Alcohol and Eyewitness Memory

Question 1

What are the NHS guidelines for alcohol?

Answer 1

Men should not drink more than 14 units of alcohol each week
Not to ‘save up’ the units for 1 -2 days but to spread it out over three or more days

Question 2

How can you measure alcohol levels? How much is over the limit?

Answer 2

80 milligrammes of alcohol per 100 millilitres of blood (0.8% BAC),

35 microgrammes per 100 millilitres of breath (0.35% BrAC) or

107 milligrammes per 100 millilitres of urine.

However take into account individual differences (gender, age, weight, food intake)

Question 3

What are the statistics for binge drinking?

Answer 3

According to Matthews & Richardson (2005):

44% of 18-24 year olds were identified as binge drinkers.

More likely to binge drink than any other age group.

More likely to offend than regular drinkers.

Question 4

What is the blood alcohol concentration curve?

Answer 4

Studies have found that the effect of alcohol on cognition depends, in part, on the different points on the ascending and descending limbs of the BAC curve (Soderlund et al, 2005; Schweizer et al, 2006).

Ascending = arousal, positive mood and aggression. Immediate memory, reasoning and info processing impaired.

Descending = sedation and negative mood. Executive function and short term memory impaired.

Question 5

When are you intoxicated?

Answer 5

Individual differences can affect this (age, gender, weight, quantity and strength of alcohol)

Drink drive limit = 0.08%

.02-.03 = mild relaxation
.04-.06 = lower inhibitions 
.07-.09 = slowed reaction time 
.09-.12 = recklessness 
.13-.16 = judgement failure 
.16-.19 = rage 
.20= blackouts 
.30= trancelike state
.

Question 6

What is the link between crime and intoxication?

Answer 6

2015/2016 victims believed the offender to be under the influence of alcohol in 39% of all violent incidents

Wales = 49%
Scotland = 42% offender under influence 

Alcohol is prevalent in domestic abuse

Crossland, kneller and Wilcock (2018) 43.96% of interviews with witnesses who were intoxicated at the time of the crime

US - Evans et al (2009) 53% of law enforcement interview average of 4 intoxicated witnesses a week

Palmer at al (2013) - analysed 639 felony cases (robbery, rape and assault)20% one intoxicated witness

Question 7

What are the perceptions of intoxicated witnesses?

Answer 7

Police - Crossland et al (2018) - police believe statements by intoxicated witnesses to be significantly less accurate with only 1.6% were considered extremely accurate

Jury - Crossland et al - 240 jury eligible individuals completed online questionnaire rating 1 of 6 witness testimonies given when either sober, moderate or severely intoxicated
Each testimony either long or short 50% told state of witness 50% were not.
Knowledge of witnesses intoxication and lesser account leads to lower credibility ratings

Question 8

What are the effects of alcohol on the body?

Answer 8

Alcohol is a central nervous system depressant
Low doses = relaxing effect, reduced tension, lower inhibitions, impaired concentration, slower reflexes, reaction time and coordination

Medium doses = slurred speech, drowsiness, altered emotions

High doses = vomiting, breathing difficulties, unconsciousness, coma, death

Question 9

What is the effect of alcohol and inattentional blindness?

Answer 9

Clifasefi et al. (2006) gave half their subjects alcohol (but told half it was a placebo) and half (but told half of them it was an alcoholic drink)

P’s asked to count number of white -short passes in a basketball clip (Simons and Chabris, 1999)

Found intoxicated p’s showed greater levels of attentional blindness than sobers.

Question 10

What is the affects of alcohol and memory?

Answer 10

Effects all 3 stages of the memory process (encoding, storage and retrieval)

Reduces ability to encode episodic memories and ability to form new long term memories.

Alcohol impairs encoding/ storage more than retrieval

Question 11

What is Alcohol Myopia Theory?

Answer 11

Developed by Steele and Josephs (1990) to explain alcohols dissociative effects on an individuals recall in similar situations.

Intoxication restricts the number and breadth of cues perceived

Alcohol reduces the ability to process and extract meaning from then cues that are perceived

AMT proposes disproportionate amount of attention is given to central salient cues (both internal and external) whilst the weaker more peripheral cues received less attention.

Assumptions:
When drunk we attend to and encode fewer available cues
Alcohol reduces our ability to process and extract meaning from the cues and info we do perceive
Inhibitory cues (e.g. bouncers) are less salient

Question 12

What does salience mean?

Answer 12

The immediate superficially understood aspects of an event which have undue influence over behaviour

Question 13

What is the Attention-allocation Model?

Answer 13

Alcohol intoxication leads to ‘short-sighted’ information processing

‘the conscious drunk may see the tree but miss the forest altogether’ Steele and Josephs (1990)

Question 14

Evaluate AMT

Answer 14

The model of the effects of alcohol on behaviour and one of the best accepted
Considerable body of research appears to support this attention allocation model in explaining the social behaviour of intoxicated people.
Griffin et al. (2010)

However little research has actually tested theory.
AMT is influential but provides no detailed account of the cognitive mechanism underpinning the so called myopic effect
It is not clear for example whether alcohol consumption reduces the overall capacity of ones attention or whether it just hampers our ability to allocate attention

Question 15

What are the effects of alcohol intoxication on witnesses?

Answer 15

Flowe and Humphries (2009) sampled 725 felony cases from archives of DA’s office - approx 33% of all eyewitnesses involved were under the influence of alcohol and drugs
Intoxicated witnesses were just as likely to provide statements to the police as sober witnesses

Question 16

What are the perceptions of intoxicated witnesses?

Answer 16

Kassin et al (2001) 90% of legal experts stated that research demonstrating poor intoxicated EW performance was reliable enough to report in court

Juror studies support this view (Benton et al 2006)

Question 17

What were the findings of Yuille and Tollestrup (1990)

Answer 17

Examined alcohols effect on EWM in the lab.
Three groups (alcohol, placebo and no alcohol)
Witnessed a staged crime of a theft involving live actors
The level of alcohol produced BAL ranging from .06 to .12ml%
50% of witnesses in all conditions provided both an immediate and delayed (1 week)50% just delayed.
One week later all p’s returned in a sober state to be interviewed and to be shown an 8 person simultaneous photographic lineup

Findings - intoxication resulted in a small but significant reduction in overall reliability of recall; fewer details provided in delayed recall.
Intoxicated witnesses exhibited a deficit in recall in both immediate and delayed recall.
Whilst alcohol had no effect on identification accuracy when the perpetrator was present in the line-up, alcohol increased the rate of false ID’s in target absent line-ups

Alcohol impairs encoding of the event rather than directly affecting the retrieval

Question 18

What were the findings of Dysart et al (2002) research?

Answer 18

Field study examining ID evidence
103 patrons approached by one or two female recruiters who a short time later has to identify from a single photograph
When photo shown was that of the person previously encountered (tp)had no effect
When photo shown of another person(TA) intoxicated p;s less likely to make a correct
rejectp’s with lower blood alcohol levels

Question 19

What were the findings of

Schreiber- Compo et al (2001) examining the type of information affected by intoxication?

Answer 19

P’s interacted with a bar tender whilst either sober, intoxicated or after placebo.

Immediately after the conversation p’s completed a written free recall task whilst some were still intoxicated

Central details - description of bartender, his actions and conversation
Peripheral details - bar environment

Support for Alcohol Myopia Theory

• no difference in central recall accuracy across drinking conditions
• Alcohol p’s provided sig. fewer accurate peripheral details

Question 20

What were the findings of Schreiber- Comp et al (2012) examining the effects of alcohol on susceptible to misinformation?

Answer 20

P’s interacted with bar tender whilst either sober, intoxicated or after placebo
During written free-recall task misinformation was introduced and p’s completed an interview

Results
No difference in the 1% of correct, false and don’t know responses across drinking conditions
Sig more incorrect details reported when misinformation introduced for all intoxication levels
Intoxicated p’s no more susceptible to misinformation effect than sober p’s

Question 21

What were the results of the eye-tracking study by Harvey, Kneller and Campbell (2013a)?

Answer 21

Sober vs. alcohol
Stimulus image
Image region (central vs. peripheral)

Areas of interest defined as central and anything else as peripheral

Some Support for AMT:
Centre of both images attracted more attention than the periphery
Whilst alcohol narrowed eye movements to the centre of both images, it made no sig. difference to memory performance

Question 22

What were the results of the eye-tracking study by Harvey, Kneller and Campbell (2013b) in which a static image was used of a forensically relevant event?

Answer 22

Combined face ID task with recognition memory test

Sober vs. Alcohol
Stimulus image
Image region central vs. peripheral

Areas of Interest - central

Alcohol reduced eye movements overall but no evidence of less visual info gathering

No main effect of alcohol and ID accuracy

Contradicts AM hyp. drunk p’s recognised just as much correct info from peripheral image regions as sobers

Question 23

What did Hagsand et al (2013) find out when comparing different alcohol levels and eyewitness accuracy?

Answer 23

P’s with Sober, Low and High alcohol levels

Watched mock crime - interviewed a week later

Found

No. correct, no. incorrect and no. of undefined
- no sig. difference between sober vs low or sober vs high conditions
But
High condition significantly less complete than Low condition

No sig. difference between all three and accuracy

Question 24

What were the results of the Crossland, Kneller and Wilcock (2016) lab and field study?

Answer 24

Study 1 - Lab
Watch video whilst either above or below alcohol limit
Week later free recall and recognition test
Found intoxication didn’t sig. affect recall accuracy

Study 2 - Field
P’s watched staged fight on night out
Week later free recall and recognition test
Found-
High alcohol level impaired memory recall when memory assessed through free recall but not recognition

Question 25

What did Altman et al. (2018) when examining memory of a video crime in a bar setting?

Answer 25

BAC ranged from .00 - .29% (Mean = .08%).
Interviewed almost immediately after seeing video (when still drunk).
Alcohol negatively affected both quantity and quality of recall.

Question 26

How can intoxicated witnesses recall be improved?

Answer 26

Crossland, Kneller and Wilcock

Given moderately drunk witnesses memory were affected by alcohol – could their memory be improved by use of the ECI?

120 participants during a night out at Bop, watched a videoed theft whilst either sober, mildly (MBAC = 0.05%) or moderately (MBAC = 0.14%) intoxicated.

A week later, in a different location, participants were interviewed using either the Enhanced Cognitive (ECI) or Structured Interview.

The ECI was found to improve the recall accuracy and completeness of witness accounts across all three drinking conditions.

So intoxicated witnesses memory recall can be improved by the ECI.

Question 27

What is better for examining the effects of alcohol; Field or Lab studies?

Answer 27

Lab - utilise low levels of intoxication (ethical issues, drink-drive limit)

• no detrimental effect of intoxication on ewm
• but interviewed whilst still drunk

Field - utilise higher levels of intoxication (double drink drive)

• detrimental effects on ewm (Crossland et al, 2016)
• recall may be improved through ECI

Question 28

What is the effect of alcohol on identification accuracy?

Answer 28

Hagsand et al (2013):
Control, low alcohol dose (0.4g/kg ethanol) or higher dose (0.7g/kg ethanol).
BAC ranged from 0.00% to 0.09% at time of witnessing event (Swedish drink drive limit is 0.02%).
No significant effects of alcohol on ID performance from either TP or TA lineups.

Harvey, Kneller & Campbell (2013):
Alcohol group (0.6ml/kg ethanol) vs control; TP/TA lineups
Alcohol group BrAC ranged from 0.05 to 0.17g/210L (UK & USA drink drive limit is 0.08g/210l = BAC of 0.08%).
No significant effects of alcohol on ID performance
Sober group however more confident in their decisions.

Question 29

Can we accurately identify reliable from unreliable identification decisions from intoxicated witnesses?

Answer 29

Dunning & Perretta (2002):
10-12 second boundary identified for accurate decisions.

Sauerland & Sporer (2007):
64.7% of correct identifications made by fast (< 18s) and confident choosers.

95% of incorrect decisions made by slow (>18s) and less confident witnesses.

Sauerland & Sporer (2009) :
97.2% of witnesses who made an ID decision within 6 seconds and 90-100% confident were accurate.

Question 30

What did Kneller and Harvey (2016) find when investigating ID accuracy in intoxicated witnesses?

Answer 30

Design:

3x2 between-subjects design.

IVs: Alcohol level (sober, intoxicated & placebo) Presence of target in the line-up (present vs. absent).

DVs: Identification accuracy, Confidence (7 point scale),Decision time (ms).

Results - No significant effect of alcohol on decisions from either TP or TA line-ups

Confidence-Accuracy:
Accurate witnesses more confident than inaccurate witnesses (p < 0.001).

Accurate identifications made significantly more confidently than inaccurate identifications (p < 0.001).

No significant confidence difference between alcohol groups.

Decision Times:

Accurate witnesses significantly faster than inaccurate witnesses.

Accurate choosers significantly faster than inaccurate choosers.

No significant effect of alcohol.

Question 31

What did Altman et al. (2018) find when analysing intoxication in a field setting?

Answer 31

Higher levels of intoxication tested in field setting

Intoxication found to have no significant effect on ID accuracy.

BUT:
Participants tested when still drunk
Biased instructions provided to witnesses (“when you finish looking at the photospread, tell me which of the men is the one you saw in the video you watched”).
Simultaneous TP & TA line-ups shown
Witnesses in both line-up conditions more likely to make a mistaken identification.

Question 32

What does the evidence from lab and bar studies suggest?

Answer 32

Evidence from lab and bar studies suggest that:

Mild levels of intoxication do not affect either memory recall or memory for faces

Moderate to high levels of intoxication affect memory for events (but the use of the ECI may help aid recall)

Moderate levels of intoxication do not appear to detrimentally affect memory for faces.

Therefore, alcohol intoxication may affect memory for events and faces differently.