Eye witness testimony (EWT) is regularly a deciding factor for courts in the criminal justice system to ‘prove’ the guilt or innocence of the criminally accused. However, inaccuracies in EWT are common, accounting for about 75% of incorrect convictions later found to be innocent using DNA evidence.
One factor that could negatively influence EWT accuracy is misleading information - i.e. any information that ‘leads’ you into giving a particular response, as opposed to a necessarily accurate response. The two types of misleading information are:
- Leading questions - questions that suggest a desired answer
- Post-event discussion – information given after an event with potential to influence memory of it (this includes leading questions).
Investigated by Loftus and Pamler were the effects of leading questions:
Showed students film clops of car accident adn then asked how fast were the cars going when the hit each other? 5 groups of ppts- different verbs used indicating a different speed at which the car was travelling. Found that vert contacted produced mean estimate speed of nearly 10 mph less that the verb smashed.
Shows how the leading question biased EW recall by suggesting a faster speed (smashed) or a slower speed (contacted).
2 explanations for this:
Wording has no enduring effect of memory of event but influences the kind of answer given.
wording of question does affect EW memory and intefers with original memory, distorting its accuracy.
PED (post-event discussion) investigated by Gabbert et al
Paired ppts and got them to watch a crime taking place on video. However, it was filmed so each ppt could see different elements of the event (different perspectives). After ppts discussed what they had seen they found that over 70% of ppts mistakenly recalled aspects that were not displayed in their video that they picked up on during PED. In control group there were no errors!