Abstract
If a subject is required to respond to either of two different target signals, reaction times (RTs) are especially fast when both target signals are presented. Separate-activation models can account for this finding. This model class assumes that each target signal is detected in a different channel and that the detection time of each channel is a random variable. If two different target signals are presented, RT is simply the lesser of the two detection times. Cumulative distribution functions of RTs are commonly used to test channel independence or, if channel independence is rejected, to evaluate the detection-time correlation. The present paper shows that it is important to consider the variability of the base time for all processes after the response has been decided on but before it has actually been carried out. It is shown that this variability influences the determination of the detection-time correlation. In addition, it is shown that Miller’s (1982) test of separate-activation models versus coactivation models can also be applied to models with variable base times.
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Ulrich, R., Giray, M. Separate-activation models with variable base times: Testability and checking of cross-channel dependency. Perception & Psychophysics 39, 248–254 (1986). https://doi.org/10.3758/BF03204931
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DOI: https://doi.org/10.3758/BF03204931