Signalled free-operant avoidance of shock by pigeons pecking a key

Two pigeons were trained to peck a key under a free-operant avoidance schedule. Then, changes in key color signalled the beginning (safe period) and the end (warning period) of the response-shock interval, with a response required to change the key color. Finally, a change in key color signalled the warning period and either a response or a shock reinstated the safe stimulus. During signalled avoidance, response rate was higher during the warning stimulus than during the safe stimulus. More responding tended to occur in the warning stimulus when it was terminated by either a response or a shock than by only a response. In either procedure, response latency during the warning stimulus was a function of the duration of the warning stimulus. In general, response and shock rate were higher during unsignalled than during signalled avoidance. When the warning stimulus was brief, the results were similar to those of unsignalled avoidance. These results confirm previous findings with pigeons, are in general agreement with data provided by other species in studies of signalled avoidance, and thereby indicate the transituationality of the key-pecking operant.     

The effects of a seven day camping experience on volunteer student counselors

An investigation of the effects of a seven-day camp experience with disturbed adolescents on approximately sixty undergraduate "camp counselors" was conducted. Measures of the types of reinforcement preferred and used as well as an overall attitude toward disturbed adolescents were obtained and evaluated. The results indicated that the student counselors did not use the type of reinforcement that they felt was most important and they did not change their attitudes toward disturbed adolescents as a result of experience. The limitations of the study are discussed as well as some suggestions for future research into practicum sites for programs training teachers of the severely disturbed.     

An illusion of auditory saltation similar to the cutaneous "rabbit"

Trains of brief clicks produced successively at 3 points in a horizontal array were not localized accurately. Observers reported clicks occurring in succession across the spaces between sources as well as at the sources themselves. The illusion is functionally related to interstimulus interval, number of clicks per speaker, and regularity of pulsing. It appears similar to Geldard and Sherrick's cutaneous "rabbit" illusion.     

Language and disfluency variables in normal speaking children from discrete chronological age groups

Thirty male and female children from three chronological age groups were compared on Developmental Sentence Score, total words spoken in a language sample, total disfluency, and eight specific disfluency subtypes. Analyses were performed to determine in differences existed among the three age groups, between sexes, and whether language and disfluency were related. No sex differences in either language or disfluency were found. Total disfluency showed only a slight decrease with an increase in chronological age between 4 and 8 years. This suggests that the major disfluency decrease must occur subsequent to age 8. Although the total disfluency changed minimally between ages 4 and 8, some of the disfluency subtypes shifted considerably. Older children were almost as disfluent as younger children, but the topography of their disfluency was different. No significant relationship was found between the disfluency and language variables studied.     

Listener ratings of severity for specific disfluency types in children

This study investigated whether some types of disfluency are perceived as more severe than others and if listener groups differ in their perception of severity for some disfluency types. Three normal speaking children were trained to produce eight types of disfluency and one sample of fluency. The experimental tape, consisting of three examples for each of the eight disfluency types and of fluency, was presented auditorily to 40 judges divided into four groups of 10 each: parents of stutterers, parents of nonstutterers, speech clinicians, and elementary school teachers. The judges rated the disfluency and fluency on a 15-point severity continuum, divided into four nominal categories of Fluent, Normal Disfluency, Mild Stuttering, Moderate Stuttering, and Severe Stuttering. Results showed that although listener groups did not significantly differ in their severity ratings, the specific types of disfluency did differ significantly. The type of disfluency emitted by a speaker is apparently more salient in perceiving and judging disfluency than the type of listener making the judgment.     

Numerical taxonomy of aphasia

Two hundred consecutively seen aphasics, 142 of them with infarcts, were examined by tests of fluency, comprehension, repetition, naming, and information content. The language scores were subjected to a minimum variance clustering algorithm separately for the total and for the infarct groups. The latter generated 10 clusters on a dendrogram. Attribute analysis of each cluster provided a clinically meaningful profile of language performance for these groups. The degree of correlation of most computer generated clusters with clinically recognized groups was high, and the homogeneity of some of the clusters is striking. An exception appears to be “conduction aphasia,” which is bimodally distributed. One of these clusters, with high fluency and low comprehension scores, was renamed “afferent conduction” aphasia, and the other, with lower fluency and higher comprehension, was renamed “efferent conduction” aphasia. The Principal Components Analysis was used to evaluate the discriminatory value of language characteristics, and the Nearest Neighbor Network Analysis was used to evaluate the significance of clustering. The dendrogram for all aphasics showed a less specific and less homogenous six clusters.