Temporal proximity and reinforcement sensitivity in multiple schedules

Distributions of reinforcers between two components of multiple variable-interval schedules were varied over a number of conditions. Sensitivity to reinforcement, measured by the exponent of the power function relating ratios of responses in the two components to ratios of reinforcers obtained in the components, did not differ between conditions with 15-s or 60-s component durations. The failure to demonstrate the “short-component effect,” where sensitivity is high for short components, was consistent with reanalysis of previous data. With 60-s components, sensitivity to reinforcement decreased systematically with time since component alternation, and was higher in the first 15-s subinterval of the 60-s component than for the component whose total duration was 15 s. Varying component duration and sampling behavior at different times since component transition may not be equivalent ways of examining the effects of average temporal distance between components.     

Parent-infant resemblance for general and specific cognitive abilities in the Colorado adoption project

Previous publications emanating from the Colorado Adoption Project have reported significant relationships between parental general cognitive ability (g) and infant Bayley MDI scores. The present study compared infant Bayley factor scores representing separable dimensions of infant cognition with parental general and specific cognitive abilities for 182 adoptive families and 164 nonadoptive families. Parent/offspring correlations between 12-month Bayley factors and parental cognitive abilities suggest only minimal relationships for both parental g and specific abilities. At 24 months, more parent/offspring resemblance was present; moreover, Bayley factors that were related to parental cognition tended to be related to parental g, not to specific abilities. The finding of significant parent/offspring relationships at 24 months between biological parents and their adopted-away infants, as well as between nonadoptive parents and their infants, suggests some genetic continuity from infancy to adulthood.     

Subcortical functions in language: A working model

The current paper explains a model of subcortical language functions that focuses on dynamic interactions between the cortex, the thalamus, and the basal ganglia in the production of spoken language. The model was derived from (a) studies of subcortical lesions and language, (b) studies of subcortical stimulation and language, (c) knowledge regarding neural pathways between various cortical and subcortical structures, and (d) indications that preverbal monitoring of language occurs. In the current model, the thalamus plays roles in cortical arousal and activation and in preverbal semantic monitoring. The basal ganglia function to regulate the degree of excitation conveyed from the thalamus to the cortex and to time the release of formulated language for motor programming. Consistency with classical syndromes of aphasia and potential applications to other areas in the neurosciences are discussed. The current theory, unlike previous formulations, is specific enough that testable hypotheses can be derived.     

On the Bradley hypothesis concerning agrammatism: the nonword-interference effect

In 1980, D. C. Bradley, M. F. Garrett, and E. B. Zurif (in D. Caplan (Ed.), Biological studies of mental processes, Cambridge, MA: MIT Press) have proposed a lexical hypothesis on agrammatism. The theoretical background of this hypothesis is described. Then two experiments are reported with normal speakers on the so-called nonword-interference effect that has been one of the two major sources of experimental evidence for this hypothesis. The first experiment replicates the original finding that the interference effect is found when the nonword starts with a content word but not when it starts with a function word. In the second experiment, it is shown that this contrast is due to an artifact of the composition of the word list. When this list contains both content and function words, rather than only content words--as in Bradley's experiments and our Experiment I--both content and function nonwords show an equally sized interference effect. The consequences for the lexical hypothesis are discussed.     

Vowel duration in stutterers participating in precision fluency shaping

The purpose of this study was to determine the extent to which stutters manipulate vowel duration to achieve fluency after participating in Precision Fluency Shaping. Nine stutterers who read an all-voiced sentence fluently before and after therapy were selected for study. Wide-band spectrograms were made of the initial phrase of the sentences, and vowel durations were computed. Results indicated that extended vowel durations were characteristic of the fluency of stutterers posttherapy. The subject that had the highest rate of disfluency after therapy also had the shortest vowel durations. Clinical implications concerning the importance of speech rate during carryover practice are made.     

GENERALIZATION OF OBJECT NAMING AFTER TRAINING WITH PICTURE CARDS AND WITH OBJECTS

Generalization of four retarded children's object naming responses to stimuli in the natural environment was assessed after training with either objects or pictures of the objects. Generalization was typically greater after training with objects. In a second experiment, half of the stimuli that showed little generalization were retrained by alternating the original training object with an object that belonged to the same stimulus class as the training stimulus. The other half were simply retrained using the object. The alternating procedure resulted in substantial increases in generalization to untrained objects.     

The effects of progressive relaxation on stress and diabetic control

Four insulin-requiring diabetic Ss were followed in single-S designs to measure the impact of progressive muscle relaxation training on blood glucose and stress levels. Measures of blood glucose, stress, activity and caloric intake were taken four times a day, along with a daily measure of anxiety. Two of the 4 Ss showed a significant decrease in blood glucose during treatment periods as compared to baseline measures. Similarly, 2 of the 4 Ss showed a significant decrease in stress levels during treatment. A multiple regression analysis revealed some significant relationships between blood glucose, stress, activity level and caloric intake. The results support previous studies that show relaxation techniques to be a viable aid in establishing greater diabetic control.     

Measuring the activity of severely and profoundly mentally-handicapped adults in ordinary housing

Earlier work on the quality of care in settings for severely and profoundly mentally-handicapped adults raised the question whether any useful purpose is served by promoting the extensive use of simple recreational materials to occupy people. Data were collected by direct observation on the activity of 6 adults living in a staffed house organized to promote engagement in household activities. Observations were taken over 5 weekdays from 07.00 to 10.00 and 15.00 to 23.00hr. The results showed that Ss spent between 22 and 67% of available time in purposeful activity. Between 27 and 65% of purposeful activity was engagement in domestic or housework tasks. Even the most handicapped people spent more time engaged in housework than in leisure and recreational tasks. The implications of these data are commented on and measurement issues which arise in ordinary housing as opposed to institutional settings are discussed.