A simple procedure for approximate factor analysis

A variation of the centroid method is described and illustrated. By the application of new rules for reflecting signs, it may be possible to reduce to insignificance the factor loadings of tests showing insignificant correlation (original or residual) with clusters of tests having relatively high intercorrelations. As a result, a factor common to any one of these clusters may be revealed by the centroid method itself with little or no need for rotation of axes or further calculations.     

A digital ultrasound recorder

A system that continuously monitors and records rodent ultrasonic vocalizations over the frequency range 10–90 kHz is described. The system records vocal frequency, sound pressure, time, and duration of call. Data are stored digitally. The system was validated by a pilot study in which distress calls of rat pups were selectively activated while they were subjected to a cold environment.     

A high-speed computer-coinpatible event recorder

Design considerations, construction information, and programming considerations of a high-speed event recorder are presented. The device records discrete events on magnetic tape for later processing by a large computer. Although the design information is general, the instrument has 120 event channels, a time resolution of up to 100 microsec, and can record 60 or more events per second.     

A simple method of factor analysis

A simple method for extracting correlated factors simultaneously is described. The method is based on the idea that the centroid pattern coefficients for the sections of unit rank of the complete matrix may be interpreted as structure values for the entire matrix. Only the routine centroid average process is required.     

A simple method for latency analysis in signal detection tasks

It proved that the difference between mean latency for incorrect responses and mean latency for correct ones in signal detection situations can be used as a measure for the separation between SN and N distributions, provided that certain plausible conditions are met. The applicability of this method to various paradigms is briefly discussed.     

VIDEOLOGGER: A computerized multichannel event recorder for analyzing videotapes

A microcomputer-assisted system that permits multiple events to be coded from videotape to a common time base is described. The system allows an operator, by pressing a button, to record the onset and offset times of any number of events. It requires a video recorder, an Apple II microcomputer, a John Bell 6522 timing card, and a pair of switches. The software package consists of five programs: one to make timing signals on the videotape, one to record the onset time and duration of the operator’s buttonpresses, one to read and print the coding data from disk, one to operate the timer, and one to process the compiled code used in the software package. All necessary wiring diagrams are shown. Software is available gratis from the authors on request.     

A simple electrode to record fetal EEG for optimal signal analysis

A simple EEG electrode for Intrauterine use In the human fetus is described. The stainless steel screw electrode possesses low noise characteristics, is constructed from commercially available material, and is easily attached to the fetal head during labor. Principles of optical signal analysis as an improved method of spectral analysis of the fetal EEG are also presented. The optical system provides visual display and hard copy output of the fetal EEG.     

A method for constructing an objective eye color chart

Detailed instructions for constructing an eye-color chart that represents a normal range of human eye colors are provided. The chart is composed of photographic color slides of human irises, magnified to 3.6 × life-aize. Iris images are sequenced according to their color and measured opacity. This enables researchers to reliably classify subjects’ Ms pigmentation according to both color and darkness. The eye color chart is easy to use and is highly reliable (between-observers measurements r ? .94). The photographic arrangement is also useful for obtaining magnified photographs of irises for documentation and illustration purposes.     

A multichannel,multiobserver portable event recorder

This paper describes a microprocessor-controlled 64-channel event recorder that supports up to eight remote keyboards utilizing a serial data transmission method. The keyboards can be connected via long twin stereo cable to the encoder unit, which stores the buffered data onto audio cassette tape. This system enables multiple observers to encode multiple events in a field or laboratory setting. The keyboard design is presented in detail.     

A solid-state cumulative recorder for an analog registry of accumulative events

A solid-state device for providing graphic records of various behavioral and physiological events in much the same manner as does the electromechanical cumulative recorder is described. This transistorized version of the cumulative recorder produces a noise-free (electrical and acoustical) analog cumulative record on analog recorders. The circuit provides for such features as: built-in calibrator; internal-reset oscillator; variable incremental step amplitude; and a FET op-amp to provide a constant. drift-free output level over long and extended reset periods. The output of the device can be displayed on one channel of a polygraph recorder with adjacent channels providing physiological and behavioral data to produce a real time correlation of analog and event signals.