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Using simple, single angular figures, including figures containing only one line, we have shown systematic misestimations of distance defined by these figures. These misestimations are not related to the absolute distance per se, but are related both to the size of the angle defining the distance, and to the part of the angle defining it. Some implications of these findings are discussed.
The flash-lag phenomenon is an illusion that affects the perceived relationship of a moving object and a briefly visible one: the moving object appears to be ahead of the flashed one. In practically all studies of this phenomenon, the image of the object moves on the retina as the object moves in space. Therefore, explanations of the illusion were sought in terms of purely visual mechanisms. Here we set up a situation in which the object's motion in space is entirely produced by passive rotation of the subject. No motion occurred on the retina. The visual display (a continuously lit stimulus and a flashed one) was mounted on a vestibular chair. While the subjects fixated this display, they were rotated in the dark at a constant speed and suddenly stopped. Perceptual misalignment (flash-lag) was robust and consistent during both the initial phase of rotation and the postrotary period when neither chair, subject, nor stimulus was actually moving. As a vestibular signal can cause an illusory spatial dissociation in the visual domain, we conclude that the mechanism of the flash-lag must be more general than was thought up-to-now.
A phantom that can be used for mapping geometric distortion in magnetic resonance imaging (MRI) is described. This phantom provides an array of densely distributed control points in three-dimensional (3D) space. These points form the basis of a comprehensive measurement method to correct for geometric distortion in MR images arising principally from gradient field non-linearity and magnet field inhomogeneity. The phantom was designed based on the concept that a point in space can be defined using three orthogonal planes. This novel design approach allows for as many control points as desired. Employing this novel design, a highly accurate method has been developed that enables the positions of the control points to be measured to sub-voxel accuracy. The phantom described in this paper was constructed to fit into a body coil of a MRI scanner, (external dimensions of the phantom were: 310 mm x 310 mm x 310 mm), and it contained 10,830 control points. With this phantom, the mean errors in the measured coordinates of the control points were on the order of 0.1 mm or less, which were less than one tenth of the voxel's dimensions of the phantom image. The calculated three-dimensional distortion map, i.e., the differences between the image positions and true positions of the control points, can then be used to compensate for geometric distortion for a full image restoration. It is anticipated that this novel method will have an impact on the applicability of MRI in both clinical and research settings, especially in areas where geometric accuracy is highly required, such as in MR neuro-imaging.
Despite the widespread incidence of childhood sexual abuse, there is insufficient investigation into the childhood sexual history of perpetrators. In addition, there is little published on the specific similarities between childhood and adult sexual histories. The present study investigates the incidence of childhood sexual abuse in a carefully characterized sample of male pedophiles compared with a demographically similar control group. Concordance between and cognitive distortions about characteristics of childhood abuse and pedophilic behavior are also studied. Twenty men with pedophilia, heterosexual type were compared with 24 demographically similar, healthy male control subjects on a questionnaire specifically designed to assess childhood sexual history in pedophiles. Sixty percent of pedophiles compared with 4% of control subjects reported adult sexual advances as a child. Seventy-five percent of pedophiles and 22% of control subjects reported a first sexual encounter before age 14 years. About 60% concordance was found between acts experienced as a child and perpetrated as an adult. Finally, numerous inconsistencies throughout the questionnaire add preliminary support for the role of cognitive distortions with regard to childhood and adult sexual history. The present findings replicate the elevated rate of childhood sexual abuse found among pedophiles and are consistent with the notion of a causative relationship between early childhood abuse and later pedophilic behavior.
Bilateral sensorineural hearing loss may introduce grossly dissimilar cochlear distortion at the two ears, causing abnormal demands to be made upon the cortical analytical centres which normally receive congruent information. As a result, the prescription of binaural hearing aids may be a handicap rather than a help. In order to explore this possibility, 10 normal subjects were presented with simulated, dissimilar cochlear distortion at the two ears. Discrimination scores with binaural presentation were poorer than the best monaural score and there were clear indications that in the former, subjects selectively attended to one ear and neglected the other. In contrast, binaural presentation of the same simulated distortion resulted in a significant improvement, compared with the monaural discrimination score. Inability of the cortex to contend with discongruent speech input from the two ears may be a factor contributing to the rejection of binaural hearing aids in some individuals.
In two size-conflict experiments, children viewed various squares through a reducing (1/2) lens while manually grasping them through a hand-concealing cloth. Then, using either vision or touch, they selected a match from a set of comparison squares. Forty 6-, 9-, and 12-year-olds participated in Experiment 1. Vision dominated the visual estimates of all three age groups; however, for the haptic estimates, the dominant modality varied developmentally: Vision dominated the 6-year-olds' haptic estimates, whereas neither modality dominated the 9-year-olds' haptic estimates, and touch dominated the 12-year-olds' haptic estimates. In Experiment 2, 24 six-year-olds were tested, as in Experiment 1; however, half of them were shown the size-distorting effects of the lens just prior to testing. Although this reduced the visual dominance of their haptic estimates, the effect was weak and short-lived. The haptic dominance seen in the data of the 12-year-olds was conspicuously absent.
Bizarreness in dreams is defined as an unusual combination of features in the phenomenal unified consciousness, that is, an incoherent simulation of the waking world. The present study investigated the specific mechanisms underlying dream image production and the phenomenal unity of consciousness by focusing on size and shape bizarreness. Data were derived from a Dream Data Bank of experimental dream studies. Analyses revealed that feature distortion was quite infrequent. Results are discussed in terms of cognitive processes proposed in a dream production model. Theoretical cognitive constructs, such as Kosslyn's imagery model, memory systems functioning, and binding, were used to speculate about these two specific types of bizarreness.
Low-frequency masking is a recent clinical procedure for the differential diagnosis of sensory hearing loss. Currently this requires the recording of the phase-dependent masked subjective threshold, which is time consuming and not always accurate. As an objective method, the recording of modulated distortion product otoacoustic emissions (DPOAEs) can be performed continuously, and with better frequency specificity. Results of measurements of the low-frequency modulated two-tone DPOAE 2f1-f2 in the human ear, and its dependence on various acoustic parameters, are presented here for the first time. Similar to the masked hearing threshold, the pattern of the phase-dependent modulated DPOAEs displayed two minima, at the phases of maximal rarefaction and condensation, respectively, with a latency of about 4 ms (suppressor frequency 32.8 Hz). The smaller dip, at maximal condensation, appeared only for a high suppressor level, and for a low level of the primary tone f2. The modulating effect measured for the primary frequencies f1 = 2.5 kHz and f2 = 3 kHz, decreased for 4 and 4.8 kHz, and vanished for 5 and 6 kHz. The results are discussed using a cubic distortion model based on the Boltzmann function for mechano-electrical transduction of the hair cells. The saturation behavior of the increase of the DPOAE level at different phases is compared with the growth rates of the DPOAE level in normal hearing and in sensory hearing loss.
An illusion of egocentric distance with concave and convex objects at a distance of 135 cm is reported. When the centre of a concave object was viewed with both eyes its surface appeared nearer than the centre of the surface of a convex object at the same distance. The distortion was about two per cent of the viewing distance with right-angle objects and about five per cent with hemicylindrical objects. The distortion was slightly reduced when size cues for distance were attached to the surfaces of the objects, absent with monocular viewing, greater with convex than with concave objects, and occurred with the generally convex surface of a model human face. Possible explanations of the findings are discussed.
A 54-year-old Japanese businessman who was found to exhibit the 'Alice in Wonderland' syndrome and went on to develop a depressive disorder is described. Lengthening and shortening of time experience continued intermittently for about 3 months, and metamorphopsia, distortion of body image, and the quick-motion phenomenon (alteration in time sense) persisted for almost 2 days without interruption. There were no abnormal physical findings. The authors review studies on 'Alice in Wonderland' syndrome and suggest that depressive illness may be a causal factor.
The accuracy of self-reported weight and the motivation of distorted reporting were studied among 169 female and 101 male college students. Although subjects were moderately accurate in their weight estimates, errors reflected women's underreporting, men's overreporting, and heavier persons' underreporting. With body mass controlled, most motivational variables had little explanatory value.
In 107 patients with different types of hearing loss (air conduction, sensorineural and combined) we ascertained the monaural discrimination loss of monosyllables with the help of the normal and distorted Freiburg speech test. It was evident that the quotient obtained from the measured discrimination is a very good and useful measure to characterise the ability to analyse the peripheral hearing system. Compared with normal hearing individuals and patients with air conduction hearing loss or combined loss of hearing, persons with perception hearing loss show a much greater and more divergent quotient. The discrimination of distorted speech depends more on age than that of normal speech; however, it is considerably reduced from the sixth decade of life onwards. The distortion test offers the expertising the possibility of improved assessment of speech discrimination by workers in a noisy environment in case of unfavourable hearing conditions, but it is also of considerable importance in fitting hearing aids and in the diagnosis of acoustic tumours.
Body weight in 42 obese and normal weight subjects was measured using a video TV monitor. Tasks included a continuous task where subjects manipulated the width of their body image on TV, and a discrete task, where they judged the accuracy of their TV image which was presented as either normal, too heavy, or too thin. Subjects rated their full body, body regions which included face, waist, and thighs, and two inanimate control objects. Results from the continuous task revealed that obese subjects overestimated body size more than normals. There was also a significant difference in the ratings of the four body regions, with all regions overestimated. Judgements were more accurate for body regions and control objects on ascending trials where the subjects had to increase the width of the image. No differences were obtained between obese and normals on judgements of the control objects. On the discrete discrimination task, a signal detection analysis revealed sensory sensitivity differences between obese and normal weight subjects. Obese subjects were poorer at detecting size distortions of the body regions. The thin/normal discrimination was more difficult than the heavy/normal discrimination. No response criterion differences were found between obese and control subjects, although subjects adopted a more strict criterion with the thin/normal discriminations. Implications of these findings for clinical intervention in eating disorders are discussed.
An experiment is described where marked hearing deficiency was induced in 28 normal-hearing subjects by means of occlusion. The primary aims were to investigate to what extent feelings of security and control are affected when hearing is suddenly reduced or distorted, and to explore the relative psychological importance attached to different sound categories other than speech. It was found that the inability to hear the movements of other people produces tension and stress and leads to feelings of insecurity and loss of control of the situation. The distortion of one's own voice leads to inhibition from speaking and might affect motivational and affectional factors. Experimental hearing deficiency can elucidate some initial disadvantages of hearing loss or use of hearing aids that are not easily seen in a clinical study.
Thirty-one eating-disordered (ED) women and 11 normal women completed tests of sex-role identity, dysfunctional cognitions, and body image. Anorexics, not bulimics, exhibited body-image distortion. All EDs (distorters and nondistorters) showed "hyperfeminine" identifications. Maladaptive cognitions were present in all EDs, but more marked in "overestimators." Body weight predicted BID better than other measures of eating pathology, which suggests important effects of weight per se in producing BID.
A review of treatment studies with rapists suggests that the currently used cognitive-behavioral treatment strategies remain limited in their success. The current article proposes that some reasons for the limited success may be that current treatment approaches do not adequately address the heterogeneity of the population, emphasize changing patterns of physiological arousal and cognitive distortions rather than psychological acceptance, and neglect to address differences in the function of sexually aggressive behavior among individuals. With the hope of decreasing rates of victimization and preventing recidivism by rapists, this article offers several treatment suggestions that should be tested empirically to determine if treatment efficacy can be increased with this population.
We show how decision makers can be induced to choose a personally inferior alternative, a strong violation of rational decision making. First, the inferior alternative is installed as the leading option by starting with information that supports this alternative. Then, the decision maker uses the natural process of distorting new information to support whichever alternative is leading. This leader-supporting distortion overcomes the inherent advantages of the superior alternative. The end result is a tendency to choose the self-identified inferior alternative. We trace the choice process to reveal the amount of distortion and its influence on preference. Self-reported awareness of distortion to support the inferior alternative is not related to the amount of distortion. The absence of valid awareness suggests that the manipulation that produces this preference violation is unlikely to be detected and that the distortion is unlikely to be corrected by the decision maker. As expected, given the lack of awareness, final confidence is just as high when the inferior alternative is chosen as when the superior one is. The discussion considers how to prevent an adversary from manipulating one's decisions using this technique.
A number of recent studies have used the graded-series method to measure the illusion and aftereffect distortions of perceived length in the minimal form of the parallel-lines configuration. However, because of some peculiar characteristics of the graded-series method, the aftereffect distortions measured with this method cannot be interpreted unequivocally as reflecting distortions of the perceived length of the test line. On the basis of the results of an experiment that examined the contribution of a possible confound present in the method, it is argued that the method should not be used to measure length aftereffects, and, furthermore, that the results of studies using this method need to be reconsidered.