On a different but related front, a study by Aleman et al. (2000) sought to investigate the Perky phenomenon, or the theory that the cognitive mechanisms involved in reality testing are similar between normal control groups and psychotic, hallucinating groups. 243 undergraduates from Utrecht University were screened for a propensity toward hallucinations by the Launay-Slade Hallucination Scale (LSHS). The LSHS purports to measure an individual’s tendency towards hallucinations by posing such questions as, “I often hear a voice speaking my thoughts aloud.” 19 high scoring participants and 17 low scoring participants were selected. Male to female ratios between groups were comparable, and the mean difference between groups was significant: t = 23.7, p < .0001.
The two selected groups were then administered both the Betts QMI Vividness of Imagery Scale and the Marks Vividness of Visual Imagery Questionnaire (VVIQ). Several experimental tasks were administered to both groups. The tasks involved both visual and auditory imagery perception comparison tasks, as well as a musical imagery task (to assess auditory modalities) and a letter imagery task (to assess visual modalities). While the precise methodology of these visual and auditory tasks varied throughout the experiment, the nature of the experiment required participants to create a mental image in order to make accurate decisions. In the perceptual condition, for example, pictures of the following objects would be presented to the participants: “pumpkin”, “lettuce” and “tomato”. In contrast, in the imagery condition, only the names of the objects were presented—thus, creating the need for the formation of mental images.
With two questionnaires and three experimental tasks (each with two subdivisions of an auditory and visual modality), replication of descriptive statistics here would likely bog down the reader and serve only to distract from the overall argument of this paper. Still, the results of Aleman’s copious work were positive: the researchers replicated earlier results showing that hallucination prone individuals report more vivid mental imagery. The two groups, however, did not differ at all on five of the six experimental imagery tasks. For this reason, Aleman et al. concluded that the—as yet unknown—cognitive processes implicated in reality testing, rather than heightened mental imagery, play a decisive role in hallucinatory events.
Aleman et al.’s introduction ironically provides highlights of the inconsistencies of the current literature regarding the more vivid mental imagery hypothesis in hallucinating individuals. Providing a brief synopsis of the literature, the researchers note how Slade (1976) and Mintz and Alpert (1972) found that hallucinating individuals experienced more vivid mental imagery compared to their non-hallucinating counterparts. Brett and Starker (1977) and Starker and Jolin (1982), on the other hand, unable to replicate the above findings, could not discern evidence of more increased vivid mental imagery in hallucinating vs. non-hallucinating patients. Aleman et al. argue that the latter two studies failed to replicate previous findings because both studies were concerned with “introspective measures of imagery, which are limited to the subjective experience of imagery.”
The underlying assumption in Aleman et al.’s critique highlights the present argument uncannily. With a lacuna of a systematic epistemological presentation and his association of internal events with subjectivity, Aleman et al.’s position smacks suspiciously of positivism. That is, Aleman et al. seem to imply that what is “out there” is objective and real, and what is inside is subjective and faulty.
Space does not permit a complete analysis and defense of the way in which internal data, of themselves, are not necessarily subjective or less real than external data. The curious reader is refered to Bernard Lonergan’s seminal work, Insight. Regardless, the original argument of this paper—that the success of future cognitional research regarding hallucinations derives by securing it in a common epistemological framework—is clearly shown. Aleman’s approach, and subsequent critique, differs from Starker and Jolin’s (1982), who in turn differ from Mintz and Alpert (1972), who in turn, no doubt, will differ from future researchers. The lack of unity comes not from their respective choice of instruments, or from their sample size, or even the statistical tests chosen, but rather from their fundamental differences of epistemological and cognitional theories.
A further explanation for the possible cognitive mechanism underlying hallucinations is the liberal response bias, which claims that hallucinatory patients will more likely report imaginary events as real. That is, the tendency to make false (and often early) detection in cases of doubt or uncertainty of the presented stimuli has been found to be correlated with hallucinating individuals. As is common, this phenomenon has been replicated in numerous studies throughout the literature. A 2005 study, again by Brébion et al., sought to extend this theory using new measures. As with Aleman et al. above, Brébion et al. similarly introduce their research by indicating the conflicting results between their research and the literature. Specifically, Brébion et al. note how Ragaland et al. (2003) reported findings that indicate a liberal response bias is associated with delusions, not hallucinations. Heinrichs and McDermid-Vaz (2004), however, were unable to detect any relationship between false word recognition and global positive symptoms scores in individuals with schizophrenia. Brébion et al. naturally conclude that Heinrichs and McDermid-Vaz (2004) misinterpreted the data, and undertake the current studies to confirm their hypothesis.
In order to test the liberal response bias hypothesis, Brébion et al. administered a word recognition test to 40 in and out patient individuals with schizophrenia. After being assessed for both positive and negative symptoms, participants were shown 16 concrete, simple words. Each list contained 8 high frequency words and 8 low frequency words. Participants were instructed that they had 45 seconds to memorize the list, and were required to read the list aloud. After a five minute pause the participants were given a blank sheet and asked to transcribe as many words as possible from memory. They were then provided a recognition sheet containing the 16 actually seen words as well as 16 distractor words, and asked to circle the words from the original list. A second word list was provided with similar instructions. In this second session, however, participants were provided the recognition sheet (with accompanying distractor words) immediately following the presentation of the original word list.
As predicted, Brébion et al. found a significant correlation between hallucination scores and response bias, and the researchers interpreted this to imply that higher levels of hallucinations are related to the propensity to make more false recognition of words not actually presented in the list. The researchers found further that anhedonia had a significant relationship with a reduction in response bias—indicating the opposite effect for that of hallucinations. During data analysis, participant scores on the National Adult Reading Test (NART) were factored, in an attempt to control for the effects of memory and verbal intelligence.
Two distinct limitations are apparent in this work. First, as in the Aleman et al. critique, requiring participant vocalization of the word unnecessarily inserts an external component to the measurement of an internal event. Second, Brébion et al. interprets the results to indicate that the liberal response bias exhibited directly implicate an external source. The problem with this assumption is that it is simply not supported by the literature. Although several studies on hallucinations indicate that patients attribute their hallucinations occurring “from outside” (ie, externalizing), there are equally ample cases where
hallucinations are reported to be from “inside” (Copoloy, Trauer and Mackinnon, 2004; Junginger and Frame, 1985). That is, Brébion et al. seem to assume that hallucinations must have an externalizing component to be a hallucination. Finally, as the literature itself shows inconsistencies, perhaps the fundamental issue at hand is the use of a paradigm that could embrace the constructs relevant to this research—concepts such as self vs. other, subjective vs. objective reality, and internal vs. external events.
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