Introduction
The purpose of this research paper will be to evaluate experimental and non-experimental studies which have been conducted on the subject of hypnosis. The experimental study selected for this research will be one conducted by Geiselman, Fisher, MacKinnon and Holland (1985) which sought to determine whether hypnosis or cognitive retrieval mnemonics was useful for enhancing the memory of eyewitnesses during police interviews. The authors assessed previous research which had been conducted on eyewitness memory retrieval where they noted that the success of a criminal-investigation mostly relied on the accuracy and complete account of events given by an eyewitness. The main findings of previous research conducted on eyewitness recall showed that accounts given by eyewitnesses were usually unreliable, inaccurate and incomplete (Geiselman et al, 1985).
The purpose of the study was therefore to identify appropriate methods (hypnosis, cognitive mnemonics) which could be used to enhance the accuracy of eyewitness accounts and also test whether these methods could be controlled empirically. The authors sought to determine whether hypnosis was a useful technique for enhancing the memory of witnesses during police interviews, basing their studies on previous research conducted by Reiser in 1974 and also Schafer and Rubio in 1978. The hypothesis that was being tested by Geiselman et al (1985) was whether cognitive interviews, hypnosis interviews or standard control interviews were effective in optimizing eyewitness memory performance (Geiselman et al, 1985).
The second study to be focused on in this research paper is a non-experimental study conducted by Graham (1982) on the use of hypnosis and eyewitness recall during police interviews. Graham bases his study on previous research which has called for the use of hypnosis as an important tool for aiding the memory of eyewitnesses during police investigations. His analysis of past research has revealed that law enforcement agencies in the US, UK and Israel have made use of hypnosis techniques during the interviewing of eye witnesses. This technique has however proved to be limited when dealing with the hypnotic susceptibility of eye witnesses involved during the interrogation exercise (Graham, 1982).
The purpose of Graham’s study was therefore to assess the evidence that supported the use of forensic hypnosis in extracting useful information from eye witnesses who were not hypnotically susceptible. The empirical evidence that Graham was testing in his non-experimental study came in the form of laboratory experiments and anecdotal reports which had been conducted in previous studies to determine the memory facilitation of individuals through the use of hypnosis. Graham in his study sought to answer whether hypnosis was an effective tool in determining the memory recall of witnesses (Graham, 1982).
Methods
The study conducted by Geiselman et al (1985) made use of an experimental design where the authors sought to compare the effectiveness of the three techniques used by law enforcement officers when interrogating eye witnesses. These three techniques were cognitive interviews which were based on the retrieval of mnemonics, the standard control police interview and the use of hypnosis. The three methods were evaluated through the use of a controlled and ecologically valid laboratory setting where eighty-nine subjects were placed in these laboratory settings to view police training films that simulated violent crime. The three types of interviews were evaluated based on three criterions which included the number of correct items the subjects were able to recall, the number of incorrect items from the elicited information and the number of items collected from the information which were confabulated. The independent variable for the study which represents the values being changed was memory recall where the ability of the subject to recall elicited information 48 hours after being subjected to the police film was assessed based on the type of interview technique that had been used by the police (Geiselman et al, 1985).
The dependent variables are those that are manipulated by the independent variable and for this study they included the three interview techniques (cognitive, hypnosis and standard control). The interviewers who totaled sixteen in number were recruited through an advert placed in the International Journal of Investigative and Forensic Hypnosis. Other interviewers were recruited from various police departments in Southern California, the Central Intelligence Agency and polygraph organizations. The materials that were used for the experiment included four films that simulated violent crimes, audio and standard cassettes, lapel microphones and play recorders which were used to record the interviews and also video cameras for the hypnosis interviews (Geiselman et al, 1985).
Graham’s study made use of the non-experimental design when trying to determine whether hypnosis was a useful technique in witness recall activities. He evaluated the various forms of literature that contain research on whether hypnosis was an effective tool that could be used for memory facilitation. Graham (1982) also evaluated past research to determine the efficacy of the existing procedures on interrogating eye witnesses during police investigations. Graham (1982) made use of anecdotal reports and laboratory experiments conducted by other researchers to determine the type of hypnotic memory facilitation activities that were used by law enforcement agencies during the interviewing of eyewitnesses
Graham (1982) analyzed research that had been conducted on variables such as learning, memory recall and age regression and their effect on hypnosis techniques used to enhance the recall of individuals. The techniques used to study these variables based on Graham’s review included controlled and uncontrolled laboratory experiments for the learning and memory recall variable, Stanford Binet IQ tests, hypnotic-waking simulators, Goodenough-Harris Drawing Tests and the Rorschach ink-blot test to examine the age regression variable (Graham, 1982).
Experiments on Hypnosis
Geiselman, R.E., Fisher, R.P., MacKinnon, D.P., & Holland, H.L., (1985). Eyewitness memory enhancement in the police interview: cognitive retrieval mnemonics versus hypnosis. Journal of Applied Psychology, 70(2): 401-412
Hypnosis is an induced state of imaginative role-enactment where a person’s mental state is placed under hypnosis or mesmerization by a hypnotist or any other medically qualified professional. The hypnosis is usually delivered through a set of preliminary instructions and suggestions delivered by the hypnotist or through self-administration or suggestions (Geiselman et al, 1985). Hypnosis is usually used to therapeutically treat patients who have suffered from some type of trauma or psychological distress and it is also used to treat patients who suffer from certain types of phobias or fears. There are various experiments which have been conducted on the effectiveness of hypnosis one of which is Geiselman et al s 1985 experiment on the effectiveness of using hypnosis or cognitive retrieval mnemonics to enhance the memory of eyewitnesses during police interviews (Geiselman et al, 1985).
In their experiment, 89 undergraduate subjects (55 males and 34 females) were exposed to police training films that simulated violent crimes to determine if they would be able to memorize the events or actions in the film 48 hours later. After 48 hours had elapsed, the subjects were questioned by 1 in 16 law enforcement officers trained and experienced in forensic hypnosis and also cognitive mnemonics in individual interactive interview sessions. Each interviewer was assigned to one of the three interview conditions that were being assessed to determine the effectiveness of each method in the memory recall of the witnesses (cognitive=6, hypnosis=7 and standard=4).
In the standard interview, the interviewers made use of questioning procedures while in the hypnosis interview the interviewers performed a hypnosis induction on each of the subjects. After this induction, the subjects were supposed to restate what they remembered from the film that elicited the information. Verbal responses were mandatory for both the standard and hypnosis interview. The cognitive interview required the interviewers to make use of four memory-retrieval techniques during the questioning of the subjects. A four-item list of techniques was used during the cognitive interview as a reference guide for the interviewers (Geiselman et al, 1985).
Each of the 89 subjects took part in two sessions of the filming of the simulations where they were required not to discuss the film with their peers. Approximately 48 hours after they viewed the films, they underwent individual interviews by the interviewers where they were assigned randomly to the three interview conditions (cognitive=33, hypnosis=30 and standard=26). They were taken through the eye-roll test for hypnotic subjects after which they were interviewed individually in separate interview rooms. Each of the 16 interviewers questioned five subjects during the course of the experiment and they also interviewed one witness of each of the violent crime simulation films (Geiselman et al, 1985).
Non-Experimental Hypnosis
Graham, F., (1982). Hypnosis and witness recall: discussion paper. Journal of the Royal Society of Medicine, 75: 793-798
Graham (1982) developed a discussion on hypnosis based on eye witness recall during police investigations by reviewing and evaluating past research conducted on whether hypnosis would be an effective method in police investigations. From his review, Graham (1982) was able to note that countries such as the UK, the US and the Middle East had already began using hypnosis in eye witness recall but this technique was limited because of the susceptibility of witnesses during the state of hypnosis. From this revelation Graham directed his studies towards establishing whether forensic hypnosis was useful as a method of extracting important information from eye witnesses which would then be used in police investigations and criminal convictions.
The variables that were examined in Graham’s research included learning, memory recall and age regression. In the learning and memory variables, Graham was able to note that the amount of studies conducted to examine these two variables were done under ill-controlled laboratory settings which gave inconclusive results on the effectiveness of hypnosis. Graham referred to an experiment conducted by Krauss et al (1974 cited by Graham, 1982) which was ill-controlled because the subjects were able to recall all elicited information within three minutes after waking. This result was disputed by an experiment conducted by Wagstaff and Ovenden in 1979 where their subjects recalled less information within three minutes of waking up from the hypnosis. Parker and Barber in their 1964 study were able to use controlled procedures that found hypnosis to be an ineffective tool of improving memory, a result that was in stark contrast to that of Krauss et al (Graham, 1982).
The evaluation of the age regression variable was also conducted in ill-controlled experimental settings meaning that suitable or appropriate results could not be gained to determine the effectiveness of this method. Age regression evaluation involved taking the subject back to their formative years once they were placed under hypnosis. True’s 1949 experiment was termed by many to be ill-controlled because the subjects claimed that they recalled exact dates of their childhood experiences. True’s study was termed to have many methodological inadequacies because the person conducting the experiment was not experimentally blind and could have given the subjects cues that would prompt their memory recall (Graham, 1982).
Results and Discussion
The results of the experiment revealed that hypnosis and cognitive mnemonics became more effective and pronounced in the subjects especially during violent crime scene simulations where the density of events was deemed to be high. The incorrect number of items that were revealed during the experiment was not any different within the three conditions set for the subject’s interviews. Geiselman et al (1985) were able to note that memory enhancement with regards to memory guidance techniques was usually common in both hypnosis and cognitive interviews for eyewitnesses. The results of the experiment revealed that both cognitive and hypnosis procedures elicited a greater identification of correct information with relation to the training films when compared to the use of standard interviewing procedures (Geiselman et al, 1985).
Based on their analysis of the results, the cognitive experiment was useful for the enhancement of witness recall and memory performance activities under conditions of experimental control and also ecological validity. The hypnosis interview was also a useful technique for memory recall despite the fact that it was not the most frequently reported outcome in most laboratory experiments. Because the study emphasized on experimental control, the hypnosis procedures did not affect the memory recall or performance of the subjects meaning that the possibility of them presenting incorrect information was limited or reduced (Geiselman et al, 1985).
The implications of these results for future research were that cognitive mnemonics and hypnosis procedures would be effective tools that could be used to recover specific kinds of information from crime scene witnesses. This means that more training would be needed for law enforcement officers and other investigators who made use of hypnosis techniques to ensure that there was accurate memory performance during the witness interviews (Geiselman et al, 1985). Graham (1982) from his analysis of previous studies and research was able to uncover vital information with regards to the effectiveness of hypnosis in witness recall. By reviewing the results of various studies, Graham (1982) was able to note that hypnosis performed on individuals was not able to facilitate any form of memory recall especially when compared to a higher degree that would yield an achievable waking state. Graham (1982) noted that hypnosis served as a means of inhibiting the memory recall of individuals placed in a hypnotic state making it difficult for them to remember any useful information.
One reason that was given for this was that individuals experienced low arousal because hypnosis usually made them feel drowsy making it difficult for them to remember any useful information. For these techniques to be effective, more practical applications and studies needed to be conducted to achieve a higher efficacy rate. Graham was able to note that despite the fact experimental work on hypnosis and eyewitness memory was incomplete, a review of the existing literature and research revealed that the techniques used by many forensic hypnotists would be more applicable to a greater number of witnesses if more training was done to enhance the effectiveness of these methods. Hypnosis had the potential of being an effective method of enhancing the memory performance of witnesses during police investigations.
Conclusion
This research paper sought to discuss experiments and non-experiments which have been conducted on hypnosis with particular focus on eyewitness recall during police investigations. The literature used in the study was able to conclusively provide vital information on hypnosis as an effective method for enhancing the memory performance of individuals especially during police interrogations.
References
Geiselman, R.E., Fisher, R.P., MacKinnon, D.P., & Holland, H.L., (1985). Eyewitness memory enhancement in the police interview: cognitive retrieval mnemonics versus hypnosis. Journal of Applied Psychology, 70(2): 401-412.
Graham, F., (1982). Hypnosis and witness recall: discussion paper. Journal of the Royal Society of Medicine, 75: 793-798.