250 likes | 380 Views
Eyewitness Memory An Application of the Cognitive Psychology of Memory. Psychology 355: Cognitive Psychology Instructor : John Miyamoto 05/14 /2014: Lecture 07-3.
E N D
Eyewitness MemoryAn Application of the Cognitive Psychology of Memory Psychology 355: Cognitive PsychologyInstructor: John Miyamoto05/14/2014: Lecture 07-3 This Powerpoint presentation may contain macros that were used to create the slides. The macros aren’t needed to view the slides. If necessary, you can disable the macros without any change to the presentation.
Outline • Eyewitness memory • Misinformation effect • Lineups versus showups • Psychologists recommendations for improving eyewitness accuracy • The recovered memory controversy • Is it possible to forget a childhood traumatic experience? • Is it possible to create a false memory? • APA recommendations regarding recovered memories of traumatic experiences. Lecture probably ends here Reminder re Legal Role of Eyewitness Testimony Psych 355, Miyamoto, Spr '14
Eyewitness Testimony • Basic source of evidence in the Anglo-American legal system. • Historically more trusted than circumstantial evidence. • Of 248 people who were exonerated through the work of the Innocence Project, 75% were convicted on eyewitness testimony (Quinlivan et al., 2009; Scheck et al., 2000). Sources of Error in Eyewitness Testimony Psych 355, Miyamoto, Spr '14
Sources of Error in Eyewitness Testimony • Intrinsic fallability of memory • Post-event suggestions by interested parties, esp. police. • Misleading post-event information (MPI) can bias memory • Misinformation effect (later in this lecture) • Misleading familiarity • Cross-racial identification • Line ups versus show ups. • Line up: Did one of these men do it? (People tend to respond as if the question is, who in this group looks the most like the person you saw?) • Sequential show up: Did Man A do it? Did Man B do it? etc. (Surprisingly less biased) Misinformation Effect Psych 355, Miyamoto, Spr '14
Lineups versus Show-Ups – What Are They? • Classic showup: Police show only one person to a witness. They ask, "Is he the man you saw?" • Classic lineup: Police show 7 people to the witness: They ask, "Do you see the perpetrator in the line up?" • Contrary to most people's expectations, show ups are more accurate than line ups. Why are showups more accurate than lineups? What is Accuracy of Eyewitness Memory? Psych 355, Miyamoto, Spr '14
What is “Accuracy” of Eyewitness Memory? Two Types of Errors: • False Alarm: True perpetrator was not present; eyewitness mistakenly identifies someone as the perpretator. • Miss: True perpetrator is present;eyewitness identifies someone else or identifies no one. Same Figure without Emphasis Rectangles Psych 355, Miyamoto, Spr '14
What is “Accuracy” of Eyewitness Memory? Two Types of Errors: • False Alarm: True perpetrator was not present; eyewitness mistakenly identifies someone as the perpretator. • Miss: True perpetrator is present;eyewitness identifies someone else or identifies no one. Psychologists use signal detection theory (SDT) and ROC curves to measure witness accuracy. Definition of “Post-Event Suggestion” Psych 355, Miyamoto, Spr '14
Post-Event Suggestion – One Source of Witness Belief • Post-event feedback effect: After the witness id's someone, the experimenter says ...... ..... "Good, you got the right man!" OR ..... [nothing] OR ..... "Actually, the suspect was the other guy. • Witness who gets positive feedback is a lot more confidentof his or her judgment when asked again (like at a trial). Misinformation Effect Psych 355, Miyamoto, Spr '14
Overview of Misinformation Effect MPI = Misleading Postevent Information • Subject sees a video or a slide sequence. • I'll call this "the video." The video usually depicts a crime. • After the video, the subject is questioned about it. Some subjects receive questions that contain misinformation (MPI or false assumptions). • Subjects receive a memory test. A misinformation effect is found if subjects who heard the misleading questions describe their memories in terms of misleading information and not the real events in the video. Introduce Loftus, Miller & Burns Experiment Psych 355, Miyamoto, Spr '14
Misinformation Effect: Loftus, Miller, & Burns (1978) Slides show a traffic accident:Car A runs a stop sign and hits Car B. • Consistent Info Condition: How fast was Car A going when it went past the stop sign? • Inconsistent Info Condition: How fast was Car A going when it went past the yield sign? • Memory test: Did Car A go past a stop sign or a yield sign? Results of Loftus, Miller & Burns Experiment Psych 355, Miyamoto, Spr '14
Results of Loftus, Miller & Burns (1978) % Correct Identification of the Stop Sign • A misinformation effect was found (it gets larger over time) MisinformationEffect Loftus & Palmer: Smashed/Collided/Bumped/Hit/Contacted Psych 355, Miyamoto, Spr '14
Loftus & Palmer (1974) • Subjects see video of a car accident. • Subjects are asked: How fast were they going when they hit/smashed/collided/bumped/contacted the other car? Loftus & Palmer Result for Broken Glass Psych 355, Miyamoto, Spr '14
Loftus & Palmer (1974) (cont.) • One week later, subjects were asked:Did you see any broken glass? * The control group were not asked about the speed of the car (no misinformation; no correct information). Why Does Post-Event Misinformation Affect Recall? Psych 355, Miyamoto, Spr '14
Why does Misleading Postevent Information (MPI) Affect Recall? • MPI replaces original memory (E. Loftus)False information replaces memory of correct information. • MPI causes source monitoring error • Subject confuses misleading postevent info in question withoriginal memory of event. Line Ups and Show Ups - Definition Psych 355, Miyamoto, Spr '14
Lineups versus Show-Ups – What Are They? • Classic showup: Police show only one person to a witness. They ask, "Is he the man you saw?" • Classic lineup: Police show 7 people to the witness: They ask, "Do you see the perpetrator in the line up?" • Contrary to most people's expectations, show ups are more accurate than line ups. Why are showups more accurate than lineups? Why Lineups & Showups Differ as Cognitive Tasks Psych 355, Miyamoto, Spr '14
Cognitive Differences Between Lineups and Showups • Classic showup: • Witness asks himself/herself: "Did I see this person do the crime?" • Classic lineup: • Witness assumes that the perpetrator is in the lineup. • Witness asks himself/herself: "Which of these men looks the most like the person that I saw?" • Improved showup = sequential showup(Goldstein refers to this as an improved lineup) • With each person, the witness asks himself/herself: "Am I sure that this is the person who I saw do the crime?" • Lindsey & Wells (1985) found that the sequential showupgreatly reduced false id when the perpetrator was not present (43% vs 17%), but did not affect the rate of true id when perpetrator was present. Mistake! Recommendations for Improving Eyewitness Memory Psych 355, Miyamoto, Spr '14
Recommendations for Improving Eyewitness Memory • Use a sequential showup(Goldstein would call it a sequential lineup). • In a showup, use non-suspects who are similar to a suspect. • Inform witness that the perpetrator may not be in a showup. • Administrator of showup should not know who is the suspect. • Get confidence rating immediately after the initial identification. Avoid giving feedback to the witness after the lineup • Use cognitive interview techniques; do not prompt the witness with leading questions. • See Wikipedia article on cognitive interview techniques:http://en.wikipedia.org/wiki/Cognitive_interview Recovered Memories - Definition Psych 355, Miyamoto, Spr '14
What Are Recovered Memories? • Definition: A recovered memory is a memory that has two characteristics: • The experiences that are remembered are shocking or traumatic. • There was an extended period in the individual's life when he or she did not remember the experiences that are eventually "recovered." recoveredmemory Now abuse no memory Time Two Questions Regarding Recovered Memories UW: Psych 355, Miyamoto, Win '12
Two Questions Regarding Recovered Memories • Is it really possible to forget traumatic events from early childhood? • If this does happen, does it happen because of special memory mechanisms (repression of painful memories) or because of the same processes that cause ordinary forgetting? Sometimes Recovered Memories are NOT True Memories Psych 355, Miyamoto, Spr '14
Sometimes Recovered Memories Are Not True Memories • B. R. (Missouri, 1992) remembered under therapy that her father, a clergyman, had repeatedly raped her between ages of 7 – 14 (with her mother's help). She remembered being pregnant twice, each pregnancy ending in an abortion. • Father had to resign. • Later, medical examination showed that she has never been pregnant and was in fact still a virgin. • (The therapist who guided the "recovery" of these memories was sued by B. R. and settled for $1 million.) • Conclusion: It is not true that recovered memories are always true memories. Sometimes Extreme Traumas ARE Forgotten UW: Psych 355, Miyamoto, Win '12
Some Traumas Can Be Forgotten • Williams (1994) interviewed 129 women who had been treated 17 years earlier at a sexual abuse clinic. • 38% had no memory of the incident for which they had been admitted. • 12% had no memory of any sexual abuse at any time. • Conclusion: It is probably not true that recovered memories are always false memories. % with No Recall of Incident that Brought Them to Clinic Theory of Recovered Memory Has Important Consequences UW: Psych 355, Miyamoto, Win '12
Theory of Recovered Memory Has Important Consequences • Claims of recovered memories have huge consequences for: ... the person who experiences the recovered memory; and ... persons accused of abuse based on recovered memories. • Consequences are social, psychological, and legal. • If certain kinds of psychological therapy can produce false recovered memories, then, as psychologists, we are obligated to learn about this and prevent it. • Theoretical issue: If true recovered memories can be documented, does the period of forgetting result from ordinary forgetting processes, or are there special mechanisms, e.g., repression or other special traumatic memory mechanisms, that explain them? False Memories Can Be Created UW: Psych 355, Miyamoto, Win '12
Creating Impossible Memories from Infancy • True memories during the 1st year of life are extremely unlikely. • Nicholas Spanos & colleagues have created false memories of early infancy: Subjects are told .... • ... that they have been selected because they have exceptionally coordinated eye movements and visual exploration skills. • ... that this is probably due to highly colored mobiles that were placed over their crib in the hospital where they were born. • To test this hypothesis, • half the subjects were hyponotized, age-regressed to the day after birth, and asked what they remembered. • half the subjects participated in a “guided mnemonic restructuring” procedure that encouraged mentally recreating the infant experience. Would Subjects Have Memories of the Hospital and Mobiles Over the Crib? Psych 355, Miyamoto, Spr '14
Would the subjects “remember” the hospital & mobiles? • 49% of the subjects agreed that these were real memories. • 16% of the subjects thought that these memories were fantasies. • Susceptibility to hyponosis was not related to belief in the infant memories. Thomas & Loftus: Imagining Something Can Create a Memory Psych 355, Miyamoto, Spr '14
Wednesday, May 14, 2014: The Lecture Ended Here Psych 355, Miyamoto, Spr '14