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PubMed1979

Border locking and the Café Wall illusion.

The Café Wall illusion (seen on the tiles of a local café) is a Münsterberg chequerboard figure, but with horizontal parallel lines which may have any luminance separating the rows of displaced squares. These (the 'mortar' lines) display marked wedge distortion which is especially affected by: contrast of the squares ('tiles'); width of the 'mortar' lines, and their luminance which must not be significantly higher than that of the light squares or lower than that of the dark squares for distortion to occur. An experiment is described from which quantitative data have been obtained by varying these parameters. It is suggested that contiguous regions of different luminance (and contiguous colour regions) are normally held in spatial register by locking from common luminance boundaries. The Café Wall illusion is attributed to this border locking producing inappropriate contour shifts from neighbouring regions of contrasting luminance when separated by narrow gaps of neutral luminance. Further implications on the border-locking notion are discussed.

Discrimination Learning↗
PubMed1995

Childhood behavioral precursors of adult symptom dimensions in schizophrenia.

The present investigation tested the hypothesis that childhood behavioral problems are differentially associated with clinical symptoms in adult-onset schizophrenia. Parents of 29 schizophrenic patients completed questionnaires concerning (1) the childhood behaviors of all their offspring from birth through 15 years of age, and (2) the symptomatology of their schizophrenic offspring. The childhood behavior scale was a modified version of Achenbach's Child Behavior Checklist (1991). Scores were derived for six childhood behavior problem factors: Withdrawal, Anxiety/Depression, Social Problems, Thought Problems, Attention Problems, and Aggression/Delinquency. Ratings of symptoms were based on parental versions of Andreasen's Scale for the Assessment of Positive Symptoms (SAPS; 1983) and Scale for the Assessment of Negative Symptoms (SANS; 1981). Symptomatology scores were computed from the SANS and SAPS following Malla et al.'s (1993) and Liddle's (1987b) tri-dimensional concept of schizophrenia: Reality Distortion, Psychomotor Poverty and Cognitive Disorganization. Regression analyses were conducted to examine the relation between childhood behavior and adult symptomatology in the schizophrenic patients. The results indicated that the Psychomotor Poverty and Cognitive Disorganization dimensions in adult patients are positively associated with Withdrawn behavior and inversely associated with Anxious/Depressed characteristics in childhood. The results are discussed in light of the distinction between primary and secondary negative symptoms, and the three dimension concept of schizophrenia.

Adolescent↗
PubMed1996

Body image distortion in anorexia and bulimia nervosa: the role of perceived and actual control.

It has been suggested that a desire for control is a central factor in eating disorders. There is, however, little evidence to support this clinical hypothesis. This experimental study examines the effects of actual and perceived control on a symptom of anorexia and bulimia nervosa-body image distortion. Using a learned helplessness paradigm, it was shown that eating-disordered and comparison women respond differently to manipulations of control. Anorexic and bulimic women appear to have a cognitive style of "mistaken pessimism," overestimating body size more when an easy task is perceived as difficult. In contrast, the comparison women are "mistaken optimists" overestimating less when they see a difficult task as being easy. The clinical implications are discussed and further research is proposed to extend these preliminary findings.

Adult↗
PubMed1997

Distorted colour discrimination in Parkinson's disease is related to severity of the disease.

The Farnsworth-Munsell 100-hue test (FMT) may be used for measurement of colour discrimination and error scores of the FMT provide an unspecific biological marker for the distinction between parkinsonian patients (PP) and healthy controls. The aim of this study was to examine the possible association between distorted colour discrimination and disease severity in untreated "de novo" PP Error scores of the FMT were significantly (P<0.0001) elevated in PP compared to age- and sex-matched controls and correlated to severity of the disease. We conclude that impaired colour discrimination is related to pathophysiology of Parkinson's disease. But it remains unclear whether these alterations of colour vision reflect striatal dopamine deficiency or changes of retinal dopaminergic pathways in PP.

Adult↗
PubMed1979

Disturbances in body image estimation as related to other characteristics and outcome in anorexia nervosa.

Body image distortion in 79 female anorexia nervosa patients were examined on a visual-size estimation apparatus during the emaciated stage of illness. Both they and an age-matched female control group overestimated their body widths, so this overestimation cannot be considered unique to anorexia nervosa. Among anorexia patients the degree of overestimation was associated with less weight gain during treatment, greater denial of illness, and several other pretreatment characteristics indicative of poor outcome.

Animals↗
PubMed1995

Distorting reality for children: body size proportions of Barbie and Ken dolls.

Using hip measurements as a constant, calculations were made to determine the changes necessary for a young, healthy adult woman and man to attain the same body proportions as Barbie and Ken dolls, respectively. Among the changes necessary were for the female to increase 24 in. in height, 5 in. in the chest, and 3.2 in. in neck length, while decreasing 6 in. in the waist, and for the male to increase 20 in. in height, 11 in. in the chest, and 7.9 in. in neck circumference. Like adults, children are exposed to highly unrealistic ideals for shape and weight.

Adult↗
PubMed2000

Object recognition may distort size perception.

Size estimation may be influenced by characteristics recalled about the object viewed. This study evaluated the influence of object familiarity on estimation of size. We compared size estimates of several familiar objects with size estimates of undefined objects matched for dimensions of pattern and color. Those estimating the size of the familiar objects made significantly larger errors than those estimating the size of the undefined objects. In a second study size estimation errors from memory were larger than when objects were directly viewed. Experience with the objects appears to decrease accuracy of estimates of size but errors may be reduced by directly observing the object.

Color Perception↗
PubMed2000

Effects of AC and DC stimulation on chinchilla SOAE amplitude and frequency.

The effects of AC and DC current on spontaneous otoacoustic emissions (SOAEs) were studied in normal chinchillas and chinchillas with selective inner hair cell (IHC) loss. Electrical stimulation was delivered through an electrode on the round window or through an electrode in scala media. SOAE frequencies ranged from 4 to 11 kHz and amplitudes ranged from 13 to 51 dB SPL. AC simulation suppressed SOAE amplitude. The suppression contours had a narrowly tuned, low-threshold tip located above the frequency of the SOAE. AC suppression contours were similar to acoustic suppression contours except that the AC suppression contours lacked a high-threshold, low frequency tail. The lowest threshold of the AC suppression contour was 3.9 microA rms whereas the lowest acoustic suppression threshold was 19 dB SPL. AC stimulation, which induced an electrically evoked otoacoustic emission, interacted with the SOAE to generate distortion product otoacoustic emissions (DPOAEs) of up to 26 dB SPL at 2f(S)-f(AC) (f(S)=SOAE). DPOAE amplitude increased with AC current, but saturated at high levels. DC current steps affected both SOAE frequency and amplitude. Positive current at the round window decreased SOAE amplitude and frequency whereas negative current increased SOAE frequency, but had little effect on amplitude. The effects of AC and DC current on SOAEs in animals with IHC loss were similar to those in normal chinchillas.

Animals↗
PubMed2004

Autochthonous experience, heightened awareness, and perception distortion in patients with schizophrenia: a symptomatological study.

Early symptoms of schizophrenia' (ESS) proposed by Nakayasu, are present during schizophrenic prodromal periods. Some of these symptoms can continue after the florid manifestation of the disease and the patients often experience them with ego-alien feelings. Autochthonous experience, heightened awareness, and perception distortion (AHP) were selected from the list of ESS. The aim of this study was to confirm both prevalence and specificity of AHP in patients with schizophrenia as well as the relevance of the presence of AHP to symptomatology of schizophrenia. A structured interview was conducted to identify the presence of AHP in three groups of subjects; a schizophrenia group (Sc) with 37 patients, an affective disorder group (AD) with 27 patients, and a control group (NC) with 39 people. The prevalence of AHP was compared among the groups. Within the Sc, the relevance of AHP to Brief Psychiatric Rating Scale (BPRS) was assessed. AHP were present significantly more frequently in the Sc. The total scores for BPRS in the schizophrenic patients with AHP were significantly higher than in the patients without AHP. There was close correlation between AHP and BPRS items, with the degree of relevance depending on the form or perceptual domain. In conclusion, AHP were characteristic of patients with frank schizophrenia. To judge whether AHP were adequately specific to frank schizophrenia, further research of larger subjects is needed. Understanding the characteristics of AHP in patients with frank schizophrenia is important in the symptomatological evaluation of schizophrenia.

Adult↗
PubMed2003

Disruption of lateral efferent pathways: functional changes in auditory evoked responses.

The functional consequences of selectively lesioning the lateral olivocochlear efferent system in guinea pigs were studied. The lateral superior olive (LSO) contains the cell bodies of lateral olivocochlear neurons. Melittin, a cytotoxic chemical, was injected into the brain stem using stereotaxic coordinates and near-field evoked potentials to target the LSO. Brain stem histology revealed discrete damage to the LSO following the injections. Functional consequences of this damage were reflected in depressed amplitude of the compound action potential of the eighth nerve (CAP) following the lesion. Threshold sensitivity and N1 latencies were relatively unchanged. Onset adaptation of the cubic distortion product otoacoustic emission (DPOAE) was evident, suggesting a reasonably intact medial efferent system. The present results provide the first report of functional changes induced by isolated manipulation of the lateral efferent pathway. They also confirm the suggestion that changes in single-unit auditory nerve activity after cutting the olivocochlear bundle are probably a consequence of disrupting the more lateral of the two olivocochlear efferent pathways.

Action Potentials↗
PubMed1992

Evidence for two discrete sources of 2f1-f2 distortion-product otoacoustic emission in rabbit: I. Differential dependence on stimulus parameters.

The results of studies of the physiological vulnerability of distortion-product otoacoustic emissions (DPOAEs) suggest that the DPOAE at 2f1-f2 in vertebrate ears is generated by more than one source. The principal aims of the present study were to provide independent evidence for the existence of more than one DPOAE source, and to determine the contributions of each to the ear-canal 2f1-f2 signal. To accomplish these aims, specific stimulus parameters were separately and systematically varied to provide detailed parametric information regarding 2f1-f2 DPOAE amplitude and phase in normal ears of awake rabbits. The findings indicate that two discrete sources, demonstrating differential dependence on stimulus parameters, dominate the generation of the 2f1-f2 DPOAE. One source of distortion is dominant above 60-70 dB SPL at moderate primary-frequency separations, and at all stimulus levels when the primary tones are closely spaced. The other source is dominant below 60-70 dB SPL at moderate primary-frequency separations, and may be dominant at all stimulus levels when the primary tones are widely separated in frequency. The results suggest that by varying stimulus parameters, it may be possible to independently study the two generator mechanisms.

Animals↗
PubMed2005

The viability of speech-in-noise audiometric screening using domestic audio equipment.

Speech-in-noise audiometry has potential application as a low-cost, self-screening test for sensorineural hearing loss. To realize this potential, the influence of variations in audio equipment and listening environment need assessment. The present study assessed: 1) the frequency response and distortion produced by a wide range of commercially available audio equipment; 2) the effects of such variations upon test results with normally hearing subjects using a simple, open-set, word-identification test; 3) the effect of distortion on the speech reception threshold using digitally applied distortion; and 4) the reliability of the test in listening environments with different levels of reverberation. In addition, preliminary tests were conducted with elderly listeners. The results indicate that variations in equipment have negligible effects on speech-in-noise audiometry. The only factor that substantially elevated normally hearing listeners' thresholds was high levels of room reverberation when using loudspeaker presentation. Variations in equipment and environment thus present no significant obstacle to the development of a self-administered audiometric screening test based on speech in noise.

Acoustic Stimulation↗
PubMed2005

Prose memory deficits associated with schizophrenia.

Memory of contextual information is essential to one's quality of living. This study investigated if the different components of prose memory, across three recall conditions: first learning trial immediate recall, fifth learning trial immediate recall, and 30-min delayed recall, are differentially impaired in people with schizophrenia, relative to healthy controls. A total of 39 patients with schizophrenia and 39 matched healthy controls were recruited. Their prose memory, in terms of recall accuracy, temporal sequence, recognition accuracy and false positives, commission of distortions, and rates of learning, forgetting, and retention were tested and compared. After controlling for the level of intelligence and depression, the patients with schizophrenia were found to commit more distortions. Furthermore, they performed poorer on recall accuracy and temporal sequence accuracy only during the first initial immediate recall. On the other hand, the rates of forgetting/retention and recognition accuracy were comparable between the two groups. These findings suggest that people with schizophrenia could be benefited by repeated exposure to the materials to be remembered. These results may have important implications for rehabilitation of verbal declarative memory deficits in schizophrenia.

Adult↗
PubMed1991

Evidence for the influence of aging on distortion-product otoacoustic emissions in humans.

Previous measures of distortion-product otoacoustic emissions (DPOAEs) in young adults suggested that these responses were capable of detecting the functional effects of auditory aging. The primary goal of the present study was to provide more detailed evidence for the influence of aging processes on the ability of healthy, older ears to generate DPOAEs. Toward this end, DPOAEs were examined in a series of human subjects, with clinically normal hearing, ranging in age from 31 to 60 years. Acoustic-distortion products were measured in two basic forms consisting of "audiograms" and response/growth or input/output functions. Distortion-product "audiograms" depicted the detailed frequency pattern of DPOAE amplitudes in response to constant-level stimuli, whereas the growth functions described the detection "threshold" and suprathreshold aspects of DPOAE activity, at specific frequencies, in response to primary tones that were systematically increased in level. The principal finding was that, when compared to emissions in young ears, DPOAEs accurately tracked the systematic deterioration of high-frequency hearing in aging individuals.

Adult↗
PubMed1995

Use of distortion product otoacoustic emissions to assess middle ear transducers in rhesus monkeys.

Distortion product otoacoustic emissions (DPOAEs) can provide an objective and noninvasive assessment of the peripheral cochlear function. Auditory brainstem responses measured from implanted rhesus monkeys have shown that middle ear transducers, coupled directly to the incus, are capable of delivering the signals to the central auditory system. The DPOAEs were used as a noninvasive method of assessing the frequency specificity of this mechanical transduction. In two rhesus monkeys implanted with the middle ear transducers, one primary stimulating tone (f1) was presented acoustically, and the other primary tone (f2) was presented by the transducer, which converted the signal into a mechanical motion of the probe tip attached to the body of the incus. The nonlinear characteristics of the cochlea produced the distortion product responses at the expected frequencies (2f1 - f2). This demonstrates the fidelity of the middle ear implant signal transduction in vivo. The DPOAEs also indicate minimal changes in the post-implant middle ear transmission. This study demonstrates that the DPOAEs can be used to assess the function of implanted middle ear transducers objectively and noninvasively.

Animals↗
PubMed1989

Distortion products in early stage experimental hydrops in the guinea pig.

The swelling of the endolymphatic spaces in experimental hydrops is likely to induce mechanical changes all along the cochlea. The selective atrophy of short and middle stereocilia on the outer hair cell above the first cochlear turn is expected to alter micromechanics and transduction. Two tone stimuli were employed in the present study to investigate cochlear distortion products in hydropic ears. Despite a substantial low frequency sensitivity loss on the CAP audiogram, 2f1-f2 distortion products recorded in the RWCM and the CAP were similar in hydropic ears and normal control ears which reflect the probable common origin of these responses--the base of the cochlea where no threshold shifts can be detected. On the other hand this distortion product in the otoacoustic emissions was considerably reduced in hydropic cochleas when the primary tones lay within the pathological part of the audiogram. The reduction of CDT emissions cannot be accounted for by hair cell loss since at the early stage of hydrops described here there is only discrete hair cell loss which is restricted to the apex of the cochlea. On the other hand the reduction in the amplitude of the CDT might reflect disturbance in hair cell function and/or cochlear mechanics above the first cochlear turn.

Action Potentials↗
PubMed1996

Cognitive inhibition and schizophrenic symptom subgroups.

Subgroups of patients with schizophrenia were examined in relation to repetition and semantic priming under conditions in which the prime stimulus was to be either attended to or ignored (unattended). Attended conditions normally would produce positive priming; and unattended conditions, negative priming (i.e., a delayed reaction resulting from inhibition of target information previously presented as to-be-ignored stimulus). Cluster analysis of participants' ratings on the Schedule for the Assessment of Positive Symptoms and the Schedule for the Assessment of Negative Symptoms revealed three subgroups that aligned broadly previous research citing with disorganization, reality distortion, and psychomotor poverty syndromes, and a fourth episodic subgroup. The Disorganization, Reality Distortion, and Episodic subgroups were associated with reduced, indeed reversed, negative priming in unattended priming conditions, whereas the Psychomotor Poverty subgroup exhibited the usual negative priming effect. Participants in the former three subgroups also exhibited reversed positive priming for the repetition condition, while the Psychomotor Poverty group displayed the expected positive priming effect. These results indicate that weakening of inhibitory processes may underlie both the reality distortion and disorganization dimensions of positive schizophrenic symptomatology, including the latent presence of these symptoms. In contrast, negative symptoms contributing to the psychomotor poverty dimension of schizophrenia are not linked to reduced inhibition. The association of positive symptom subgroups with reversed positive priming suggested that, for these participants, stimuli and task differences have an impact on the preattentive activation of information underlying such priming. It is proposed that a "reduced inhibition" model of schizophrenic symptomatology may need to be extended to account for influences on preattentive processing.

Adolescent↗
PubMed2005

Obstacle avoidance in novel visual environments improved by variable practice training.

Motor performance on simple tasks improves after training in variable practice. We asked if locomotor skill during an obstacle-avoidance task in a novel sensorimotor environment improved through training in variable practice on other complex tasks. 40 normal adults practiced gross motor skills while wearing either sham lenses, one of several visual distortion lens (constant practice), or three different visual distortion lenses (variable practice). Posttests on obstacle avoidance with novel lenses showed significantly better scores with variable practice and one of the constant groups vs sham lenses. Constant and variable practice groups did not differ. Thus, performance in a novel environment improves after training on similar type novelty, even when practice and test conditions differ. Constant practice was effective only if the subjects used the lens efficacious in training. Variable practice increases the likelihood of efficacious training when adaptive performance is required in a novel environment.

Adult↗