Congruent Color Words Research Articles

The impairing effect of dyspnea on response inhibition.

Dyspnea (=breathlessness) is an aversive and threatening symptom in various prevalent diseases. Established treatment procedures aim for behavioral changes in dyspneic patients in order to treat dyspnea successfully. To achieve these behavioral changes, response inhibition as one key executive function for goal-directed behavior is an important prerequisite. However, the impact of dyspnea on response inhibition is widely unknown. Therefore, the present study aimed at testing whether experimentally induced dyspnea would impair response inhibition. Thirty-six healthy participants performed the color-word Stroop task during an unloaded baseline and a resistive load-induced dyspnea condition. Response inhibition was investigated using behavioral measures (reaction time, accuracy) and, based on literature, the late positive complex (LPC) in the electroencephalogram. Furthermore, the N400 was investigated in an exploratory analysis. The results showed significantly reduced accuracy for incongruent compared to congruent color-words in the Stroop task during the dyspnea condition (p < .001) which was paralleled by a smaller LPC and a more negative centro-parietal N400 for incongruent color-words during the dyspnea compared to the baseline condition (p < .05). Possibly, during dyspnea more neural resources are allocated towards the semantic processing of incongruent color-words indexed as the N400 which are then not available for the partly overlapping LPC as an index for response inhibition. These findings demonstrate that resistive load-induced dyspnea has an impairing effect on response inhibition in healthy participants, both in terms of behavioral performance and respective neural processing. This might impair treatment efforts aimed at behavioral changes in patients suffering from dyspnea.

The Role of Visual Stimuli in Cross-Modal Stroop Interference.

It has long been known that naming the color of a color word leads to what is known as the Stroop effect (Stroop, 1935). In the traditional Stroop task, when compared to naming the color of a color-neutral stimulus (e.g. an X or color patch), the presence of an incongruent color word decreases performance (Stroop interference), and a congruent color word increases performance (Stroop facilitation). Research has also shown that auditory color words can impact the color naming performance of colored items in a similar way in a variation known as cross-modal Stroop (Cowan & Barron, 1987). However, whether the item that is colored interacts with the auditory distractor to affect cross-modal Stroop interference is unclear. Research with the traditional, visual Stroop task has suggested that the amount of color the visual item displays and the semantic and phonetic components of the colored word can affect the magnitude of the resulting Stroop interference; as such, it is possible the same components could play a role in cross-modal Stroop interference. We conducted two experiments to examine the impact of the composition of the colored visual item on cross-modal Stroop interference. However, across two different experiments, three test versions, and numerous sets of trials, we were only able to find a small effect of the visual stimulus. This finding suggests that while the impact of the auditory stimuli is consistent and robust, the influence of non-word visual stimuli is quite small and unreliable and, while occasionally being statistically significant, it is not practically so.

Semantic Conflict Processing in the Color-Word Stroop and the Emotional Stroop

With the aim of establishing the temporal locus of the semantic conflict in color-word Stroop and emotional Stroop phenomena, we analyzed the Event-Related Potentials (ERPs) elicited by nonwords, incongruent and congruent color words, colored words with positive and negative emotional valence, and colored words with neutral valence. The incongruent, positive, negative, and neutral stimuli produced interference in the behavioral response to the color of the stimuli. The P150/N170 amplitude was sensitive to the semantic equivalence of both dimensions of the congruent color words. The P3b amplitude was smaller in response to incongruent color words and to positive, negative, and neutral colored words than in response to the congruent color words and colored nonwords. There were no differences in the ERPs induced in response to colored words with positive, negative, and neutral valence. Therefore, the P3b amplitude was sensitive to interference from the semantic content of the incongruent, positive, negative, and neutral words in the color-response task, independently of the emotional content of the colored words. In addition, the P3b amplitude was smaller in response to colored words with positive, negative, and neutral valence than in response to the incongruent color words. Overall, these data indicate that the temporal locus of the semantic conflict generated by the incongruent color words (in the color-word Stroop task) and by colored words with positive, negative, and neutral valence (in the emotional Stroop task) appears to occur in the range 300–450 ms post-stimulus.

Restrained eaters preserve top–down attentional control in the presence of food

This study investigated the attentional control of restrained eaters when exposed to food. Restrained (N=55) and unrestrained eaters (N=56) completed a color word Stroop task. Top–down attentional control was assessed by adaptation effects (the Stroop effect is smaller when the previous trial is an incongruent color word than a congruent color word). Adaptation effects differed between restrained and unrestrained eaters according to the type of background image presented (high-fat food vs. non-food). Specifically, in restrained eaters adaptation effects did not differ as a function of image. In contrast, adaptation effects in unrestrained eaters were not observed with high-fat food. Motivation to either approach or avoid food may explain these differences.

Think the thought, walk the walk – Social priming reduces the Stroop effect

In the Stroop task, participants name the color of the ink that a color word is written in and ignore the meaning of the word. Naming the color of an incongruent color word (e.g., RED printed in blue) is slower than naming the color of a congruent color word (e.g., RED printed in red). This robust effect is known as the Stroop effect and it suggests that the intentional instruction – “do not read the word” – has limited influence on one’s behavior, as word reading is being executed via an automatic path. Herein is examined the influence of a non-intentional instruction – “do not read the word” – on the Stroop effect. Social concept priming tends to trigger automatic behavior that is in line with the primed concept. Here participants were primed with the social concept “dyslexia” before performing the Stroop task. Because dyslectic people are perceived as having reading difficulties, the Stroop effect was reduced and even failed to reach significance after the dyslectic person priming. A similar effect was replicated in a further experiment, and overall it suggests that the human cognitive system has more success in decreasing the influence of another automatic process via an automatic path rather than via an intentional path.

The Nature of the Automatization Deficit in Chinese Children with Dyslexia

Clarifying whether automatization deficits constitute the primary causes or symptoms of developmental dyslexia, we focused on three critical issues of the dyslexic automatization deficit, namely universality, domain specificity, and severity. Thirty Chinese dyslexic children (mean age 10 years and 5 months), 30 chronological-age-, and 30 reading-level-matched children were tested in 4 areas of automaticity: motor, visual search, Stroop facilitation effects, and automatic word recognition. The results showed that the dyslexic children performed significantly worse than the CA-controls but not the RL-controls in all the tasks except for Stroop congruent-color words, on which they performed worse than children in both control groups. The deficits reflect a lag in reading experiences rather than a persistent cognitive deficit.

Effects of Stroop Interference on Categorical Perception in Simultaneous Color Discrimination

Two experiments were conducted to assess the effects of verbal interference on categorical perception. The task involved simultaneous color discrimination with no memory demands, and a concurrent Stroop task was employed as verbal interference. Exp. 1 demonstrated that categorical perception was eliminated by an incongruent color word (i.e., Stroop interference), but not by a congruent color word or nonword fixation crosses. Exp. 2 demonstrated that categorical perception decreased when the intensity of Stroop Interference was increased, and it increased when correct verbal coding was enhanced. These results provide further evidence that interfering with verbal coding disrupts categorical perception, suggesting that verbal coding has a crucial role in categorical "perception." It is also suggested that categorical perception could occur at the encoding or decision level but not at the storage or memory level. The possible mechanisms for categorical perception are also discussed.

How personal earthquake experience impacts on the Stroop interference effect: An event-related potential study

Event-related brain potentials (ERPs) were measured when 24 Chinese subjects performed the classical Stroop task. All of subjects had experienced the great Sichuan earthquake (5/12), with 12 people in each of the Far (Chengdu city) and the Close (Deyang city) earthquake experience groups. The behavioral data showed that the Stroop task yielded a robust Stroop interference effect as indexed by longer RT for incongruent than congruent color words in both the Chengdu and Deyang groups. Scalp ERP data showed that incongruent stimuli elicited a more negative ERP deflection (N400-600; Stroop interference effect) than did congruent stimuli between 400-600 ms in the Chengdu group, while the Stroop interference ERP effect was not found in the Deyang group. Dipole source analysis localized the generator of the N400-600 in the right prefrontal cortex (PFC) and was possibly related to conflict monitoring and cognitive control.

Double dissociation between action-driven and perception-driven conflict resolution invoking anterior versus posterior brain systems

The ability to select and integrate relevant information in the presence of competing irrelevant information can be enhanced by advance information to direct attention and guide response selection. Attentional preparation can reduce perceptual and response conflict, yet little is known about the neural source of conflict resolution, whether it is resolved by modulating neural responses for perceptual selection to emphasize task-relevant information or for action selection to inhibit pre-potent responses to interfering information. We manipulated perceptual information that either matched or did not match the relevant color feature of an upcoming Stroop stimulus and recorded hemodynamic brain responses to these events. Longer reaction times to incongruent than congruent color–word Stroop stimuli indicated conflict; however, conflict was even greater when a color cue correctly predicted the Stroop target's color (match) than when it did not (nonmatch). A predominantly anterior network was activated for Stroop-match and a predominantly posterior network was activated for Stroop-nonmatch. Thus, when a stimulus feature did not match the expected feature, a perceptually-driven posterior attention system was engaged, whereas when interfering, automatically-processed semantic information required inhibition of pre-potent responses, an action-driven anterior control system was engaged. These findings show a double dissociation of anterior and posterior cortical systems engaging in different types of control for perceptually-driven and action-driven conflict resolution.

Stroop interference and the timing of selective response activation

Objective To examine the exact timing of selective response activation in a manual color-word Stroop task. Methods Healthy individuals performed two versions of a manual color-word Stroop task, varying in the probability of incongruent color-words, while EEG was recorded. Results Stroop interference effect was manifested as longer reaction times for incongruent relative to congruent color-words, and was larger in a task version where incongruent color-words were presented less frequently. Whereas the congruence between color display and word meaning did not affect average stimulus- and response-locked lateralized readiness potential (LRP) onset latencies nor response-locked LRP amplitudes, P3 peak latencies were longer and stimulus-locked LRPs were smaller for incongruent than congruent trials. Conclusions These data are consistent with the idea that behavioral Stroop interference reflects delays in processing stages preceding color-based selective response activation in a subset of trials. They also do not exclude additional delays after color-based selective response activation, at least up until some 200 ms before the overt response. Significance This chronometric analysis allows for a parcellation of the Stroop interference process that may be applied in psychopathology.

The effect of Stroop interference on the categorical perception of color

In two experiments, we examined the effects of Stroop interference on the categorical perception (CP; better cross-category than within-category discrimination) of color. Using a successive two-alternative forced choice recognition paradigm (deciding which of two stimuli was identical to a previously presented target), which combined to-be-remembered colors with congruent and incongruent Stroop words, we found that congruent color words facilitated CP, whereas incongruent color words reduced CP. However, this was the case only when Stroop interference was presented together with the target color, but not when Stroop stimuli were introduced at the test stage. This suggests that target name, but not test name generation, affects CP. Target name generation may be important for CP because it acts as a category prime, which, in turn, facilitates cross-category discrimination.

Acute tryptophan depletion improves performance and modulates the BOLD response during a Stroop task in healthy females

To gain more insight into the effect of low brain serotonin (5-HT) on brain activation related to conflict, the present study examined the effect of acute tryptophan depletion (ATD) on performance and the blood oxygen level dependent (BOLD) response during a combined cognitive and emotional Stroop task. Fifteen healthy female volunteers were tested during a placebo and tryptophan depletion session in an event-related fMRI design. ATD improved performance during Stroop interference. Two effects of ATD on the BOLD response were found. Firstly, ATD increased the BOLD response in the anterior cingulate cortex (ACC) (BA 32) when incongruent color words were compared with congruent color words in the first Stroop block the participants performed. Secondly, ATD increased the BOLD response in the left precuneus (BA 31) and cuneus (BA 18) during congruent color words. ATD did not affect the BOLD response accompanying emotional stimuli. However, we showed that ATD increased the interference of negative words on color naming. This finding was explained in terms of an emotional processing bias in favor of negative words, which leads to stronger interference of these words. In line with previous studies, the present study showed that a temporary reduction of 5-HT improved Stroop performance and changed the underlying brain activation pattern in healthy female participants. Moreover, we replicated our previous finding that ATD modulated the BOLD response in the dorsomedial prefrontal cortex during tasks that require cognitive control.

Brain mechanism of Stroop interference effect in Chinese characters

Event-related brain potentials were measured when 11 healthy Chinese subjects finished Chinese Characters Stroop tasks. The behavioral data showed that the Stroop task yielded a robust Stroop interference effect as indexed by longer RT for incongruent than congruent color words. Scalp ERP analysis revealed the neurophysiological substrate of the interference effect: a greater negativity in the incongruent as compared to the congruent was found between 350 and 550 ms poststimulus over midline fronto-central scalp regions. Dipole source analysis (BESA software) of the difference wave (incongruent–congruent) indicated that a generator localized in prefrontal cortex (PFC) contributed to this effect, possibly related to conflict processing and response selection. The results provided electrophysiologic evidences of the brain and cognitive mechanism of Stroop interference effect in Chinese characters and suggested that the difference between Chinese characters and English words had influence on temporal patterns of the Stroop interference effect.

Attentional and physiological characteristics of patients with dental anxiety

Twenty patients with dental anxiety were investigated while seated in a dental chair in a dental clinic. Heart rate (HR), heart rate variability (HRV), and skin conductance level (SCL) were recorded while the patients were exposed to scenes of dental treatment as well as a Stroop attentional task. Results showed an attentional bias with longer manual reaction times (RT’s) to the incongruent compared to the congruent color words as well as the threat compared to the neutral words. Longer RT’s to the incongruent and the threat words were found in the low HRV patients compared to the high HRV patients. Furthermore, all patients showed an increase in HR during exposure and the Stroop task compared to baseline. The HRV showed a decrease during the exposure and the Stroop task compared to baseline. HR and HRV did not differ between exposure and the Stroop task. Moreover, HR and HRV did not return to baseline levels during the recovery period. The SCL showed an increase from baseline to exposure, from exposure to the Stroop task and a decrease in the recovery phase. Results showed the importance of vagal cardiac control in attentional, emotional, and physiological processes in patients suffering from dental fear.

An ERP study of the temporal course of the Stroop color-word interference effect

The electrophysiological correlates of the Stroop color-word interference effect were studied in eight healthy subjects using high-density Event-Related Potentials (ERPs). Three response modalities were compared: Overt Verbal, Covert Verbal, and Manual. Both Overt Verbal and Manual versions of the Stroop yielded robust Stroop color-word interference as indexed by longer RT for incongruent than congruent color words. The Incongruent vs Congruent ERP difference wave presented two effects. A first effect was a medial dorsal negativity between 350–500 ms post-stimulus (peak at 410 ms). This effect had a significantly different scalp distribution in the Verbal and Manual Stroop versions, with an anterior–medial focus for overt or covert speech, and a broader medial–dorsal distribution for the manual task. Dipole source analysis suggested two independent generators in anterior cingulate cortex. Later on in time, a prolonged positivity developed between 500–800 ms post-stimulus over left superior temporo-parietal scalp. This effect was present for all the three response modalities. A possible interpretation of these results is that Stroop color-word interference first activates anterior cingulate cortex (350–500 ms post-stimulus), followed by activation of the left temporo-parietal cortex, possibly related to the need of additional processing of word meaning.

Processing in the Stroop task: Mental set as a determinant of performance.

Abstract Subjects took part in a Stroop experiment in which they responded to the print color of an irrelevant word that spelled a congruent or incongruent color word. In the CLASSIFY condition, subjects were instructed to map one color to one response button and the other color to another response button. In the DETECT condition, subjects were instructed to signal the presence of a target color with one response button, and its absence with another response button. The CLASSIFY instructions produced the standard result: The incongruent condition was slower than the congruent condition. In contrast, there was no Stroop effect given DETECT instructions. These results are discussed in terms of mental set as an important determinant of processing, and contrasted with the received view that reading the irrelevant word is largely automatic and virtually always results in a Stroop effect. In many variants of Stroop's (1935) classic experiments, subjects are asked to identify the color of a word while ignoring the word. The standard result is that the time to identify the color when it is paired with an incongruent color word is slower than when it is paired with a congruent color word or a neutral word. The most widely accepted view is that reading the irrelevant word is, in some sense mandatory, with interference in identifying the color a common consequence (see MacLeod, 1991, for a review). Is the Stroop effect inevitable, or can it be circumvented? Surely, there are trivial manipulations that may reduce or eliminate the Stroop effect: making the words too small (or too large), too briefly presented, or permitting the subjects to squint or defocus. However, these techniques do not inform us as to the underlying psychological processes. Manipulations that tax the limits of visual resolution aside, are there instructional manipulations that alter the subject's mental set, and thus protect against the proclivity to read the word, or against the impact of this reading? Further, and most central here, can such an effect be demonstrated under conditions where the stimuli and the overt response required are the same as those that produce the Stroop effect? There have been a number of previous attempts to reduce the effect of an incongruent word with procedural manipulations; some of these are discussed below. Our claim is that the approach adopted here differs from these earlier attempts, and that our results emphasize once again the importance of mental set. These earlier studies suggested that differences in the way that subjects conceive of a task and the implicit S-R mapping dramatically altered the magnitude of the Stroop effect. To put it another way, the mental set adopted by the subject strongly affects the way Stroop stimuli are processed. The present experiment provides further evidence for this contention under conditions where the stimuli and the overt responses required are identical across two instructional sets. Indeed, we demonstrate that a simple but subtle change in the way the subject is instructed to perform the task (viz. considering the task as one of DETECTION rather than CLASSIFICATION) essentially eliminates the Stroop effect.(f.1) Prior to a detailed treatment of our experiment, we provide a brief summary of several pertinent studies that sought to modulate Stroop-type effects using instructional manipulations. Egeth, Blecker, and Kamlet (1969) had subjects orally report the color of plastic strips on which either XXXX (their Stroop Control condition) or color words (their Stroop condition) were printed. They found longer response times (RTs) for their Stroop condition than for this control condition. Next, subjects were asked to make color judgments about pairs of color strips that contained either xxxx (Comparison Control), or color words that were either identical or different (Comparison Color). This experiment tested whether the same/different status of the word pair would affect same/different RTs to the color pairs. …

A Computerized Stroop Experiment that Demonstrates the Interaction in a 2 × 3 Factorial Design

This article describes a computerized Stroop-type experiment that demonstrates the effects of an interaction in a factorial design. The independent variables in this experiment are (a) the presentation of a congruent color word with a color bar or the presentation of a conflicting color word with a color bar and (b) the spatial placement of the color word above, on, or below the color bar. The dependent variable is the reaction time for the subject to say the color of the bar. Data for six semesters of an experimental psychology lab course indicate a significant difference between the conflicting and congruent conditions and a consistent significant interaction between the two independent variables. The computer program that runs this experiment is described, and explanations for the interaction are discussed.

Effects of Speed Vs. Accuracy in Vocal Reaction Time to Visual Half-Field Presentations of Incongruent (Stroop) Color-Words

Incongruent color-words were briefly flashed initially to the left or right hemisphere using the visual half-field (VHF) technique. In half of the trials, subjects were requested to name the word, in half of the trials they were requested to name the ink the word was written in. Congruent color-words and neutral words served as control-stimuli. Vocal reaction time (VRT) and errorfrequency were used as dependent measures. Half of the subjects were instructed to try to be as fast as possible in the task (Speed group), the other half were instructed to try to be as accurate as possible in the task (Accuracy group). All subjects were right handed males. Results showed significantly longer VRTs in the Accuracy group, more errors in the Speed group to right-field projections (initial left hemisphere input) of the incongruent color-words during the colornaming condition. Thus, the present results have revealed; (a) significant effects of hemispheric asymmetry in an incongruent color-words paradigm; and (b) that the speed vs accuracy dimension interferes with hemisphere differences.

Visual Half-Field Presentations of Incongruent Color Words: Effects of Gender and Handedness

Right-handed (dextral) and left-handed (sinistral) males and females (N = 15) were compared for language lateralization in a visual half-field (VHF) incongruent color-words paradigm. The paradigm consists of repeated brief (< 200 msec) presentations of color-words written in an incongruent color. Presentations are either to the right or to the left of center fixation. The task of the subject is to report the color the word is written in on each trial, ignoring the color-word. Color-bars and congruent color-words were used as control stimuli. Vocal reaction time (VRT) and error frequency were used as dependent measures. The logic behind the paradigm is that incongruent color-words should lead to a greater cognitive conflict when presented in the half-field contralateral to the dominant hemisphere. The results showed significantly longer VRTs in the right half-field for the dextral subjects. Furthermore, significantly more errors were observed in the male dextral group when the incongruent stimuli were presented in the right half-field. There was a similar trend in the data for the sinistral males. No differences between half-fields were observed for the female groups. It is concluded that the present results strenghten previous findings from our laboratory (Hugdahl and Franzon, 1985) that the incongruent color-words paradigm is a useful non-invasive technique for the study of lateralization in the intact brain.

Hemispheric asymmetry in the processing of Stroop stimuli

Subjects responded to Stroop (incongruent color and color word) and non-Stroop (congruent color and color word) stimuli, presented to the left or right visual field, under four instructional conditions (color, word, memory color, memory word). The typical Stroop effect was present in the simple conditions (color, word) with no hemispheric asymmetry. In the memory conditions, there was hemispheric asymmetry in the Stroop effect, with reduced interference in the right hemisphere for memory color responses, and in the left hemisphere for memory word responses. The difference in results was attributed to the possibility for selective attention to a target, rather than a dimension, in the memory conditions.