In eyewitness memory research, a distinction is made between estimator variables and system variables.
Estimator variables are characteristics of the witness or the witnessed event that influence the quality of information retrieved (age and sensory acuity of the witness, viewing conditions such as lighting, noise, duration of the witnessed event, presence of a weapon, etc.). We can't control these but can use information about these conditions to evaluate the probable reliability of reports (how well can a witness identify color of eyes or clothing under conditions of very low light). System variables are characteristics of the investigation that influence the quality of information produced. These are procedures that we have some control over (do we use a sequential or a serial lineup identification procedure?, is the officer in charge blind to which individual is suspected as the perpetrator, does the witness get feedback after an identification, how are questions worded, does the witness have access to discussions with other witnesses or media coverage before giving his/her report or doing an identification, etc.). The ways in which these procedures can improve (e.g., the cognitive interview procedure) or detract from witness accuracy has generated an extensive research literature. In several instances, police investigative procedures have been changed to improve the quality of information obtained from witnesses. See Gary Well's web site for an extensive review of this work. Some evidence (such as hypnotically enhanced recollection) is no longer admissible as evidence in many states as a result of research that demonstrates how vulnerable to distortion witness memory is under the conditions of hypnotic suggestibility. Claudia J. Stanny, Ph.D. Director, Center for University Teaching, Learning, and Assessment Associate Professor, Psychology University of West Florida Pensacola, FL 32514 - 5751 Phone: (850) 857-6355 or 473-7435 e-mail: [email protected] CUTLA Web Site: http://uwf.edu/cutla/ Personal Web Pages: http://uwf.edu/cstanny/website/index.htm -----Original Message----- From: Stuart McKelvie [mailto:[email protected]] Sent: Monday, March 09, 2009 8:15 AM To: Teaching in the Psychological Sciences (TIPS) Subject: RE: [tips] Eyewitness testimony Dear Tipsters, To play the Devil's Advocate slightly: One person (a policeman or possibly prosecutor, I think) stated that eyewitness testimony evidence was still important and sometimes crucial to making a case against a suspect. And we saw some changes in procedures to make line-up ID more valid. My question is: Ca we identify the conditions under eyewitness testimony should be regarded as suspect and those under which it should be regarded as trustworthy (valid)? Sincerely, Stuart ___________________________________________________________________ Stuart J. McKelvie, Ph.D., Phone: (819)822-9600, Extension 2402 Department of Psychology, Fax: (819)822-9661 Bishop's University, 2600 College Street, Sherbrooke, Québec J1M 1Z7, Canada. E-mail: [email protected] Bishop's University Psychology Department Web Page: http://www.ubishops.ca/ccc/div/soc/psy ___________________________________________________________ -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: March 9, 2009 1:12 AM To: Teaching in the Psychological Sciences (TIPS) Subject: [tips] Eyewitness testimony The USA television programme "60 Minutes" had an interesting presentation of the weakness of eyewitness testimony tonight, illustrated with a dramatic and instructive (true) case in which a woman falsely identified someone as her rapist. Elizabeth Loftus makes a brief appearance; the heavy lifting is left up to Gary Wells. As is so often the case nowadays, it took DNA to set things right. The piece ends with a most unlikely friendship. http://www.cbsnews.com/stories/2009/03/06/60minutes/main4848039.shtml See the videos parts 1 and 2; and also a short featuring Loftus on Bugs Bunny's visit to Disneyland. Stephen ----------------------------------------------------------------- Stephen L. Black, Ph.D. Professor of Psychology, Emeritus Bishop's University e-mail: [email protected] 2600 College St. Sherbrooke QC J1M 1Z7 Canada Subscribe to discussion list (TIPS) for the teaching of psychology at http://flightline.highline.edu/sfrantz/tips/ ----------------------------------------------------------------------- --- To make changes to your subscription contact: Bill Southerly ([email protected]) --- To make changes to your subscription contact: Bill Southerly ([email protected]) --- To make changes to your subscription contact: Bill Southerly ([email protected])
