EXPERIMENT 2: BEVOIS STUDY

The participants were 68 children aged five to nine years divided on the basis of school year group. The youngest year group were five to six years (N=17), the intermediate group were six to seven years (N=19), and the oldest age group were eight to nine years (N=31). There were an approximately equal number of children in each of the four conditions.

The event took the form of two strangers taking part in a school assembly by reading and acting out a poem. The event lasted about 10 minutes and memory was tested approximately a week later. As in the previous study there were three interviewers (all were female) and an interview protocol was strictly adhered to by each interviewer. Each interview began with a practice session in which children were asked to describe what they did when they brushed their teeth in the morning. In most cases the children gave a brief account without any prompting. The interviewer then asked them to give a second account but this time it was preceded by the specific instruction to try harder, to change perspective, to change context or to change order. The younger children (five to six year olds) required more prompting in the last three conditions as they did not readily understand the instructions. Our observations during the practice session suggested that with guidance and prompting children became familiar and felt comfortable with the techniques. However, it was not possible to conclude from this that the children understood and could apply the techniques when asked to describe the event (this point is taken up in discussion).

The categories into which recall data could be placed were determined by the nature of the event (see Table two for a list of categories) and we followed the procedure for coding and scoring outlined earlier.

A three (age) by four (condition) analysis of variance on total correct information (free recall and cued recall data pooled) showed a significant main effect of age F(2,55)= 5.19, P<.01 with the eight year olds producing significantly more correct information than the five year olds (Scheffé's S= 6.23, P<.01). The intermediate age group (six and seven years) did not differ significantly from either of the other two groups (cf. Davies, Tarrant, & Flin, 1989). There were no significant differences in errors or accuracy (number of items correctly recalled as a proportion of total number of items) as a function of age or condition (all Fs <1). It is interesting to note that the younger children recalled less information but were no less accurate (cf. Poole and White, 1992, Saywitz et al., 1992).

An examination of age differences in total correct information as a function of information type showed significant effects for descriptive details F (2, 55)=3.57, p<.05. with the eight years olds producing more information within this category than the five year olds (Scheffe's S=4.55, P<.05). There was also a significant age effect on subjective information F (2,55)=4.43, p<.05 with the eight year olds producing more information in this category than the 5 year olds (Scheffé's S= 1.42, p<.05). Given the small frequency of errors within each category, the analysis of error type has to be interpreted with caution.

TABLE 2: Experiment 2: Mean number of details recalled in each condition

There was no significant main effect of condition on total correct information F(3,55)=2.20, P>.05 or errors. There were significant differences between conditions in total information (total correct plus errors F (3, 64) =2.85, P<.05) with the try harder and change order conditions producing more information than the change perspective instruction (Fisher PLSD= 7.78 and 7.43 respectively, p<.05). However, more errors occurred in these conditions, although as indicated earlier there was no significant main effect of condition on error means (F(3,64)=2.33, p=.08). There were no significant interactions between age and condition on any of the measures (all Fs <1).

To summarise the data from Experiment two, there were no significant differences between the try harder control and mnemonic instruction conditions in total correct or incorrect information elicited. The results showed the youngest age group produced less correct information than the two older age groups but did not produce more errors and were no less accurate. In the absence of significant interactions between age and condition it is not possible to comment on age differences in performance under each condition. There are however, some notable trends in the means which warrant attention in further studies: (1) Inspection of the means for total correct information suggest the youngest age group perform less well under the context conditions as compared to the eight year olds which is consistent with the recent findings of Pipe et al., (1993) and (2) the youngest age group perform less well under the perspective conditions (cf Saywitz, et al., 1992) and we argue below that this may be due in part to the difficulty the children have understanding this instruction.

In the three studies there were no significant between group differences in the effects of CI instructions as compared to a try harder control group. This leads to the conclusion that the memory enhancing effects of CI reported in earlier studies may be due to increased interviewer and interviewee motivation to work harder. We are undertaking further research to explore this hypothesis in more depth. One factor relating to use of the CI that has been overlooked in earlier research is that it relies upon the co-operation of the interviewer and witness. The way in which the CI instructions are communicated and the extent to which the witness understands them is therefore critical in determining the success or failure of the procedure. For example, with respect to the change perspective instruction we found that interviewees were more likely to understand what we meant if we asked them to adopt a different location perspective rather than a different person perspective (cf. Saywitz et al., 1992).

The necessity to prompt with specific questions poses an additional problem in interpreting the effects of CI on recall performance: namely, that any increases in information obtained with CI instructions may be an artefact of the language that has to be used to fulfil the instructions given, and not a product of memory improvement. For example, in one study (Memon et al., 1992) we found the CI increased the reporting of details about the location of various people and objects (cf. Smith, 1979) as compared to a similar interview where the special CI instructions were not applied. It was also noted in one of the studies reported in the present paper (Experiment 2) that the 'change order' instruction tended to produce more information about the timing of events. Such details may of course be relevant in some cases (cf. Fisher and Geiselman, 1992).

The difficulty in communicating the CI instructions to the witness is one problem. Another is that it is not clear to what extent the success of CI resides in the motivation of the CI interviewer to produce a better interview and more information. The CI clearly takes more time and effort to perform than what has been described as a standard interview (George, 1992, Saywitz et al., 1992). The major way in which the CI components may differ from the 'try again' instruction is in the 'novel' way they request the interviewee to recall further information. Although more recent studies of CI (e.g. Köhnken et al., 1992) have tried to ensure their control groups received equivalent levels of training to cognitive interviewers the motivational element has, prior to our studies, not been sufficiently addressed in earlier studies of CI. Future studies of CI need to include a try harder group as an additional control group and compare this group's performance with that of the so called standard interview group.

Physical context cues and props may have powerful effects on recall (See Gee and Pipe, 1993 for a recent review). Yet, in the present studies we found no effects of context. Gee and Pipe argue that young children (six year olds) are less likely to use spontaneously generated cues such as imagery, and the re-enactment of an event using cues and props makes communication easier than merely reinstating the environmental context. They also show that the types of cues used and the method of presenting them are important determinants of the amount and accuracy of information reported. This reinforces the point that was made earlier about the communication of CI techniques.

Because of its potential application in the field of police interviewing, it is essential to scrutinise very carefully the experimental data related to CI. An ESRC funded study is currently underway to look more closely at the ways in which differences in interviewer style, interviewer non-verbal behaviour and witness motivation may influence the potency of any effects obtained with the CI.

Acknowledgements

We are grateful to the staff and pupils of Taunton College and Bevois Town School in Hampshire for their participation in this research. We are also grateful to Trudy Wright for her help with data collection and to Sigi Sporer for his comments on an earlier draft of the paper.