Deck 4: Section 1: The Psychology of Forensic Identification: Dna, Fingerprints, and Physical Trace Evidence

Question 1

What type of influence do the CSI TV dramas have on jurors?

Answer 1

Main points:
• Some attorneys contend that jurors have unrealistic beliefs about the availability and strength of evidence.
• Some prosecutors complain that the effect of CSI leads to fewer convictions.
• Most studies on the "CSI effect" find no effect of watching CSI on juror's decisions or expectations.
• There is evidence that jurors trust forensic identification results too much, even when evidence is faulty (and it may have nothing to do with watching CSI shows).

Question 2

How can error rate be reduced in forensic investigations?

Answer 2

Main points:
• Strict rules and procedures for handling evidence should be enforced to avoid any contamination.
• Routine re-testing of traces by a different examiner should be instituted to reduce individual biases.
• Double-blind testing of examiners (when the examiner does not know he or she is being tested and does not know the answer to the test) should be a standard procedure.
• Ideally, forensic labs should be independent of either the defense or the prosecution and financed by a neutral source.
• Peer review of studies of forensic techniques and clear declaration of financial interests should be a standard procedure.

Question 3

How does reliability differ from validity? Use examples to illustrate both.

Answer 3

Main points:
• Reliability refers to consistency of measurement, either from one test to the next or from one examiner to another.
• Validity means that we are measuring what we say we are measuring
• An example should include multiple measurements to illustrate reliability and assessing the match between the measure's results and reality to illustrate validity.