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 & Dioso-Villa, 2007), but was initially a supposedly positive effect as CSI was seen as pro-prosecution (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.

Raw evidence Zoomed in evidence

Visual example of real ‘enhanced’ evidence

This is what jurors get This is what jurors expect

Visual example of unreal ‘enhanced’ evidence

• 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 decision-making, “The CSI Effect” merits serious investigation.’

• 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’.

Is there evidence for the 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

8.01

5.19

2.28

0

2

4

6

8

10

Reliable Unreliable Impossible

(chance = 3.66)

F2,328 = 385.40, p < .0005

Results 2: pattern of expectationsResponses to reliable techniques

0102030405060708090

100

Reliable Unreliable Impossible

Per

cen

tag

e

Responses to unreliable techniques

0102030405060708090

100

Reliable Unreliable Impossible

Per

cen

tag

e

Responses to impossible techniques

0102030405060708090

100

Reliable Unreliable Impossible

Per

cen

tag

e

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.

• 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?

Next steps and practical implications

Contact details

J.A.J.Turner@open.ac.uk

http://www.open.ac.uk/socialsciences/psychology/cogpsypanel/