Two aspects of the data, however, seem to challenge the models. In line with previous studies, we found an inconsistent RT moment ordering between compatibility conditions in the Simon task, Selleck NVP-BEZ235 but not in the Eriksen (see Figs. 5B and 7B). Moreover, compatibility and color saturation combined additively in the two conflict tasks. In the next section, we provide a final test of the SSP and the DSTP by fitting them to the RT distributions and accuracy data of the previous experiments. This test is more powerful than the RT mean and SD approach taken so far, and should provide a detailed picture of the relative strengths and deficiencies of the models. We also fit an alternative version

of the SSP, proposed post hoc by White, Ratcliff, et al. (2011). This model features a lack of attentional shrinking in the compatible condition, and was motivated by the empirical finding that subjects tend to minimize attentional effort whenever possible. When the perceptual intensity of the target and flankers is similar, as in a standard Eriksen task, each item provides the same quantity of evidence. There is no real advantage of shrinking attention on the target in compatible trials, and a lack of shrinking

does not alter the model’s behavior (the constant drift rate in compatible trials would remain unchanged). This is not true when the perceptual intensity of the target and flankers is manipulated independently. In the original SSP, if ptar < pfl, the drift rate in compatible trials would become time-varying and would progressively converge toward ptar. However, a lack of attentional shrinking would always induce a constant drift rate, partly determined www.selleckchem.com/products/gsk2656157.html by pfl. There are two interesting properties of

this alternative SSP model. First, simulations reveal a pattern that resembles our empirical findings: the incompatible mapping lowers the intercept of Wagenmakers–Brown’s law but does not affect its slope (see Appendix D). Second, the model can potentially predict an inversion of RT moments between compatibility conditions. Consider a scheme where the perceptual input of the irrelevant stimulus attribute pirrel 4 is lower than that of the relevant attribute prel. This is plausible in the Simon task, because the location of the stimulus is not mafosfamide perceptually relevant, and should provide less evidence compared to the color. In compatible trials, the constant drift rate would be partly determined by pirrel. The shrinking of attention in incompatible trials would cause the drift rate to converge toward prel and become progressively stronger compared to that of compatible trials. This scheme leads to a reduction of RT variability for incompatible trials and thus to an inconsistent RT moment ordering between compatibility conditions. For the sake of completeness, we also fit an alternative version of the DSTP with no late selection in compatible trials. Time-varying diffusion models were tested against group data from the previous Eriksen and Simon experiments.