Hypnotic susceptibility and the perception of afterimages and dot stimuli

Three experiments were conducted to determine the relationship between hypnotic susceptibility level and the susceptibility to several perceptual phenomena. Experiment I required subjects to observe an induced afterimage in a light-proofed environment and to report the frequency of direction and color changes. In addition, subjects reported the persistence of the afterimage. Experiment II involved the observation of a black dot against a white background, with frequency of observed movement being the dependent measure. Experiment III was similar to the second experiment except that the stimulus was encompassed by a frame. In Experiments I and II, subjects judged high in hypnotic susceptibility reported perceiving the strongest effect. This phenomenon was virtually eliminated in the third experiment. These results were interpreted as supporting a process whereby subjects judged high in hypnotic susceptibility are better able to selectively attend to relevant cues in a stimulus array during conditions of perceptual impoverishment.     

Goal-directed fantasy, hypnotic susceptibility, and expectancies

We conducted an initial screening session in which hypnosis was presented as a "test of imagination" and administered with other imagination measures. In a second session, we instructed high- and low-hypnotizable subjects to imagine along with suggestions but to resist responding to motoric suggestions. Subjects received either instructions to use goal-directed fantasies (GDFs) or no facilitative instructions. Sizable individual difference effects were secured. Hypnotizable subjects exhibited more suggestion-related movements and reported greater involuntariness than did low-hypnotizable subjects. With GDF instructions, low- and high-hypnotizable subjects reported equivalent GDF absorption and frequencies. However, hypnotizable subjects exhibited greater responsiveness and reported greater involuntariness than did those low in hypnotizability, even when their GDFs were equivalent. Thus, no support was generated for the hypotheses that sustained, elaborated suggestion-related imagery mediates response to suggestion (Arnold, 1946) or that absorption in suggestions is of particular importance for low-hypnotizable subjects (Zamansky & Clark, 1986). Our finding that measures of response expectancy paralelled responding and reports of nonvolition support the hypothesis that expectancies mediate the relation between imagination, involuntariness, and responding (Kirsch, 1985; Spanos, 1982). Hypnotizable imagining subjects in the study discussed here exhibited greater responsiveness than a comparable sample of subjects did in a previous countersuggestion study (Lynn, Nash, Rhue, Frauman, & Stanley, 1983) in which no attempt was made to foster an association between imagining and involuntary responding in the initial screening session.     

Imagery ability and the identification of fragmented pictures and words

High and low imagery individuals completed two paper-and-pencil identification tasks involving fragmented pictures and fragmented words. Although a trend was present for spatial measures of imagery ability to correlate more highly with picture than with word identification, high imagers nevertheless surpassed low imagers on both tasks. An interpretation emphasizing the spatial-imaginal demands of both tasks is suggested. Significant correlations between word identification and some verbal measures, as well as self-reported imagery, may have resulted from the differential priming of verbal and imaginal strategies following subtle procedural changes in the two experiments described.     

Assessing vividness of mental imagery: The Plymouth Sensory Imagery Questionnaire

Mental imagery may occur in any sensory modality, although visual imagery has been most studied. A sensitive measure of the vividness of imagery across a range of modalities is needed: the shorter version of Bett's Questionnaire upon Mental Imagery (Sheehan, 1967 , J. Clin. Psychology, 23, 386) uses outdated items and has an unreliable factor structure. We report the development and initial validation of the Plymouth Sensory Imagery Questionnaire (Psi‐Q) comprising items for each of the following modalities: Vision, Sound, Smell, Taste, Touch, Bodily Sensation, and Emotional Feeling. An exploratory factor analysis on a 35‐item form indicated that these modalities formed separate factors, rather than a single imagery factor, and this was replicated by confirmatory factor analysis. The Psi‐Q was validated against the Spontaneous Use of Imagery Scale (Reisberg et al., 2003 , Appl. Cogn. Psychology, 17, 147) and Marks' ( 1995 , J. Mental Imagery, 19, 153) Vividness of Visual Imagery Questionnaire‐2 (VVIQ‐2). A short 21‐item form comprising the best three items from the seven factors correlated with the total score and subscales of the full form, and with the VVIQ‐2. Inspection of the data shows that while visual and sound imagery is most often rated as vivid, individuals who rate one modality as strong and the other as weak are not uncommon. Findings are interpreted within a working memory framework and point to the need for further research to identify the specific cognitive processes underlying the vividness of imagery across sensory modalities.     

Multiple predictors of hypnotic susceptibility

In this article, we report two experiments in which various measures thought to be related to hypnotizability were analyzed by stepwise discriminant analysis techniques. Absorption (Tellegen, 1981, 1982; Tellegen & Atkinson, 1974) and preference for an imagic style of thinking (Isaacs, 1982) were robust predictors of hypnotizability; each variable accounted for significant variance in hypnotizability at their respective steps in two samples and correctly classified a significant proportion of low- and high-hypnotizable subjects in the discriminant analyses. The addition of two other variables in Experiment 2--a Sleep-Dream score derived from Evans's (1977) Cognitive Control of Sleep Mentation subscale and Gibson's (1985) Dream Questionnaire, and the Belief in the Supernatural subscale of the Taft (1969) Experience Questionnaire--increased the correct classification of the medium-hypnotizable subjects from chance levels to 74%. It is argued that a confirmatory and hierarchical approach is needed in future studies to explore correlates of hypnotizability more fully.     

Influences of closure,occlusion, and size on the perception of fragmented pictures

Two experiments examined the ability to recognize a repeated figure in stimuli where only fragments of the figures were presented. Fragments were either closed or open regions presented either with or without an occluder that filled the spaces between the fragments (Experiment 1). Recognition performance was significantly better for open fragments, with or without an occluder, contrary to previous assertions that the occluder is the important factor for recognition. When stimulus size was varied, an occluder hindered recognition performance in the smallest size condition relative to unoccluded stimuli, which were equally easy to recognize across all size conditions (Experiment 2). The size results support the idea of size invariance in object naming. The difficulty in the smallest occluded condition is discussed in terms of differences in global and local processing depending on visual angle and sparsity     

Categorical perception of stereoscopic stimuli

Two studies of the stereopsis model of Richards were conducted using a between-subjects balanced design and a repeated trials procedure rather than the within-subjects procedure of Richards. Measures of the accuracy of discrimination between classes of retinal disparity were defined by the method of successive intervals in place of the d’ index of SDT. The results support the predictions (1) of symmetric discrimination functions for convergent and divergent stimuli, (2) of greater discrimination for stimuli of 45 min of retinal disparity than for the stimuli of 15 min disparity, (3) of greater variability for the stimuli of greater disparity, and (4) of the use by nonanomalous subjects of at least two different processing mechanisms for stimuli of different disparity classes. The results do not support the prediction (1) of different processing mechanisms for foveal stimuli differing in figure-ground contrast or (2) of greater usefulness for monocular stimuli as a null disparity reference condition, as compared with binocular null disparity stimuli. Similar results were found for two stimulus shapes, a bar and a disk of equal area. Unreliability of subjects’ response systems was suggested as a factor in the prediction of figure-ground contrast changes and as a factor in the classification of subjects as stereo anomalous. The pattern of accuracy of discrimination between classes of disparity stimuli also raises questions of the adequacy of the simple stereopsis model.     

On the successive perception of simultaneous stimuli

Attention, Perception, & Psychophysics - When Ss hear two messages concurrently over different “channels” (e.g., different ears, different voices, etc.), they tend to report first...     

Enhancing hypnotic susceptibility: interpersonal and rapport factors

This research supported the hypothesis that hypnosis can be thought of as a set of potentially modifiable social-cognitive skills and attitudes. A low-interpersonal-training treatment devised by Gorassini and Spanos (1986) was compared with a treatment designed to modify not only cognitive factors but also to augment rapport with the trainer and diminish resistance to responding (high-interpersonal training). Fifty percent of the initially unhypnotizable subjects in the high-interpersonal condition tested as being highly susceptible to hypnosis (high susceptibles) at posttest on the Harvard Group Scale of Hypnotic Susceptibility (Shor & Orne, 1962); 25% of the unhypnotizable subjects in the low-interpersonal condition responded comparably. Eighty-three percent of the medium-susceptibility (medium susceptibles) subjects tested as being highly susceptible at posttest in both conditions. Practice-alone control subjects' performance was stable across testings. The study was the first to demonstrate that treatment gains generalize to a battery of novel, demanding suggestions (generalization index) that have been found to differentiate highly susceptible subjects from unhypnotizable simulating subjects. The importance of rapport was evidenced by the finding that rapport ratings paralleled group differences in hypnotic responding and that rapport correlated substantially with susceptibility scores at posttest and with the generalization index. Whereas initial hypnotizability scores correlated significantly with retest susceptibility scores, initial hypnotizability failed to correlate significantly with the generalization index.