In psychological experiments, participants are typically instructed to respond as fast as possible without sacrificing accuracy. How they interpret this instruction and, consequently, which speed-accuracy trade-off they choose might vary between experiments, between participants, and between conditions. Consequently, experimental effects can appear unpredictably in either RTs or error rates (i.e., accuracy). Even more problematic, spurious effects might emerge that are actually due only to differential speed-accuracy trade-offs. An often-suggested solution is the inverse efficiency score (IES; Townsend & Ashby, 1983), which combines speed and accuracy into a single score. Alternatives are the rate-correct score (RCS; Woltz & Was, 2006) and the linear-integrated speed-accuracy score (LISAS; Vandierendonck, 2017, 2018). We report analyses on simulated data generated with the standard diffusion model (Ratcliff, 1978) showing that IES, RCS, and LISAS put unequal weights on speed and accuracy, depending on the accuracy level, and that these measures are actually very sensitive to speed-accuracy trade-offs. These findings stand in contrast to a fourth alternative, the balanced integration score (BIS; Liesefeld, Fu, & Zimmer, 2015), which was devised to integrate speed and accuracy with equal weights. Although all of the measures maintain "real" effects, only BIS is relatively insensitive to speed-accuracy trade-offs.
The backward crosstalk effect (BCE) in dual tasking means that characteristics of Task 2 of 2 subsequently performed tasks influence Task 1 performance. This observation indicates that certain features of the second response are already activated to some degree before the first response is selected. Therefore, the BCE challenges bottleneck models, which assume that Task 2 response selection does not begin until Task 1 response selection is finished. Instead, an extended model with a capacity-unlimited response activation stage prior to the bottleneck as the locus of the BCE was suggested. To determine the exact locus of the BCE within the stages of task processing, 5 experiments were carried out. Experiments 1 to 4 were psychological refractory period-like experiments with 3 subsequent tasks. A prebottleneck locus of the BCE was ruled out in Experiments 1 to 3 by using the locus of slack logic. Additionally, a postbottleneck locus of the BCE was ruled out in Experiment 4 by using the effect propagation logic. To further support this latter conclusion, Experiment 5 applied a go-signal manipulation. Taken together, the results of all 5 experiments strongly suggest that the BCE has its locus in the capacity-limited stage, which contradicts the widely accepted notion that a capacity-unlimited stage of response activation preceding response selection proper is the locus of the BCE. (PsycINFO Database Record
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