Laterally induced impedance effects in vision

A linear integral equation for a system of mutually impeding points is developed and solved explicitly. Particular solutions are shown to be subharmonic functions for a large class of stimuli. Specialized forms of the general equation presented in this paper occur within a number of mathematical models of Mach bands. In addition to these known spatial properties, our results also show that the time course of this basic equation may be useful in developing models of transient neural activity as well as of temporal psychophysical phenomena, such as the Broca-Sulzer effect. Further, a spatial transfer function much like the low-frequency cutoff of empirically derived modulation transfer functions follows directly from our basic integral equation if the additional assumption of spatial homogeneity is imposed.     

Determining a child's strong and weak areas of functioning on the Stanford-Binet: A simplication of Sattler's SD method

Interpreting areas of strength and weakness on the Stanford-Binet presents problems for many clinicians. Sattler's SD method for determining normal variability provides an objective approach for dealing with this issue, and is thus a valuable tool for Binet interpretation. However, Sattler's procedure is beset by practical problems that limit its usefulness. The aim of this paper was to develop a simplification of Sattler's technique (in the form of a table) to make it easier to use and to apply to the Binet profile of any child tested. An illustration is included to demonstrate the role of the table for generating hypotheses about a child's strong and weak areas of functioning. Cautions are discussed regarding the application of the interpretive procedure.     

An eight-channel computer-controlled scanning electromyograph

A measurement system is described for the computerized detection, digitizing, and storage of electromyographic (EMG) signals from up to eight muscle groups. The use of a channel scanning technique allows almost simultaneous multichannel recording with minimal circuit redundancy. Specifically, the scanning electromyograph allows several EMG preamplifiers to share expensive isolation, signal-conditioning, and interface circuitry. The design incorporates monolithic integrated circuit preamplifiers and includes optical isolation of the preamplifier circuitry for protection of the subject. Hybrid active filter modules allow convenient selection of system bandpass characteristics. Key measurement parameters are software programmable. The scanning electromyograph is inexpensively constructed from readily available componentry. Specifications for all functional blocks within the instrument are comparable to those of commercial instrumentation.     

An inexpensive digital millisecond timer and event counter

A simple circuit for a digital millisecond timer and event counter is described. The total cost of the unit including all components, a power supply, and an enclosure is less than $30. Daily use in simple reaction time experiments has demonstrated the reliability of the design.     

The quantitative measure of pattern representation in images using orientation-specific color aftereffects

A quantitative method is developed for assessing the quality of pattern information in imagery, using the magnitude of color aftereffects as an objective index. Subjects were given instructions to project imagined bar patterns of particular width and orientation onto adapting color fields, in such a manner as to simulate standard conditions for establishing the McCollough effect. Our control procedures indicate that the resulting orientation-specific complementary color aftereffects cannot be attributed to the conditioning of particular directions of eye scanning movements to color processing during adaptation, or to other possible sources of experimental bias. Furthermore, subjects who rated themselves prior to the adaptation procedure as having relatively vivid imagery showed significantly larger aftereffects than those who reported having relatively low imagery. These results not only provide an important confirmation of our earlier finding that imagination can replace physical pattern information in the formation of basic color-feature associations in the human visual system, but also demonstrate that these aftereffects can provide a practical measure of the fidelity of pattern representation in visual images.     

Covert and overt rehearsal and elaboration during treatment in the development of assertive behavior

The present investigation examined the effects of covert and overt rehearsal and client elaboration of situations designed to train assertive behavior. Nonassertive clients (n = 61) received one of four treatments resulting from the 2 × 2 factorial combination of Modality of Rehearsal (covert vs overt) and Elaboration (elaboration vs no elaboration of training situations). A delayed-treatment group was included in the design to serve as a no-treatment control condition before subjects were assigned randomly to one of the above treatments. Treatment led to significant improvements on self-report and behavioral measures of assertiveness and self-efficacy. Covert and overt rehearsal were equally effective. However, elaboration of training situations significantly enhanced the effects of covert and overt rehearsal. Treatment effects were maintained up to a 6-month follow-up, transferred to novel role-playing situations, and brought clients within the range of other subjects (n = 45) who regarded themselves as adept in social situations requiring assertive behavior and who had not sought treatment.