An instrumented method for assessment and remediation of stuttering: A single-subject case study

A single-subject experimental design was used to investigate the feasibility of applying non-invasive laboratory instrumentation for examining speech physiology to assessment and biofeedback-based remediation of stuttering. Physiologic assessment facilitated the development of behavioral goals directed at changing respiratory and phonatory behaviors for this subject. Visual biofeedback therapy produced reduction in respiratory discontinuities and increased phonatory continuity, concomitant with reduced perceivable molar dysfluency. Methods used in this case illustrate a variety of options and problems related to clinical use of instrumentation. Results suggest that signals which represent respiratory, phonatory, and articulatory physiologic events may be clinically practical for evaluating and altering perceivable dysfluency.     

Short-term retention of response outcome as a determinant of serial reversal learning

The correlation between short-term retention of the outcome of the preceding response and overall learning proficiency was investigated for serial reversal learning. Pigeons were trained to asymptote on a serial reversal problem and then were presented a percentage reinforcement schedule where only some correct trials were rewarded. Nonrewarded correct trials were treated exactly as incorrect trials. The difference in error probability following the two types of correct trials was then used as a measure of short-term retention. When intertrial intervals (ITI) were short (6 sec), substantial differences occurred. When the ITI's were increased, the difference in accuracy declined regularly to no difference at an ITI of 60 sec. This demonstration of a short-term retention gradient, coupled with the finding that overall reversal learning was much better with the shorter ITI's, suggests that a primary mechanism of improvement in serial reversal learning is the acquisition of a conditional discrimination based on the outcome of the preceding response.     

Alphanumeric category effects: Evidence against the sufficiency of a localization explanation

The Hatfield Polytechnic, Hatfield, Herts ALIO 9AB, England The experiment utilized a serial choice reaction time (RT) paradigm in which only one alphanumeric stimulus was presented per trial, and the target set consisted of a single identified item. The categorical relationship between the target and nontarget items was varied as a property of blocks of trials. Target and nontarget RTs were smaller when the specified target item (e.g., the number 6) was categorically distinct from the nontargets (e.g., letters) than when it was from the same category (e.g., digits). The processing of catch-trial stimuli (items from the alternate category to the nontargets) and homographie category-ambiguous items was inhibited only in the former, between-category, condition. The results are contrasted with those obtained in visual search tasks. They suggest that a “locational-cue” explanation of alphanumeric category effects is inadequate.     

Preference and resistance to change in concurrent variable-interval schedules

Pigeons were trained on a multiple schedule in which separate concurrent schedules were presented in the two components of the schedule. During one component, concurrent variable-interval 40-sec variable-interval 80-sec schedules operated. In the second component, concurrent variable-interval 40-sec variable-interval 20-sec schedules operated. After stable baseline performance was obtained in both components, extinction probe choice tests were presented to assess preference between the variable-interval 40-sec schedules from the two components. The variable-interval 40-sec schedule paired with the variable-interval 80-sec schedule was preferred over the variable-interval 40-sec schedule paired with the variable-interval 20-sec schedule. The subjects were also exposed to several resistance-to-change manipulations: (1) prefeeding prior to the experimental session, (2) a free-food schedule added to timeout periods separating components, and (3) extinction. The results indicated that preference and resistance to change do not necessarily covary.     

The dimensions of stage theories

Stage theories are commonly used to represent the structure of cognitive processes in the domains of cognitive processing and cognitive development. Hierarchical unidimensional theories consisting of a single sequence of stages through which development proceeds in one direction only have predominated. However, a review of stage theories revealed that a two-dimensional, interactive (multidimensional) structure is warranted. Particularly in the area of cognitive development, results of research have supported subdivision of the stages of prominent unidimensional theories. Following this trend a small number of theorists have developed multidimensional theories, most of which consist of a sequence of stages in which each stage contains a number of subsidiary stages or levels. The emergence of a similar trend in other domains is examined, and the prospects of using an existing multidimensional framework to enable future comparisons and integration of different stage theories is explored.