Luminance control of a small computer CRT display: A very cheap technique

An inexpensive way to produce continuous variation in the luminance of a computer-controlled CRT display is described. One application of that system to the study of motion-analyzers in human vision is discussed briefly.     

A computer interview language: Programming the on-line interactive computer

Seven computer interview and two disk file commands are executed by a computer program to display multiple-choice questions on a CRT video screen, to record clients’ answers, and to branch to various sets of questions. The program interpreting these commands uses little computer memory and does not require change each time the interview is altered or expanded. It can be written in almost any general-purpose programming language.     

Teaching experimental psychology with on-line computers

The purpose of this paper is to describe the use of on-line computers in the teaching of experimental methodology. Computer models are featured.     

Interpersonal referential communication experiments with a small computer

A LINC-8 computer is used with a Tektronix 611 CRT for presenting verbal information, and a slide projector for displaying facial photographs in studies of interpersonal referential communication.     

Implementation of experimental procedures in the PACER system of on-line control

PACER comprises an Executive and associated routines that together provide the run-time facilities commonly needed by experiment control programs. Although the implementation is specific to a particular PDP-11 installation, the nature of the support provided is of more general interest. Simple experimental procedures are straightforwardly handled by direct program control of timing and of external apparatus, and by direct inspection of the states of input lines connected to such apparatus. For more complicated situations, where events may not occur in a strict sequence, it becomes more convenient to make use of priority interrupts to inititiate response to events. Tasks to be performed under interrupt control are coded by the user as special subroutines known as “Actions.” It is a feature of PACER that the user can arrange for the Executive to run Actions automatically at specified times. The main program is then able to carry out processing that it would not be able to undertake if it had to make repeated checks on the time.     

Building a programming language for a small computer: Reinventing the wheel

The language SP-12 for a PDP-12 computer is described. SP-12 is an example of how a special-purpose language can be constructed from a set of machine-language subroutines that are called by a simple interpreter. Symbolic source programs make it easy to learn the language. Preliminary translation of the source program into binary code, using an assembler, greatly increases the speed of the interpreter.     

Implementation of experimental designs and storage of results in the PACER system of on-line control

PACER has been developed for use with assembly language programs running on a DEC PDP-11/05 machine. The system comprises an Executive and associated routines to perform many of the tasks common to experiment control programs. Attention has been given to the provision of routines to allow the implementation of experimental designs. Experimental variables are referred to asfactors, and the values of these variables are manipulated indirectly through the use of numerical labels, orlevels. Factors are described in tabular form, and means are provided for the independent or joint randomization of the associated levels. Experimental results can then be stored as functions of specified factors and output at the end of a session in a format corresponding to the structure of the experimental design.     

Use of on-line computers in experimental psychology: Hardware considerations

A series of modules provide students with the basic skills to set up and use a computer to run psychological experiments. The modules include basic knowledge of AC/DC power supplies, relay switching, analog/digital conversion, integrated circuit board design and soldering, and elementary programming (FORTH and BASIC). These skills are then utilized to build an interface board and to design and run actual on-line experiments. The hardware orientation is combined with computer skills and experimental methodology to allow students to experience all stages of modem psychological experimentation.     

Mind-operated devices: mental control of a computer using biofeedback.

This study investigated whether people could learn to control a computer using a biofeedback interface that integrated their galvanic skin response (GSR), heart rate, and temperature. Twenty participants played a computer game using the biofeedback device, both individually and in pairs. Results indicated that most people learned to control the game after a single training session. The GSR measure was the most sensitive means of control. Pairs of participants controlled the device more effectively than single individuals did.     

Rapid acquisition of a sidman avoidance response

Rats were trained on a Sidman avoidance task with a 22-sec R-S and a 6-sec S-S interval for six daily 30-min training sessions. Disabling the response lever during and 0.5 sec after shock termination represented one factor in the 2 by 2 factorial design and the presentation of a feedback light cue accompanying an effective response was the other. Rats in the lever-disable condition with feedback light made significantly more avoidance responses than the other treatment groups. In a second experiment, daily 60-min sessions were observed. Using a lever-disable plus feedback light treatment, rats made more avoidance responses and received fewer shocks during the second 30-min as opposed to the first 30 min period.     

Sequential response bias in randomized response sequences: A computer simulation

In this study sequential bias in randomized response sequences is simulated by computer. The computer model assumes that response bias is composed of two components. The first is a repetition avoidance tendency, which is simulated by a memory search through the seven most recently produced responses, and the second is a repetition tendency for the two most recently produced responses. This repetition tendency is assumed to be related to the better availability of recently produced responses. Both processes together give a reasonable approximation of human subjects' data.The results can be explained by the assumption that subjects try to control perseveration tendencies by using a comparison-based memory search mechanism.     

Planning and on-line control of catching as a function of perceptual-motor constraints

Two experiments were conducted in order to investigate the adaptability and associated strategies of the human perceptuo-motor system to deal with changing constraints. In a catching task, perceptual-motor constraints were internally controlled by coupling movement onset of the catch and the illumination circuit in the lab: upon the first movement of the catcher, all lights went out within 3 ms. The authors studied (a) how much movement time catchers prefer if no visual information is available after movement onset, and (b) how movement execution changes under such temporal constraints. It was hypothesised that, in order to accomplish successful catching behaviour, (1) movement initiation would be postponed in order to allow sufficient information uptake before the lights went out, and (2) an alternative control strategy would have to be mobilised, since on-line control becomes inappropriate when catching in the dark. In the first experiment, the adaptation process to the light-dark paradigm was investigated. In the second experiment, the conclusions from experiment 1 were challenged under varying ball speeds. In order to maintain catching performance, subjects initiated the catch approximately 280 ms before ball-hand contact. Next to changes in temporal structure of the catch and subtle kinematic adaptations, evidence for a change in the control mode emerged: while an on-line control strategy was adopted under normal illumination, catching movements seemed to be executed as planned in advance when catching in the dark. Additionally, perceptual constraints seem to determine the time of movement initiation, rather than motor constraints. These results emphasize the capability of the human perceptuo-motor system to adjust promptly to new task constraints.