Perceptual ambiguity and stability of reversible figures

In this work, the results of two experiments on ambiguous patterns are reported, which have been obtained by presenting a series of stimuli designed, in both cases, to reduce gradually the ambiguity of the patterns. Such reduction has been performed by respectively increasing or decreasing the amount of graphic details in the experiments. Data of both experiments show a lengthening of mean reversal time. The increase in the stability of one percept can be regarded as associated with the increasing difficulties encountered by an observer in organizing and restating the alternative "hypothesis" through the perceptual mechanisms. The loss of balance in the durations of percepts is discussed in terms of their different informational contents. Finally, in Exp. 1 an analysis is made to evaluate to what extent an addition of perceptual cues, designed to reinforce a three-dimensional interpretation of a pattern, can influence its figure-ground alternation.     

Function of the blood-cerebrospinal fluid barrier and selected biochemical cerebrospinal fluid components in senile dementias of various types

Some selected CSF and serum components were determined in demental patients classified by the Hachinski test into vascular and primary-degenerative groups. As for the vascular group, the frequency distribution of the serum/CSF albumin ratios characterizing the barrier function corresponds to that of controls, in primary-degenerative cases, however, it is shifted to higher values. In vascular dementia higher CSF LAP activities pointing to actual cell damaging processes in the CNS were found. The concentrations of lactate and some trace metals in CSF and serum are not suitable for differential diagnostic purposes.     

Body-image disturbances and bulimia nervosa: An empirical analysis of recent revisions of the DSM-III

In the recent revision of the DSM-III, the diagnosis of bulimia nervosa includes the criterion of persistent overconcern with body shape and weight, which may be conceptualized as a form of body-image disturbance. The new diagnostic criteria for bulimia nervosa include only those who exhibit a binge-purge eating patern, excluding binge-eaters who, in the older DSM-III, receive a diagnosis of bulimia. This study was conducted to investigate body-image disturbances in bulimia nervosa and simple bulimia (i.e., binge-eating without purging). The experimental design included two control groups, obese and normal subjects, in order to determine whether the binge-eater had body-image disturbances different form those of normal and overweight samples. The study evaluated 596 subjects (417 normals, 109 bulimia nervosa subjects, 50 binge-eaters, and 30 obese subjects) in terms of perception of current body size and selection of ideal body size. Results indicated that the bulimia nervosa group selected a current body size larger than that selected by normals and an ideal body size smaller than that chosen by normals. However, bingeeaters did not differ from the obese control group on either current or ideal body size. These results are discussed in terms of the recent debate regarding the diagnosis of bulimia nervosa and sociocultural influences upon body-image disturbances.     

128 Halftone patterns for printing gray-level images on a laser printer

This paper presents a set of 128 halftone patterns on an 8 × 8 block size. The patterns have been designed to produce an acceptable gray-scale rendition when the halftone is seen from a distance and, at the same time, to allow comparisons to be made among the intensity values of individual pixels at a closer look. A Pascal program is also presented that produces halftones on an HP Laserjet+ laser printer, and sample halftones are shown. Finally, a method is proposed that prevents images digitized with a 4:3 aspect ratio from being distorted when halftones are printed at the usual 1:1 aspect ratio.     

EFFECTS OF COMMUNITY-BASED,VIDEOTAPE, AND FLASH CARD INSTRUCTION OF COMMUNITY-REFERENCED SIGHT WORDS ON STUDENTS WITH MENTAL RETARDATION

Community-referenced sight words and phrases were taught to adolescents with mild and moderate mental retardation using three instructional methods in two locations. Words were presented on flash cards in a school setting, on videotape recordings in a school setting, and on naturally occurring signs in the community. During each session, participants were taught one third of the words in each of these conditions and were then tested at the community sites. A constant prompt delay procedure was used to promote stimulus control to the experimenter's cue initially and then to transfer control to the textual stimuli used for training. A multiple baseline across participants design was employed. Results showed rapid acquisition of the community-referenced sight words in all three training conditions and generalization from the flash card and videotape conditions to the community sites.     

Quantitative Analysis of IRT Variability During the First Training Stages of a Variable-Interval Schedule in Rats

Five rats were reinforced under variable-interval schedules with different average interreinforcement intervals (30 seC., 1 min, 2 min, and 4 min). Each animal was run only two sessions of each schedule. The interresponse times (IRTs) were recorded and analyzed. The autocorrelation function of the IRT series and of the IRT time series (number of responses per time interval) were calculated, and absence of periodicity in the subject’s behavior was demonstrated. Frequency distribution of IRTs showed in all cases a similar shape and could be fitted to a gamma probability density function in 60% of cases with a signification level of .01 (Kolmogorov-Smirnoff test). The frequency distributions of the IRT time series were distributed as a Poisson process with a .05 significance level. These results suggest that during variable-interval schedules the responses of the animal can be modeled as a random process characterized by a gamma distribution, as a first approximation.

     

Scores on the State-Trait Anxiety Inventory for children in a longitudinal study of pubertal Spanish youth.

Changes in scores on the State-Trait Anxiety Inventory for Children for a sample of 534 pubertal adolescents were longitudinally studied over a period of 4 years. Biological development and other variables were investigated. For the 310 boys, A-trait scores decreased significantly with age. The 224 girls showed significantly higher scores than boys in all years of the study. No significant relationship was found between anxiety and pubertal maturity. The year-to-year persistence in symptomatology of anxiety ranged between 55.6% and 66.1% for girls and between 48.5% and 53.1% for boys. Girls showed bi- and tri-annual persistence between 31% and 50%, and boys between 13% and 27%. Neuroticism scores formed the best predictor of A-trait scores. Symptomatology of anxiety is not transient during early adolescence, so personality may provide a risk indicator in the development of anxiety.     

Ontogenesis of object discrimination

This paper develops a mathematical model for results in the Freudian tradition on the unfolding of object discrimination. It is an axiomatic rendering of traditional and current psychoanalytic formulations. The theory of the instincts is presented in a structured fashion, leading to the result that the genital stage ideally achieves an optimal adaptive prototype. This is supported by computing a Shannon entropy on the instincts and demonstrating that the prototype reduces entropy (ideally) to 40% of its former maximal value. The model provides increasingly general, age-appropriate, definitions of reality sense.     

Relationship between psychological stress and lymphocytic 5′-ectonucleotidase

The relationship between psychological stress and lymphocytic 5-ectonucleotidase, an enzyme marker for lymphocyte differentiation, was studied. Lymphocytic 5-ectonucleotidase was decreased significantly by about twofold in persons experiencing psychological stress, with a corresponding change in Total Mood Disturbance scores of the Profile of Mood States. Enzyme values were reversible in that they returned to normal once the stress had been reduced. Administration of high doses of ascorbate to severely depressed patients also normalized 5-ectonucleotidase activities, and implied that low enzyme values in stressed persons may be mediated by oxygen radical damage. This finding was consistent with previous reports of heightened inflammatory responses occurring in depressed patients. The primary cause of lowered 5-ectonucleotidase during stress may be the breakdown in the homeostatic mechanisms of the hypothalamic-pituitary-adrenal axis and immune system resulting in lymphoid tissue resistance to corticosteroids. It is suggested that this lowering of lymphocyte 5-ectonucleotidase may contribute to stress-mediated immune suppression by inhibiting lymphocyte maturation.