EXPERIMENT ONE: THE TAUNTON COLLEGE STUDY

AN EMPIRICAL TEST OF THE 'MNEMONIC COMPONENTS' OF THE COGNITIVE INTERVIEW

Ray Bull
Portsmouth University

Abstract

This paper reports some preliminary research in which the various mnemonic components of the Cognitive Interview were isolated and compared with an instruction to try harder. The purpose of this was to control for possible motivational effects. Adult and children (aged 5- 9 years) were asked to recall details of a staged event under one of four instruction conditions. In the first condition, they were encouraged to reinstate context; in the second condition to change perspective; in the third condition to report the event on reverse order and in the fourth condition to try harder. There were no significant differences in correct recall or errors as a function of instruction condition. An analysis of different types of information reported in the interviews suggested some types of information were more frequently reported. Accuracy rates were high and while the older children recalled more information correctly they were no more accurate than the younger children. The implications of the findings are discussed with reference to some of the theoretical and methodological issues raised by research on cognitive interviewing.

INTRODUCTION

Experimental studies of human memory have clearly demonstrated its limited capacity to store information, its reconstructive nature and its deterioration over time (e.g. Kail, 1979). It is also well established that the recall of information from memory is influenced by the strategies used to gain access to that information (Ornstein, Medlin, Stone, & Naus, 1985). This knowledge has in recent years, been applied to the practical problem of remembering in the context of eyewitness memory. The cognitive interview (CI) was developed by Geiselman and Fisher as a procedure for increasing the amount of correct information recalled by a witness (Geiselman, Fisher, MacKinnon & Holland, 1985). CI was presented in the form of four 'mnemonic' strategies and was derived from pooling research on retrieval pathways, encoding specificity, and schema related recall. The success of the CI relative to a standard police interview has been attributed to the cognitive, memory enhancing components of the procedure (e.g. Geiselman, 1988). In the 'enhanced' CI (Fisher and Geiselman, 1992) a further increase in recall is attributed to other, more 'social' aspects of the interview setting and procedure.

The aim of this paper is to evaluate experimentally the effectiveness of the cognitive components of the CI procedure using adult and child witnesses to staged events. Empirical support for the technique was generated by several studies of eyewitness memory performed by Fisher, Geiselman and colleagues which have been replicated by researchers in Germany. (See Memon & Köhnken, 1992 for a recent review).

This paper reports some preliminary research in which the various mnemonic components of the CI were isolated and compared with a control group and in which we attempt to control for possible motivational elements induced by the CI (e.g to try harder). This paper also examines age differences in recall of event information and the effectiveness of CI instructions with child witnesses. This follows an earlier study with six year olds where the full CI was no more effective than a good standard interview (Memon, Cronin, Eaves & Bull, 1992). The Cognitive Interview. The original CI procedure (e.g. Geiselman et al., 1985; 1986) comprises four 'cognitive' (mnemonic) techniques. The CI-trained interviewer encourages the interviewees/witnesses to use these techniques to help them remember. The CI techniques are derived from two principles regarding the structure of memory. Firstly, according to Tulving (1974), multiple retrieval pathways exist to a given encoded memory of an event and so a variety of retrieval cues or strategies are needed to maximise the chances of a complete recall. Two such strategies are the 'change order' and 'change perspective' instructions which encourage interviewees to recount events in a variety of orders, and from a variety of perspectives, respectively. These techniques have been shown to be effective in eliciting extra details (Loftus & Fathi, 1985; Anderson and Pichert, 1978) and may work in part by reducing the extent to which prior knowledge, expectations and schema influence and/or limit recall (Norman and Bobrow, 1978).

The second principle adopted in the CI is Tulving & Thomson's Encoding Specificity theory (1973). A memory trace is made up of several features; to maximise recall, an effective retrieval cue needs to comprise as many of these features as possible. Context provides cues which increase feature overlap between initial witnessing and subsequent retrieval contexts (cf. Flexser & Tulving, 1978). Context reinstatement involves emotional elements ('How were you feeling at the time?'), which may work via state-dependent effects, perceptual features ('Put yourself back at the scene of the crime and picture the room, how did it smell, what could you hear?'), and sequencing elements ('What were you doing at the time?').

The perspective, order and context instructions are directly related to memory theory. The status of the fourth - an instruction to the witness to report every detail irrespective of perceived importance or triviality as a mnemonic technique is not as clear. In practice, this instruction is given in conjunction with the instructions that precede each free recall by the witness, and is a means of enhancing the communication by the witness of the information elicited by whichever of the other techniques is being used at the time. Thus, use of this instruction recognises that, from a forensic point of view, even seemingly trivial facts can be important. For the purposes of this study, the 'report every detail' instruction will not be considered as a separately assessable mnemonic technique, primarily because alone it does not instruct the witness to make a recall attempt, but instead is given as a supplementary instruction to those that do (Eaves, 1992).

The CI was developed, tested and refined in a series of studies employing trained interviewers (police and students), simulated incidents and police training films (e.g. Geiselman et al., 1985), and, more recently, in field studies using a small sample of detectives and witnesses to real events in Florida (Fisher, Geiselman & Amador, 1989) and in the U.K. (George & Clifford, 1991). Later studies of the CI have largely used the 'enhanced' version which includes some general principles for improving communication and facilitating the effective use of context reinstatement.

Acquisition of mnemonic competency A review of the effects of rehearsal on memory retrieval across various groups shows that older children are more likely to engage in active rehearsal than younger ones and are more efficient in the implementation of mnemonic strategies (e.g. Ornstein et al., 1985). However, there is also evidence to suggest that if children are directed to relevant cues and sufficiently prompted to use cues, ages differences in recall performance are eliminated (Kobasigawa, 1974, Pipe, Gee and Wilson, 1993).

This evidence suggests the cognitive interview, if appropriately applied, may facilitate recall in child witnesses. The CI has been modified in recent years and tested using children as witnesses to staged events. Memon and Köhnken (1992) review the recent research, a sample of which will be outlined here. Studies by Geiselman and colleagues (Geiselman & Padilla, 1988; Saywitz, Geiselman & Bornstein, 1992) suggest that CI (the original procedure) is as effective with children as it is with adults, particularly if children are familiarised with the CI before being questioned. However, Köhnken, Finger, Nitschke and Hofer (1992) report a substantial increase in confabulated details when the enhanced version of CI was used with children.

In an earlier study, we compared the original CI with an interview that was identical to it in all respects apart from the mnemonic techniques (this latter interview being called the standard interview or SI). We found no significant differences between CI and SI in a between subject or within subject comparison (Memon et al., 1992). There were qualitative differences in the interview transcripts which suggested that not all the child interviewees understood and could use the CI techniques (cf. Cronin, Memon, Eaves, Küpper & Bull, 1992). Interviewers showed some individual differences in their application of the various CI instructions. This was also noted in the Saywitz et al (1992) study, where an overall positive effect of CI was recorded. On the basis of this earlier research we refined some of the CI instructions and incorporated a practice session in our design to encourage the children in this study to actively use the CI techniques. Before presenting the research, the methodological issues pertaining to the cognitive interview literature will be summarised. Previous Research on CI: Methodological Problems _ In earlier studies of CI (e.g. Geiselman et al., 1985) the experimenters set out to evaluate the effectiveness of the CI by comparing it with a 'Standard Interview' (SI). Usually these SI's were modelled upon the police investigative interviewing practices used by officers untrained in CI techniques. Some of the officers had never received interview training of any description. The success of the CI over the SI has often been attributed to its mnemonic components. However, in the absence of a suitable control group (that is, interviews identical to the CI save for its special techniques) it is not possible to say why the CI is more effective.

The scoring procedure (particularly the definition of a 'correct detail' and an 'incorrect' and 'confabulated' detail ) has not been fully discussed in any of the previous publications. Some studies report an increase in confabulations when CI is used. Köhnken and Brockmann (1988) report an increase in confabulations with CI, but it is not clear what constitutes a confabulated detail.

Finally, recent research suggests the CI technique results in substantial increases in correct information recalled with nine to ten year olds (Köhnken et al., 1992). However, in the same study there was a corresponding increase in confabulated details. In this particular study, the CI interviewers asked twice as many questions as the SI interviewers and errors fell largely into the person and action description category. This work suggests it is important to monitor the type of errors that may occur when CI techniques are applied.

The justification for including a 'try harder 'control group. The observed success of the CI may be due to relatively more recall attempts than are generated by the SI (cf. Scrivner and Safer, 1988). In addition, motivation may be higher in the CI groups merely because of the complex instructions they receive. A 'try harder' control group was therefore used in the studies presented below.

THE PILOT STUDY

The pilot study (Eaves, 1992) examined the recall- enhancing properties of each of the mnemonic components of the original CI by studying them individually, comparing each one with the other two and the control group. The data from this study suggested that when the mnemonic techniques of the cognitive interview are isolated and tested individually, their so called mnemonic effects are no more apparent than the motivating effects of the 'try harder' instruction. The design employed in the pilot study was retained in subsequent studies of CI in order to examine the effectiveness of the individual CI instructions (the change context, change perspective and change order) compared with a try harder control using larger samples of college students (experiment one) and children of different ages (experiment two). In each study interviewer differences were minimised by use of a fixed interview protocol in each condition.

EXPERIMENT ONE: THE TAUNTON COLLEGE STUDY

There were 68 participants in this study: all were biology students (aged 17 and 18 years) attending a local sixth form college. The participants were randomly distributed across conditions: try harder (N=14), context reinstatement (N=18), change perspective (N=17) and change order (N=19).

The staged event involved a postgraduate student from the university (a stranger to the class) who interrupted a lesson in order to request the students' help in completing a questionnaire. Interviews took place 10-14 days after the event. Each of three interviewers followed a clear interview protocol for each condition. This comprised an initial free recall in which subjects were specifically asked to give as much information as possible about the person and event, followed by one of the four instruction conditions: (i) Try harder; (ii) Change Perspective (iii) Reinstate Context; (iv) Change Order. Full details of the instructions are available from the first author. In each condition, the first recall consisted of a narrative account of the event. If, on completion, the participants had neglected to make any reference to a description of the man, of what he did, of what he said, or of what happened to him, they were prompted once for each of these elements. This ensured that neglecting to mention an element would not be misidentified as inability to recall anything about it

Coding and scoring of data. There were three coders and scorers. Each coder went through a sample of transcripts and assigned information to various categories. At this point accuracy of details were not assessed. Inter-coder discrepancies were discussed by working through all the codes given for each transcript and coding rules were modified once a consensus had been reached.

The coding scheme that was used was determined to some extent by the details of the to-be-remembered event. For example, the central feature of the event was the 'questionnaire' that participants were asked to complete. Thus we had a category where information about the questionnaire was placed. The other categories were: person descriptions, person action, location of persons and objects, temporal information and subjective information (information that was uncheckable including impressions of the event and person). Errors were coded as incorrect details (e.g. a blue shirt reported when the shirt was green) or confabulations (e.g. jacket reported when there was no jacket). Errors were coded and scored in the same way as correct details. For example, "he wore a green shirt and carried a black briefcase" was coded as a person descriptor with correct details assigned the following scores: one point for green and one point for shirt and errors scored as follows: one error score for black and one for briefcase.

Results.

A one way ANOVA showed no significant differences across conditions in free recall of correct or incorrect details (all F's<2). The number of errors in the free recall accounts were small (mean error rate =0.6%). All but two accounts were free from confabulations. A series of one way ANOVAs were then performed on the pooled accuracy data (i.e free recall score combined with additional details elicited following instructions). There were no significant differences between conditions across any of the comparisons (all Fs<1). As indicated in table one, the means tended to favour the 'try harder' control group with the context reinstatement condition producing the least amount of overall correct information. An examination of types of information elicited under each condition showed some interesting trends. The amount of location information differed across conditions F ( 3, 64)=7.71, p<.01, with more details about locations in the try harder as compared to context conditions (Fisher PLSD=.589, p<.05). Furthermore, there were more details in the change perspective conditions as compared to the change context conditions ( Fisher PLSD =.559, P<.05). The change order condition elicited more temporal details as compared to the change perspective condition (Fisher PLSD= .552, p<.05). These trends will be discussed in the conclusion section of the paper.

TABLE 1: Experiment 1: Mean number of details recalled in each condition

There were no significant interviewer differences in total information, total correct information or errors (all Fs<1).

The main conclusion drawn from this study was that the CI instructions have no general effect over and above the motivational element to try harder. Since the interviewers correctly followed the interview protocols each time, such a finding cannot be attributed to the failure to instruct interviewees in the use of the technique. It may be the case however, that the interviewees were not following the instructions. When participants were asked informally at the end of the study which techniques they had used the only one mentioned was context reinstatement. It may be the case that our interviewees had not understood the instructions sufficiently. In the next study we included a 'practice session' to give interviewees an opportunity to try out the techniques. As discussed above, there is some evidence to suggest that a practice session may maximise any beneficial effects of the CI (Saywitz et al., 1992).