7. Factors effecting the accuracy of EWT (2) ✪ ω ✪

Why may anxiety have a negative effect on EWT? (hint: stress hormones, fight or flight, cues, weapons)

Anxiety causes the release of stress hormones (e.g. adrenaline as a part of the fight of flight response). This can reduce our ability to focus on important cues, so recall is worse.

• One approach to studying anxiety and eyewitness testimony (EWT) is to look at the effect of the Prescence of a weapon, reducing a witness’s recall for other details of the event.

Who performed the procedure on anxiety’s negative effect on recall?

Johnson and Scott (1976)

• participants believed they were taking part in a lab study

• while in a seated waiting room, some participants heard a conversation in the next room and then saw a man walk past them carrying a pen and with grease on his hands (low anxiety condition).

• other participants overheard a heated arguement in the next room, the sound of breaking glass and then a man emerged holding a knife with blood on it. (high anxiety condition)

The participants were than asked to pick the man out from a set of 50 photos, and 49% who had seen the man carrying the pen were able to identify him.

The corresponding figure for the participants who had seen the man holding the blood-covered knife was 33%.

• the tunnel theory of memory argues that people have enhanced memory for central events. weapon focus as a result of anxiety can have this effect.

Why may anxiety have a positive effect on recall?

Anxiety also increases alertness and this may improve memory for an event as we become more aware of the cues in the situation.

Who performed the procedure on anxiety’s positive effect on recall?

Yuille and Cutshall (1986)

• conducted a study of an actual shooting in a gun shop in Vancouver Canada. The shop owner fatally shot a thief.

• There were 21 witnesses - 13 took part in the study.

• They were interviewed four to five months after the incident and these interviews were compared with the original police interviews at the time of the shooting.

• Accuracy was determined by the number of details reported in each account.

• The witnesses were also asked to rate how stressed they had felt at the time of the incident ( on a 7 point scale) and whether they had any emotional problems since the event (sleeplessness)

The witnesses were very accurate in their accounts and there was little change in the amount recalled or accuracy after five months - in fact some witnesses had increased accuracy. Those participants who reported the highest levels of stress were most accurate (about 88% compared to 75% for the less-stressed group).

This suggests that anxiety does not have a detrimental effect on the accuracy of eyewitness testimony in a real-world context and may even enhance it.

Who came up with the reasoning for the contradictory findings?

Yerkes and Dodson (1908)

-according to them, the relationship between emotional arousal and performance looks like an inverted U.

• Deffenbacher (1983) reviewed 21 studies pf EWT and noted contradictory findings on the effects of anxiety.

• He used the Yerkes-Dodson law to explain the findings.

• When we witness a crime/accident, we become emotionally and physiologically aroused. That is, we experience anxiety (emotional) as well as physiological changes in our body ( the fight or flight response).

• Lower levels of anxiety/arousal produce lower levels of recall accuracy, and then memory becomes more accurate as the level of anxiety increases.

• However, there is an optimal level of anxiety, which is the point of maximum accuracy.

• If a person (or eyewitness) experiences any more arousal, then their recall suffers a drastic decline.

Evaluate the effects of anxiety on EWT. (hint: unusualness not anxiety, measuring anxiety, support for positive effect and its counterpoint)

Unusualness not anxiety ❌

Johnson and Scott - may not have tested anxiety.

The reason participants focused on the gun may be because they were surprised at what they saw rather than scared.

• Pickel (1998) conducted an experiment using scissors, a hand gun, a wallet or a raw chicken as the hand-held items in a hairdressing salon video (where scissors would be high anxiety, low unusualness). Eyewitnesses accuracy was significantly poorer in both of the high unusualness conditions (chicken and hand gun)

This suggests that the weapon focus effect is due to unusualness rather than anxiety/threat and therefore tells us nothing specifically about the effects of anxiety on EWT.

Measuring anxiety ❌

The way that anxiety and EWT is measured may act as an extraneous variable.

• Carey Marr and colleagues (2021) considered the way that anxiety is measured in studies of anxiety and EWT.

• Anxiety may be measured subjectively (e.g. self report) or objectively (e.g. recording physical changes in the body, such as heart rate)

• when both types of measure are used within the same study, the self reported experience of anxiety doesn’t always match the physiological changes being observed.

This suggests that the apparent effects of anxiety in a research study may be more of a function of the way anxiety is measured ( an extraneous variable) rather than the anxiety itself.

Support for positive effects ✅

Research showing that anxiety can have positive effects on the accuracy of recall.

• Christianson and Hubinette (1993) interviewed 58 witnesses to actual bank robberies in Sweden. some of the witnesses were directly involved (e.g. bank workers) and some were indirectly involved (e.g. bystanders).

• The researchers assumed that those directly involved would have experience the most anxiety.

• It was found that recall was more than 75% accurate across all witnesses.

• The direct witnesses (most anxious) were even more accurate.

These findings from actual crimes confirm that anxiety does not reduce the accuracy of recall for eyewitnesses and may enhance it

counterpoint:

Christianson and Hubinette interviewed their participants several months after the event (4 to 15 months).

• the researchers therefore had no control over what happened to their participants in the interviewing time (e.g. post event discussions)

• The effects of anxiety may have been overwhelmed by these other factors and impossible to assess by the time the participants were interviewed.

Therefore it is impossible that a lack of control over extraneous variables may be responsible for Christianson and Hubinette’s findings, invalidating their support.