Effects Of Stress On Eyewitness

Eyewitnesses that witness a crime, especially violent crime, commonly experience stress. Stress is a negative emotional state that causes both physiological changes and cognitive changes. High stress causes increased arousal, increase in heart rate, blood pressure and muscle tone. A person feels stress when encountering a threat and that causes high anxiety. High levels of stress can leads to holes in memory of eyewitnesses when asked to recall details such the persons involved. (Aharonian & Brian)

The Yerkes-Dodson law proposes that the relationship between arousal and performance is an inverted U, in which moderate increase in arousal causes performance to increase but with too much arousal, performance decreases (Diamond, Campbell, Halonen

The difference between peripheral and central memory shows us why sometimes eyewitness have memory of details and sometimes they do not. Research and Meta analyses show that stress has more of a negative impact than a positive impact on eyewitness testimony, as they face difficulty in identifying a perpetrator from a lineup and recall certain details of the crime. In these studies, witnesses are typically asked to report information in two ways; interrogative and narrative. In narrative, witnesses are asked to say what they recall and have the ability to chose what information they want to report. The interrogative type of recall is when the police ask specific questions that the witness needs to respond to. High stress situations cause a greater decline in the accuracy of the interrogative e recall than the narrative recall. This might be because in the narrative recall, witnesses are free to report details and they may opt to remove information that they are not sure of. But, research into the effects of stress on eyewitness memory suffers from methodological complications, as there is a limit of the amount of stress we can put on a participant. Also, even with highly arousing materials, the participant do not feel personally threatened by the event and they feel as if they are bystanders, not the victim itself, and that influences their stress level, their behavior, degree of attention