MICROMANAGING TIME - MEASURING AND CONTROLLING TIMING ERRORS IN COMPUTER-CONTROLLED EXPERIMENTS

Computer-controlled experiments present a number of potential sources of error in timing the presentation of events, including video refresh rate, keyboard scanning rate, and disk I/O times. A terminate-and-stay-resident routine implementing multiple millisecond-accuracy timers is presented. Interfaces permitting use of the timer with several higher level languages (C, FORTRAN, Pascal, and QuickBASIC) are described, as is a design for a two- to four-button response system using the computer's printer port. A general strategy is described for using multiple timers to control and measure variation in critical experimental events. A C language program is provided to benchmark variation in the time required to perform common experimental tasks (screen refreshing, switching video pages, disk I/O, loop calculations), and results are summarized for several representative computers that use the IBM design. © 1990 Psychonomic Society, Inc.