Estimating response time hazard functions: An exposition and extension

The hazard function of a response time distribution describes the temporal dimension of a response process and completely characterizes the distribution. The function can be estimated by a quadratic spline which is constrained to have one of a number of simple functional forms. The estimator can also be employed when the response time is an unobserved component in a parallel or serial pair of processes.     

Hemispheric alpha asymmetries during an electromyographic biofeedback procedure for stuttering: A single-subject experimental design

A single-subject “double-reversal” experimental design was used to investigate the use of electromyographic (EMG) biofeedback on the dysfluent behaviors of a right-handed male stutterer. A systematic decrease in EMG amplitude accompanied a progressive approximation of increased verbal complexity resulting in increased fluent behavior. Electroencephalographic (EEG) alpha data (8–12 Hz) gathered during baseline and pre- and post- treatment sessions appeared to co-vary with changes in fluency with right hemispheric suppression associated with greater dysfluencies and left hemispheric alpha suppression with decreased dysfluencies. The results are discussed relative to stutterer's adoption of differing behavioral production strategies for fluent speech that are associated with hemispheric information processing strategies.     

Left hemisphere superiority for pronounceable nonwords,but not for unpronounceable letter strings

Right-handed adults were asked to identify bilaterally presented linguistic stimuli under three experimental conditions. In Condition A, stimuli were three-letter pronounceable nonwords (such as TUP), and subjects were asked to report them by naming them. In Condition B, stimuli were three-letter pronounceable nonwords, and subjects were asked to report them as strings of letters. In Condition C, stimuli were more or less unpronounceable letter strings (such as UTP) created by rearranging the letters of pronounceable nonwords, and subjects reported them as strings of letters. Pronounceable nonwords were found to be better identified from the right visual hemifield irrespective of the way in which they were reported. Unpronounceable letter strings did not produce any visual hemifield difference. Nonwords are of interest because they can be seen as potential words that lack both specific semantic properties and entries in the subject's internal lexicon. The results of the experiment are consistent with the view that both the left and right cerebral hemispheres are able to identify letters but the left hemisphere is more sensitive to the pronounceability of the nonwords. This may happen either because the left hemisphere can make better use of resemblances to real words or because it has access to spelling to sound correspondence rules.     

Dichotic listening ear asymmetry: Patterns of longitudinal development

Dichotic listening research with children has continued to be prevalent although numerous authors have described both theoretical and methodological limitations with traditional dichotic listening free-recall paradigms. The present research adds to this growing skepticism by reanalyzing two major longitudinal studies of children's ear asymmetries. These two studies, based in different countries (United States, Holland), utilized highly similar paradigms (free-recall digits), subjects (males), and age levels (kindergarten and second and fifth grade). The questions of ear advantage development, patterns of ear advantages, and the relationship between dichotic listening performance and reading skills are addressed from the multiple statistical methodologies represented in the literature. From these analyses, support for all of the major hypotheses regarding the developmental patterns of dichotic listening performances could be obtained from the same data samples. The use of traditional free-recall dichotic listening paradigms are not recommended for use with children. The implications for future research are discussed.     

A developmental perspective on reading dysfunction: Accuracy and rate criteria in the subtyping of dyslexic children

Children referred with specific reading dysfunction were subtyped as accuracy disabled or rate disabled according to criteria developed from an information processing model of reading skill. Multiple measures of oral and written language development were compared for two subtyped samples matched on age, sex, and IQ. The two samples were comparable in reading fluency, reading comprehension, word knowledge, and word retrieval functions. Accuracy disabled readers demonstrated inferior decoding and spelling skills. The accuracy disabled sample proved deficient in their understanding of oral language structure and in their ability to associate unfamiliar pseudowords and novel symbols in a task designed to simulate some of the learning involved in initial reading acquisition. It was suggested that these two samples of disabled readers may be best described with respect to their relative standing along a theoretical continuum of normal reading development.     

Comparison of the performances of a fluent and a nonfluent aphasic on a pantomimic referential task

The pantomimic performances of a typical Broca's (nonfluent) and Wernicke's (fluent) aphasic were compared with each other and with four normal control subjects on a simple task of nonverbal referential communication. Both aphasic subjects demonstrated only about 50% accuracy in their pantomimic communication. Also, measures were obtained of the motoric fluency of the pantomimes of all subjects and comparisons were made between the fluent and nonfluent aphasics. These measures demonstrated distinct differences in the fluency patterns of the pantomimes of the two aphasic subjects similar to the differences in speech fluency which distinguish and characterize these two types of aphasia; that is, the fluent aphasic pantomimed fluently and like the control subjects and the nonfluent aphasic pantomimed nonfluently. The quantitative and qualitative similarities in the fluency patterns of the speech and the pantomimic behaviors of the aphasic subjects are discussed in terms of their implications for a definition of aphasia.     

Speech and bimanual hand organization in adult stutterers and nonstutterers

A multivariate approach was used to investigate the relationship between speech fluency and bimanual handwriting in right-handed male stutterers and nonstutterers. Handedness was determined by the Harris Test of Lateral Dominance. Subjects were required to write the numbers 1 through 12 simultaneously, as quickly as possible. Speech measures were derived from the Stuttering Severity Instrument and from a reading passage. Stutterers performed more poorly than nonstutterers on all speech measures. There were no differences in bimanual handwriting performance for the dominant hand. However, stutterers performed more poorly than nonstutterers in nondominant handwriting. There were no relationships between speech measures and bimanual handwriting for stutterers or nonstutterers. Some stutterers performed better on the handwriting task than did some nonstutterers. It is suggested that disorganization in interhemispheric integration functions may be a more fundamental problem in stuttering than is incomplete cerebral dominance.     

Pause loci in stuttered and normal speech

The mainstream of research comparing types of disfluency in stuttered and normal speech has typically omitted consideration of pause. In contrast, psycholinguisticresearch addressed to disfluency in normal speech alone has revealed the salience of pause in the study of fluency/disfluency. The research reported here, which focused on the antecedents and sequelae of filled pauses, revealed substantial differences in pattern of pause occurrence between stuttered and normal speech samples obtained from 20 matched subjects. The results are discussed in reference to relevant findings from the research on pause in normal speech.     

The use of a portable delayed auditory feedback unit in stuttering therapy

A portable on-the-body delayed auditory feedback was used in the establishment and transfer modes of fluent speech in a stutterer while he was on the Monterey Fluency Program. The performance of the client was compared with a “standard” population of stutterers. The portable DAF was comparable to the larger DAF in establishment and superior in transfer with minimal behavioral and technical problems. Use and potential value of the portable DAF in transfer and maintenance phases of therapy are discussed.