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.
Department of Applied Mathematics and Computer Science, Ghent University, Ghent, Belgium. armand.declercq@rug.ac.be
Armand
A
De Clercq
Geert
G
Crombez
Ann
A
Buysse
Herbert
H
Roeyers
D006801:Humans; D008838:Microcomputers; D011597:Psychomotor Performance; D011930:Reaction Time; D013998:Time Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*