The perception of temporal deviations in isochronic patterns

In a study of perceptual synchronization with an isochronic sequence, subjects were given the following task: They heard an isochronic sequence of tones in which the last interval was either correct or too long. Their task was to detect irregularity. The independent variables were the number of tones heard and the time interval between them. The dependent variable was the difference limen (DL) for the detectability of the irregularity. Two experiments were performed in this study, differing in the way in which the trials were blocked: In Experiment 1, stimuli with the same period were presented in blocks, whereas in Experiment 2, the period of the stimulus was randomized. The results show that in Experiment 1 the number of tones in the stimulus did not affect the detectability of the anisochrony. In Experiment 2, the number of the DL was a decreasing function of the number of tones heard. Moreover, the decrease of the DL was larger than one would expect from a simple model of information integration, which assumes that subjects improve their performance by averaging their percepts of the first intervals in the sequence. The difference between this task and experiments on the discrimination of temporal intervals is discussed.     

Categorical perception of rhythmic patterns

Summary In this study the task of the subject is to identify a rhythm which is a member of a set of patterns interpolated between two rhythms: One rhythm in a 6/8 and the other in a 4/4 metrum. The subjects first learn the one-to-one association of the different patterns with a numerical label. They then perform a complete identification experiment. One complication of the task is that the tempo varies randomly from trial to trial. The identification matrix is analyzed in terms of discriminability of neighboring rhythmic patterns. Two questions are of interest. First, whether variations within a rhythmic category can be discriminated better than chance and second, whether the discrimination function is nonmonotonic, with a peak at the boundary between the rhythms. The results indicate that the answer to both questions is positive.     

Catamnestic studies of patients with writer's cramp following inpatient psychotherapy

The paper gives the results of a follow-up study of 58 patients after psychotherapeutic treatment as in-patients for writer's cramp. Where as immediately after discharge 74.1% of the patients felt an improvement in their condition, at the time of the follow-up study only 17.2% were demonstrably improved, with 37.9% subjectively feeling an improvement over their state before treatment as in-patients. These results suggest that the customary psychotherapeutic methods employed have less effect on the evidently multifactorial extrapyramidal-motor basic complaint but rather have the effect of improving the patient's ability to cope with this in daily life.     

Iatrogenic damage to the nervous system]

A survey is given of the most important findings in respect of iatrogenic damage to the nervous system on the basis of published reports and the author's own findings, taking special account of lumbar puncture and suboccipital puncture, myelography, contrast-medium encephalography, ventriculography and cerebral angiography. The possibility of damage such as the danger of embolism in diagnostic and therapeutic vascular puncture is referred to. Among the lesions caused in the course of therapy, the side-effects of treatment with drugs, effects of radiation, effects resulting from anesthesia, sequelae of neural therapy and of manual manipulations, sequelae of operations, and postvaccinal encephalopathies are discussed. The necessity of systematic morphological examinations for exact assessment of ioatrogenic lesions is stressed. Iatrogenic damage due to neglect of diagnostic and therapeutic measures is also considered.     

Independent feature processing in the visual system

Summary A recognition experiment with a set of simple visual patterns was performed. The patterns were composed of three binary features: Lines, angles and curve segments. The pattern sets differed with respect to the distance between components and the symmetry of the arrangement. The empirical confusion matrices were analysed assuming two different models: A model assuming independent feature analysis and a model that assumes that one of the features is analysed independently of the other two. The main result was that quite a large distance between features was necessary to achieve independent processing of the features. Moreover, in the asymmetric pattern set the predictions of the independence model were better than in the symmetric pattern set.