My Initial Hypothesis
The cognitive interview increases the credibility of eyewitness testimony by decreasing memory error and confabulations. Information is the lifeblood of a criminal investigation. The ability of investigators to obtain useful and accurate information from eyewitnesses of crimes is crucial to effective law enforcement, yet full and accurate recall is difficult to achieve (Stewart, 1985). Such elicitation of complete and accurate recall from people is important in many aspects of life; specifically, eyewitness recall may determine whether a case is solved. Principle advocates of the cognitive interview (Fisher, Geiselman, Holland & MacKinnon, 1986) claim that the said interviewing technique can increase both the quantity and quality of information obtained from an eyewitness. Other empirical research surrounding the cognitive interview suggests the same idea: the cognitive interview increases the effectiveness of eyewitness memory retrieval during investigative interviews without any apparent negative consequences (Fisher, et al., 1986). The Empirical Evidence
By looking at studies related to the topic of cognitive interviewing as a means to elicit useful and accurate information from eyewitnesses, it becomes evident that not only is there a great interest in the subject, but that it is generally effective. A study conducted by Fisher (1986) investigated whether the cognitive interview increases the credibility of eyewitness testimony. Sixteen detectives from the Robbery Division of Metro-Dade Police Department, Dade County, Florida were selected to perform a total of 88 interviews over a period of four months, and they were divided into two groups: one group was trained in the cognitive interview, and the other was untrained and served as the control. The interviews concerned primarily victims of commercial robbery and purse-snatching. A significant difference was found between the experimental and control groups; specifically, the cognitive interview elicited 47 percent more information than the standard police investigation. However, 85 percent of all statements elicited under either condition were correct (Fisher, 1986). In summation, the study suggested that while the amount of information collected in the cognitive interview is greater, the cognitive interview does not necessarily improve the credibility of eyewitness accounts.
Another study conducted by Cutshall and Yuille (1989) also investigated whether the cognitive interview increases the credibility of eyewitness testimony. Several simulation experiments were undertaken, employing staged scenarios in Los Angeles Police Department training films that depicted realistic criminal events. The subjects were undergraduate students, and the interviewers were experienced law enforcement officials who were instructed to either implement standard police interviewing techniques, or cognitive interviewing techniques. Subjects were interviewed by the interviewers approximately 48 hours after the viewing the film. The cognitive interview elicited 35 percent more correct information than did the standard interview, but the two types did not differ on incorrect information or confabulations (Cutshall & Yuille, 1989). Again, the study suggested that the amount of information collected in the cognitive interview is greater than standard police interviews, but the cognitive interview does not necessarily improve the credibility of eyewitness accounts.
Similar results have been found in a more recent, comparable field study conducted by Clifford and George (1992) with a group of British police investigators. Police investigators tape recorded interviews with real-life victims and witnesses of robbery prior to training, using standard police interviewing techniques. Half of the group underwent cognitive interview training over four 60-minute sessions, and later tape recorded...