Jim Turner, The Open University
Exploring the CSI Effect: What do potential jurors think they know
about forensic evidence?
ICCCR ‘Constructions of Evidence’ conference, July 2011
What is the ‘CSI Effect’?
‘The General Public’ (i.e. everyone) has a certain expectation of forensic
science, shaped by media representations of forensic science –
particularly fictional ones – and this may affect jury verdicts.
‘The notion of the CSI Effect probably originated with prosecutors’ (Cole & DiosoVilla, 2007), but was initially a supposedly positive effect as CSI was seen as proprosecution (unlike other pro-defence programmes, e.g. Perry Mason).
It very quickly became seen as a negative (for prosecutors) as ‘the show made
prosecutors’ jobs more difficult by whetting jurors’ appetites for convincing …
forensic evidence’ (Cole & Dioso-Villa).
This was picked up by the media – Cole & Dioso-Villa report 416 news pieces on
the CSI Effect between 2002 and 2007 alone – and became the CSI Effect as we
now know it.
Visual example of real ‘enhanced’ evidence
Raw evidence
Zoomed in evidence
Visual example of unreal ‘enhanced’ evidence
This is what jurors get
This is what jurors expect
• Kruse, 2010: CSI discourse as ‘truth’ and ‘wishful thinking’ about certainty
in uncertain situations (i.e. criminal cases).
Implications of the ‘CSI Effect’?
‘Many prosecutors, judges and journalists have claimed that watching television
programs such as CSI: Crime Scene Investigation has caused jurors to wrongfully
acquit guilty defendants when the prosecution presents no scientific evidence in
support of the case.’ (Shelton, Kim & Barak, 2006).
‘…theoretically just as probable that the effect could both raise and lower the bar in
terms of jurors’ likelihood to acquit’ (Shelton, Kim & Barak, 2006).
• Podlas, 2006: ‘… if CSI contributes to the pop cultural landscape that
shapes perceptions of the legal process or if it impacts juror decisionmaking, “The CSI Effect” merits serious investigation.’
Is there evidence for the CSI Effect?
• Is there really a CSI effect?
• A few studies seem to show an over-expectation of forensic evidence
• Shelton, Kim & Barak, 2006: survey-based – jurors (real, awaiting
cases, surveyed about expectations of evidence) expected forensic
evidence to be presented and to be high–quality.
• Schweitzer & Saks, 2007: hypothetical evidence in marginal case:
‘Compared to non-CSI viewers, CSI viewers were more critical of the
forensic evidence presented at trial, finding it less believable’ (NS).
• BUT Kim, Barak & Shelton, 2009: no effect on juror verdicts (real,
awaiting cases, given hypothetical case): ‘alleged CSI Effect’.
• BUT this is all predicated on potential jurors having an unrealistic
expectation of what ‘forensic science’ can do. Do they though?
The present study
• Can ‘the general public’ differentiate between forensic science that is ‘real’
and that is ‘unreal’?
• With ‘real’ science, can they tell what is (relatively) error-free and what is
‘error-prone’?
• Does exposure to CSI-type programmes have an effect?
Survey design
• Online survey of ‘knowledge of forensic science’
• Presented descriptions of 33 potential ‘forensic science techniques’
• Respondents answered whether each was:
• ‘Reliable’
• ‘Unreliable’
• ‘Not possible’
• Briefing gave examples to clarify the response categories:
• ‘Reliable’ – measuring rainfall and temperature
• ‘Unreliable’ – meteorological weather forecasting
• ‘Impossible’ – weather forecasting with Tarot cards
• Also asked about jury eligibility, educational background, professional
background…
• … and TV viewing habits (inc. police procedurals, science documentaries,
news broadcasting, etc.)
Results 1: accuracy of expectations
• Overall, respondents got 15.47 items correct (sd 2.54) – chance would be 11
10
8
8.01
6
5.19
4
2
(chance = 3.66)
2.28
0
Reliable
Unreliable Impossible
F2,328 = 385.40, p < .0005
Results 2: pattern of expectations
100
90
80
70
60
50
40
30
20
10
0
Reliable
Unreliable
Impossible
Responses to unreliable techniques
100
90
80
70
60
50
40
30
20
10
0
Reliable
Unreliable
Impossible
Responses to impossible techniques
Percentage
Percentage
Percentage
Responses to reliable techniques
100
90
80
70
60
50
40
30
20
10
0
Reliable
Unreliable
Impossible
Results 3: is there a CSI Effect…?
• These results could just be a general expectation that science ‘can do
anything’, so was there any effect of watching police procedurals?
• Correlated general measure of watching police fiction with scores
• Correlation with total score was small, but significant (Spearman’s rho = .163, n = 161, p = .039, two-tailed) and negative
• Broken down by type of technique:
• Reliable; rho = .029, n = 161, p = .646, two-tailed
• Unreliable: rho = -.112, n = 161, p = .071, two-tailed
• Impossible: rho = -.122, n = 161, p = .052, two-tailed
Summary
• Our respondents had unrealistic expectations of forensic science…
• In the direction of expecting too much of it…
• Particularly if they watch police procedurals a lot.
• So there is some evidence for a CSI effect.
Next steps and practical implications
• Follow-up will be to investigate the relative weight given to different types of
‘evidence’, for example:
• Different types of forensic evidence
• Physical versus eyewitness
• Are there mediating factors, for example:
• Science education?
• Law education?
• Is it possible to protect against the CSI effect?
• Jury selection?
• Judge’s instructions / warnings?
• Expert evidence?
Contact details
J.A.J.Turner@open.ac.uk
http://www.open.ac.uk/socialsciences/psychology/cogpsypanel/