Comparison of deaf and hearing children on body-object localization.

20 profoundly deaf and 20 normal hearing children from ages 10 to 13 were compared as to their ability to locate visually the position of apparent vertical and the apparent location of the longitudinal axis of the body under erect and 30 degrees left and right body-tilt. Both deaf and normal hearing children were able accurately to locate a rod to the apparent visual vertical, but deaf children were significantly more accurate in aligning a rod to their apparent body-position than hearing children. This finding is discussed from both a learning view and from a hypothesis of developmental lag.     

Semantic expectancy effects on word access

Summary Access to word-representations in memory was studied in an experiment that used a lexical decision task: Ss had to decide whether a string of letters was a word or a nonword. Independent variables were context-similarity and semantic expectancy. The former is defined in terms of the categorical relationship that holds between a set of context words and the subsequently presented test word. The second refers to the cue-value given to subjects as to the likelihood with which related or unrelated test words would be presented. Cue-values did not provide information on the likelihood with which word or nonword decisions were required, but only on the most probable semantic relationship holding among context and test words. In theory, Meyer and Ellis' (1970) race model for word access was extended for the present purpose. It is shown that the two search processes assumed to mediate lexical access interfere on the basis of limited processing capacity, at least under the special conditions prevailing during the experiment. Furthermore, it is shown that Ss effectively manage to control the point in time at which they decide to issue a nonword response. Cuing for related test words tends to produce faster nonword decisions than cuing for unrelated words.This paper reports work that was conceived and begun at Stanford University, Calif., USA, where the author spent a year as a post-doctoral fellow. This fellowship was made possible by the Deutsche Forschungsgemeinschaft, Bad Godesberg, Federal Republic of Germany, Grant Schm 350/1. I am grateful to R.C. Atkinson, S. Monsell, P. Matthews, and D. Vorberg for supporting this research in a number of ways.     

Motivational control of motor performance by goal setting in a dual-task situation

Summary The goal-setting approach to task motivation is applied to examine the way in which subjects control their performance on two concurrently performed tasks under the guidance of different goals in a dual-task situation. The tasks were a simple auditory-manual reaction time (RT) task and a visual-manual pursuit-tracking task. The goal conditions assigned alternatively to the tasks differed with respect to goal specificity and feedback information (KR) given after the trials. It is shown that the improvement of performance in the task with hard, specific goals is achieved in both cases at the cost of the concurrently performed other task which, on the basis of a lack of feedback and a rather unspecific goal instruction, should have a lower priority. The data reveal some strategies hidden behind these overall changes of the average performance at both tasks. For the RT task, the adjustment to the different goals is mainly achieved by changes in the temporal control or preparatory processes as can be inferred from the RT distributions as well as from the analysis of some typical errors. For the tracking task, changes in the tracking accuracy within the overlapping RT intervals are the best indicators for the performance control under the different goal conditions.This research was supported by a grant from the Deutsche Forschungsgemeinschaft (Kl 408/4-2)     

Variations in WISC-R patterns of learning disabled children

The WISC-R was administered to 19 learning disabled students at the time of diagnosis and following a period of time in special program placements. Group analyses indicated fluctuations between testing times in the Verbal and Full-Scale IQs and the V-P IQ discrepancies. Small but significant differences in Verbal, Performance and V-P scatter indices were observed at one or both testings in comparison to the normal standardization sample. Although the suggested group pattern for learning disabled children based on the Bannatyne categories was confirmed on both occasions, there was considerable variation for individual subjects.     

An auditory evoked potential study of consonant perception in different vowel environments

Auditory evoked responses (AER) to series of consonant—vowel syllables were recorded from temporal and parietal scalp locations from 20 right-handed female college students. Averaged AERs were submitted to principal components analysis and analysis of variance. Seven components of the group's AERs were found to reflect various aspects of the stimulus parameters. One component reflected changes over only the left hemisphere to different consonants independent of the following vowel sound. A second component changed systematically over both hemispheres in response to only consonant changes. A third component systematically changed for the different consonants depending on the following vowel.     

Assessing stereomotion thresholds with a high-resolution computer monitor

We investigated the feasibility of a computer-graphics-based method of assessing stereomotion thresholds (Silicon Graphics Stereoview stereoscopic system). Stereomotion thresholds for a rectangle oscillating in depth were determined with the use of a dual randomly interleaved staircase design. In a group of 31 naive observers, the average thresholds of 5.97′ of arc forcrossed stereomotion and 6.00′ of arc foruncrossed stereomotion were comparable to those assessed in earlier work done with optics-based techniques. By assessing the thresholds for a rectangle that was defined either by lateral motion or by changing size, in a group of experienced observers, we were able to show that any potential residual translational motion present in the display would not have influenced the stereomotion thresholds. Our findings suggest that this computer-graphics-based technique may be a reasonable alternative to optics-based methods of assessing stereomotion thresholds.