A simple and sensitive method to measure timing accuracy

Timing accuracy in presenting experimental stimuli (visual information on a PC or on a TV) and responding (keyboard presses and mouse signals) is of importance in several experimental paradigms. In this article, a simple system for measuring timing accuracy is described. The system uses two PCs (at least Pentium II, 200 MHz), a photocell, and an amplifier. No additional boards and timing hardware are needed. The first PC, a SlavePC, monitors the keyboard presses or mouse signals from the PC under test and uses a photocell that is placed in front of the screen to detect the appearance of visual stimuli on the display. The software consists of a small program running on the SlavePC. The SlavePC is connected through a serial line with a second PC. This MasterPC controls the SlavePC through an ActiveX control, which is used in a Visual Basic program. The accuracy of our system was investigated by using a similar setup of a SlavePC and a MasterPC to generate pulses and by using a pulse generator card. These tests revealed that our system has a 0.01-msec accuracy. As an illustration, the reaction time accuracy of INQUISIT for a few applications was tested using our system. It was found that in those applications that we investigated, INQUISIT measures reaction times from keyboard presses with millisecond accuracy.     

Measuring reaction time and controlling the video display in experiments on an IBM PC

The problems of using the IBM PC XT/AT or their clones in experiments are recognized because of the slow, inadequate and awkward timing procedures of these microcomputers. Some specific solutions to these problems are described, including a compiled BASIC approach using real time procedures accurate to 1 millisecond (although resolution to 1 microsecond can be achieved) and synchronization of the video display with the program. Programs are available from the authors on receipt of a 5 1/4 inch floppy disc or $10.     

STEREO: A program to analyze stereotyped open field locomotion

In rats, amphetamine produces stereotyped locomotion which is characterized by perseverative movement along a fixed route around the perimeter of an open field. The program described in this paper is designed to facilitate analysis of stereotyped locomotion by measuring the repetitive nature of trips between adjacent quadrants of the apparatus using a method described by Mueller, Hollingsworth, and Cross (1989a) which subdivides locomotion into a series of trip lengths. The program is written in Microsoft QuickBASIC to run on an IBM PC/XT or compatible machine. Data from the program can be read by spreadsheets.     

STEREO: A program to analyze stereotyped open field locomotion

In rats, amphetamine produces stereotyped locomotion which is characterized by perseverative movement along a fixed route around the perimeter of an open field. The program described in this paper is designed to facilitate analysis of stereotyped locomotion by measuring the repetitive nature of trips between adjacent quadrants of the apparatus using a method described by Mueller, Hollingsworth, and Cross (1989a) which subdivides locomotion into a series of trip lengths. The program is written in Microsoft QuickBASIC to run on an IBM PC/XT or compatible machine. Data from the program can be read by spreadsheets.     

Millisecond accuracy video display using OpenGL under Linux

To measure people’s reaction times to the nearest millisecond, it is necessary to know exactly when a stimulus is displayed. This article describes how to display stimuli with millisecond accuracy on a normal CRT monitor, using a PC running Linux. A simple C program is presented to illustrate how this may be done within X Windows using the OpenGL rendering system. A test of this system is reported that demonstrates that stimuli may be consistently displayed with millisecond accuracy. An algorithm is presented that allows the exact time of stimulus presentation to be deduced, even if there are relatively large errors in measuring the display time.     

NASA TLX: Software for assessing subjective mental workload

The NASA Task Load Index (TLX) is a popular technique for measuring subjective mental workload. It relies on a multidimensional construct to derive an overall workload score based on a weighted average of ratings on six subscales: mental demand, physical demand, temporal demand, performance, effort, and frustration level. A program for implementing a computerized version of the NASA TLX is described. The software version assists in simplifying collection, postprocessing, and storage of raw data. The program collects raw data from the subject and calculates the weighted (or unweighted) workload score, which is output to a text file. The program can also be tailored to a specific experiment using a simple input text file, if desired. The program was designed in Visual Studio 2005 and is capable of running on a Pocket PC with Windows CE or on a PC with Windows 2000 or higher. The NASA TLX program is available for free download.     

More on millisecond timing and tachistoscope applications for the IBM PC

This paper describes a method of establishing time intervals at a precision of better than 1 msec, using QuickBASIC 4.0, for running real time experiments on an IBM PC without an 8087 coprocessor. This method is far superior to the TIMER function provided by BASIC, which has a precision of only 110 msec. Also described is an assembly language subroutine that corrects a problem in QuickBASIC 3.0 and QuickBASIC 4.0 to allow proper switching between screens in the CGA text mode for use of the PC as a tachistoscope. A tachistoscope program listing shows how to use the screen subroutine and how to establish intertriai intervals and record reaction times using the timing subroutines.     

The PC tachistoscope has 32 pages

Page switching is the basis of the PC tachistoscope, and usual accounts of page switching on the PC refer to a maximum of 8 available pages. This article shows how to achieve up to 16 pages in 40-column text mode and up to 32 pages in low-resolution graphics mode using conventional page switching combined with the bit-plane layering technique described by Bokhorst (1995). A high level C program is presented to show how this is done. When 32 pages are in use, the images must be monochrome.     

A 6809 single-board computer system for the control of behavioral experiments

A computer system consisting of a 6809 single-board computer in conjunction with an IBM-compatible Personal Computer (PC) is described for the control of behavioral experiments. The single-board computer uses the C programming language to program experimental events. Each component of the system (the single-board computer, a digital interface, the PC, and the software) is outlined with its capabilities and drawbacks noted.     

Accurate reaction time research with the TRS-80 microcomputer

Procedures for reaction time research with 1-msec accuracy are described using the video display of the TRS-80 microcomputer. The LVB Corporation interface is also employed. Use of the cassette recorder as a voice key in this research is illustrated. A sample assembly language program is presented.     

Beating the memory drum: Rapid sequential visual presentation (RSVP) on a 4K PDP-8

A program for presenting alphanumeric strings in rapid succession on a Videoterminal is described. Rates of up to 30 items/sec can be obtained with relatively “slow” systems by creating a push-up stack in the terminal’s display memory and scrolling the items past a small display window during presentation. Advantages of such a program are discussed, and the system is compared to mechanical techniques of rapid sequential visual presentation.     

A theoretical expectancy table calculator

A program for calculating theoretical expectancy tables is described. These tables are useful for communicating the meaning of correlation coefficients, since they display the relationship in a simple way. The program allows users to go beyond empirical expectancy tables, which are routinely calculated, by allowing the table to reflect corrections for effects such as unreliability and restriction of range.     

A low-cost high-speed digital data acquisition and display system

A flexible and inexpensive data acquisition and display system based upon the KIM-1 microcomputer module is described. A simple signal-conditioning circuit and program are shown that will allow events to be counted at rates to 1,000/sec and stored in successive time bins. The program counts events from each of two event detectors and stores the count of each detector in an independent set of time bins. Up to 127 16-bit bins are available to each event detector and bin width can be varied from 1 msec to 1 min. A separate input can be used to time-lock data collection to a specific stimulus allowing poststimulus histograms or IRTs to be collected. The collected data can be sequentially displayed as a decimal number on a built-in LED display and stored for later analysis on an inexpensive audio cassette recorder.     

An external millisecond timer for the Apple Macintosh with applications to cross-modal lexical priming

The circuit and program described in this report allow researchers to use Macintosh personal computers to conduct research that requires timing with millisecond accuracy. This is accomplished with external response keys and an external clock that sends characters through the Macintosh’s serial port. For researchers interested in cross-modal lexical priming tasks, a tachistoscopic slide shutter is incorporated to allow for accurately timed presentation of visual stimuli. Because the visual display and response keys are external to the computer, display and reaction times are not subject to the timing constraints inherent to the keyboard or the Macintosh Event Manager. All circuit diagrams and code are in the public domain.     

A tachistoscopic software system for use in remote timesharing applications

A program is described that permits the use of an Imlac PDS-1 display computer, in conjunction with a host timeshare system, as a software-controlled tachistoscope. Alphanumeric and graphic message strings are received from the host computer over a telephone line, and are then displayed for specified periods of time in sequence. The display computer records the S’s responses and reaction time and reports this information back to the host computer for recording and analysis. The system is designed so that the burden of software development for the realization of a specific experimental plan is shifted to the large-capacity host machine, and it can utilize all of the features of standard FORTRAN as implemented on the host computer system.     

Millisecond interval timer and auditory reaction time programs for the IBM PC

Many types of behavioral research require the determination of elapsed time, for example to establish interstimulus intervals and to measure reaction time. The use of an IBM PC for on-line control of such applications is limited by the poor timing resolution ordinarily available. The IBM BIOS time information that is used for the BASIC TIMER function can result in interval timing errors as great as 110 msec. A machine language subroutine is described that can provide 1-msec accuracy. A BASIC program is also described that employs this subroutine to measure auditory reaction time.     

Millisecond timing on PCs and Macs

A real-time, object-oriented solution for displaying stimuli on Windows 95/98, MacOS and Linux platforms is presented. The program, written in C++, utilizes a special-purpose window class (GLWindow), OpenGL, and 32-bit graphics acceleration; it avoids display timing uncertainty by substituting the new window class for the default window code for each system. We report the outcome of tests for real-time capability across PC and Mac platforms running a variety of operating systems. The test program, which can be used as a shell for programming real-time experiments and testing specific processors, is available at http://www.cs.dal.ca/~macinnwj. We propose to provide researchers with a sense of the usefulness of our program, highlight the ability of many multitasking environments to achieve real time, as well as caution users about systems that may not achieve real time, even under optimal conditions.     

ODAP: a stand-alone program for observational data acquisition

A software program written to collect real-time, observational data is described. The flexible program allows customized behavior codes and observational durations and simultaneously records both timed and counted events. The data are collected by means of single keystrokes, automatically stored to disk with 100th of a second resolution and summarized for each observational session. The program’s database files are dBASE III PLUS compatible and may be browsed, edited, or converted to ASCII files from the program’s main menu. Field testing demonstrated the efficiency and interobserver reliability of the program (for frequency,r=0.81; for durational behaviors,rs=0.89 and 0.96). The software operates on IBM XT/AT/PS 2s and most clones with PC/MS DOS version 2.0 or greater.     

A computer-controlled cardiotachometer

A versatile display system for presenting heart rate information is described. The display has a table with 10 rows and 50 columns. This 10 by 50 matrix contains all integers from 0 to 499, so that it can display the instantaneous R-R intervals of a rat’s EKG to the nearest millisecond. At each beat 1 of 10 vertically and 1 of 50 horizontally arranged indicator lights are turned on to provide the coordinates for reading the table. Either beat-to-beat or averaged heart rate or period is displayed. Small and large changes can be easily and accurately observed on the same scale. The lights are controlled by a PDP-8/e. A listing of the assembler program is presented.     

A multiprocessor system for generating visual displays and controlling experiments

A laboratory is described that is based on an IMSAI 8080 microcomputer and an IMLAC graphics display system. Procedures for using the system are described and illustrated.