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.     

Control of responding during stimuli that precede transitions in reinforcement frequency

Pigeons' responses were reinforced on a variant of a mixed variable-interval extinction schedule of reinforcement in which the transition to the higher reinforcement rate was signaled by a trace stimulus projected on the response key prior to the onset of the component correlated with food delivery. In the first of two experiments, the duration of the trace stimulus preceding the component correlated with food delivery was varied from 1.5 to 50.0 s and in the second experiment, the reinforcement frequency in the same component was varied from 10 to 60 reinforcers per hour. Pigeons pecked at the trace stimulus preceding the onset of the component correlated with food delivery even though responding was not reinforced in its presence and only one of the changes in reinforcement rate (i.e., from extinction to reinforcement) was signaled. The rate of pecking during the trace stimulus was a function of its duration but not of the reinforcement frequency in the following component. Higher rates generally occurred at the shorter trace-stimulus durations. Component responding following the offset of the trace stimulus was under discriminative control of the trace stimulus whether or not responding occurred in the presence of the trace stimulus.     

Money versus pain: experimental study of a conflict in humans.

Ten healthy human males volunteered to be subjects in an experiment in which they were to be paid to endure a painful sensation. This sensation was produced by isometric muscular contraction in the thighs. For each of six sessions the subjects received either a payment that was changed for each session (0.2, 0.5, 1.25, 3.125, 7.8125 French francs per 20 s) or a lump sum. At the beginning of a session, the subjects assumed a seated position against a wall, but without a seat, and the duration for which they could hold this position was the chief variable measured. Heart rate, blood pressure, and magnitude estimation of pain were also recorded periodically throughout each session. Pain was reported after a mean delay of 15 +/- 7 s (SE), and the magnitude estimates then increased linearly with time. The duration of maintaining the painful position increased linearly in relation to the logarithm of the increase in the amount of payment. Thus, utility of money decreased when pitted against pain.     

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.     

Effects of simulated stuttering on listener recall

In an investigation of the effects of simulated stuttering on listener recall, a presentation was varied on two factors: degree of stuttering (mild or severe) and information value of stuttered words (low or high). A control presentation featuring non-stuttered speech also was prepared. Five groups of 16 subjects were randomly assigned to, and participated in, one of the five listening conditions. Then they completed a 20-item recall test. A one-way analysis of variance revealed sognificant differences among the five conditions. Two-way analysis of variance disclosed no main effects. However, a significant interaction showed that recall was lowest in the severe stuttering-high information condition. The results are discussed in terms of attention to critical information.