The Cognitive interview

In its original form the CI comprised several memory retrieval techniques together with some supplementary techniques for recalling specific details (Geiselman, 1994). The original CI cognitive techniques drew upon the theoretical principle that there are several retrieval paths to memory for an event and information not accessible with one technique may be accessible with another (Tulving, 1974). One of the main CI techniques is mentally to reconstruct the physical and personal contexts that existed at the time of the witnessed event. This is based upon the assumption that context reinstatement increases the accessibility of stored information (Tulving & Thomson's Encoding Specificity Hypothesis, 1973). Context reinstatement is achieved with various instructions from the interviewer to the witness. For example, the witness is encouraged to recreate mentally the environmental aspects of the original scene, to comment on his/her emotional reactions and feelings at the time, and to describe any sounds, smells and physical conditions. The instruction to reinstate context is administered prior to eliciting a narrative account of the event (i.e. before free report). A further context reinstatement instruction is administered prior to the questioning part of the interview in order to obtain more specific details (see Memon, Wark, Bull and Koehnken, in press for examples). Fisher and Geiselman (1992) suggest that more recall details can be elicited by activating and probing a witness's mental image of the various parts of an event, such as a suspect's face, clothing, objects. With reference to the dual coding hypothesis (Paivio, 1971) a distinction is drawn between conceptual image codes (an image stored as a concept or dictionary definition) and pictorial codes (the mental representation of an image). The latter are believed to elicit more detailed information than the former. For example, in retrieving information about a face using the concept code, one may be able to access information that the face is disfigured. If then asked to form an visual image of the face a witness may be able to give more details of this, such as the presence of a scar across the cheek.

Another CI technique is to ask the witness to `report everything'. For instance, witnesses are encouraged to report in full without screening out anything they consider to be irrelevant or for which they have only partial recall (Fisher & Geiselman, 1992).

There are two additional CI techniques-the instruction to recall the event in different orders (i.e. to recall from the beginning, the end and/or the most salient detail) and to recall from different perspectives- from the perspective of another person or by placing oneself in a different location- that form part of the original procedure. These techniques may work, in part, by reducing the extent to which prior knowledge, expectations and schema influence and/or limit recall (Norman & Bobrow, 1978). However, there are some concerns about using these techniques, such as the possibility of interviewees misunderstanding the instructions as a request for inferences or speculations (see Memon, Cronin, Eaves & Bull, 1993; Memon & Koehnken, 1992). Moreover, police officers are reluctant to use these techniques for these reasons (George, 1992) and concerns about presenting evidence arising from the use of this technique in court. Finally, previous research has shown that the reverse order recall instruction has no benefits over an instruction to merely make one additional retrieval attempt (Memon et al, in press). The present study will not include these elements of the original CI in the training of interviewers.

Following the early success of the original CI procedure, a content analysis of real police interviews was undertaken (Fisher, Geiselman & Raymond, 1987a) and deficiencies in communication skills were noted. The enhanced CI was an important development as it was specifically directed towards addressing problems with the typical police interview. The current paper will concentrate on the enhanced version of the CI since it is the one recommended to professionals (Fisher & Geiselman, 1992).

The enhanced CI utilises the techniques of the original CI. In addition to these specific strategies, an interviewer trained in the use of the enhanced CI attempts to facilitate interviewer-witness communication by building rapport with the witness and by transferring control to the witness. The latter is achieved by (a) making it clear to the witness that the interviewer does not have knowledge of the event and that the witness has to do the work; (b) allowing the witness time to think and respond, and (c) timing questions to suit the witness. The rapport building, together with transfer of control, is thought to increase the flow of information (Fisher & Geiselman, 1992; Memon, 1996). Hence any increase in amount of information reported may partly be a consequence of communication and rapport and not solely of cognitive memory enhancement. Indeed in the counselling domain the association of rapport and transfer of control with good interviewing practice is nothing new. In 1965, Richardson, Dohrenwood and Klein wrote:

`Rather than impose his questioning framework on the respondent, the experienced interviewer adapts his pace, idiom and thought to those of the respondent.' (p. 285).

The enhanced CI is essentially a non-directive interview (Roethlibergert & Dickson, 1946) and its `communication' components resemble techniques used by Carl Rogers (1942) in counselling and psychotherapy. An important question, therefore, is whether the success of the enhanced CI is due more to the use of the purposely included non-directive interview techniques (such as those described immediately above) than to its cognitive `memory retrieval' techniques.

So what evidence is there to suggest the CI is an effective procedure to use when interviewing witnesses? In early studies which examined the effectiveness of the original CI (e.g., Geiselman, Fisher, Mackinnon & Holland, 1985) it was compared with a "standard" interview or the techniques police officers typically use (see Fisher, Geiselman and Raymond, 1987a)[2]. This showed that with relatively brief training students and police officers could elicit significantly more correct information from witnesses (college students and non-college samples) without influencing the error rate. Tests of the enhanced CI found that it could generate even more information than the original CI (Fisher, Geiselman, Raymond, Jurkevich and Warhaftig, 1987b). Again, the numbers of errors that were elicited and the proportion of correct and incorrect information (accuracy) was unaffected. In light of these results, the enhanced CI was presented as a reliable repertoire of techniques to maximise the recall of a witness (Fisher & Geiselman, 1992). More recent attempts at replicating the earlier studies have identified a number of problems. The CI does not always facilitate recall when compared to a structured interview (Memon, Cronin, Eaves & Bull, 1993; Memon, Cronin, Eaves and Bull, 1996a) or a recognition checklist (Cohen and Java, 1995). When CI training is ineffective, trained interviewers may fare worse than an untrained group (Memon, Milne, Koehnken & Bull, 1994). Furthermore, recent tests of the CI which have consistently shown that while the CI and control groups do not differ in accuracy rates there is an increase in the number of errors generated in the CI condition (Bekerian, Dennett, Reeder, Slopper, Saunders & Evans, 1994; Koehnken, Finger, Nitschke, Hoefer & Aschermann, 1992; Memon et al, in press; Milne, Bull, Koehnken & Memon, 1995; McCauley & Fisher, 1995; Mantwill, Koehnken & Aschermann, 1995). Further laboratory research on the CI is therefore needed in order to understand the conditions under which the CI will be effective and when it may not.

From a practical perspective, it is important to show that the CI is more effective than the techniques currently in use by police officers and others as Fisher and Geiselman have done. From a theoretical perspective, a proper experimental control group is needed to demonstrate that the CI techniques themselves are causing the effects and not some artifactual side effect arising from the training or quality of the CI interviewers. In the present research we sought to construct a control condition (the structured interview or SI) in which the quality of training in communication and questioning techniques was comparable to the CI condition. The structure of this training for our CI and SI followed that recommended to professionals who interview witnesses, both adults (Koehnken, 1995) and children (the 1992 Government recommended Memorandum of Good Practice, see Bull, 1992; 1995). The essence of these recommendations is to treat the interview as a procedure in which a variety of interviewing techniques (including components of the structured interview) are used in relatively discrete phases proceeding from free recall to open questions to closed questions. Thus the structured interview is a suitable control. Moreover, the CI versus SI comparison in the present study lets one examine the effect of mnemonic techniques (communication techniques are held constant). The SI versus untrained will enable us to look at the effect of communication techniques.

With respect to the increases in errors, further research is needed to understand the conditions in which these errors are likely to occur so as they may be prevented. It should be noted that the increases in errors is relatively small when compared to the large gains in correct details (see Memon et al in press). Nevertheless, errors are obviously of great concern from a forensic perspective. Research is required in order to understand where in the interview they occur, whether they are associated with the use of particular techniques, and the types of information that is likely to be erroneously recalled. Based upon our earlier research (Memon et al, in press; Milne et al, 1995) we predict that the errors will occur in the questioning phase. The questioning phase in the CI is characterised by the use of imagery probes and detailed questioning. The increase in errors could be a result of instructions to elicit images in detail (Bekerian, Dennett, Hill & Hitchcock, 1990), source misattributions due to similarities between imagined and perceptual details (Carris, 1992), and /or to the use of specific questions. Data from the SI group (specific questions without imagery) will facilitate the further examination of these hypotheses.

The aims of this study are therefore two fold. The first is to determine the extent to which the effects of the enhanced CI may be a result of improved rapport and communication between the interviewer and witness. The second is to consider the possible aspects of the enhanced CI which may give rise to the reporting of errors. The enhanced CI is compared with a structured Interview (SI) and untrained control (UI) group.

Method

Design

The effects of interview condition (Cognitive, Structured or Untrained) on total correct recall, errors and confabulations were examined using a between-subjects design.

Participants

Data were collected from sixty-six participants (forty female and twenty-six male) who were `sixth form' students at a local college. They were aged between 16 and 19 years of age (mean=16 years, 7 months) and were randomly assigned to the experimental conditions. Previous studies of the CI have tended to use older age groups (e.g Geiselman et al, 1985) or children (e.g. McCauley & Fisher, 1995). Adolescents are just as likely to serve as witnesses in the criminal justice system and therefore this age group was selected for the present study.