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Nice guys check twice — Questioning the assumptions of the capacity coefficient

Dr. Zachary Luke Howard
University of Western Australia ~ Psychology
Paul M Garrett
University of Melbourne
Daniel R. Little
The University of Melbourne ~ Psychological Sciences
Dr. Ami Eidels
University of Newcastle, Australia ~ Psychology
James T. Townsend
Indiana University ~ Department of Psychology

Systems Factorial Technology (SFT) is a popular framework for that has been used to investigate processing capacity across many psychological domains over the past 25+ years. To date, it had been assumed that no processing resources are used for sources in which no signal has been presented (i.e., in a location that can contain a signal but does not on a given trial). Hence, response times are purely driven by the "signal-containing'' location or locations. This assumption is critical to the underlying mathematics of the capacity coefficient measure of SFT. In this presentation, we show that stimulus locations influence response times even when they contain no signal, and that this influence has repercussions for the interpretation of processing capacity under the SFT framework, particularly in conjunctive (AND) tasks - where positive responses require detection of signals in multiple locations. We propose a modification to the AND task requiring participants to fully identify both target locations on all trials. This modification allows a new coefficient to be derived. We apply the new coefficient to novel experimental data and resolve a previously reported empirical paradox, where observed capacity was limited in an OR detection task but super capacity in an AND detection task. Hence, previously reported differences in processing capacity between OR and AND task designs are likely to have been spurious.





Cognitive Modeling
Reaction Times
paper and data? Last updated 2 months ago

Zach - nice work. please consider adding a link to the paper/preprint here. Also, are you making your data available anywhere for the new experimental designs?

Dr. Leslie Blaha 1 comment

thanks for the very interesting talk, I will read the preprint! I new nothing of the SFT or SIC, but it seems to me that there is an interesting parallel between the question you are raising and a dissociation which I find very crucial when understanding decision: that between automatic and voluntary signals contributing to decision. Visual signal...

Dr. Aline Bompas 1 comment
methodology question Last updated 3 months ago

HI Zachary (and the group of authors). This is very interesting research, thank you for sharing information about how to adapt the task to meet certain expectations. My question is about the method used. It is rather a-typical to use no stimulus redundant condition as a response. When I tried to imagine the task, I feel it should work for the proce...

Mario Fific 3 comments