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• Reliability Of The Testimony Of People With Intellectual Disabilities

APPENDIX: Psychological studies on the reliability of children’s testimony

A1 MUCH RESEARCH HAS BEEN UNDERTAKEN in relation to aspects of children’s memory. For accounts which attempt to condense the information see: J R Spencer and Rhona Flin, The Evidence of Children: The Law and the Psychology;¹⁹⁹ Lucy S McGough, Child Witnesses: Fragile Voices in the American Legal System;²⁰⁰ the Ontario Law Reform Commission, Report on Child Witnesses;²⁰¹ and Stephen J Ceci and Maggie Bruck, Jeopardy in the Courtroom: A Scientific Analysis of Children’s Testimony.²⁰²

A2 It is generally agreed that what any person remembers is partly reconstructed; that is, memory depends in part on knowledge and other sources of information in addition to that recorded when an event was first experienced. Many theoretical analyses treat memory as involving three stages. Processes involved with each stage will influence how accurately and completely any witnessed event will later be recalled. First is the acquisition stage when information is encoded in memory. During this stage, processes relating to perception, attention and understanding may influence which information is encoded (or recorded) in memory and how well is it encoded.

A3 Second is the retention stage, the period of time that passes between the event and the eventual recollection of a particular piece of information. Memories may change simply as a function of time, especially following very long delays, but also, for example, as a result of similar, intervening experiences, rehearsal of the event,²⁰³ and exposure to other information about the event.

A4 Third is the retrieval stage, during which a person recalls the information about the event. Recall is influenced by the cues available to retrieve the memory; for example, as provided by questions, or physical cues such as photographs or reinstatement of the original context of the event, as well as the social context in which the person is asked to recall the information. The accuracy and comprehensiveness of any person’s recall therefore depends on the nature of the event to be remembered, the intervening time interval and the occurrence of other, related events, why the person is asked to recall their memories, and by whom, and the kinds of retrieval cues provided at the time of recall.

A5 It is generally agreed that the memories of both adults and children are fallible. Adults, like children, may be mistaken in their perceptions and confused in their memories. The appropriate question to ask is whether children are predictably less reliable than adults. Although much of the research on this topic is focused on different questions and some findings conflict, common themes are apparent.

A6 For many memory tasks, such as those which involve recognition, even quite young preschool children are as reliable as adults.²⁰⁴ Memory is not a simple function of age, and a combination of children’s knowledge, skills and social factors influence children’s memories and their ability to recall past events. There is also reasonable consensus that children’s abilities to recall and communicate develop with age. Although preschool children can recall accurate details about personally experienced events over a period of years,²⁰⁵ most writers consider that the memories of young children (that is from preschoolers up to the age of 12) are more vulnerable to fading than older children and adults.²⁰⁶ But if, when information is initially acquired,

• the child has a superior knowledge of the subject matter; or
• the event is personally significant;²⁰⁷ or
• the actions are central and familiar to the child,

then children’s memories may be enhanced, and any developmental disadvantages overcome.²⁰⁸

A7 Children may, however, have difficulty ordering complex and less familiar events, or be unable to recall the exact date of events, or have difficulty estimating distance or speed. These difficulties can be overcome by asking a child to position events in time in relation to an important event in the child’s life, such as a birthday, and by asking a child to give relative estimates of things such as speed or height; for example, by asking a child to compare the height of the suspect with the height of the interviewer. It must be remembered that adults sometimes have the same difficulties and prefer to give relative estimates.

A8 Children’s memories are also affected by the intervention of factors present when the child is recalling memories. Factors such as delay, stress, the interviewing technique, the presence of a support person, the perceived status of the interviewer in relation to the child, and the environment in which questioning takes place may all influence the recall process.

A9 These findings are relevant to interviewing techniques; for example, children who are asked to freely recall an event are generally regarded as being as accurate as adults, but they report less information, partly because of less developed communication skills. The younger the child, the less spontaneous they will be and therefore the less detail will be reported. There appear, therefore, to be age differences in quantity but not quality of freely recalled details. All witnesses, but children in particular, remember more details than they spontaneously report. Children may therefore require more assistance than adults to recall all they know; for example by the use of cued questions.

A10 Unfortunately, this need for assistance can increase the risk of distortion, and much recent research has focused on the topic of suggestibility.²⁰⁹ It seems fair to conclude from recent research that although the accuracy of both adults and children can be affected by leading or suggestive questions,²¹⁰ the ability to resist the influence of external suggestion increases with age.²¹¹ Suggestibility should, however, be distinguished from compliance. Children may change their account of an event not because their actual memory of the event has altered or become confused but because they wish to comply with an adult in authority’s suggestion or because they interpret an adult’s repeated questioning as an indication that their first response was judged “wrong”.²¹²

A11 Research indicates that whether children are more susceptible to suggestive information than adults probably depends on the interaction of age with other cognitive and social factors.²¹³ A child (and also many adults) will be less open to suggestion if:

• the event is familiar, or personally significant;
• the information is central to the event from the child’s perspective;²¹⁴
• there is minimal delay between the event and the reporting of it;²¹⁵
• the interviewer is skilled;²¹⁶
• the interview surroundings are supportive;
• the child does not perceive the interviewer as an authority figure who must be obeyed or pleased;²¹⁷
• the child is not embarrassed about the information they are asked to recall;²¹⁸ and
• the event is salient or distinctive.

A12 Many of these factors would also operate to reduce the suggestibility of an adult witness.

Reliability of the testimony of people with intellectual disabilities

A13 It is difficult to make generalisations about the ability of witnesses with intellectual disabilities to give reliable evidence. People with very limited intellectual and behavioural capacities may be perfectly truthful and capable of accurately remembering what they saw or what happened to them.²¹⁹ In contrast, there may be some people at the upper end of the relevant intellectual and behavioural scale who are not good witnesses because they have forgotten important facts or they are unwilling or unable to tell the truth.

A14 Research suggests that even people with moderate and severe intellectual disabilities can communicate accurately when the situation is a natural one: for example, one that involves a clear reason for communicating, a logical consequence of communicating, and familiar objects or tasks.²²⁰ However, there is some evidence that people with intellectual disabilities are more acquiescent than other people,²²¹ and that they are more likely to answer “yes” if questions are framed in such terms that they can only answer “yes” or “no”.²²² Questioning techniques may therefore be a cause of distortion in answers rather than memory deficits in the person being questioned.²²³

A15 The reliability of witnesses with mental disorders, in contrast to those with intellectual disabilities,²²⁴ will depend on several factors. The evidence of a person whose illness is in remission or well controlled will be no more or less reliable than a witness with no mental illness. The nature and severity of mental disorders vary considerably, and the symptoms of many have no implications for reliability. The ways in which reliability may be affected will depend on the nature of the illness. For example, some people in an acute phase of a mental illness such as schizophrenia may have delusions or hear voices. At that time, their grasp on reality may be poor, and they may be unable to differentiate between fact and fantasy. People affected by mood disorders may be impaired in other ways – thinking may be slowed and concentration or motivation lacking, even though they may be able to accurately remember information about past events. Alternatively, during mania, lack of inhibitions, poor judgement and overvaluing of their own opinions and insight will also impact on the reliability of their evidence.