Cerebral evoked responses in schizophrenia

Results of previous studies of evoked responses in schizophrenic disorders are reviewed, and data from a new study of somatosensory recovery functions in schizophrenia are presented. Subjects in the latter study were 18 schizophrenic patients and 18 nonpatients matched for age and sex. Latencies and amplitudes of eight consecutive evoked-response peaks were measured. Only one amplitude and one latency of the response to the first stimulus discriminated between patients and controls, whereas four amplitudes and three latencies of the second response did so. Amplitude recovery was less in patients, whereas latency recovery was greater. The data verified previous findings of impaired amplitude recovery in schizophrenia, but did not confirm previous findings of increased amplitude in response to a single stimulus. Evoked-response deviations so far determined are not specific to schizophrenic disorders, inasmuch as they have been found in several other psychiatric syndromes. The data are in accord with the idea that psychiatric disorders involve deviant cerebral processing of sensory information.     

Warm and cool thresholds as a function of rate of stimulus temperature change

Ss lifted three weights in sequence with instructions to judge the average heaviness of the weights. In agreement with previous work, a recency effect was obtained, with the later weights having more influence on the judgment. In contrast to previous work, a discrepancy was found from predictions based on the hypothesis that the judgment was an average of the felt heavinesses of the weights. The discrepancy had the appearance of a response end-effect, and was eliminable by a scaling procedure based on functional measurement.     

Attention and auditory evoked responses to low-detectability signals

Comparisons were made between cortical evoked responses obtained under two conditions: (1) while Ss were reading, and (2) while they were attempting to count auditory signals. The amplitudes of evoked responses to low-detectability auditory stimuli were found to be approximately doubled when the Ss were required to count the number of stimuli, as compared to amplitudes recorded when they were reading. The duration of the response was also markedly increased. These increases in response amplitude and duration are considerably greater than those observed in earlierexperiments, where high-levelsignalswere used. Inter-S variability of the waveform of the averageevoked response was observed to be much less when the Ss counted the stimuli. In another experiment the level of the auditory signalwas varied over a range of approximately +4 to -4 decibels relative to the listeners’ behavioral thresholds. The per cent of signalswhich they counted varied from near-zero to 100, over this range, and the evoked response concurrently showed a variation from “unmeasureable” to approximately 8 microvolts.     

Modification of a response bias through differential amount of reinforcement

A procedure is described for assessing response bias to either the form or color dimension of a compound standard stimulus. Responding was assessed under conditions of equal reinforcement (three tokens) for responding to either the form or color dimension. Under these conditions, the four male subjects (aged 7 to 11 yr) differentially responded to the form dimension. After a bias was assessed, the number of tokens delivered contingent upon form responses was reduced. After a reversal in differential responding, the equal-reinforcement condition was reintroduced. Two of the subjects returned to their initial response bias when equal reinforcement for either dimensional response was reintroduced, and two maintained the reversal established during the differential-reinforcement phase. For the latter two subjects, differential reinforcement was again imposed, in favor of form. This partial replication reinstated their original pattern of response bias.     

Testing independence in two-way contingency tables with data subject to misclassification

The misclassification process is represented by a stochastic matrix containing the probabilities that an individual who belongs in one cell is counted as belonging to another (or perhaps the same) cell. These probabilities are supposed known. If misclassification in the row direction is independent of that along the column variable then the size of the usual chi-square test is unchanged. It is shown how to calculate loss of power in this case and also how to calculate the change in size of the test if the errors are not independent. A modified test criterion is suggested when errors are not independent and a numerical example is included.     

Student Opinion on the Location of Occupational Information on a University Campus

A questionnaire survey revealed student needs, knowledge, and use of occupational information, as well as opinions about the most suitable location of such a resource on the Oregon State University campus. Results indicated that most students did not know where occupational information was available and only a small percentage knew there were occupational files in the Counseling Center and the University library. The great majority (almost 9 out of 10) wanted the University to provide a central occupational library, with most naming the Student Union (40 per cent) or the University library (25 per cent) as the best location. The Counseling Center was mentioned by only 2 per cent of the students.