Threshold units: a correct metric for reaction time?

Zele, Andrew J., Cao, Dingcai, & Pokorny, Joel (2007) Threshold units: a correct metric for reaction time? Vision Research, 47(5), pp. 608-611.

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Purpose: To compare reaction time (RT) to rod incremental and decremental stimuli expressed in physical contrast units or psychophysical threshold units.

Methods: Rod contrast detection thresholds and suprathreshold RTs were measured for Rapid-On and Rapid-Off ramp stimuli.

Results: Threshold sensitivity to Rapid-Off stimuli was higher than to Rapid-On stimuli. Suprathreshold RTs specified in Weber contrast for Rapid-Off stimuli were shorter than for Rapid-On stimuli. Reaction time data expressed in multiples of threshold reversed the outcomes: Reaction times for Rapid-On stimuli were shorter than those for Rapid-Off stimuli. The use of alternative contrast metrics also failed to equate RTs.

Conclusions: A case is made that the interpretation of RT data may be confounded when expressed in threshold units. Stimulus energy or contrast is the only metric common to the response characteristics of the cells underlying speeded responses. The use of threshold metrics for RT can confuse the interpretation of an underlying physiological process.

Impact and interest:

15 citations in Scopus
15 citations in Web of Science®
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ID Code: 7455
Item Type: Journal Article
Refereed: Yes
DOI: 10.1016/j.visres.2006.12.003
ISSN: 0042-6989
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Copyright Owner: Copyright 2007 Elsevier
Deposited On: 08 May 2007 00:00
Last Modified: 12 Nov 2012 22:52

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