The effect of anxiety on eyewitness testimony

How does a stressful situation, such as the presence of a weapon, affect the accuracy of eyewitness memory?

Is there a difference between laboratory and real life studies of anxiety in EWT?

Anxiety and cognitive performance
Inverted U theory (Deffenbacher, 1983)
Inverted U theory states that at low levels of anxiety cognitive performance (in this case memory accuracy) will be at a relatively low level, but as anxiety increases then so does cognitive performance until it reaches an optimal level after which any further increase in anxiety level leads to a rapid drop in cognitive performance.

Inverted U theory and eyewitness testimony
If we apply this theory to eyewitness testimony we can predict that stressful incidents, such as being a victim or witness to a crime, will lead to witnesses having relatively inaccurate memories of the event as their anxiety levels at the time would have been above the optimal level.

Research support for this theory and its relevance to eyewitness testimony can be found in a field experiment carried out by Peters (1988) using participants who were visiting a health centre for routine injections. On arrival at the health centre participants met a researcher who took their details and recruited them for the study. They then visited the nurse who gave them their injections before theory went back home. One week later, when asked to select the nurse and researcher from a set of photographs, participate were significantly more able to identify the researcher than the nurse. If we assume that meeting the researcher created a low to moderate level of anxiety, and being given an injection by a nurse created a high level of anxiety then the results are as would be predicted by inverted U theory. However this conclusion is not without its flaws as field experiments are difficult to control and participants probably spent more time face to face with the researcher than the nurse.


Weapon focus
Loftus (1979)
Participants in this study were left in a waiting area outside a laboratory whilst waiting for the “real” study to start. While they were waiting one of two situations occurred. In the first situation they overheard a discussion in the laboratory about equipment failure, followed by a man leaving the laboratory holding a pen and with grease on his hands. In the second situation participants overheard a heated discussion in the laboratory with the sound of breaking glass and crashing chairs, followed by a man leaving the laboratory carrying a paper knife covered in blood. The participants were later asked to identify the man from a set of 50 photographs with the result that 49% correctly identified the man holding the pen, but only 33% could identify the man with the bloodstained knife.

Loftus argued that participants were less able to correctly recall the man with the knife because they had their attention absorbed by the knife (presumably because it was potentially a source of danger to them), and so were distracted from the appearance of the man holding it. This has become known as weapon focus and explains how witnesses to violent crimes may accurately recall central details (e.g. the type of weapon and what was done with it), but may be less accurate at recalling periphery details such as the appearance or clothing of a criminal.

Real world research into anxiety and eyewitness testimony
Yuille & Cutshall (1986)
Yuille & Cutshall interviewed 13 witnesses to a real life shooting in which a storeowner in America was injured and the thief was shot dead. Some of the witnesses had been very close to the incident whist others had viewed it from a distance away. The researchers found that the witnesses closest to the event gave the most detail, that all of the witnesses were able to give accurate accounts several months later, that they were seemingly unaffected by misleading questions, and that the witnesses that had been the most distressed at the time of the incident actually gave the most accurate testimony several months later.

Christianson & Hubinette (1993)
110 witnesses of 22 real life bank robberies were interviewed some time after the robberies. Some of the witnesses had been onlookers or customers in the bank, and others were bank employees who had been directly threatened or subjected to violence during the robberies. The findings were that the victims were surprisingly accurate in their recall of the robbers’ clothing and behaviour, and that the accuracy was still evident 15 months later.

The results of these studies are surprising as they are completely opposite to those that inverted U theory and weapon focus would predict. The witnesses were neither so distressed that their cognitive performance was very low, nor was their attention overly absorbed by the presence of a weapon. But as it was an uncontrolled study then it could be that the witnesses had discussed the shooting so often, been interviewed so many times, and even read about the event in the newspapers that their memories may not be entirely their own.

The difference between laboratory and real world research into anxiety and eyewitness testimony
Real world research into eyewitness testimony has a valuable advantage over laboratory research as it has very high ecological validity. In laboratory studies, participants are exposed to often unrealistic scenarios presented in an unrealistic way, and to a certain extent there are demand characteristics as they are expecting to be asked about the event they are shown. Real world events are sudden, unexpected, have high levels of emotion and stress involved, and provide the only real way to test how accurately witnesses recall events; however they are also uncontrolled and it is impossible to account for how witnesses may discuss the event with one another, are interviewed by authorities, and what they read before the researchers get the chance to interview them. Both laboratory and real life studies are therefore important, but it is very interesting how the methods provide contrasting results.




A Level exam tips
Answering a 12 mark question (PSYA1 AQA A specification)
Outline and evaluate research into the effect of anxiety on eyewitness performance.
6 AO1 marks would come from a description of relevant research studies. Choosing 3 studies, perhaps 1 lab study and 2 real life ones, and describing them in simple paragraphs would be sufficient.

6 AO2 marks would then come from evaluating the studies and explaining what the evaluation means for the validity of the research. Focus on control of extraneous variables, cause and effect, ecological validity, and population validity or generalisabilty.