Malingering on the RAVLT Part II. Detection strategies

Archives of Clinical Neuropsychology 17 (2002) 223 – 233 Malingering on the RAVLT Part II. Detection strategies Karen Sullivan*, Cassandra Deffenti, Beth Keane School of Psychology and Counselling, Queensland University of Technology, Carseldine, Queensland 4034, Australia Accepted 17 January 2001 Abstract In this study two potential indices of malingering derived from the Rey Auditory Verbal Learning Test (RAVLT) were evaluated as a means of detecting malingering. These were indices based on discrepancies between recognition– recall scores and differences in the serial position effect (SPE). Sixty undergraduate students were randomly assigned to one of four conditions: malingerers, malingerers-with-warning, warning-only, and control. Incentives were offered to participants in all conditions to encourage faking in a believable manner (malingering conditions), or to encourage optimal performance (nonmalingering conditions). Two predictions were made. First, it was predicted that the serial position curve for subjects in malingering conditions would show suppression of primacy effects relative to nonmalingerers. Second, it was predicted that recall would be better than recognition for subjects in malingering conditions compared to nonmalingering conditions. The utility of these indices was also explored in the context of providing subjects’ with warnings regarding use of methods to detect malingering. Results indicated that both indices failed to reliably differentiate between malingerers and nonmalingerers, and warnings failed to modify participants’ behaviour. D 2002 National Academy of Neuropsychology. Published by Elsevier Science Ltd. Keywords: Neuropsychology; Malingering; RAVLT; Serial position effect * Corresponding author. E-mail address: (K. Sullivan). 0887-6177/02/$ – see front matter D 2002 National Academy of Neuropsychology. 0 8 8 7 - 6 1 7 7 ( 0 1 ) 0 0 11 0 - X Downloaded PII: from Shttps://academic.oup.com/acn/article-abstract/17/3/223/2078 by guest on 10 May 2018 224 K. Sullivan et al. / Archives of Clinical Neuropsychology 17 (2002) 223–233 1. Introduction There is a growing body of literature reflecting attempts to identify and improve malingering detection strategies in a neuropsychological context (see Heubrock & Petermann, 1998 for a recent review). For example, methods of detection that have been investigated previously include attempts to identify discrepancies in information provided at interview, during testing, and through observation, as well as attempts to examine test scores to determine the presence of atypical patterns of performance (Haines & Norris, 1995; Rogers, Harrell, & Liff, 1993). Atypical patterns of performance that have been investigated for their potential to distinguish malingerers from nonmalingerers include below-chance performance and performance that deviates from patterns produced by reliable cognitive phenomenon (e.g., absence of priming effects, serial position effects (SPEs), or higher rates of recall than recognition on memory tasks). This paper focuses on the absence of SPEs and atypical discrepancies between recognition–recall as a means of detecting malingering. 2. Serial position effects SPEs are typically found on verbal list learning tasks and describe a pattern of results that can be consistently demonstrated in healthy adults (Haberlandt, 1997). That is, when asked to recall a list of words, the first and last third of a list are more likely to be remembered than words from the middle of the list. The increased likelihood of recall of words from these positions produces a U-shaped pattern of results that is indicative of primacy and recency effects. Differences in SPEs have been explored as a means of detecting malingering previously. For example, Bernard (1991) showed that SPEs differentiated malingerers from nonmalingerers on the Rey Auditory Verbal Learning Test (RAVLT). Malingerers were found to suppress recall of words in the first third of the list, demonstrating significantly reduced primacy effects relative to nonmalingerers. The rationale for exploring the SPE as a tool for detecting malingering is based on the nature of this phenomenon. That is, as an index of implicit memory function, serial position curves usually occur beyond the awareness of the person completing the memory task, and as such, can be reliably demonstrated. Therefore, the absence of SPEs might indicate an attempt to consciously modify responses, producing an atypical pattern of results. Studies attempting to replicate Bernard’s (1991) finding of reduced primacy effects among malingerers have yielded contradictory results. For example, a later study conducted by Bernard, Houston, and Natoli (1993) found no significant differences in SPEs between simulators and controls. Although malingerers performed significantly worse than controls on the RAVLT, results from both groups conformed to the U-shaped curve that is characteristic of normal primacy and recency effects. Similarly, Flowers, Sheridan, and Shadbolt (1996) showed that serial position curves for malingerers and nonmalingerers had the same shape, and groups could not be differentiated based on a comparison of SPEs. Given this inconsistent pattern of results, it is unclear to whether the analysis of SPEs can be used to detect malingering, or more specifically, to identify deliberately poor performance. K. Sullivan et al. / Archives of Clinical Neuropsychology 17 (2002) 223–233 225 There may also be some contexts in which analysis of SPEs is more effective than others, although this has not been investigated previously. For example, it may be possible to demonstrate the utility of an SPE-based index in contexts where a warning about malingering is explicitly provided. The warning literature suggests that would-be malingerers, when informed that methods of detecting malingering will be employed during assessment, modify their behaviour and do not perform as poorly as ‘‘unwarned’’ malingerers (Johnson & Lesniak-Karpiak, 1997). A possible explanation for this result lies in deterrence theory (Sullivan, Keane, & Deffenti, in press). However, it has also been suggested that warnings may result in more sophisticated attempts to malinger (Youngjohn, Lees-Haley, & Binder, 1999). This suggestion is based around concerns that rather than deterring would-be malingerers from faking or exaggerating deficits, warnings may produce malingerers who are more difficult to detect. If this is the case and the provision of warnings produces more ‘‘sophisticated’’ malingerers, analysis of differences in SPEs (or other indices of atypical performance that are usually beyond the subject’s awareness) might enable this to be detected. 3. Recognition–recall Another approach to the detection of malingerers based on atypical patterns of performance involves use recognition– recall discrepancy scores. For example, it is generally accepted that healthy people recall less than they recognise (B (...truncated)