Incongruent Color Words Research Articles

P2-13: Location word Cues' Effect on Location Discrimination Task: Cross-Modal Study

As is well known, participants are slower and make more errors in responding to the display color of an incongruent color word than a congruent one. This traditional stroop effect is often accounted for with relatively automatic and dominant word processing. Although the word dominance account has been widely supported, it is not clear in what extent of perceptual tasks it is valid. Here we aimed to examine whether the word dominance effect is observed in location stroop tasks and in audio-visual situations. The participants were required to press a key according to the location of visual (Experiment 1) and audio (Experiment 2) targets, left or right, as soon as possible. A cue of written (Experiments 1a and 2a) or spoken (Experiments 1b and 2b) location words, “left” or “right”, was presented on the left or right side of the fixation with cue lead times (CLT) of 200 ms and 1200 ms. Reaction time from target presentation to key press was recorded as a dependent variable. The results were that the location validity effect was marked in within-modality but less so in cross-modality trials. The word validity effect was strong in within- but not in cross-modality trials. The CLT gave some effect of inhibition of return. So the word dominance could be less effective in location tasks and in cross-modal situations. The spatial correspondence seems to overcome the word effect.

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.

Attentional Focus Manipulations Affect Naming Latencies of Neutral But Not of Incongruent Stroop Trials

People are slower and more error-prone when indicating the color of incongruent color words compared to that of neutral stimuli. This Stroop effect results from the concurrent semantic analysis of the word stimulus. It has long been considered a prime example of the automaticity of semantic activation. However, coloring as well as cuing only a single letter both reduce the Stroop effect to the point of being absent. Proposed underlying mechanisms include the blocking of semantic activation, an improved selectivity between the interfering stimulus dimensions, and slowed color processing. In order to test the validity of these differing accounts of the single-letter Stroop effect, we compared vocal responses to standard and single-letter Stroop stimuli in two experiments. Irrespective of whether participants maintained a wide (Experiment 1) or a narrow (Experiment 2) attentional focus, both single-letter coloring and single-letter cuing increased reaction times to neutral Stroop stimuli but left those to incongruent stimuli unaffected. Both curtailed semantic activation and improved selection for action should, however, speed up reactions to incongruent stimuli. Our data thus support an explanation of the single-letter Stroop phenomenon in terms of impeded color processing, possibly as a result of color-color interference.

Dopamine β‐hydroxylase gene associates with stroop color‐word task performance in Han Chinese children with attention deficit/hyperactivity disorder

The cognitive deficits observed in attention deficit/hyperactivity disorder (ADHD) are candidate endophenotypes for genetic association studies. Dopamine β-hydroxylase (DβH) converts dopamine to norepinephrine, and its activity is under strong genetic control. Prior studies suggest association between ADHD and DBH gene. The present study examined associations between a putative functional single nucleotide polymorphism (SNP) at DBH with performance on the Stroop task in patients with ADHD and in healthy control subjects. A total of 812 Han Chinese youths with DSM-IV ADHD and 233 unaffected controls were included in the study. Comprehensive phenotype data were collected, including performance on a series of Stroop interference tests examining inhibition of response to interfering stimuli. DBH SNP -1021C/T was genotyped using the 5'-exonuclease (TaqMan®) method. Compared to unaffected controls, children with ADHD performed significantly worse in all categories of the Stroop test. In ADHD cases, DBH genotype at -1021C/T significantly associates with reaction times of incongruent color word parts but not the interference times, with TT genotype performing significantly better in both reaction time and interference time than other two genotype groups. DBH genotype did not associate with cognitive performance in unaffected controls or in the combined group. DBH genotype at -1021C/T associates with differences in performance on the Stroop task in children with ADHD.

A Combi-Stroop test for measuring food-related attentional bias.

There are methodological complexities with the supraliminal-lexical versions of the modified versions of the Stroop tests that could be responsible for inconsistencies across the literature (Field & Cox, 2008). We tested whether a combination of subliminal-pictorial and classic Stroop tests can differentiate between dieters' and nondieters' food attentional bias (FAB). Participants were dieters (n = 30) and nondieters (n = 32) who were tested 3 hr after having a meal. Each picture from among 24 high-calorie and 24 low-calorie food pictures was presented for 32 ms before the appearance of a congruent or an incongruent color word, in response to which participants were required to manually report, via a tagged keyboard, the correct color of the word as quickly and accurately as possible. Color-naming latencies and interference scores were calculated. Dieters showed the highest reaction times to incongruent color words following high-calorie food pictures; overall, dieters showed significantly higher FABs than nondieters. The Combi-Stroop test has differential validity. Moreover, findings suggest that FAB can result from early allocation of dieters' attention to food-related stimuli.

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.

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.

A slow component of classic Stroop interference

The interference in colour naming may extend beyond critical Stroop trials. This “slow” effect was first discovered in emotional Stroop tasks, but is extended here to classical Stroop. In two experiments, meaningless coloured letter strings followed a colour word or neutral word. Student participants (Experiment 1), and 18 stroke patients and 18 matched controls (Experiment 2) showed substantial interference by incongruent colour words, both in the word trial (fast component) and in the subsequent string trial (slow component). Different patient subgroups emerged from the comparison of Stroop performance with the controls. An association of fast and slow components was only found in one subgroup. Exploratory analyses revealed no clear differences in damage location between subgroups. Fast interference caused by colour-meaning conflict may be specific for classical Stroop, but the broader occurrence of slow effects suggests a more generalised process of disengagement from attention-demanding stimuli.

P01-248 - Comparison of the emotional stroop effect on Korean children with ADHD and emotional disorder

ObjectiveIn classical stroop task ADHD children show core deficit in interference control in the condition of the incongruent color word: more errors and slower speed. In previous studies children with emotional disorder were found to show attentional bias in emotional stroop task in which children are asked to name quickly the color of emotional words such as ‘anxious’, ‘worried’, ‘sad’ and ‘disappointed’, while ignoring the meaning of the words. The aim of this study was to evaluate emotional stroop effect between ADHD and emotional disordered children to investigate attentional bias toward emotional stimuli.MethodsThe subjects were 22 ADHD children and 14 children who have emotional disorder, including anxiety, tic or depressive disorder. Classical stroop task as well as emotional stroop task, IQ test, State-Trait Anxiety Inventory for Children(STAIC) and Children's Depression Inventory(CDI) were administered individually to all children.Results1.Children with emotional disorder obtained higher CDI and STAIC scores than ADHD children.2.There were no significant group difference in emotional stroop task between children with emotional disorder and ADHD even after controlling IQ.ConclusionsWe could not found that children with emotional disorder show more attentional bias toward anxiety or depression-relevant stimuli than ADHD children. Further research with large subjects and more sophisticated assessment of emotional problem is needed to elucidate emotional stroop effect.

From orthography to meaning: an electrophysiological investigation of the role of phonology in accessing meaning of Chinese single-character words

Homophone interference effects in Stroop experiments are often taken as evidence for the hypothesis that semantic access in written Chinese language is mediated by activation of phonological processing. We here aim to test this hypothesis with Chinese single-character words by means of event related potential (ERP) recordings. Using color words, homophones of color words and color-word associates as materials in a Stroop task, we found behavioral Stroop interference effects for all stimulus types and an N450 for incongruent color words and color-word associates. Critically, there was no difference in the ERP waveforms elicited by congruent and incongruent homophones in the N450 time window. However, in a later time window (600–800 ms) the incongruent homophones elicited an apparent positivity over left posterior regions. A similar effect was also observed for incongruent color words. These findings thus indicate that phonology does not play an important role in semantic activation of Chinese single-character words, and that the behavioral Stroop effects for homophones possibly arises at later stage of lexical processing.

The eyes fixate the optimal viewing position of task-irrelevant words

We evaluated whether one's eyes tend to fixate the optimal viewing position (OVP) of words even when the words are task irrelevant and should be ignored. Participants completed the standard Stroop task, in which they named the physical color of congruent and incongruent color words without regard to the meanings of the color words. We monitored the horizontal position of the first eye fixation that occurred after the onset of each color word to evaluate whether these fixations would be at the OVP, which is just to the left of word midline. The results showed that (1) the peak of the distribution of eye fixation positions was to the left of the midline of the color words, (2) the majority of the fixations landed on the left side of the color words, and (3) the average leftward displacement of the first fixation from word midline was greater for longer color words. These results suggest that the eyes tend to fixate the OVP of words even when those words are task irrelevant.

Contextual control of biconditional task performance: Evidence for cue and response competition in rats

A novel paradigm is presented that was designed to mimic aspects of cue and response competition seen in humans in conflict procedures such as the Stroop task. Rats were trained simultaneously on two biconditional discrimination tasks, one auditory and one visual, in two different contexts: C1, in which A1:LP1-->R, A2:LP2-->R; and C2, in which V1:LP1-->R, V2:LP2-->R, where C1/C2 represent different training contexts (produced by different operant chambers), A1/A2 are different auditory cues, V1/V2 are different visual cues, LP1/LP2 are discrete operant responses, and R is reward. At test, rats received presentations of audiovisual compounds of these training stimuli in extinction. These compounds had dictated either the same (A1V1 or A2V2) or different (A1V2 or A2V1) responses during training: termed congruent and incongruent trials, respectively. Experiment 1 showed that following equal training on the two biconditional tasks, the contextual cues came to control responding to conflicting information provided by incongruent stimulus compounds such that animals responded according to the stimulus element previously trained in that test context. Experiment 2 demonstrated that differential training on the biconditional discriminations (with rats receiving training on the two discriminations in the ratio 3:1) resulted in greater interference from the overtrained task when animals were tested in the undertrained context. This finding is similar to the classic Stroop asymmetry seen in human performance whereby dominant word reading interferes with colour naming for incongruent colour-word compounds. Further analysis also revealed some evidence for a reverse Stroop effect in which the undertrained stimulus element interfered with performance on the overtrained task.

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.

A case for inhibition: Visual attention suppresses the processing of irrelevant objects.

The present study investigated the ability to inhibit the processing of an irrelevant visual object while processing a relevant one. Participants were presented with 2 overlapping shapes (e.g., circle and square) in different colors. The task was to name the color of the relevant object designated by shape. Congruent or incongruent color words appeared in the relevant object, in the irrelevant object, or in the background. Stroop effects indicated how strong the respective area of the display was processed. The results of 4 experiments showed that words in the relevant object produced larger Stroop effects than words in the background, indicating amplification of relevant objects. In addition, words in the irrelevant object consistently produced smaller Stroop effects than words in the background, indicating inhibition of irrelevant objects. Control experiments replicated these findings with brief display durations (250 ms) and ruled out perceptual factors as a possible explanation. In summary, results support the notion of an inhibitory mechanism of object-based attention, which can be applied in addition to the amplification of relevant objects.

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.

An investigation of myocardial aerobic capacity as a measure of both physical and cognitive workloads

With increased automation and supervisory control, the physical content of jobs has decreased while cognitive workload has increased. The cardiovascular system responds to both physical and cognitive stresses, and their combination, by causing an increase in both heart rate (HR) and blood pressure. The increase in HR and blood pressure cause an increase in myocardial contractility, which results in an increase in myocardial oxygen consumption ( MV O 2 ) . The rate–pressure product (RPP), given by the product of HR and systolic blood pressure, is a very reliable indirect measure of MV O 2 . With this in mind, an experiment was conducted on 12 able-bodied male students from the University population. Subjects were required to perform three cognitive tasks (Stroop Incongruent Color-Word Test, simulated public speaking, and calculating task) under two physical conditions (riding a Schwinn Airdyne at a constant speed of 1/3 of their estimated maximum HR, and seated at rest on the Schwinn Airdyne). HR and blood pressure were monitored throughout the testing period. Results of the analysis of the randomized block design indicated that both cognitive and physical tasks had a significant effect on RPP. Additionally, the findings from this study indicated that RPP can be used as an objective measure to separate the components of cognitive workload and cognitive stress in combined tasks. Relevance to industry Rate–pressure product may be used as a measure of occupational workload, both cognitive and physical. It may be possible to use RPP measures to set limits on workloads and for establishing work allowance.

Age Differences in Stroop Interference in Working Memory

Working memory capacity can be conceptualized as the ability to use controlled attention in short term memory (Engle, Tuholski, Laughlin, & Conway, 1999). We tested this idea in young and older adults by combining the task demands of two neuropsychological tests, word span, and Stroop color-naming. Young and older adults were asked to name the colors of a series of congruent and incongruent color-words (between 2 and 6 words/trial). After all the color-words were presented participants attempted to recall the colors in their serial order. This task required inhibition of the prepotent word reading response (i.e., color naming), with a concurrent memory load (caused by the need to maintain already named colors in short-term memory). Older adults showed greater interference effects, and these interference effects increased as a function of memory load. Regression analyses showed that measures of working memory capacity and executive function accounted for unique variance in incongruent color-word errors for older adults. Defining working memory capacity as the ability to use controlled attention in short-term memory may be a fruitful way to think about this concept in studies of executive function.

Differences between Chinese morphosyllabic and German alphabetic readers in the Stroop interference effect

The goal of our study was to localize the source of the stronger Stroop interference effect found in morphosyllabic readers as compared with alphabetic readers. Twenty-three Chinese and 24 German undergraduate students were tested in a Stroop paradigm with the following stimuli: color patches, color-neutral words (e.g.,friend printed in yellow), incongruent color-associated words (e.g., blood printed in blue), and incongruent color words (e.g., yellow printed in blue). Results revealed no differences in German and Chinese students' response times to color patches. Chinese participants, however, showed longer color naming latencies for neutral words as well as for color words and color-related words. No differences between German and Chinese participants were found when print color latencies for neutral words were subtracted from print color latencies for color words and color-related words. This result does not support theories which suggest that for morphosyllabic readers there is a direct route from orthography to the semantics of a word. We rather argue, with reference to dual route models of reading, that access from print to phonology is faster for morphosyllabic than for alphabetic readers, and therefore interference caused by conflicting phonologies of color name and written word will be stronger in Chinese readers than in German readers.

Reduced Task-Set Inertia in Parkinson’s Disease

This study investigated the relationship between cognitive inhibition and set-switching costs in 13 patients with Parkinson’s disease (PD) and 16 control subjects using a set-switching task with fully predictable switches. Incongruent colour-words and numerals were presented in either baseline (only colour-words or only numerals) or alternating lists (colour-words and numerals in alternation). Words required either a word-reading or colour-naming response whereas numerals required either a value-naming (value of the digits) or group-size naming (number of digits) response. Stroop interference was found to be increased and practice effects on nondominant tasks reduced in PD patients, suggesting that the ability to increase control over interference from irrelevant prepotent responses may be implicated in PD. Switch costs of PD patients were reduced on the first few trials of alternating dominant task lists and increased towards the end of alternating nondominant task lists. Both effects were explained as resulting from a reduced ability to maintain task-sets where selection of correct responses relies on inhibition of irrelevant stimulus-response mappings.