You don't need to know this study, but the results are really useful for discussing individual differences in memory and it's a good example of a cognitive field experiment.

LOFTUS' RESEARCH INTO INDIVIDUAL DIFFERENCES IN MEMORY

When studying individual differences in memory, researchers focus on two types of memory: 

• Accuracy: how much do individuals correctly recall?
• Suggestibility: how influenced are individuals by leading questions and misinformation that causes them to have false memories

Loftus et al. (1992) investigated these variables with an opportunity sample of 1989 visitors to a Science Museum in San Francisco. The sample included children and the elderly as well as adults from different backgrounds.

Visitors watched a 75-second film of a crowd scene, at the end of which a man is nearly run over by a van and assaulted by an officer with a baton. They were later asked 10 questions about the episode on a computer screen. 6 yes/no questions measured Accuracy; there were 2 leading questions (half the participants were misinformed about the colour of the van and the officer's uniform) and 2 questions measuring Suggestibility (asking about the colour of the van and the officer's uniform).

This was a field experiment, because the participants were real visitors to the Science Museum. The IV is (1) whether or not the participants were given leading questions and the DVs are whether they falsely recalled a white van and white uniform and their score for Accuracy. It uses Independent Groups design (because half the participants were put in the Suggestibility group by being given a leading question and the other haldf was a Control group who did not get a leading question).

However, it is also a natural experiment, because Loftus et al. recorded the (2) age, (3) occupation, (4) gender and (5) educational level of participants for comparison purposes. These are naturally-varying IVs.

Loftus found that average accuracy was 74%. 26-35 year-olds were most accurate (77%) and the elderly (age 65+) group were the least accurate (56%). Children (age 5-10) and the elderly (age 65+) got the lowest scores for accuracy and were also the most suggestible.

Males and females scored similarly, except in the elderly group, where females were much more accurate than males (69% versus 43%).

The unemployed were the least accurate (65%) and people working in trade/technical scored the highest (77%). Oddly, accuracy was low for lawyers (66%) and the police (68%). Artists got unusual scores: they were average for accuracy, but very suggestible (54% affected by leading questions compared to 17% in the artists control group).

Education did make a difference, with the most educated groups being more accurate but suggestibility was not affected by education.

Loftus concludes that there are individual differences in memory ability, both in accuracy and suggestibility.

• Popular ideas about the very young and the elderly having worse memories seem to be true.
• Popular ideas about some professions (like lawyers and police) having good memories seem to be false.
• Differences between male and female memory only appear in old age.
• Students are in fact reasonably representative.
• In general, people with inaccurate memory tend to be the most suggestible, but not always: Loftus proposes that people like artists with very visual memories may be accurate but easily misled by leading questions about colour.

APPLYING PSYCHOLOGY TO INDIVIDUAL DIFFERENCES IN MEMORY
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Memory in Students

Loftus' research shows that students are quite representative as a group. As an educated population, their memories tend to be more accurate than less educated people. As younger adults, they are not as suggestible as children, but they are not yet as accurate in their memory as older people in their 30s. Largely-male student samples don't seem to be a problem because the differences between male and female memory only start to appear in their 60s.

Researchers who want their samples to be as representative as possible could use students, but should make an effort to include people without college education as well.

EVALUATING INDIVIDUAL DIFFERENCES IN MEMORY (AO3)
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Strengths

Individual differences in memory are supported by lots of research. Loftus et al.'s natural experiment in a field setting shows differences in the accuracy and suggestibility of memory between children, adults and the elderly, but also between people with different levels of education and different occupations. There also seem to be gender differences in memory among the over-65s.

Weaknesses

There is a validity problem with any natural experiment like the one by Loftus et al., because in a natural experiment you are not manipulating the IV so you can't be sure what the cause-and-effect relationship is. For example, does education improve your memory or is it that people who already have good memories do best at education? Do people's memories improve as they grow out of childhood or do they just get better at doing memory tests for other reasons (concentration, vocabulary, etc).

Applications

Individual differences might help the police deal with eyewitnesses. Loftus et al. suggest that children and the over-65s (especially elderly men) have the worst accuracy and are very suggestible, so leading questions must be avoided. Adults in their 30s have the best memories, so their testimony should be taken very seriously.

Comparisons

Reconstructive Memory might explain these differences too. Schemas explain why some people are more suggestible than others. Children might not have developed schemas yet and the elderly might have out-of-date schemas. Educated people might use different schemas from uneducated people and groups like the salespeople and technicians might learn different schemas from unemployed people. However, this doesn't explain the poor accuracy of police officers and lawyers, who ought to have scored higher.