recalling an observed event is likely to combine event-‐specific informa9on with general schema9c informa9on that may be irrelevant or contradictory to the actual circumstances.

Perhaps more importantly for many issues of witness iden9fica9on, schemas may bias us to interpret incomplete and ambiguous informa9on in a certain way.


15. Seeing (and remembering) what we expect to see For example, Tuckey and Brewer (2003b) report a study in which

“eyewitnesses” to a simulated bank robbery interpreted ambiguous informa9on according to their schema about bank robbers:

•  Male, wearing dark clothing and/or wearing a disguise

•  Schema content study reported in Tuckey and Brewer, 2003a When the simulated bank robber was gender-‐ambiguous with a

completely covered head and face, the witnesses were more likely to report informa9on congruent with their bank robbery schema (a male robber) rather than simply repor9ng an ambiguous figure.


16. Closing thoughts

There is some debate about the degree to which empirical studies of memory apply to real crimes and real witness iden9fica9on situa9ons (see the Memory textbook, chapter 13).

While Tuckey and Brewer's experiments are a laboratory example about an uncommon type of crime, consider the extremely serious implica-ons of cultural schemas that tell us that “criminals” are likely to be males from ethnic minori-es, or that any teenager in a hooded sweatshirt is an ASBO wai-ng to happen.


16. Closing thoughts

Hopefully our memory unit has begun to illuminate how-‐-‐while memory is largely robust and adap9ve-‐-‐it can fail in significant ways both for individuals like Clive Wearing, and as an informa9on-‐processing system that is suscep9ble to considerable distor9ons and processing biases.

Our models of memory and our aNempts to endow ar9ficial intelligences with human-‐like processing capaci9es must consider and account for these weaknesses, as well as strengths.


References

Course texts

•  Memory (Baddeley, Eysenck, & Anderson, 2009) Other resources, available through the library or Google Scholar

•  Seman9c memory content in permastore: Fily years of memory for Spanish learned in school (Bahrick, 1984).

•  Memory: A contribu9on to experimental psychology (1885, translated 1913). An online version is available at hNp://psychclassics.yorku.ca/Ebbinghaus/index.html


References •  Professor Graham Pike's videos on eyewitness misiden9fica9on, through Open University

–  First video hNp://www.open.edu/openlearn/body-‐mind/psychology/misiden9fica9on-‐can-‐you-‐iden9fy-‐the-‐criminal

–  Second video hNp://www.open.edu/openlearn/body-‐mind/psychology/iden9fica9on-‐evidence

•  How schemas affect eyewitness memory over reprated reteieval aNempts (Tuckey & Brewer, 2003a)

•  The influence of schemas, s9mulus ambiguity, and interview schedule on eyewitness memory over 9me. (Tuckey & Brewer, 2003b)


Documents

Recall,&forge6ng,&and& eyewitness&misiden-ﬁca-on&