A random-pulse generator with adjustable pulse duration

An electronic device for generating random pulses of adjustable duration within a minimal and maximal interval boundary is described. The instrument is useful in electro- and psychophysiological research where randomization of stimulus input is required.     

Two-channel random pulse generator

The amplification of random thermal noise is utilized to generate two channels of pulses whose frequencies are random with time. The phase relationship between the two channels is also random with time. The pulses can be used to randomize presentation of stimuli for experimentation or training.     

A clock pulse generator (CPG) for behavioral time research

A device is described which (1) generates very accurate time calibration tones suitable for tape recording along with experimental behaviors, and (2) creates from such a recorded tone an easy-to-read structured pulse train for oscillographic tracings. Calibration tones at 1-, 5-, and 10-kHz pulse rates are derived from a crystal oscillator module and are made available for tape recording at one output of the device. The second output produces a four-level structured pulse train in which there is one pulse for each cycle of the calibration tone (every 10th is a little larger, every 100th a little larger yet, and every 1,000th larger still). An example of the use of this device in speech, timing research is given.     

A simple encoding and recording system for small group observation

A simple and inexpensive system for coding and recording interaction patterns in small groups is described. It consists of a keyboard and a standard tape recorder, and it is capable of storing sequential data using up to 36 codes. Its main application is in the study of speaker-target patterns, but it can also be used in encoding up to 12 behavioral codes, or six speakers and 6 codes. The keyboard costs less than $200 and is used with conventional tape recorders and minicomputers available at most research sites.     

A digital system for recording startle,responses in small animals

An easily constructed, isometric startle-recording system is described. The animal enclosure is attached to a plywood board-which, in ten, is mounted in a “springboard” arrangement. Movement is detected by a phonocartridge mounted beneath the chamber, and a digital record of this movement is obtained through the use of a voltage-to-frequency converter. A brief experiment in which the system was used to assess the rat’s reaction to electric footshock is also presented.     

A new device to present textured stimuli to touch with simultaneous EEG recording

The study of touch has recently grown, due mainly to the extensive use of several types of actuators that stimulate several subsystems of touch. There is a widespread interest in applying these mechanisms to the study of the neurophysiological correlates of tactual perception. In this article, we present a new device (the tactile spinning wheel [TSW]) for delivering textured surfaces to the finger pad. The TSW allows one to control several parameters of the stimulation (angular speed, texture, etc.) and, connected to an EEG recording system, makes it possible to study neural electrophysiological events. The device consists of a rotating platform on which the tactile stimuli are fixed, a system that synchronizes stimuli onset with the EEG system, and an electronic interface that controls the platform. We present the technical details of the TSW, its calibration, and some experimental results we have obtained with this device.     

A device for recording automatic audio tape recording

Adaptation of a commercially available timer for use as a means of operating an audio tape recorder several times during the day is described. Data on a mother's rates of commanding her children were collected via both physically present observer and recorder methods in order to compare the usefulness of the recordings with direct observation. There was a high positive relationship between observer-recorder command rates, with the observer rates being consistently higher, when data were collected via both methods simultaneously as well as at different points in time.     

Modified recording procedure for the determination of I/t-curves with arterial pulse recording and acoustic signal generation

I/t-curves were derived by means of a piezo-electric transducer. To receive the minimum responses more than just optically, an amplifier, which was coupled to a transducer, generated an acoustic signal. This modified technique serves to objectivity of the minimum response, which is important in the recording of the I/t-curves. As has been shown in a great number of tests, this procedure has proved to be useful in practice.     

An artificial eye for evaluating videobased eye recording systems

Videobased corneal-reflection-to-pupil-center systems are widely used in eye movement research. In this paper, an artificial eye drawn on a computer screen is presented. The artificial eye provides a way to simulate measurements of eye position in human subjects. The method allows testing videobased systems on the level of the signal and on the level of the calibration algorithm used to map the eye position parameters to stimulus space. In addition, the artificial eye can be used to evaluate specific hypotheses concerning the functioning or malfunctioning of the eye recorder and as a help in developing data analysis programs.     

Simulated unit pulses for calibrating

A small battery-powered instrument generates sinusoidal pulses of approximately the shape of neuronal pulses. The output consists of alternate positive and negative pulses across a 10 k ohm source resistance. Such a signal allows a quick assessment of the amplification system and indicates possible losses through shunt capacitances along the connections between S and amplifier input.     

A method for calibrating an eye-monitoring system for use with infants

An algorithm for calibrating data from an infrared corneal reflection eye movement monitor is described. The algorithm is designed for use with infants and other noninstructable subjects.     

A system for recording family sessions

A diagrammatic technique for recording family sessions is presented. The Interaction Chronogram is a visual display system originally devised for use in group psychotherapy by Cox, but can be modified for work with families. The system permits a family session to be summarized diagrammatically and aids review of a family's treatment. A 'diagnostic' and treatment session with one family is presented to illustrate the system's use.     

A stand camera for line-of-sight recording

The paper describes a method that has been extensively used to superpose a spot marking the position of the line-of-sight on photographs of stimulus scenes. The spot, reflected from the cornea, determines the line-of-sight with an accuracy of plus or minus 1°. Some of the useful measurements that can be made of fixation patterns are described. Two basic themes have guided the experimental applications: the relation between attention and the line of sight, and the association between peripheral and central vision. Comparisons among age groups have also demonstrated the erratic and piecemeal nature of children’s visual input. Comparisons among scenes have shown that certain areas of a picture, judged highly informative, receive most of the visual fixations. More than 20 other laboratories have also used the camera in a wide range of research on perception, cognition, and psycholinguistics.     

A test-signal generator for low-frequency instrumentation

An instrument for generating simultaneous sinusoidal test signals m the range of 1–32 Hz for EEG equipment checkout procedures is described. A composite signal is produced by a method that separates the functions of waveform generation and control of output frequencies at which that waveform appears. The general technique may be applicable in a number of situations involving low-frequency instrumentation, as with other types of physiological monitoring. Possibilities and methods for elaboration or modification of the circuit are suggested.     

Low-noise microvolt level calibrator for measurement of performance of biosignal recording systems

A calibrator, the noise level of which is below the noise level generated in the preamplifier system, was needed for testing and development of a multichannel recording system. A multichannel preamplifier head assembly was used for recording cortical, subcortical, and cerebellar slow potentials and multiunit activity in freely moving cats and restrained rabbits. An inexpensive, battery-powered, lownoise voltage signal generator for calibration of the preamplifiers is described. The circuit provides a square-wave output at a frequency of 10 or 1000 Hz, and the peak-to-peak (p-p) amplitude can be selected at 10, 100, or 1000µV. The measured output noise of the calibrator is below 2µV (p-p, 0.1–6000 Hz). The frequency and amplitude values can be easily adapted for different purposes by changing a few component values. An amplified (gain 1,000×) test output for direct oscilloscope monitoring is included in the calibrator circuit.