An optical encoder and XY oscilloscope interface for the IBM PC

This paper outlines a prototype dual-purpose interface card for the IBM PC for use in research on motor learning and control. The card enables automatic interfacing for up to four angular optical encoders and presents high-speed visual data on an XY oscilloscope. In addition, it uses two single-chip microcontrollers with minimal external hardware, providing a more powerful instrument than is available in discrete hardware. Two microcontrollers operate independently of the experimental computer (IBM PC), using a common interface allowing the exchange of data. This interface card frees the experimental computer from the workload associated with optical encoders and high-speed XY displays, resulting in less complex experimental setups and data collection programs.     

Role of optical flow field asymmetry in the perception of heading during linear motion

During linear translation through a stationary environment, the pattern of optical flow generated on each retina is symmetrical when the head is aligned with the heading, but during lateral gaze the optical flow is asymmetric. We assessed whether human subjects could use the magnitude of this asymmetry to determine the direction of heading during passive translation through a 3-D environment. When allowed to move their heads in order to look in the direction of self-motion, subjects indicated their heading precisely and accurately. When the head was locked in alignment with the misaligned body, and gaze adjustments were not allowed, responses were quite precise, but showed a large bias which increased with increasing heading angle.     

Objects and attributes in divided attention: Surface and boundary systems

A series of experiments investigated concurrent discriminations of surface and nonsurface attributes, including color, brightness, texture, length, location, and motion. In all cases but one, results matched those previously reported: Interference occurred when two discriminations concerned different objects, but not when they concerned the same one. In the two-object case, interference was the same whether discriminations were similar (e.g., two surface discriminations) or different (e.g., one surface, one boundary). Such results support a model of visual attention in which separate visual subsystems are coordinated, converging to work on surface and boundary properties of the same selected object. A partial exception is color: For reasons that are unclear, color escapes twoobject interference except from other, concurrent surface discriminations     

The kinematics,movement phasing and timing of a skilled action in response to varying conditions of uncertainty

This study was designed to provide a detailed analysis of the parameters which interact to produce a field hockey drive. The drive was performed by an elite performer under two conditions of uncertainty (Blocked and Random). The subject was asked to drive a field hockey ball toward a specified target. In the Blocked condition the speed of the approaching ball remained constant (20, 30 and 40 m.p.h.) while in the Random condition these speeds were randomly assigned to each trial. Cine analysis of the subject's successful responses under the two experimental conditions led to an investigation of the kinematics, phasing, and timing of the stroke. The subject placed emphasis upon varying the initial phases of the stroke (i.e., backswing and preparatory phases) in order to produce a temporally consistent ballistic downswing to ball contact. It seemed likely that the subject appraised the ball speed that was being delivered and then incorporated additional stick movement to ‘mark time’ before initiating temporally consistent movement phases, as spatial uncertainty increased, the subject delayed her response initiation, but then tended to respond in intervals of one reaction time for each stroke phase. Consistency was evident for displacement and initiation point values, but to a lesser extent than existed for the other variables. However, as a result of this adjustment in spatial location and displacement of the stick end during the preliminary phases of the response, the subject was able to produce a consistent and accurate ballistic downswing.     

Similarity and contrast in memory for relations

The paper reports four experiments concerned with memory for sets of categorically related or unrelated nouns, as a function of the extent to which initial processing focused on categorical or distinctive features of the nouns. The general finding is that distinctive features are valuable for later intracategory discrimination in recall and recognition, but categorical features are not, as judged by cued recall, recognition, measures of association between items, and categorical intrusion errors. A theoretical framework, based on the diagnostic value of features for various classifications, is offered as an account of the results.     

Competent and incompetent criminal defendants: a quantitative review of comparative research

Thirty studies comparing competent and incompetent criminal defendants (N = 8,170) were quantitatively reviewed to identify variables associated with judgments about defendants' competency to stand trial. Effect sizes reflecting the magnitude of the relationship between competency status and defendant characteristics were derived and averaged across studies. The characteristics most strongly related to incompetency were (a) poor performance on psychological tests or interviews specifically designed to assess defendants' legally relevant functional abilities, (b) a psychotic diagnosis, and (c) psychiatric symptoms reflective of severe psychopathology. To a lesser degree, traditional psychological tests, previous psychiatric hospitalization, previous legal involvement, marital resources, and demographic characteristics were also related to competency status. Although these results are generally consistent with the legal standard for competency to stand trial, some of the correlates of competency may reflect potential biases in the decision-making process. Limitations of existing research and directions for future inquiry are discussed.     

Problem-oriented training promotes spontaneous analogical transfer: Memory-oriented training promotes memory for training

Spontaneous analogical transfer is the use of information from one problem to solve another problem, without an explicit hint to use the previous information. The results of five experiments were that if subjects tried to solve a training problem before hearing its solution, or tried to explain a training story's solution before hearing the correct explanation, spontaneous transfer was more likely than it was if subjects had studied the same training passage for memory before hearing its solution or explanation. The advantage of problem-oriented processing over memory-oriented processing occurred even though solution attempts nearly always failed, and the advantage was not reduced if the target problem was tested 15 min later rather than immediately after training. We propose that problem-oriented processes performed at study are appropriate processes to use at test. Further support for the account comes from subjects' memory for the training passages; the advantage for problem-oriented processing on solution tasks was mirrored by an equally substantial advantage for the memory-oriented subjects on a recall task.     

A factor analytic study of teachers' ratings of the personality of school children

Teachers' rating on 70 adjectives that described the personality of school children were factor analysed. Four main factors emerged, and the adjectives loading most highly on each were selected to form four subscales of a New Teachers Rating Scale (NTRS). The subscales were named Good Pupil, Extraversion, Psychoticism and Neuroticism. Normative data for the scale were reported. Correlations with self-rated personality inventories such as the JEPQ, JEPI and CPQ indicated that: the Extraversion subscale correlated with JEPI-E and CPQ-Exvia, the Psychoticism subscale correlated with EPQ-P, CPQ-Exvia and CPQ-Anxiety, while the Good Pupil subscale correlated positively with JEPI-E, and negatively with JEPQ-P and CPQ-Anxiety. The Neuroticism subscale did not correspond to Eysenck's measures of Neuroticism but correlated with CPQ-Anxiety. Test-retest reliability of the subscales ranged between 0.75 and 0.92. The usefulness of the NTRS in complementing self-rated personality measures and the need to explore the nature of self-rated and teacher-rated neuroticism were discussed.     

Consistency and error in motor performance

Two response measures that described the consistency and accuracy of motor performance were investigated. A pursuit tracking task was used as the vehicle whereby changes in perceptual motor performance could be monitored over several learning trials. The intra-individual variability of a subject's tracking response was compared to the root mean squared error that was accumulated during each block of trials. Whereas both response measures were sensitive to the changes in performance that occured as a result of practice, neither could be considered sufficiently informative as to be used as a sole indicator of skill acquisition. It appears that both consistency and error measures are needed to describe the subjects' performance as they acquire a perceptual motor skill.