Software timing of events in cognitive psychology experiments

Real-time systems for controlling cognitive psychology experiments typically use hardware clocks. However, systems using software clocks have comparable reliability, accuracy, and resolution, and the advantages of lower cost and hardware simplicity. Four types of software clocks are described and evaluated. Problems in implementing software clock systems are described, along with their solutions. Software clock routines for Apple II series microcomputers are presented.     

Improved real-time control on the apple by mimicking an on-board 60-Hz clock

By delivering the vertical synch pulse to the maskable interrupt, it is possible to supply the Apple with a functional on-board 60-Hz clock that operates virtually independently of the CPU. This modification makes it easier to program more complex experiments involving independent control over stimulus exposure duration and the timing of response latency.     

An Apple microcomputer-based laboratory system for the study of visual-motor behavior

An apparatus for studying motor control and visual-motor coordination is described. The system consists of an Apple II+ with two expansions boards installed. One board provides advanced graphics capabilities; the other interfaces the Apple with a digitizing tablet and also provides a real-time clock. Target stimulus and visual feedback concerning self-produced movement (i.e., a cursor) are displayed on a standard video monitor, and movement data are sampled by the digitizing tablet. Software consists of about 3K bytes of assembled 6502 code and a 2K byte Applesoft BASIC program. The system is inexpensive, versatile, and particularly well suited for developmental research. It has been used with human subjects as young as 3 years of age.     

On-line Apple II for the recording and analysis of complex motor movements

The system described here was prompted by the need for a method of separately recording various components of a complex motor act. The task involved vertical, horizontal, and turn components. Our particular interest was the relation between integration of components and level of skill demonstrated. The peripheral equipment provides a separate analogue output for each component and plugs directly into the Apple’s game-paddle input. Trial data are stored directly on disk and can be retrieved for subsequent graphical plotting and analysis. The Apple II accommodates up to four inputs and returns results for movements as fast as .05 sec. The programming system can be used, without modification, for a wide variety of motor tasks. No additional interface or clock is required.     

Amplitude measures of operant response: Implementation with Apple Pascal

Because operant conditioning studies involving force of response as a dependent variable require high-speed A/D conversion, conventional operant software, which treats the input datum as a dimensionless event, is generally unsuited for this kind of work. The author describes a complete Apple-based hardware-software ensemble that measures and records on diskette the peak force, duration, time integral of force, and interresponse time for individual operant responses. Data acquisition and control programs were written in Apple Pascal linked to selected assembly language modules. The real-time base was derived from an inexpensive crystal clock interfaced     

Screen display and timing synchronization on the Apple IIe and Apple Ilgs

The logic of the vertical blanking interval (VBL) Softswitch in the Apple Ilgs is the reverse of the logic of the VBL in the Apple IIe. Programs written for the Apple IIe that synchronize the videoscan with the experiment control program timing by sensing the VBL pulse will therefore function incorrectly when run on an Apple Ilgs. Procedures for modifying existing synchronization routines are discussed. A flexible alternative program that senses the type of computer on which it is running and accordingly adjusts the logic of the synchronization routine is described.     

A split-screen electronic messaging system for Apple II computers

A method is described for configuring an Apple II+ or Apple IIe computer to create a multiuser, multiwindowed, electronic messaging system for use in computer-mediated communication research.     

M.T.S.: An adaptable microcomputer-based testing system

An Apple II + computer-based human testing system is described. The system, which was developed using the Pascal language, provides library units of low-level procedures to rapidly access a clock, collect responses, control video output, control a touch-sensitive monitor, and display high-resolution graphics. Built-in hardware and software checks provide a high degree of system reliability. Use of easily altered text files for control of trials within a task and inclusion of and ordering of tasks within a session allows the system to be readily adapted.     

Screen blanking on the Apple IIe

Screen blanking on the Apple IIe can be controlled by software after an annunciator output is connected to the chip enable line (Pin 18) of the character generator (UF4). Using Annunciator 3 gives the same functional results with the Apple IIe as does Reed’s (1979) hardware modification for the Apple II and Apple II+.     

A propositional analyst’s assistant

A system (PAN) that is designed to assist both the inexperienced and the experienced user in performing propositional analysis is described. The system is implemented in UCSD Pascal on the Apple II and Apple He microcomputers.     

A voice-activated key for the Apple Macintosh computer

An interface circuit to connect a microphone to an Apple Macintosh computer is described. The Apple Macintosh mouse port is used as the input port, and the microphone activation simulates a mouse press.     

PsychLib: A library of machine language routines for controlling psychology experiments on the Apple Macintosh computer

The hardware and system software of the Apple Macintosh computer are described, and their implications for conducting psychological research is discussed. A library of machine language routines for presenting auditory and visual stimuli and recording response latencies is described.     

What is Apple-Psych?

Apple Psych, a system of software subroutines written in Apple Pascal and 6502 assembly language, was designed to run real-time psychological experiments on the Apple II, II+, and IIe microcomputers. This paper describes the minimum system requirements necessary to run Apple-Psych, the capabilities of the basic system, and the advantages and disadvantages of using Apple-Psych. Because the utility of a system to a researcher is often linked to its flexibility and expandability, this paper includes a brief discussion of hardware expansions already supported by the Apple Psych software and hardware expansions that would require additional software support.     

Event-related potential data acquisition on the Apple II+/IIe

Event-related potential (ERP) research is a valuable technique for understanding neural mechanisms underlying cognition. With few exceptions, this research has used minicomputer-based data-acquisition systems, thus limiting ERP research to labs with large computers. The hardware and software presented here allow the Apple II+ or Apple IIe microcomputers to present stimuli and collect data from as many as three electrode sites. A fourth electrode site may be used to monitor eyeblinks and allows the exclusion of those trials in which an eyeblink occurs. After the data are collected and averaged, they are stored by subject, task, and electrode on disk where they subsequently may be displayed, analyzed, or downloaded to a mainframe computer.     

Using an Apple II to control a two-field projection tachistoscope

A suite of programs is described that enables an Apple II+ microcomputer to control slide projectors and shutters as a two-field projection tachistoscope. This system is portable and allows more precise exposure timings and more complex visual stimuli to be used than are possible with earlier systems.     

Some simple Apple II software for the collection and analysis of observational data

Two general-purpose software packages for collecting and analyzing observational data from a variety of settings are discussed. One package is designed for coding mutually exclusive behavioral states using the Apple’s keyboard as an input device. The other is designed to monitor temporally overlapping behaviors, and it makes use of the Apple II’s built-in game-control button inputs to indicate up to three behavioral states that may occur simultaneously.     

Experimental control and data acquisition with BASIC in the Apple computer

Laboratory experiments can be precisely controlled and data can be collected using the BASIC language on an Apple II+ computer with 48-KB RAM, disk drive, and two timer-I/O cards. The Apple BASIC makes machine language output control routines necessary, but quite convenient. By compiling BASIC, 50–100 inputs/sec are handled. Applications range from operant research and analog data collection to use of the Apple color display capability for stimulus presentations and response recording.     

Optical and electronic systems for spatial and temporal analysis of video images

In this paper are described two systems for spatial (two-dimensional coordinates) and temporal analysis of video images. In the optical version, the Apple IIe generates a pointer on an Apple monitor; the pointer is then superimposed on the video image of a second video monitor, by reflecting the pointer with a half-silvered mirror. In the electronic version, a special card was designed for the Apple IIe to generate a pointer directly on the other video monitor. Both systems use the same software. The procedures of spatial and temporal data acquisition and storage are described as well as the reading, writing, printing, removing, listing, chaining, and dating operations of the digital and graphics files.     

Adding drift to the decomposition of simple isochronous tapping: an extension of the Wing-Kristofferson model

The Wing-Kristofferson model (A. M. Wing & A. B. Kristofferson, (1973a, 1973b) decomposes the variance of isochronous finger tapping into 2 components: a central clock component and a peripheral motor component. The method assumes that there is no drift in the intertap intervals. A new method is introduced that further decomposes the clock component drift and drift-free clock variance. The method was studied through simulation and empirical analyses. Clock variance was the most prominent, followed by drift, and then motor variance. Individual and group differences were larger for the motor and drift variances than for the drift-free clock variance, so that group differences observed in the past may have been partially due to the failure to fully remove drift. The authors argue that the methods presented and extensions thereon show great promise in extending a method in wide use since 1973.