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Scale Invariant Contrasts of Response Latency Distributions

51 Pages Posted: 10 Feb 2013  

Natarajan Sriram


Brian A. Nosek

University of Virginia

Anthony G. Greenwald

University of Washington

Date Written: December 17, 2006


Individual differences in general speed lead to a positive correlation between the mean and standard deviation of mean latency. This “coarse” scaling effect causes the mean latency difference (MLD) to be spuriously correlated with general speed. Within individuals, the correlation between the mean and standard deviation of trial latencies leads contrasted distributions to increase their overlap as an MLD of fixed width is translated to the right. To address this “fine” scaling effect, contrasts based on within subject latency transformations including the logarithm, standardization, and ranking were evaluated and turned out to be distinctly superior to the MLD. Notably, the mean gaussian rank latency difference was internally consistent, eliminated fine scaling, meliorated coarse scaling, reduced correlations with general speed, increased statistical power to detect within subject and between group effects, and has the potential to increase the validity of inferences drawn from response latency data.

Keywords: Latency Difference, Scale Invariance, Ranking, Standardization, Gaussian Latency

JEL Classification: C14

Suggested Citation

Sriram, Natarajan and Nosek, Brian A. and Greenwald, Anthony G., Scale Invariant Contrasts of Response Latency Distributions (December 17, 2006). Available at SSRN: or

Natarajan Sriram (Contact Author)

Implisci ( email )

1999 English Oaks Cir N
Charlottesville, VA 22911
United States

Brian Nosek

University of Virginia ( email )

1400 University Ave
Charlottesville, VA 22903
United States

Anthony Greenwald

University of Washington ( email )

Seattle, WA 98195
United States

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