Comparing perception of Stroop stimuli in focused versus divided attention paradigms: Evidence for dramatic processing differences

Abstract

A huge set of focused attention experiments show that when presented with color words printed in color, observers report the ink color faster if the carrier word is the name of the color rather than the name of an alternative color, the Stroop effect. There is also a large number (although not so numerous as the Stroop task) of so-called “redundant targets studies” that are based on divided attention instructions. These almost always indicate that observers report the presence of a visual target (‘redness’ in the stimulus) faster if there are two replications of the target (the word RED in red ink color) than if only one is present (RED in green or GREEN in red). The present set of four experiments employs the same stimuli and same participants in both designs. Evidence supports the traditional interference account of the Stroop effect, but also supports a non-interference parallel processing account of the word and the color in the divided attention task. Theorists are challenged to find a unifying model that parsimoniously explains both seemingly contradictory results.

Selective attention modulates the effect of target location probability on redundant signal processing

“…These results supported the previous findings that selective attention affects the decision processes in two ways Eidels et al, 2010;Yang, 2011;Yang et al, 2013;Yang et al, 2011;Yang et al, 2014): (1) The processing order for multiple signals varied from parallel to serial when the participants were explicitly aware that the targets were unequally distributed across space. Specifically, parallel processing was adopted during the information accumulation stage when targets were equally distributed and when participants did not notice the unequal target location probability.…”

“…To infer the processing capacity, the capacity coefficient (Eidels, Houpt, Altieri, Pei, & Townsend, 2011;Townsend & Nozawa, 1995) and two inequalities, the race-model inequality (or Miller inequality; J. Miller, 1982) and the Grice inequality (Grice, Canham, & Boroughs, 1984;Grice, Canham, & Gwynne, 1984), were tested.…”

“…These findings go beyond the theoretical suggestions that some multiple-signal processing strategies are related to a system's processing capacity. For example, a coactive system usually has supercapacity, whereas the processing capacity of a standard serial system is limited (Colonius and Townsend, 1997;Eidels et al, 2011;Townsend, 1972, Fig. 14 Results of the C(t) (thick solid lines), race-model bound (dashed lines), and Grice bound (dash-dot lines) for each participant in Experiment 3. Thin solid lines above and below the C(t) represent the 95 % CI for C(t) Townsend & Nozawa, 1997;Wenger & Gibson, 2004;Wenger & Townsend, 2001).…”

A reach-to-touch investigation on the nature of reading in the Stroop task

“…Our experimental design was limited to only two colors and to a manual (rather than vocal) mode of response, both known to limit the magnitude of the Stroop effect (see also Eidels et al, 2010). Nonetheless, a marked Stroop effect was registered in the forced-reading task of the current study, suggesting that the effect can emerge even with two colors and a manual mode of responding.…”

“…The Stroop effect is calculated as the difference in response time (RT) between congruent trials and incongruent trials, and demonstrates the unintended influence of the word. It is one of the most replicated experimental effects in cognitive psychology, yet despite years of research, there is no agreed theoretical resolution as to the cause of the effect (MacLeod, 1991;Eidels et al, 2010;Eidels, 2012).…”