Kim P. Roberts (1996) How Research on Source Monitoring can Inform. Psycoloquy: 7(44) Witness Memory (15)

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PSYCOLOQUY (ISSN 1055-0143) is sponsored by the American Psychological Association (APA).
Psycoloquy 7(44): How Research on Source Monitoring can Inform

Commentary on Memon & Stevenage on Witness-Memory

Kim P. Roberts
Section on Social and Emotional Development
National Institute of Child Health & Human Development
BSA Building, Room 331
9190 Rockville Pike
Bethesda, MD 20814


Two major themes of the cognitive interview are multiple retrieval attempts and the use of imagery. This commentary provides an overview of how repeated retrieval attempts and imagery affect source monitoring ability, and cautions on the premature acceptance of repetitive imagery techniques as a forensic tool with child witnesses.


Cognitive interview, errors, eyewitness memory, facilitated recall, police procedures, questioning, recovered memories, structured interview.
1. Memon and Stevenage (1996) provide a concise overview of the theoretical bases of the cognitive interview (CI) technique, and current research assessing the efficacy of the CI. This commentary focuses on two aspects of the CI: repeated retrieval attempts (for example when asking a witness to describe an event in different temporal orders and from different perspectives) and imagery techniques (for example, when the interviewer directly probes images that the witness holds to elicit further information).

2. The use of imagery is fundamental to the administration of the CI (see Fisher & Geiselman, 1992 for examples) and researchers have shown that imagery techniques can lead to the reporting of additional items of information (e.g., Bekerian, Dennett, Hill & Hitchcock, 1992). Similarly, it is well documented that the use of multiple retrieval attempts can facilitate recall (see Brainerd, Reyna, Howe & Kingma, 1990). Memon and Stevenage (1996) rightly note that imagery techniques may also lead to an increase in errors. Research from the source monitoring literature indicates that imagery techniques may compromise accuracy when they are used repetitively (as in a CI). In particular, multiple imagery requests can be dangerous in the situation in which a witness thinks about an event that was not actually perceived. To illustrate this claim, a brief overview of the relevant source monitoring research is reviewed first, and then the commentary focuses on the special case of child witnesses.


3. The CI employs the use of imagery techniques to elicit additional information from the witness. Douglas (1996) highlighted the importance of research into individual differences in imagery ability. In this commentary, potential problems with the imagery techniques of the CI that can be applied to all witnesses are discussed.

4. Research on source monitoring has shown that when an individual is asked to think about an event repeatedly, the ability to distinguish between what actually happened and what was imagined can be impaired. For example, Johnson, Raye, Wang and Taylor (1979) found that the more times that a picture was imagined, the more likely it was that the participants claimed to have actually seen the picture. More recently, in a study of memory for word lists, Payne, Elie, Blackwell and Neuschatz (1996) found that the number of non-presented words that participants claimed were actually presented increased with successive recall attempts. In other words, repetitively imagining and recalling events can cause poorer source monitoring.

5. Although imagery per se may not be a poor memory technique, the explicit demands to imagine in the CI may cause a decrease in accuracy. Markham and Hynes (1993) showed that adults who were good imagers did not confuse perceived and imagined shapes, unless they were explicitly instructed to imagine the shapes. In other words, interviewees who spontaneously imagine events may have the capacity to monitor the sources of their memories accurately, but when explicitly asked to do so this ability decreases. As noted by Memon and Stevenage (1996) and others (e.g., Foley, Durso, Wilder & Friedman, 1991), people often visualize spontaneously, and therefore the CI should be developed to maximize this spontaneous imagery and minimize explicit repeated imagery demands until we have a greater understanding of the role that imagery plays in monitoring memories.

6. The effects of imagery on memory is also dependent on what aspects of the event the witness is encouraged to focus. Johnson and Suengas (1989) found that when encouraged to focus on perceptual aspects of the event, participants were subsequently more likely to report perceptual information for both perceived and imagined events (so much so that judges were unable to distinguish between descriptions of perceived and imagined events). In another study, the descriptions of perceived and imagined events were more similar for participants who had rehearsed thoughts and feelings associated with the events than those of participants who had rehearsed perceptive aspects of the events (Suengas & Johnson, 1988). Therefore, thinking about apperceptive aspects of events (such as how the witness felt at the time) can make imagined events "have as much cognitive and emotional content as memories for perceived events" (Suengas & Johnson, 1988, p. 388). It may be that if witnesses rehearse both perceptive and apperceptive aspects of events equally there is no detrimental effect on source monitoring. However, this has yet to be experimentally investigated.

7. Distinguishing memories of perceived and imagined events is also poorer if an individual engages in overt rehearsal and speaks aloud (see Bentall & Slade, 1988). In a CI a witness is encouraged to verbally communicate to the interviewer the content of the imagery, and this may cause poorer source monitoring if the witness is not advised to apply further checks on the source of those images.


8. Although, it has been pointed out elsewhere that isolated components of the CI may be problematic for children, for example the change perspective component (Cronin, Memon, Eaves, Kupper & Bull, 1992), it is argued here that the imagery component as it currently stands may also be problematic for younger witnesses.

9. There is evidence that imagery may be a useful procedure for many aspects of child development such as reasoning (Dias & Harris, 1990) and recall skills (Pressley & Levin, 1980). We also know that children remember perceived events better than imagined events (e.g., Gordon, Jens, Hollings & Watson, 1994; Gordon, Jens, Shaddock & Watson, 1991; Parker, 1995), that they do not spontaneously report imagined events if interviewed soon after an event (Gordon, et al., 1994), and we know how much children confuse perceived with imagined events decreases over time (Huffman, Crossman & Ceci, 1996; Poole & Lindsay, 1996). Inappropriate interviewing techniques may interfere with these skills. The use of repetitive imagery (as in the CI) may be one way that children's accuracy is compromised (see Ceci, Huffman, Smith & Loftus, 1994a; Ceci, Loftus, Leichtman & Bruck, 1994b for examples of how repeated imagery can produce inaccurate reports from children). Ways in which repetitive imagery techniques may have a negative effect on children's accuracy are now discussed.

10. Children aged 6-years and older are as good as adults at distinguishing between memories of what they have done and what others have done (e.g., Foley & Johnson, 1985; Foley, Johnson & Raye, 1983). However, it is not yet clear under what circumstances children can accurately distinguish between memories of perceived and imagined events, and therefore caution is urged when using imagery techniques with children. Some studies have found that 6-year-olds have difficulty distinguishing actions that they have performed and imagined performing (Foley & Johnson, 1985), or words that they have said and imagined saying (Foley, et al., 1983). However, Roberts and Blades (1995) found that 4-year-olds could distinguish between performed and imagined actions when allowed to act out the pretence in a simple hiding game. Until we know more about children's source monitoring abilities, asking children to explicitly imagine and report on events could have negative consequences for the accuracy of their reports if they confused what actually happened with what they imagined previously or during the CI.

11. The imagery necessary for the change perspective component of the CI may also have negative consequences on the source monitoring abilities of children. Foley and Ratner (1996) found that 4-year-olds claimed that they had placed a piece on a collage that an adult had placed when the children were instructed to imagine themselves performing the action. Therefore, asking children to imagine themselves as another person may lead to greater source confusions.

12. There have also been several studies which show that children find source monitoring more difficult when the same actor is involved in the perceived and imagined events, especially if the actor is a person other than the child (Lindsay, Johnson & Kwon, 1991; Markham, 1991; Nigro & Dyk, 1989; see Johnson, Foley & Leach, 1988 for similar results with adults). Therefore, there are potential confusions when children remember actual and imagined events involving the same person.


13. Source monitoring is sometimes inaccurate because the criterion for judging the source of the memory is lowered (see Johnson, Hashtroudi & Lindsay, 1993). For example, if a witness has repeatedly visualized an event, he may adopt a lax "familiarity" criterion, assume that a detail was perceived because it is familiar, and cease more stringent analysis of the source (Lindsay, 1994). Although it is desirable to find ways of encouraging witnesses to report the maximum amount of information possible, techniques such as the "report everything" and the imagery components of the CI may also reduce the criterion for judging the source of memories, and hence inaccuracies can be reported. For example, if interviewees are reporting everything that they know about an incident, they may report details that they have heard in the media or from another witness at the event but believe that they perceived this information first hand (see Roberts & Blades, in press, for examples of how memories of real-life and televised events can be confused). Research on techniques that increase the amount reported whilst maintaining accuracy such as that currently being conducted by Debra Poole and Steve Lindsay in analog studies, as well as research in the field by the author and her colleagues at the National Institute of Child Health and Human Development, is necessary.

14. Further research is also needed on the effects of demanded imagery on different types of events. There may be differences between imagery that is spontaneous and implicit (such as a dream) and imagery that is explicitly presented from another source (such as when a child is coached to allege abuse). Some studies have presented children with a fictitious event and encouraged the child to imagine that event (e.g., Ceci, et al., 1994a; Ceci, et al., 1994b). These studies could closely assume the dynamics of a coaching experience when the child is told what to imagine. Although it is more difficult to research, more information on how imagery techniques can affect spontaneously imagined events would contribute to better interviewing techniques for children.

15. In summary, caution is urged for the use of the imagery techniques in multiple retrieval attempts in the CI. Drawing from the research discussed above, it is recommended that repeated imagery techniques be used only with carefully selected witnesses such as adults who are interviewed soon after an event. The use of repetitive imagery is not recommended with young children until further research is carried out. It is preferred that interviewers try to maximize children's ability rather than give them tasks which are beyond their capability and which could produce inaccuracies leading to erroneous assumptions that children cannot be accurate witnesses.


The author is grateful to Mark Blades for helpful comments on an earlier draft of this commentary.


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