Is There Semantic Conflict in the Stroop Task?

This research addressed current controversies concerning the contribution of semantic conflict to the Stroop interference effect and its reduction by a single-letter coloring and cueing procedure. On the first issue, it provides, for the first time, unambiguous evidence for a contribution of semantic conflict to the (overall) Stroop interference effect. The reported data remained inconclusive on the second issue, despite being collected in a considerable sample and analyzed with both classical (frequentist) and Bayesian inferential approaches. Given that in all past Stroop studies, semantic conflict was possibly confounded with either response conflict (e.g., when semantic-associative items [SKY_blue] are used to induce semantic conflict) or with facilitation (when color-congruent items [BLUE_blue] are used as baseline to derive a magnitude for semantic conflict), its genuine contribution to the Stroop interference effect is the most critical result reported in the present study. Indeed, it leaves no doubt - in complete contrast to dominant single-stage response competition models (e.g., Roelofs, 2003) - that selection occurs at the semantic level in the Stroop task. The immediate implications for the composite (as opposed to unitary) nature of the Stroop interference effect and other still unresolved issues in the Stroop literature are outlined further.

Assessment of Stroop Color Word Interference Test-TBAG form performance in subjects with tinnitus

PURPOSE

To evaluate ordinary behavioral pattern suppression performance of individuals with tinnitus under disruptive effect using Stroop Color Word Interference Test-TBAG Form (SCWT), and to determine the impact of acoustic stimulus on this performance.

METHODS

40 individuals with subjective tinnitus at Slight and higher severity according to Tinnitus Handicap Inventory (THI) (16 females, 24 males; mean age: 42.02 ± 10.00) (Study group), and 40 healthy individuals (Control group) (18 females, 22 males; mean age: 38.85 ± 10.25) were included in this study. All individuals were subjected to audiological evaluation. SCWT was applied with and without acoustic stimulus (NB noise), and test completion durations were recorded.

RESULTS

It was determined that the duration for completion of 5 sections of SCWT, both in the presence of and without acoustic stimulus, was longer in the Study group than the control group. In the presence of acoustic stimulus, it took longer for the individuals with tinnitus to complete sections 4 and 5, and the control group to complete sections 3, 4 and 5 in SCWT in comparison with the lack of acoustic stimulus.

CONCLUSION

It was determined that SCWT performance of the individuals with tinnitus was worse than the individuals without tinnitus, both in the presence of and without acoustic stimulus. It was found that SCWT performances of both groups with acoustic stimulus were better than their test performances without acoustic stimulus.

Some further clarifications on age-related differences in Stroop interference

Both the locus and processes underlying the age-related differences in Stroop interference are usually inferred from changes in magnitudes of standard (i.e., overall) Stroop interference. Therefore, this study addressed these still-open issues directly. To this end, a sample of younger (18-26 years old) and healthy older (72-97 years old) was administered the semantic Stroop paradigm (that assesses the relative contribution of semantic compared to response conflict both of which contribute to overall Stroop interference) combined with a single-letter coloring and cuing (SLCC) procedure. Independently of an increased attentional focus on the relevant color dimension of Stroop words induced by SLCC (as compared to all letters colored and cued, ALCC), greater magnitudes of standard Stroop interference were observed in older (as compared to younger) adults. These differences were due to greater magnitudes of response conflict whereas magnitudes of semantic conflict remained significant and unchanged by healthy aging and SLCC. Thus, this direct evidence places the locus of age-related differences in Stroop interference at the level of response conflict (as opposed to semantic and/or both conflicts). In terms of processes underlying these differences, the reported evidence shows that both age-groups are equally (in)efficient in (a) focusing on the relevant color dimension and (b) suppressing the meaning of the irrelevant word-dimension of Stroop words. Healthy older adults are simply less efficient in suppressing the (pre-)response activity primed by the fully processed meaning of the irrelevant word-dimension. Standard interpretations of age-related differences in Stroop interference and a more general issue of how attentional selectivity actually operates in the Stroop task are therefore reconsidered in this paper.

Behavioral and electrophysiological investigation of semantic and response conflict in the Stroop task

By combining the semantic Stroop paradigm (e.g., Klein in American Journal of Psychology 77:576-588, 1964) with a single-letter coloring (SLC) procedure (e.g., Besner et al. in Psychonomic Bulletin & Review 4:221-225, 1997), this research investigated whether the frequently reported Stroop-related event-related potential (ERP) effect arising about 400 ms after stimulus onset (Ninc) is sensitive to the semantic and/or the response conflict. Consistent with our past findings (e.g., Augustinova et al. in Psychonomic Bulletin & Review 17:827-833, 2010), SLC speeded up reaction times for standard-incongruent items only, indicating that SLC reduced the response conflict that these (but not color-associated and neutral) items involve. Ninc amplitudes were more negative for standard-incongruent and color-associated than for color-neutral items. Importantly, this difference was not modulated by SLC. Hence, the behavioral and ERP results conjointly suggest that the Stroop-related Ninc is sensitive to semantic rather than to response and/or general conflict.