RESEARCH ARTICLE


The Timing Accuracy of General Purpose Computers for Experimentation and Measurements in Psychology and the Life Sciences



Andrew Wallace*, Guy Madison
Department of Psychology, Umeå University, SE-751 42, Sweden


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Creative Commons License
© 2012 Wallace and Madison

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Psychology, Umeå University, SE-751 42, Sweden; Tel: (0)73-620 5455; Fax: (0)90-786 66 95: E-mail: guy.madison@psy.umu.se


Abstract

General purpose computers find increased use within behavioural, psychological, and neuroscientific experi-mentation, which raises concern for the timing accuracy that can be obtained with such systems. Here, we assessed the timing accuracy of such machines, considering both differences between different hardware and different versions of the Windows™ operating system (OS); Windows XP, Vista and Windows 7. The variability varied widely across machines and OS versions. The indeterministic variability within each OS and computer combination was mostly within +/-30 ms, and had a non-normal distribution with many small deviations and few large deviations. These large deviations are a char-acteristic feature that seems to constitute occasional additional delays up to about 150 ms. Thus, although measurements recorded from a general purpose PC running Windows should have an accuracy of -30 to +50 ms, occasionally larger variations suggest that experiments need a large test base to avoid significant distortions of the results.

Keywords: General purpose computers, Timing, Life Sciences, Windows™ operating system.