Relationship between two nontraditional procedures for assessing speech-sound discrimination

Test of speech-sound discrimination are used by special educators, reading specialists and speech-language pathologists in assessing children's ability to differentiate between speech sounds occurring in standard English. Such tests are important in determining if speech-sound articulation errors are caused by difficulty in making such differentiations. However, during the past 10 years, these tests have been criticized on the basis of their reliability and validity. The purpose of this study was to examine the use of two alternative methods of assessing speech-sound discrimination with a school-aged population to determine if they elicited responses in a similar manner.     

H-reflexes during a motor skill acquisition task

H-reflex amplitudes were studied during the acquisition of a motor skill involving coordinated isometric plantarflexion at the ankle joints as subjects learned to trace a triangular pattern on an oscilloscope screen by controlling plantarflexion torque applied against load cells. Torque feedback was presented on a subject oscilloscope with the right foot controlling a vertical cursor and the left foot a horizontal cursor. Eleven subjects reached criterion performance. H-reflexes were recorded from the right soleus and timed to the initiation of soleus muscle activity to plantarflex the foot. Average time to complete one trial decreased from 9 sec. in the prelearning block to 4 sec. postlearning. No single learning strategy was evident as subjects varied widely in their levels of H-reflex amplitude, but during postlearning, H-reflex amplitude became consistent within subjects as tracing performance became faster and accurate.     

Pitch motion with random chord sequences

Perception of global pitch motion was studied through psychoacoustic experiments with random chord sequences. Chords contained either six or eight (fixed) tone elements, being sinusoidal, sawtooth-like, or Shepard tones, which were either on or off according to a probability controlled by the experimenter. Sequences of 2, 4, 5, or 8 chords were used. Identification by subjects of the perceived direction of overall pitch motion (up or down) was found to be well accounted for by a model in which the ultimate pitch motion percept is given by a sum of contributions from selected element transitions--that is, transitions between adjoining tone elements in successive time frames only. In its simplest form, this dipole contribution model has only one free parameter, the perceptual noise for an element transition, which was estimated for various acoustic tone representations and chord arrangements. Results of two experiments, which were carried out independently in two different laboratories, are reported.     

Visual perception of surface curvature: psychophysics of curvature detection induced by motion parallax

The continuous approach to optic-flow processing shows that the curvature of a moving surface is related to a second spatial derivative of the velocity field, the spin variation (Droulez & Cornilleau-Pérès, 1989). With this approach as a theoretical framework, visual sensitivity to the curvature of a cylinder in motion was measured using a task of discrimination between cylindrical and planar patches. The results confirm the predictions suggested by the theory: (1) Sensitivity to curvature was always greater when the cylinder axis and the frontal translation were parallel than when they were orthogonal. The ratio of curvature detection thresholds in the two cases was between 1.3 and 2.5; the value predicted from the spin variation theory is about 2. (2) Sensitivity to curvature increased strongly with the velocity of the motion but was only weakly affected by its amplitude and the duration of viewing for the range of values used in our experiments.     

Secondary enuresis in institutionalized conduct-disordered children

The incidence of secondary enuresis in 16 institutionalized conduct-disordered children was examined. In contrast to a control group of 16 noninstitutionalized conduct-disordered children, the former showed significantly more enuretic behaviour. Also, enuresis began within 6 mo. of the children's separation from their families, suggesting this problem is very likely related to the emotional trauma surrounding the change in living conditions. However, the small number of subjects limits further interpretation of the findings.     

Abnormal optokinetic and perceptual span parameters in cerebellar-vestibular dysfunction and related anxiety disorders

As prior studies indicated abnormal cerebellar-vestibular-based sensorimotor mechanisms and neurological and ENG diagnostic parameters in anxiety disorders and because ocular fixation and sequential scanning are cerebellar-vestibular-modulated, it appeared reasonable to measure these and related ocular functions in matched samples of anxiety-disordered and control subjects. In this study, the optokinetically-determined fixation, sequential scanning, and perceptual span capacities obtained by means of a newly revised blurring-speed method were significantly lower or impaired in 70 anxiety-disordered patients vs 70 controls. Such data supported further the hypothesis that there may be cerebellar-vestibular predispositions to anxiety disorders and the optokinetically-based tracking method may prove useful in separating a diverse array of CV-determined or related anxiety symptoms from those of other origins. However, independent validation as well as additional studies of anxiety disorders using larger samples vs random or "normal" controls are required before conclusions are justified.     

Using item-specific instructional information in achievement modeling

The problem of detecting instructional sensitivity (item basis) in test items is considered. An illustration is given which shows that for tests with many biased items, traditional item bias detection schemes give a very poor assessment of bias. A new method is proposed instead. This method extends item response theory (IRT) by including item-specific auxiliary measurement information related to opportunity-to-learn. Item-specific variation in measurement relations across students with varying opportunity-to-learn is allowed for.This paper was presented at the 1987 AERA meeting in Washington, DC. This research was supported by grant OERI-G-86-003 from the Office of Educational Research and Improvement, Department of Education. The author thanks Michael Hollis and Chih-fen Kao for valuable research assistance, and appreciates valuable comments made by an anonymous reviewer.     

Reading long words embedded in sentences: informativeness of word halves affects eye movements

The possibility was explored that the informativeness of a specific region within a word can influence eye movements during reading. In Experiment 1, words containing identifying information either toward the beginning or toward the end were displayed asymmetrically around the point of fixation so that the reader was initially presented with either the informative or noninformative zone. Words were read with shorter summed initial fixation time when the reading was started from the informative zone. In Experiments 2 and 3, the target words were presented in sentences that were to be comprehended. More attention was given to the informative endings of words than to redundant endings. The latter were also skipped more often. The duration of the first fixation was not affected by information distribution within the word, whereas the second fixation duration was. The results of these experiments lend good support to the hypothesis of immediate lexical control over fixation behavior and to the notion of a convenient viewing position.