Investigative interviewing: the literature - New Zealand Police

More documents

Recommendations

Info

Investigative Interviewing: viewing: THE LITERATURE MEMORY The first experimental studies of memory were published in 1885 by German psychologist Hermann Ebbinghaus, and tens of thousands of memory studies have been conducted since (Loftus & Calvin, 2001). These clearly demonstrate that the human brain has the ability to retain a vast quantity of information and experience acquired over a lifetime. But memory is not like a video recorder that records everything it sees, or a computer that can retrieve everything stored on it. Instead: “Human memory is cluttered. Memories don’t get lost so much as they become distorted or hard to find. We may like to say that we’ve lost something - but often, an hour later, it pops uninvited into our consciousness, where it has been lurking all along. The serious difference between computer and human memory is that we don’t pop out a pristine copy of the original event, the way a computer does. Instead, we reconstruct things as best we can from all the clutter. We guess. Often that isn’t good enough, especially for a fair judicial process. Or just one’s self respect; it’s embarrassing to be badly wrong and we’ll deny an error even to ourselves” (Loftus & Calvin, 2001). Research Much of the research has focused on identifying conditions that affect recall. For example, the pioneering work of Elizabeth Loftus provided strong evidence of the influence of ‘postevent contamination’ i.e. new information that people unconsciously incorporate into their previously stored memories (Davies, 1995; Wells & Loftus, 1984). Her first study (Loftus & Palmer, 1974, cited in Davies, 1995) involved participants viewing a 10-second film of a traffic accident, then being asked questions which described the two cars as having either ‘smashed’ into or ‘hit’ each other. She found that the severity of the verb had a marked impact on answers about the speed and presence of glass. In her second classic study, volunteers were shown slides of a traffic accident which involved the presence of either a ‘Stop’ sign or a ‘Yield’ (give way) sign. Subsequent questions referred to the sign in either a consistent or inconsistent manner, with observers then being asked to select the slides they had seen originally. Where observers had been given misleading information, only 41 percent were able to correctly identify the original slides. Loftus (1989) proposed three different interpretations of the ‘misinformation effect’: • the ‘destructive updating’ or ‘alteration’ hypothesis, whereby the original memory representations are altered by later information and thus entirely new memories are created containing elements from both the original and the misleading information; • the ‘supplementation’ viewpoint whereby the witness does not notice the vital detail in the first place but assimilates it into the original memory after being given the misleading information; and • the ‘coexistence’ viewpoint whereby both the original and the misleading postevent information are taken in but the more recent memories are more easily accessible. These different interpretations have been of practical importance because they influence the way attempts might be made to correct a memory that has been biased. For example, in successfully testing the coexistence theory, Bekerian and Bowers (1983, cited in Loftus, 1989) concluded that countering the effects of misleading postevent information is dependent on using appropriate retrieval techniques to access the original memory, such as by reinstating the original sequence of events. Although carried out in laboratory conditions, using mostly students as the ‘eyewitnesses’, the findings of these and similar experiments have provided a large body of evidence confirming the contamination of memory. Some of this evidence was hotly debated, as witnessed by the legal controversy surrounding supposed ‘recovered’ memories of childhood sexual abuse (Lindsay & Read, 1994). However, one could speculate that if highly motivated and relaxed students display impaired memory performance, then an even worse performance could be expected of witnesses without such characteristics being interviewed in less than optimal conditions. How the memory y works Given the fallibility of memory, it is vital that police interviewers understand how memory works, the ways in which errors and omissions arise, and how they themselves can influence what interviewees tell them (Cohen, 1999; Milne and Bull, 1999; CFIS, 2004). This understanding allows interviewers to judge more accurately how much witnesses can be expected to recall about a to-be-remembered (TBR) event and how much weight can be placed on the testimony they produce. For convenience, two diagrams from the literature are shown below. These illustrate and summarise the research findings on memory. 28
REVIEW OF INVESTIGATIVE INTERVIEWING Three separate memory y stores The multi-store model of memory is shown in Figure 1 below: Retrieval Stimulus Input Sensory Stores Recording Process Short-Term Memory Recording Process Long-Term Memory Response Output Retrieval Rehearsal Lasts 1-4 seconds Stores raw uncoded Visual and auditory information Lasts 6-12 seconds Capacity of about 7 items Acoustic or visual code Lasts potentially indefinitely Capacity limited by Interference but potentially very large Mainly semantic coding Organisation crucial for retrieval Figure 1: The multi-store model of memory (originally proposed by Atkinson & Shiffrin, 1968, cited in Cohen, 1999, p5). Cohen’s explanation of the model [in a slightly abbreviated form] is as follows: 1. The sensory store is believed to hold raw, uninterpreted information perceived by the sense organs (e.g., sight, sound, smell). Only a sub-set of the information that enters the sensory stores is selected and passed on to the short-term store. 2. Short-term memory corresponds to the current contents of consciousness i.e. what you have in mind at any one moment. It has a brief duration and a strictly limited capacity. It is also very fragile in that any distraction or new incoming information will cause items to be bumped out and lost. However, it is possible to maintain the contents by ‘rehearsing’ information either aloud or subvocally e.g., repeating a phone number you are about to dial. Only a proportion of information in short-term memory passes into long-term memory. 3. The duration and capacity of long-term memory is virtually unlimited, although information only becomes available to conscious awareness through an act of recollection. Some long-term memories cannot be recollected. Memory y processes So what happens when people try to remember something? Milne and Bull (1999, p11) describe the three memory processes that form a sequence of stages: encoding, storage and retrieval. “Encoding concerns the process through which information is entered into memory. A physical input, such as the appearance of a perpetrator, is transformed into a representation that memory receives. This perpetrator’s appearance that has just been encoded is stored in memory. At interview, a few hours or days later, an interviewee may need to describe the perpetrator, therefore he or she attempts to retrieve this information from memory.” Errors can occur at the acquisition stage, or may be introduced at the retention (storage) stage, or they can occur during the retrieval or narration stage (Yarmey, 2003). An indepth exploration of the risks of corruption of memory caused by outside events, mental and physical disorder and illness, and the vulnerabilities of certain categories of witness can be found in “Analysing Witness Testimony” edited by Heaton-Armstrong, Shepherd and Wolchover (1999). 29
Page 1: R E V I E W O F I N V E S T I G AT
Page 4 and 5: ABOUT THE AUTHOR Mary Schollum (BA,
Page 6 and 7: Investigative Interviewing: viewing
Page 82 and 83:
Investigative Interviewing: viewing
Page 84 and 85:
Page 86 and 87:
Page 88 and 89:
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
show all

Investigative interviewing: the literature - New Zealand Police

Create successful ePaper yourself

Delete template?

Save as template?