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PubMed1991

Marijuana use, introspectiveness, and mental health.

Conflicting evidence suggests that marijuana use may be associated with either positive or negative mental health. This study explores the possibility that the association of marijuana use with mental health differs among various subgroups of users. Specifically, we investigate the hypothesis that marijuana use and the personality disposition of introspectiveness interact in their effects on psychological well-being. Results support this hypothesis and show that marijuana use is associated significantly with psychological distress for highly introspective individuals. In contrast, marijuana use has no such association for those low on introspectiveness. Additional evidence shows that marijuana use involves primarily self-oriented cognitive and emotional experiences for highly introspective individuals, whereas for those low on introspectiveness it is characterized more often by perceptual distortions and sensorimotor sensations.

Adult↗
PubMed1990

A case of bupropion-associated delirium.

The authors report a case of bupropion-associated delirium characterized by disorganized thinking, memory impairment, fear, and agitation but not disorientation, delusions, hallucinations, or other perceptual distortions. Symptom onset appeared to be dose-related, and a sustained therapeutic response was subsequently obtained at a lower dose of bupropion without recurrence of delirium. Abnormal bupropion metabolism and elevated plasma metabolite levels did not account for the adverse reaction, which instead was hypothesized to reflect dopaminergic effects of bupropion.

Antidepressive Agents↗
PubMed1981

Amblyopic abnormality involves neural mechanisms concerned with movement processing.

In strabismic amblyopia the detection of apparent movement for counterphase gratings is considerably more impaired than the detection of pattern. No such anomaly is found for the detection of changes from a blank field when gradual or abrupt onsets or offsets of the temporal grating presentation are used. Similarly, normal peripheral vision is relatively poor in detecting alternation of spatial phase. It is concluded that the observed movement abnormality does not reflect a loss in sensitivity of transient mechanisms but rather a visual insensitivity to spatial phase. This would explain why perceptual distortions and low optotype acuity occur in amblyopes with normal contrast sensitivity.

Amblyopia↗
PubMed1980

Enuresis: a functional equivalent of a fetish.

The split in the ego between consciousness and unconsciousness which sometimes eventuates in fetishism can also be clinically manifested in sleep disturbances, depersonalization, dejà vu and a variety of alterations in the sense of reality. It is suggested that this same split comprises the central dynamic mechanism in enuresis. The sleep disturbance which accompanies enuresis involves a confusion between waking and sleeping, sometimes taking the form of a dream that one is awake. Three patients(adult males) revealed in the course of their analyses that they suffered from childhood enuresis accompanied by a sleep disturbance. Milder forms of sleep disturbances persisted into adult life. In these analyses, certain perceptual distortions, difficulties in the sense of reality, and between fantasy and reality, confusions between waking and sleeping, could all be linked to the functional split between consciousness and unconsciousness and eventually to disavowal of the female genitals. The enuresis represented a functional equivalent of the fetish (and it may be that the urinary stream itself actually served as a fetish). Psychological test data from nine enuretic boys were examined as well. This material clearly demonstrated that these boys wished to deny the differences between males and females, that they suffered from sleep disturbances and that they confused reality and fantasy, sleeping and waking. The combined data suggest the existence of a functional split in the ego used in the service of defence, the product of a regressive fixation and a reinstatement of an archaic mode of thought.

Adolescent↗
PubMed1997

The nature and extent of body-image disturbances in anorexia nervosa and bulimia nervosa: a meta-analysis.

OBJECTIVE: Although body-image disturbance is among the diagnostic criteria for anorexia nervosa and bulimia nervosa, the nature and extent of this disturbance have not been precisely identified. This is the purpose of this first meta-analysis of extant research on body image and eating disorders. METHOD: Using contemporary techniques, the meta-analysis systematically examined 66 studies (from 1974 to 1993) of perceptual and attitudinal parameters of body image among anorexics and bulimics relative to control groups. RESULTS: Attitudinal body dissatisfaction, both questionnaire and self-ideal discrepancy measures, produced substantially larger effect sizes than did perceptual size-estimation inaccuracy. Body dissatisfaction measures, whether global or weight/shape related, differentiated bulimic and anorexic groups (with bulimics having more dissatisfaction), whereas perceptual distortion indices did not. Somewhat larger effects occurred with whole-body than with body-part size-estimation assessments. Size distortion among patients with eating disorders appears unlikely to reflect a more generalized sensory/perceptual deficit. DISCUSSION: Scientific, conceptual, and clinical implications of these findings are delineated.

Anorexia Nervosa↗
PubMed2005

Lexical information drives perceptual learning of distorted speech: evidence from the comprehension of noise-vocoded sentences.

Speech comprehension is resistant to acoustic distortion in the input, reflecting listeners' ability to adjust perceptual processes to match the speech input. For noise-vocoded sentences, a manipulation that removes spectral detail from speech, listeners' reporting improved from near 0% to 70% correct over 30 sentences (Experiment 1). Learning was enhanced if listeners heard distorted sentences while they knew the identity of the undistorted target (Experiments 2 and 3). Learning was absent when listeners were trained with nonword sentences (Experiments 4 and 5), although the meaning of the training sentences did not affect learning (Experiment 5). Perceptual learning of noise-vocoded speech depends on higher level information, consistent with top-down, lexically driven learning. Similar processes may facilitate comprehension of speech in an unfamiliar accent or following cochlear implantation.

Adolescent↗
PubMed2003

Squared error as a measure of perceived phase distortion.

Based on two well-known auditory models, it is investigated whether the squared error between an original signal and a phase-distorted signal is a perceptually relevant measure for distortions in the Fourier phase spectrum of periodic signals obtained from speech. Both the performance of phase vector quantizers and the direct relationship between the squared error and two perceptual distortion measures are studied. The results indicate that for small values the squared error correlates well to the perceptual measures. However, for large errors, an increase in squared error does not, on average, lead to an increase in the perceptual measures. Empirical rate-perceptual distortion curves and listening tests confirm that, for low to medium codebook sizes, the average perceived distortion does not decrease with increasing codebook size when the squared error is used as encoding criterion.

Fourier Analysis↗
PubMed1999

Two-dimensional distortion of space representation in unilateral neglect: perceptual and response-related factors.

The paper reports the results of an experiment in which left-neglect patients were required to point at the location they judged vertically to correspond (within the frame of the visual stimulus display they were given) with a cue that was variably located along a left-right axis lying proximally or distally with respect to the left-right axis over which they had to give their response. Patients were found to make rightward errors as in a similar, single-case study. The significant positive correlation between those errors and the degree of response bias on a manual-response version of the Milner Landmark Task suggests that rightward pointing errors made by left-neglect patients in conditions such as those set in the present experiment are due to a dysfunction selectively affecting an output-related component of space representation.

Aged↗
PubMedDate not supplied

Centration-distortion error: a criterion of perceptual dysfunction.

This was a study to determine whether centration, as a perceptual process, could be a criterion for differentiating between neurologically impaired and emotionally disturbed children. Centration was defined by Piaget as a prolonged involuntary attachment of a sensory modality to one part of a field, causing perceptual errors of exaggerations and distortions. It is hypothesized that centration would affect motor behavior, producing effects on drawing tasks characterized by separation of designs or their parts, coincident with distortions of the figures drawn. The neurologically impaired children were identified as having primary difficulties with perception whereas the emotionally disturbed children would have primary difficulties with intellection. The centration-distortion error would characterize the drawing of the neurologically impaired but not those of the emotionally disturbed children. A sample of 44 children was selected, each with EEG records, psychological tests and psychiatric interviews used as differential criteria for the groups. Eleven children were diagnosed as having minimal brain damage, 33 as emotionally disturbed. Three psychologists scored the Bender Gestalt tests, blind, for indicators of brain injury and emotional disturbance as defined by Koppitz' criteria, and for the centration-distortion error. The hypothesis was upheld at the .001 level of confidence, validating an earlier pilot study.

Affective Symptoms↗
PubMed1980

Principles of perceptual organization and spatial distortion: the gestalt illusions.

In five interleaved experiments, conducted with 94 observers, it is shown that organization of the visual field according to gestalt principles results in measurable spatial distortions. Using the principles of proximity, similarity, good continuation, and two types of closure, it was found that interior distances (within a perceptual unit or group) are underestimated relative to exterior distances. The relationship between these spatial distortions and the resultant perceptual organization are discussed.

Distance Perception↗
PubMed1997

[Limits of perceptual robustness in perspective distortion].

Pictures often do not appear distorted even when viewed at oblique angles. Three hypotheses have been put forth to explain this robustness of virtual space toward affine transformations. First, array specificity holds that the perception of depicted space is fully specified by the information available at the point of observation. Second, the notion of a compensatory mechanism involves an unconscious recreation of the scene according to the original viewpoint. Third, the indiscrimination hypothesis denies the ability of the visual system to resolve or detect affine transformations up to a certain degree. Three experiments were conducted to investigate these claims. Using a double projection technique devised by Cutting (1987), Experiment I showed that observers are able to discriminate and compensate, to some degree, for affine transformations if information about the projection surface is available. However, observers relied on relative image velocities rather than reconstructing the object. In Experiment 2 additional observer motion was simulated. In single and double projection trials that required more difficult judgments of object rotation, compensation was poor and observers seemed to rely on local cues. Finally, real and simulated rotation of the projection surface revealed that observers are able to compensate for only one primary projection surface slant. The results reject the indiscrimination hypothesis and support the notion of array specificity.

Adult↗
PubMed1977

Distortions and disappearances of geometrical patterns.

Prolonged observation of a stationary grating has a number of perceptual consequences. Initially the lines appear well-resolved and straight. The lines then take on a wavy and oscillating appearance, which is followed by scintillation of the pattern. The scintillations are often accompanied by cloudy disappearances of the grating. A streaming or scintillating aftereffect is visible subsequently, upon viewing a homogeneous surface. The literature concerning these effects is reviewed and several experiments are reported which examined the apparent waviness and scintillating disappearances. The basis for the apparent waviness remains unresolved. It is suggested that the scintillations are produced by small involuntary eye movements over the contours and that the associated disappearances might be due to binocular rivalry.

Eye Movements↗
PubMed1992

The body image detection device versus subjective measures of weight dissatisfaction: a validity comparison.

Several procedures have been developed to measure body image distortion. A recently developed device is the Body Image Detection Device (BIDD), which includes a measure of perceptual size distortion (BPI) and subjective ratings of relative weight (SRI). Initial studies have supported the validity and reliability of the BIDD BPI and SRI in mainly bulimic patients, though studies which question the validity of the BIDD (especially the BPI) have appeared. One purpose of the present study was to examine the BIDD's validity in anorectic as well as bulimic patients and to compare both to a psychiatric control group. A second purpose of the study was to compare the validity of the BIDD to alternative measures. Thus, this study also compared the BIDD indices with simple measures of body weight dissatisfaction. The results did not support the validity of the BIDD BPI as a measure of body image disturbance, moderately supported the SRI, and did support the measures of weight dissatisfaction.

Adult↗
PubMed1984

Interaural octave phase-shift detection and aural harmonic distortion.

A continuous 400-Hz tone (60-75 dB SPL) and 250-msec bursts of an 800-Hz tone (10 dB SL) were delivered dichotically. Four out of nine listeners were able to detect a 180 degree interaural phase shift. When a subaudible continuous 800-Hz tone was added to the ear with the 400-Hz tone, interaural phase-shift detection depended on the phase relation of the added tone to the 400-Hz tone. These results are shown to be consistent with the hypothesis of aural harmonic distortion.

Attention↗
PubMed1978

Role of kinaesthesia in arousal and learning behavior.

This article presents a rationale of the significance of kinaesthesia. The development of arousal in the central nervous system is primarily peripheral and based on kinaesthesia. Consistent adaptive behavior results from adequate kinaesthetic perception and is the foundation for intersensory integration. Without kinaesthesia learning develops unevenly, as in children with learning disabilities. Inconsistent, bizarre behavior evident in psychopathology may result from inadequate, distorted kinaesthetic perception. Visual and auditory perceptual processes have been researched but the essential role of kinaesthetic perception has been neglected. The implications of adequate kinaesthesia are relevant to teaching and to psychotherapy.

Arousal↗
PubMed2006

Effect of modulation maskers on the detection of second-order amplitude modulation with and without notched noise.

The mechanisms underlying the detection of second-order amplitude modulation (AM) were explored. The detectability of second-order AM (fixed depth for each subject) was measured for first- and second-order modulation rates of 16 and 2 Hz, respectively (slow-rate pair), and 50 and 10 Hz, respectively (fast-rate pair), with no masker, a low-band modulation masker (centered at 2 or 10 Hz), and a high-band modulation masker (centered at 16 or 50 Hz). This was done in the absence and presence of an audio-frequency notched noise centered at the carrier frequency of 4000 Hz. Both modulation maskers were "low-noise" noises, to prevent overmodulation. In the absence of notched noise, both modulation maskers impaired performance for the slow-rate pair, but only the low-band masker impaired performance for the fast-rate pair. When notched noise was present, the low-band masker had no significant effect for either rate pair and the high-band masker had an effect only for the slow-rate pair. These results suggest that second-order AM detection is mediated both by an envelope distortion component at the second-order rate and by slow fluctuations in the output of a modulation filter tuned to the first-order rate. When notched noise is present, the distortion component plays little role.

Adult↗