Research into Eyewitness Testimony

EWT is a legal term referring to the evidence provided in court by a witness to a crime, witht he intention of identifying a perpetrator.

Elizabeth Loftus said that memory is reconstructive in its nature, and that its quality is affected by the form of questionning recieved after an event. She said that leading questions effect the encoding of the original memories and after a while the new information is remembered as if it really happened. This is called the post-event effect.

Loftus (1974) investigated into the accuracy of memory recall after a car accident, in particular whether leading questions have any effect. She showed 45 students 7 different films of car accidents, then asked them a series of questions afterwards - with one critical question: "about how fast were the cars travelling when they hit eachother?". One group recieved this, whilst the other 4 recieved a variation, with the word 'hit' being replaced by either smashed, bumped, collided or contacted.

The average speeds for each word were as follows: Smashed (40.8 mph), Collided (39.3 mph), Bumped (38.1 mph), Hit (34 mph) and Contacted (31.8 mph).

The difference in scores indicates that the form of questioning recieved after an event can effect the accuracy of memory recall.

Loftus and Palmerthen conducted a follow-up study, which backed up her original theory. The original procedure was followed, but this time only 'smashed' and 'hit' were used. A week later, the participants were asked if they saw any broken glass (there wasn't any), and this was compared to a control group who had been asked no prior questions about speed. The results showed that those in the 'smashed' condition were significantly more likely to report broken glass than those in the 'hit' condition. Therefore, they concluded that leading questions have a significant effect on memory, and we reconstruct our memories based on new information after an event.

1. One weakness of this research is that Loftus used her own students as participants. Thus, they would be aware that they were being tested upon, and possibly guess the aim. This means that demand characteristics would be present as an extraneous variable, and possibly confound the results. Therefore, the studies can be said to have low internal validity as participants reaction to demand characteristics was measured, instead of the effect of the IV on the DV.

2. Another weakness of the research is the fact that she used university students. This means that she would have a biased sample as university students are above the average IQ - meaning that the sample was unrepresentative. Therefore, the findings would have low population validity as they cannot be effectively generalised to other populations.

Research into EWT can be criticised in general for lacking emotion.

"A weakness of research into EWT is the fact that it is conducted in a lab. This is an artificial setting, and participants do not experience the same emotions as witnesses to real-life events. This means that the conditions measured are non-threatening, unlike real-life encounters. Therefore, results can be criticised for having low ecological validity."