CHANGES IN REPEATED REPRODUCTION OF WEIGHT AS A FUNCTION OF ADAPTATION LEVEL

The retention of memorized weights was repeatedly tested by the reproduction method, the subject's state of adaptation for weight being systematically changed between the tests. The reproduction scores were found to vary as approximately linear functions of the adaptation level. This relationship was unaffected by changes in the degree of learning of the memorized weight and in several other variables. The 'anchoring' and retention of weight, and different indicators of adaptation level, are discussed.     

ON QUALITATIVE CHANGES IN THE RETENTION OF FORMS

An experiment was performed to test the following prediction: If a pattern is learned in terms of 'schema with correction', and the subject's conception of the figural schema is changed during the retention interval, the 'memory' of the pattern will change correspondingly. Following the repeated presentation of a pattern S , and the memorization of a related pattern A , patterns deviating from S more and more in a predetermined direction were interpolated. This led to a highly significant systematic error of the predicted kind in the subject's performance when he subsequently was given a recognition test for A.     

Stimulus variation and sequential judgements of duration

When a series of reproductions of an interval is made in the absence of a standard the judgements progressively lengthen. The similarity between stimulus conditions in this type of time estimation experiment and the conditions which produce a decrement in human vigilance is discussed. It is argued that failure to detect cues for the passage of time reduces the amount of time perceived to elapse. Reproduced judgements must consequently be increased in length to match remembered standards. The hypothesis is then made that the kind of variation in background stimulation which facilitates vigilance should increase the frequency of detection of cues for duration and reduce reproduced judgements. This hypothesis is tested with 80 subjects and a reversal of the serial reproduction effect is found on trials with changed background conditions.     

Object perception and object-directed reaching in infancy

Five-month-old infants were presented with a small object, a larger object, and a background surface arranged in depth so that all were within reaching distance. Patterns of reaching for this display were observed, while spatial and kinetic properties of the display were varied. When the infants reached for the display, they did not reach primarily for the surfaces that were nearer, smaller, or presented in motion. The infants reached, instead, for groups of surfaces that formed a unit that was spatially connected and/or that moved as a whole relative to its surroundings. Infants reached for the nearer of two objects as a distinct unit when the objects were separated in depth or when one object moved relative to the other. They reached for the two objects as a single unit when the objects were adjacent or when they moved together. The reaching patterns provided evidence that the infants organized each display into the kind of units that adults call objects: manipulable units with internal coherence and external boundaries. Infants, like adults, perceived objects by detecting both the spatial arrangements and the relative movements of surfaces in the three-dimensional layout.     

Electrophysiologic studies of alcohol dependent patients

Electrophysiological methods were used to examine 52 ward patients with a long history of alcohol abuse. Alertness fluctuations were much more common in the EEG than among the healthy control subjects. 86.5% of the ENG findings were abnormal and indicated demyelinisation in most cases. The latence times of the brain stem potentials were longer than normal in about half of the patients and were definitely pathological in 13.5%. There was no statistical correlation between drinking habits and the results of the examination. Unknown pathogenetic factors are therefore suspected. The polytopic pattern of damage necessitates the use of a broad range of signostic techniques.     

Neurophysiologic findings in chronic alcohol abuse

Neurophysiological examinations of 100 long term alcohol dependent patients who were having neuropsychiatric treatment, showed symptoms of polytopic damage of the peripheral and central nervous system. The results show that for recognition of the damage an extensive diagnostic programme must be used.     

Auditory food cue conditioning: Effects of spatial contiguity and taste quality

The effects of spatial location of an auditory stimulus and quality of a potentiating taste on the aversive conditioning of an auditory food cue were investigated. In Experiment 1 rats ate salty food activating a tone from a speaker either in (spatially contiguous with) or displaced from the food and were then made ill. It was found that spatial contiguity during conditioning resulted in avoidance of food with a contiguous or a displaced tone in testing, and spatial displacement during conditioning resulted in avoidance of food only if the tone was also displaced in testing. Experiment 2 was identical, except rats ate salty, bitter, or sweet food with a displaced tone during conditioning and testing. The salty and bitter food groups demonstrated an avoidance of noisy food relative to the sweet food group. These results indicate that spatial contiguity interacts with taste quality in the conditioning of nongustatory food cues.     

Pure optic ataxia and visual hemiagnosia – extending the dual visual hypothesis

Goodale and Milner's two visual system hypothesis is an influential model for the understanding of the primate visual system. Lesions of either the ventral (occipito‐temporal) or the dorsal (occipito‐parietal) stream produce distinct and dissociated syndromes in humans: visual agnosia is typical for ventral damage, whereas optic ataxia (OA) for dorsal damage. We studied the case of a 59‐year‐old left‐handed woman with a circumscribed lesion around the left posterior occipital sulcus, extending to the underlying white matter. Initially, she presented with a central visual field OA, which regressed to an OA to the right visual hemifield during the 3 months observation period. In addition, tachistoscopic experiments showed visual hemiagnosia to the right visual hemifield. In line with the findings of the neuropsychological experiments, the analysis of the structural MR data by means of a trackwise hodologic probabilistic approach revealed damage to the left superior longitudinal fasciculus and to the left inferior longitudinal fasciculus, indicating an impairment of both the dorsal and the ventral stream. The combination of OA and visual hemiagnosia in the same patient has never been previously described. The present case study thus provides further insights for the understanding of visual processing.