When witnessing a real-life crime, it is likely that cortisol production will be heightened which could increase reliability of memory due to selectiveattention increasing.
+Al’Absi et al. (2002) found that cortisol disrupts workingmemory but enhances selectiveattention (as witness may have been preparing for fight or flight)
If a crime is particularly stressful, arousal may be too high to focus on the detail of the crime and reliability of memory will be reduced.
+According to Yerkes and Dodson (1908) there is an optimal level of arousal where attention will peak.
Reliability of eyewitness memory may be strongest in the cases of giving specific details of a traumatic event.
-Kramer et al. (1991) exposed subjects to images of murder victims as a traumatic stimulus finding overall memory was poorer, so elevated levels of stress reduce recall accuracy.
Emotions which result in fixation of high stress levels may reduce the reliability of eyewitness memory as peripheral details are less well recalled or remembered.
-Christianson (1992) claimed when the main event is emotional, witnesses fixate faster, more often, and for longer on stimulus
stress in relation to eyewitnesses - Physical or emotional tension caused by a factor or situation of the crime
Arousal levels increase when an eyewitness is subjected to stress meaning they may not be able to focus on the details of the crime and their memory of the event may be impaired influencing the reliability
Qin et al (1997) suggest that stress can affect the way eyewitnesses encode memories at the time of the crime