Thursday, 19 May 2011

Test how much you know about the reliability of memory

In the latest in a series of investigations into how much people know about eye witness memory, Svein Magnussen and Annika Melinder have compiled 12 questions about memory and put them to 857 licensed members of the Norwegian Psychological Association. The correct answers were based on the latest consensus findings in the field of memory research. The Norwegian psychologists scored an average of just 63 per cent correct, no better than achieved by Norwegian judges (63 per cent) in prior research, and only slightly ahead of the general public (they scored 56 per cent on average).

This blindspot for understanding memory isn't a uniquely Norwegian problem. Past research has established that US and Chinese judges, US law students and undergrads all have limited knowledge about the factors that affect eye witness testimony.

The findings have serious implications for the understanding of memory processes in court, especially the limitations of eye witness accounts. Magnussen and Melinder said their findings support the official guidance of the British Psychological Society's Research Board that being a fully credentialed psychologist does not by itself make someone a memory expert. "A memory expert is someone whose expertise is recognised," states the 2010 version of the report. "Recognition of relevant expertise should usually be in the form of outputs that are publicly verifiable, for example, peer-reviewed publications, other publications, and presentations at professional meetings. Of these, peer-reviewed publications are the most important."

So how would you have fared at the memory quiz? Here are the test items in shortened form:

1) Is a person's confidence in their memories a good predictor of the accuracy of those memories?
2) Is it true that eye witness testimony reflects not just what a witness originally saw and heard, but also other information obtained later on from the police, other witnesses etc?
3) Is a witness's ability to recall minor details about a crime an indication of the accuracy of their identification of the perpetrator?
4) Does intense stress at the time of an event impair the accuracy of the memory of that event?
5) Can their attitudes and expectations affect a person's memory of an event?
6) Does the presence of a weapon tend to impair a witness's memory for a perpetrator's face?
7) Does most forgetting tend to occur soon after an event?
8) Do children have better memories for events than adults?
9) How far back into their childhood can most people remember?
10) Are traumatic memories from childhood that are "recovered" in therapy (having never before been recalled) likely to be false?
11) Are dramatic events more or less likely to be forgotten?
12) Is it possible for a perpetrator to have forgotten their criminal act because they've suppressed that specific memory?

Here are the answers: 1) No, 2) Yes, 3) No, 4) Yes, 5) Yes, 6) Yes, 7) Yes, 8) No, worse, 9) to the age of three to four years 10) Yes, 11) Less, 12) No

So how did you do? As well as their overall relatively poor performance, Magnussen and Melinder found that psychologists performed better than the public on question (1) but actually performed worse on questions (6) and (7). "It is particularly surprising that so few psychologists were familiar with the normal course of forgetting, the classic Ebbinghaus function," they said.

Some of the answers may strike you as more controversial than others. On the question of recovered memories, Magnussen and Melinder wrote: "Repression is not among the mechanisms of forgetting acknowledged by current memory science, and the available evidence does not support the idea of repression." They go on to say that well-controlled prospective studies of childhood sexual abuse victims suggest strongly that memories of abuse are not forgotten.

What about the idea that criminals can't selectively forget a criminal act? Although psychogenic amnesia is a real phenomenon (that is, amnesia in the absence of any detectable brain damage or disease), Magnussen and Melinder argue that these "mnestic blocks" typically cover periods of weeks or even years, not the specific instances in time that are often claimed by offenders.

Another point of clarification is that whilst trauma interferes with the details of a memory, it actually makes that memory more persistent and vivid, hence the apparent contradiction of questions (4) and (11).

The researchers call for better scrutiny of memory expertise by the courts and they lament that "psychlore appears to be a stronger determinant of the theoretical ideas [about memory] than are the results of empirical research", even among the majority of qualified Norwegian psychologists.

ResearchBlogging.orgMagnussen, S., and Melinder, A. (2011). What Psychologists Know and Believe about Memory: A Survey of Practitioners. Applied Cognitive Psychology DOI: 10.1002/acp.1795

This post was written by Christian Jarrett for the BPS Research Digest.


Alex Fradera said...

Interesting stuff. As an ex-memory researcher who's done stuff on eyewitness memory, I cheerfully concede 3 errors - although I have the reverse pattern to the 'psychologist' one, for whatever that's worth.

Glad to see the clarification on question 12 - although I would nitpick their item development, "suppressed just that specific memory" would be clearer to their intent.

It's also worth mentioning, beyond psychogenia, that there are other ways that someone can commit an act and have no memory of it. The one that springs to mind is when the act is committed without the individual's conscious awareness, such as in a hypoglycemic shock state or arguably a drug-induced state. Here, of course, the issue is of not encoding the memory properly, rather than forgetting it. I was privy to some such cases and others of the automaton defence when working in Mike Kopelman's lab at KCL, who also worked with a number of psychogenic cases during my tenure.

I'd also question the consensus on repressing memories. There is certainly evidence that we can suppress memories; I came across this stuff in 2004 through Michael Anderson's work, and it looks like it's still building a case:
now whether there is an argument to be had about repressing vs suppressing memories, I don't know. As I say, I'm an ex-memory researcher now!

Christian Jarrett said...

Hi Alex, thanks for some really interesting points, especially regards crimes committed without conscious awareness. I should just clarify that I've paraphrased the test questions and the answer system, so it's possible any specific problems with the wording are mine rather than the fault of the authors (although I have tried to keep their meaning).

Cached said...

I've just finished a forensic psych degree, and can happily say I got 11/12. Looks like the forensic focus, and classes specifically about eyewitness memory actually achieved something!

Zander said...

Got 11/12 with the last one wrong. Not bad considering I would have been guessing without a day of cramming the topic a few weeks ago for an exam.

Would like to have seen how the psychologists in the sample who have actually performed memory research fared, as although results differences by employment background are discussed, I don't think disparities based on areas of expertise are. Surely some psychologists really don't need to know the answer to all of these questions anyway, just like how any Mastermind contestant would be expected to fail miserably if they attempted another person's specialist subject. That said, it's a bit odd that the psychologists scored worse than the judges on #7 - that one seems rather more 'general knowledge' than most of the other questions posed.

Joan said...

Was correct on all except #7, which is odd as I am very aware of the forgetting curve. Sadly, I think that the notion of repressed memories is still alive and well.

Anonymous said...

Note that Norwegian judges are probably not political appointees or elected officials: different population from US judges.

Sian G said...

Very pleased to get 12/12 - butI do teach the topic of memory at A level so would be worried if I didnt perform well!!
I was a little concerned to see that Judges only averaged 62% on this test - surely they need a strong awareness of what can affect EWT!?!

Sian G said...

I teach the memory topic at A level and can happily report scoring 12/12 on this!!

I am however concerned that judges were on average only getting 62% - I would of thought it imperative that they understood factors that could affect EWT!?!

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