Figure 1
Idealized predictions for the R1-R2 and the S1-R2 BCE as a function of stimulus brightness. The R1-R2 BCE is assumed to have its locus within the capacity-limited central stage and should thus not interact with stimulus brightness (left panel). For the S1-R2 BCE, two options are conceivable (middle and right panel). If the S1-R2 BCE has its locus outside the perceptual stage, a pattern similar to the R1-R2 BCE should emerge (middle panel). If, however, the S1-R2 BCE has its locus within the perceptual stage, some kind of interaction with stimulus brightness should emerge (right panel).
Figure 2
Trial structure and tasks of the two different block types. In each trial, participants first responded to the color of the frame in a manual two-choice task by pressing a left or right key (Task 1). Then, participants responded to the identity of the letter in a vocal two-choice task (Task 2). In R1-R2 BCE blocks, the responses were the words ‘left’ and ‘right’, and in S1-R2 BCE blocks, they were ‘red’ and ‘green’. In the depicted example, Stimulus 1 is a green frame that requires a left index finger response in Task 1. In Task 2 of R1-R2 BCE blocks, the identity ‘H’ requires a vocal utterance of the word ‘left’, while the letter ‘S’ indicates a ‘right’ utterance. In this trial, the R1-R2 relation is compatible. In Task 2 of S1-R2 BCE blocks, the identity ‘H’ requires a vocal utterance of the word ‘green’, while the letter ‘S’ indicates a ‘red’ utterance. In this trial, the S1-R2 relation is compatible.
Figure 3
Task 1 response times (RT1; in milliseconds) as a function of compatibility and brightness, displayed separately for each block type (R1-R2 BCE: left panel, S1-R2 BCE: right panel). Error bars indicate 95% confidence intervals after removing inter-subject variability.
Table 1
Task 1 and Task 2 Mean Response Times and Error Rates as a Function of Compatibility, Brightness, and Block Type.
| Block type | Brightness | Task 1 | Task 2 | |||||
|---|---|---|---|---|---|---|---|---|
| Compatibility | Compatibility | |||||||
| Incompatible | Compatible | Δ | Incompatible | Compatible | Δ | |||
| RT | ||||||||
| R1-R2 | Bright | 641 | 576 | 65 | 1174 | 1090 | 84 | |
| Dark | 661 | 607 | 54 | 1204 | 1123 | 81 | ||
| S1-R2 | Bright | 637 | 584 | 53 | 1228 | 1138 | 90 | |
| Dark | 660 | 603 | 57 | 1257 | 1158 | 99 | ||
| ER | ||||||||
| R1-R2 | Bright | 6.3 | 2.0 | 4.3 | 4.4 | 2.6 | 1.8 | |
| Dark | 6.9 | 3.2 | 3.7 | 4.1 | 2.6 | 1.5 | ||
| S1-R2 | Bright | 4.2 | 3.1 | 1.1 | 4.2 | 2.3 | 1.9 | |
| Dark | 4.5 | 3.5 | 1.0 | 4.7 | 2.5 | 2.2 | ||
[i] Note: RT = response time; ER = error rate; Δ = difference between compatible and incompatible trials, resembling the crosstalk effects within the respective conditions.
Figure 4
Illustration of a tentative model for the S1-R2 and the R1-R2 BCE. The capacity-limited central stage (orange) comprises two (maybe cascaded) processes separated by a diagonal and dotted line. Task 2 (the identity task) is illustrated separately for the S1-R2 BCE and the R1-R2 BCE. Note that the stimuli and responses shown here are taken from Experiment 1 (R1-R2 BCE) and 2 (S1-R2 BCE) of Hommel (1998). The model assumes that the locus of the S1-R2 BCE is in the capacity-limited process of stimulus classification (SC), whereas the locus of the R1-R2 BCE is in the capacity-limited process of response selection (RS). Grey arrows indicate the source of the two BCEs in response activation (RA) of Task 2. (P = perceptual stage, M = motor stage, subscripts indicate Task 1 and 2, respectively).