The trouble with eyewitness testimony

Transcription

1 Begin with a demo. The trouble with eyewitness testimony Look carefully at the following faces and try to remember them as best you can. April 1, 2008 Dana Roark, Ph.D. End.test later! 1

2 Again, DNA frees a convict 12:02 AM CST on Tuesday, October 31, 2006 By ROBERT THARP / The Dallas Morning News DNA testing is unlocking prison doors for another wrongfully convicted Dallas man on Tuesday, bringing to 10 the number of felony exonerations in the county after such tests in the last five years. After maintaining his innocence for more than 25 years, Larry Fuller, 58, is expected to be released from custody without any opposition from prosecutors after an afternoon hearing. He was convicted of aggravated rape in 1981 and sentenced to 50 years in prison based on a sexual assault victim's identification of him. The woman initially told police that she could not provide a detailed description of the man beyond a vague idea of his skin tone, race and height. The attack occurred about an hour before sunrise, and the only light in the room came from a window and the dial from a small clock radio. About a week after the attack, a detective showed the woman photos of six men, including an image of Mr. Fuller. The woman told police that Mr. Fuller's photo "looks a lot like the guy," but she was not positive. A detective returned a few days later with another photo lineup that included a more recent photo of Mr. Fuller with a beard. The woman identified Mr. Fuller's image but said she did not think her attacker had facial hair. During Mr. Fuller's trial, the victim testified that she was certain he was the man who raped her. Mistaken eyewitness identifications account for up to 80% of all wrongful convictions (Scheck, Neufeld, & Dwyer, 2001) Jurors deliberated 35 minutes before returning a guilty verdict. Juries find eyewitness testimony very compelling especially when it is offered with a high level of confidence. There is almost nothing more convincing than a live human being who takes the stand, points a finger at the defendant, and says That s the one! ---Elizabeth Loftus, 1979 Research has shown no correlation between accuracy and confidence of eyewitnesses (Smith, Kassin, & Ellsworth 1989) The perils of line-ups (Busey & Loftus, 2007) Culprit presented along with 5 fillers who fit the description Live or photographs Challenge is to administer an identification procedure that is unbiased An innocent suspect has no greater chance of being identified than do the fillers 2

3 4 main ways line-ups can be biased (Busey & Loftus, 2007) Oddball bias Physical bias: fillers don t fit the witness description For example. White male with gap between teeth If fillers don t fit, then then functional size of line-up is reduced Physical bias: oddball Suspects picture is physically different from the fillers Larger, smaller, different background, different clothing, etc. Real example of line-up used in Tacoma, WA Suspect chosen by participants 26% of the time (chance = 17%) Oddball effect is problematic even if it is very subtle 4 main ways line-ups can be biased (cont.) (Busey & Loftus, 2007) Lack of double blind procedures Police officer conducting the line-up shouldn t know the who the suspect is Rarely done in practice Officer may inadvertently lead the witness. Is there anyone else you think it might be? Unconscious transference Witness has viewed the suspect at some time other than at the crime live in the same neighborhood Familiarity may bias identification Social pressure Eyewitnesses make errors if they have been pressured to provide a specific answer (Roebers & Schneider, 2000) Exactly when did you first see the suspect? Pressure to come up with a memory More accurate testimony if (Roediger & McDermott, 2000): people are allowed to report in their own words given sufficient time allowed to say, I don t know. Eyewitness compliance ---eagerness to please (Ost et al., 2002) Did you see the television fragments of 1997 fatal crash Dianna, Princess of Whales? 44% said yes, although no footage of this event exists! The effect of positive feedback Errors are more likely if suspects have been given positive feedback (Wells & Bradfield, 1998) Is it number 3? Good, you identified the suspect. Even a simple okay can be enough to make participants report during trial that they are very sure A little corroboration is a powerful thing Even if during the line-up they took 30 minutes to make a decision Witnesses talking to one another right after the incident Psychological evidence The I-never-forget-a-face idea Only partly true Familiar faces vs. unfamiliar faces People are very good at recognizing faces they know well 3

4 People are very poor at recognizing faces they ve seen only briefly or met only recently new classmates bank teller, etc. Here comes your face recognition test Why? the same face can look very different under different viewing conditions lighting changes different expression different viewpoints, etc. OLD or NEW? OLD 4

5 OLD or NEW? OLD or NEW? OLD or NEW? NEW NEW OLD 5

6 CONCLUSION Face recognition can be quite difficult if the learning and test images are very different, imagewise. Unfamiliar face recognition is a much different kind of task than recognizing people you know well such as an old friend or family relative 10 very different images of (ex) P.M. Tony Blair Demonstration 2 20 very different images of Paul McCartney The suspect Do you think you could recognize this person from a line-up? What factors would make it easier or harder? 6

7 The lineup Other perceptual factors viewing time lighting conditions degree of focused attention cross-racial effects distance of the viewer (example) A 1997 murder case in Alaska involving the murder of a teenage boy, resulted in the trial of 2 suspects. The centerpiece of the prosecution s case was the testimony of Arlo Olson, who, while drunk, had seen the perpetrators at night and from a distance of 450 ft. The defense lawyers called upon Geoffrey Loftus as an expert witness to educate the jury about: Equivalent representations of a face viewed from different distances 1. perceptual problems of memorizing suspects 2. why Mr. Olson would have chosen the suspects from the line-ups 3. how it was possible to have a clear, confident memory that was false resizing the image { blurring the image Simulated distance of a face viewed from 450 feet away 7

8 Lessons from eyewitness suggestibility Memories are malleable A synthesis, not a video tape Memories can change based on what we read, see, and are told Source confusions are common Being told about something vs. remembering something Psychological science has yet to determine a reliable method for telling whether a memory is true or false Flashbulb memories Extremely vivid, long lasting memories for unexpected, emotionally laden and consequential events 9-11 OJ Simpson verdict Kennedy assassination Are these memories more accurate than everyday memories? Actual: NO Perceived accuracy: YES Flashbulb memories 9/11 research (Talarico & Rubin, 2003) Interviewed participants Sept 12 Also asked about an everyday memory When did you first hear the news? Who first told you the information? Results: Flashbulb memories Enhanced vividness Enhanced confidence But no increase in accuracy for flashbulb vs. everyday memories Re-interviewed 7, 42, or 242 days later for both types of memories Flashbulb memories The act of retrieving a memory often leads to distortions Retelling the story Can help via rehearsal processes But can also lead to insertions that become incorporated into a memory for an event Memory is a constructive process Impossible memories can be implanted with strong suggestion (Loftus, 1995, 1997) You re family told us about this event Lost in the mall Rescued by a lifeguard Spilled punchbowl at a wedding 8

9 Misleading post-event information Fake photographs Loftus, 1979 Participants view one of two slides Afterwards given either consistent or inconsistent information Then asked to identify which picture they originally saw 75% accuracy when given consistent information 41% accuracy with inconsistent information Tell me everything you can remember about this event, no matter how trivial (Wade et al., 2002) 50% partially or clearly recalled the event Lots of detail I m pretty sure it occurred when I was in 6th grade I think my mum is on the ground taking the picture Weapon Focus Errors are more likely if eyewitness s attention has been distracted by something arousing during the event Divided attention Eyewitness errors also can lead to failure to convict a guilty person Juries may label an eyewitness unreliable if: Eyewitness misremembers details Story contradicts another story Myths of memory often drive a jury s decisions What can be done to minimize the problems associated with eyewitness memory? What can be done to minimize the problems associated with eyewitness memory? 9