The Psychology of Criminal Investigation: Task 1.1
Loftus and Palmer (1974) were interested in the accuracy of people’s memory after witnessing a car accident, in particular to find out if misleading information affected an eye witness’s immediate memory recall.
Loftus and Palmer carried out two experiments; the main focus was on how misleading information can influence eyewitness testimony; in terms of visual imagery, language and the wording of questions. (www.simplypsychology.org)

Primarily the researchers showed participants a series of slides of car crashes, they were then asked ‘How fast the cars going when they hit into each other? The verb was substituted for other participants with words such as ‘smashed’ , ‘collided’, ‘bumped’ and ‘contacted’.
Their findings show that the estimated speed given by participants varied according to the verb used. ‘Smashed’ produced an average estimate of 41mph whereas ‘hit’ reduced the estimates to 34mph and to 32mph for ‘contacted.’ This suggests that the language and type of describing word used when questioning witnesses and suspects in police interviews can distort the accuracy of eyewitnesses immediate recall. The study indicates that the form of questioning can have a significant effect on a witness answer therefore material can be altered during retrieval resulting in the memory of the event being permanently affected.
Loftus and Palmer conducted a second experiment to see if memory was actually altered by misleading post-event information. A new group of participants were selected to watch the film of the car crash, they were put into three groups; with one group they used the word ‘smash, second group ‘hit’ and the third group were not asked a question about the film.

When participants were asked a week after viewing the film whether they saw any broken glass at the scene (there was none in the actual footage), participants in the smashed group were more likely to say yes. Therefore, a leading question that encouraged them to remember the vehicles going faster also encouraged them to remember that they saw non-existent broken glass. The question appears to have modified the memory itself. quote
This Loftus and Palmer study had implications for police interviews as the type of question could influence a witness’s testimony; however this was an artificial experiment which lacked ecological validity as watching a video is not as emotionally arousing as a real life event which potentially affects recall. In fact a later study by Foster et al (1994) found that participants who thought they’d witnessed a real robbery gave a more accurate description of the robber. (Cardwell and Flanagan, 2008, Page 17)
In another experiment by Loftus et al (1978) participants were shown slides of events leading up to a car accident, one of which featured a car stopping in front of a yield sign. After viewing the slides, participants read a description of what they saw. Some of the participants were given descriptions that contained misinformation, which stated that the car stopped at a stop sign. Following the slides and the reading of the description, participants were tested on what they saw. The results revealed that participants who were exposed to such misinformation were more likely to report seeing a stop sign than participants who were not misinformed. (en.wikipedia.org)
Other factors such as stress, anxiety, and weapon- focus effect and proximity to person or event can all affect eyewitness testimony and their memory recall.
A real life example of a miscarriage of justice; which supports the argument that not all eyewitness testimony is valid and may need improving is the case of Anthony Capozzi who was sent to prison for 35 years in 1987 for the rape of two women based on the evidence given by the victims during the trial. Capozzi had a prominent three-inch scar on his face but none of the victims had mentioned this feature when describing their attacker. Biological