D. C. Donderi

Nightmares and bad dreams : Their prevalence and relationship to well-being

This study, for the first time, distinguishes between nightmares and bad dreams, measures the frequency of each using dream logs, and separately assesses the relation between nightmares, bad dreams, and well-being. Eighty-nine participants completed 7 measures of well-being and recorded their dreams for 4 consecutive weeks. The dream logs yielded estimated mean annual nightmare and bad-dream frequencies that were significantly (ps < .01) greater than the mean 12-month and 1-month retrospective estimates. Nightmare frequency had more significant correlations than bad-dream frequency with well-being, suggesting that nightmares are a more severe expression of the same basic phenomenon. The findings confirm and extend evidence that nightmares are more prevalent than was previously believed and underscore the need to differentiate nightmares from bad dreams.

Visual Complexity: A Review.

The idea of visual complexity, the history of its measurement, and its implications for behavior are reviewed, starting with structuralism and Gestalt psychology at the beginning of the 20th century and ending with visual complexity theory, perceptual learning theory, and neural circuit theory at the beginning of the 21st. Evidence is drawn from research on single forms, form and texture arrays and visual displays. Form complexity and form probability are shown to be linked through their reciprocal relationship in complexity theory, which is in turn shown to be consistent with recent developments in perceptual learning and neural circuit theory. Directions for further research are suggested.

Decision latencies of “same” and “different” judgments

When a subject is asked to judge whether two stimuli are “same” or“different,” the time he takes to reach the decision same is frequently unequal to the time he takes to reach the decision different. We studied this discrepancy as a function of several variables, including stimulus modality, “codability” vs.“noncodability” of test stimuli, interstimulus interval, and discrimination difficulty. Results of four different experiments performed on a total of 111 subjects showed codability and discrimination difficulty to be the most important factors. Stimuli that are codable (i.e., which can be categorized by absolute judgment) yield a shorter latency for decision same, and noncodable stimuli (i.e., those requiring a reference stimulus for categorization) yield a longer latency for decision same. The modality of test stimuli, the prothetic or metathetic nature of the dimension to be judged, and simultaneous vs. successive presentation of the stimuli appear not to be crucial factors.

Parallel processing in visual same-different decisions

Two to 13 geometrical shapes were exposed simultaneously to S who decided whether all shapes were the same or whether one was different from the rest. Correct different decisions were usually faster than correct same decisions, but latency was independent of the number of shapes presented. We conclude that input from all the shapes was simultaneously processed into either one or two shape categories, and that a decision-theory choice was made between “same” (one shape category) and “different” (two shape categories) independent of the total number of shapes. This parallel processing is thought to be a characteristic of codable stimuli. Some observed same-different latency reversals were probably caused by a shift in the same-different criterion on the continuum for one- vs two-category decisions.

Prevalence of Auditory, Olfactory, and Gustatory Experiences in Home Dreams

Although numerous studies have investigated the content of laboratory and home dream reports, surprisingly Little is known about the prevalence of various sensory modes in dreams. 49 men and 115 women completed a battery of questionnaires and kept a home dream diary for two to three consecutive weeks. Retrospective responses to the questionnaire indicate that approximately 33% of men and 40% of women recalled having experienced sensations of smell or taste in their dreams. A total of 3372 dream reports were collected and scored for unambiguous references to auditory, olfactory, and gustatory experiences. Auditory experiences were reported in approximately 53% of all dream reports. Olfactory and gustatory sensations occurred in approximately 1% of all dream reports. A significantly greater percentage of women than men reported one or more dreams containing references to olfactory sensations. The results lend support to previous studies which have shown that a variety of sensory experiences, although relatively rare, can occur in dreams.

An Information Theory Analysis of Visual Complexity and Dissimilarity

The subjective complexity of a computer-generated bitmap image can be measured by magnitude estimation scaling, and its objective complexity can be measured by its compressed file size. There is a high correlation between these measures of subjective and objective complexity over a large set of marine electronic chart and radar images. The subjective dissimilarity of a pair of bitmap images can be predicted from subjective and objective measures of the complexity of each image, and from the subjective and objective complexity of the image produced by overlaying the two simple images. In addition, the subjective complexity of the image produced by overlaying two simple images can be predicted from the subjective complexity of the simple images and the subjective dissimilarity of the image pair. The results of the experiments that generated these complexity and dissimilarity judgments are consistent with a theory, outlined here, that treats objective and subjective measures of image complexity and dissimilarity as vectors in Euclidean space.

Jungian personality typology and the recall of everyday and archetypal dreams.

Hypotheses concerning the relations among personality types, neuroticism, and the recall of archetypal dreams were derived from Jungian theory. Dream records were obtained from a nonclinical population in two stages: first, recall of the most recent, most vivid, and earliest remembered dreams (N = 146), and then dream recall on awakening, over an average of 23 nights, from 30 of the first-sample subjects. A total of 697 dreams was recorded. Subjects also completed the Eysenck Personality Inventory (EPI) the Myers-Briggs Personality Inventory, and a Dreaming Questionnaire. Dream archetypality was rated in accordance with procedures of H. Y. Kluger. The distribution of archetypal dreams across earliest (n = 106), most vivid (n = 105), and most recent (n = 102) dream types matched Klugers earlier results. The dream diary recall data showed that Jungian intuitives, as measured via Myers-Briggs continuous scores, recalled more archetypal dreams; introverts, as measured via Myers-Briggs continuous scores, recalled more everyday dreams; high EPI neuroticism scorers recalled fewer archetypal dreams. The results support several propositions of Jungian personality theory.

Dream Content, Dream Recurrence and Well-Being: A Replication with a Younger Sample

A multivariate comparison was made among fifty-two recurrent, past-recurrent, and nonrecurrent dreamers aged eighteen to twenty-one. The participants completed measures of well-being and collected a fourteen-day sample of their own remembered dreams. Multivariate analysis showed that recurrent dreamers scored low on psychological well-being and reported more negative dream content. As was true in an earlier study, a single psychometric dimension, which we call psychological well-being, discriminated between the recurrent dream group and the other two groups over the entire set of well-being and dream content variables. As was true in two previous studies, dream archetypality was negatively correlated with a measure of neuroticism. We conclude that in both late teenagers and older adults, recurrent dreams occur in times of stress, are accompanied by negative dream content, and are associated with a deficit in psychological well-being.

Sensed presence as a correlate of sleep paralysis distress, social anxiety and waking state social imagery.

Isolated sleep paralysis (ISP) is a common parasomnia characterized by an inability to move or speak and often accompanied by hallucinations of a sensed presence nearby. Recent research has linked ISP, and sensed presence more particularly, with social anxiety and other psychopathologies. The present study used a large sample of respondents to an internet questionnaire (N=193) to test whether these associations are due to a general personality factor, affect distress, which is implicated in nightmare suffering and hypothesized to involve dysfunctional social imagery processes. A new measure, ISP distress, was examined in relation to features of ISP experiences, to self-reported psychopathological diagnosis, to scores on the Leibowitz Social Anxiety Scale and to scores on a new questionnaire subscale assessing social imagery in a variety of waking states. Three main results were found: (1) ISP experiences are only weakly associated with a prior diagnosis of mental disorder, (2) sensed presence during ISP is associated preferentially with ISP distress, and (3) ISP distress is associated with dysfunctional social imagery. A general predisposition to affective distress may influence the distress associated with ISP experiences; overly passive social imagery may, in turn, be implicated in this affect distress influence.

Parallel visual processing: Constant same-different decision latency with two to fourteen shapes

Fourteen Os were shown 2, 5, 8, 11, or 14 geometric shapes at a 200-msec exposure. The maximum visual extent was the same for all numbers of shapes. The stimulus conditions were: all shapes identical, 1 shape different from the rest, and, for 5 to 14 shapes, 3 shapes different (4 shapes in all). The number of shapes, the condition, and the shapes used varied randomly through the sequence of 160 exposures. Decision latency to correct same or different response was independent of the number of shapes presented. Correct same and three-different decisions were faster than one-different decisions, but with two shapes different decisions were faster than same. The results suggest that same-different decisions are made with information processed in parallel from many stimuli