Selective processing of threat cues in posttraumatic stress disorder

Vietnam combat veterans with (n = 15) and without (n = 15) posttraumatic stress disorder (PTSD) performed a modified Stroop task in which they named the colors of neutral words (e.g., INPUT), positive words (e.g., LOVE), obsessive-compulsive disorder (OCD) words (e.g., GERMS), and PTSD words (e.g., BODYBAGS). In contrast to normal controls, PTSD patients took significantly longer to color-name PTSD words than to color-name neutral, OCD, and positive words. Because Stroop interference reflects involuntary semantic activation, it may provide a quantitative measure of intrusive cognitive activity--the hallmark symptom of PTSD.     

Filling a gap in the semantic gradient: Color associates and response set effects in the Stroop task

In the Stroop task, incongruent color associates (e.g., LAKE) interfere more with color identification than neutral words do (e.g., SEAT). However, color associates have historically been related to colors in the response set. Response set membership is an important factor in Stroop interference, because color words in the response set interfere more than color words not in the response set. It has not been established whether response set membership plays a role in the ability of a colorassociate to interfere with color identification. This issue was addressed in two experiments (one using vocal responses and one using manual responses) by comparing the magnitude of interference caused by color associates related to colors in the response set with that of interference caused by color associates unrelated to colors in the response set. The results of both experiments show that color associates unrelated to colors in the response set interfered with color identification more than neutral words did. However, the amount of interference was less than that from color associates that were related to colors in the response set. In addition, this pattern was consistent across response modalities. These results are discussed with respect to various theoretical accounts of Stroop interference.     

The Color of Sin: White and Black Are Perceptual Symbols of Moral Purity and Pollution

ABSTRACT— Three studies examined automatic associations between words with moral and immoral meanings and the colors black and white. The speed of color naming in a Stroop task was faster when words in black concerned immorality (e.g., greed ), rather than morality, and when words in white concerned morality (e.g., honesty ), rather than immorality. In addition, priming immorality by having participants hand-copy an unethical statement speeded identification of words in the black font. Making immorality salient in this way also increased the moral Stroop effect among participants who had not previously shown it. In the final study, participants also rated consumer products. Moral meanings interfered with color naming most strongly among those participants who rated personal cleaning products as especially desirable. The moderation of the moral Stroop effect by individual differences in concerns about personal cleanliness suggests that ideas about purity and pollution are central to seeing morality in black and white.     

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.     

Skeletal structure of printed words: evidence from the stroop task

Do readers encode the sequencing of consonant (C) and vowel (V) phonemes (skeletal structure) in printed words? The authors used the Stroop task to examine readers' sensitivity to skeletal structure. In Experiment 1, CVC nonwords (e.g., pof) facilitated the naming of colors with congruent frames (e.g., red, a CVC word) but not with incongruent ones (e.g., green). In Experiment 2, the color black (a CCVC frame) was named faster with a congruent CCVC frame (e.g., grof) compared to either CCVCC (e.g., groft) or CVC (e.g., gof) incongruent controls. Finally, in Experiment 3, the color pink (a CVCC frame) was named faster with a CVCC frame (e.g., goft) compared to either CCVCC or CVC incongruent controls. In most cases, congruent frames shared no segments with the color name. These findings demonstrate that readers automatically assemble the skeletal structure of printed words.     

The visual-auditory color-word Stroop asymmetry and its time course

Four experiments examined crossmodal versions of the Stroop task in order (1) to look for Stroop asymmetries in color naming, spoken-word naming, and written-word naming and to evaluate the time course of these asymmetries, and (2) to compare these findings to current models of the Stroop effect. Participants named color patches while ignoring spoken color words presented with an onset varying from 300 msec before to 300 msec after the onset of the color (Experiment 1), or they named the spoken words and ignored the colors (Experiment 2). A secondary visual detection task assured that the participants looked at the colors in both tasks. Spoken color words yielded Stroop effects in color naming, but colors did not yield an effect in spoken-word naming at any stimulus onset asynchrony. This asymmetry in effects was obtained with equivalent color- and spoken-word-naming latencies. Written color words yielded a Stroop effect in naming spoken words (Experiment 3), and spoken color words yielded an effect in naming written words (Experiment 4). These results were interpreted as most consistent with an architectural account of the color-word Stroop asymmetry, in contrast with discriminability and pathway strength accounts.     

Attention, spatial integration, and the tail of response time distributions in Stroop task performance

A few studies have examined selective attention in Stroop task performance through ex-Gaussian analyses of response time (RT) distributions. It has remained unclear whether the tail of the RT distribution in vocal responding reflects spatial integration of relevant and irrelevant attributes, as suggested by Spieler, Balota, and Faust (2000). Here, two colour-word Stroop experiments with vocal responding are reported in which the spatial relation between colour and word was manipulated. Participants named colours (e.g., green; say "green") while trying to ignore distractors that were incongruent or congruent words (e.g., red or green), or neutral series of Xs. The vocal RT was measured. Colour words in colour, white words superimposed onto colour rectangles (Experiment 1), and colour rectangles combined with auditory words (Experiment 2) yielded Stroop effects in both the leading edge and the tail of the RT distributions. These results indicate that spatial integration is not necessary for effects in the tail to occur in vocal responding. It is argued that the findings are compatible with an association of the tail effects with task conflict.     

Phonology in the bilingual Stroop effect

In a bilingual Stroop task, we examined between-language interference among proficient Japanese-English bilingual speakers. Participants named ink colors either in Japanese or in English. The Japanese color terms were either phonologically similar to (i.e., loan words) or dissimilar from (i.e., traditional color terms) English color terms. For both response languages, a significant between-language Stroop effect was found despite the orthographic dissimilarity between the languages. The magnitude of the between-language interference was larger with the phonologically similar terms. These findings implicate direct links connecting phonologically similar matching words in the lexicons of proficient bilingual speakers of dissimilar languages and imply that phonological processing in lexical access occurs even when the access is done unintentionally.     

Sentence interference in the Stroop task

In two experiments on Stroop interference, we examined whether sentences can be processed without the intention of the reader. Participants named the ink colors in which words in sentences were printed, and the ink colors in which the same words, randomly arranged, were printed. In Experiment 1, sentences yielded longer response times (RTs) and more errors than did nonsentences, but only when they included words that were highly relevant to the color-naming task (i.e., color and color-related words). In Experiment 2, sentences yielded more errors than did nonsentences, and sentences in which the color words matched the set of ink colors yielded longer RTs than did nonsentences. The results indicate that sentence processing can be obligatory when the component words are highly relevant to the task.     

材料类型和颜色典型性影响颜色-物体Stroop效应

通过两个实验考查材料类型和颜色典型性对颜色-物体Stroop效应的影响。实验1,考查颜色-物体（图片）Stroop效应。结果颜色典型性差异显著,命名图片的颜色和图片的名称都产生显著的颜色-物体Stroop效应。实验2,考查颜色-物体（词语）Stroop效应。结果颜色典型性差异显著,命名词语的颜色产生颜色-物体Stroop效应,命名词语的名称未产生颜色-物体Stroop效应。结论,材料类型和颜色典型性影响颜色-物体Stroop效应。     

Double response to Stroop stimuli.

To reexamine Klein's 1964 findings we carried out two experiments on the double response made to Stroop stimuli. In Exp. 1 incongruent color-word stimuli were presented on a CRT online with a microcomputer. A color-word card was used in Exp. 2. Subjects were asked to read words before naming colors or, conversely, to name colors before reading words. An analysis of variance (the task x the type of task) was performed on response times in both experiments. Two main effects and interactions were nonsignificant. Some subjects made an error-like reverse-order response on the double-response task. The present findings do not support Klein's findings or the competition explanation of the Stroop effect.     

Emotion, memory, and attention in the taboo Stroop paradigm

This study tested the binding hypothesis: that emotional reactions trigger binding mechanisms that link an emotional event to salient contextual features such as event location, a frequently recalled aspect of naturally occurring flash-bulb memories. Our emotional events were taboo words in a Stroop color-naming task, and event location was manipulated by presenting the words in different task-irrelevant screen locations. Seventy-two participants named the font color of taboo and neutral words, with instructions to ignore word meaning; in one condition, several words were location consistent (i.e., always occupied the same screen location), whereas in another condition, several colors were location consistent. Then, in a surprise recognition memory test, participants recalled the locations of location-consistent words or colors. Although attention enhanced overall location memory for colors (the attended dimension during color naming), emotion (taboo vs. neutral words) enhanced location memory for words but not colors. These results support the binding hypothesis but contradict the hypothesis that emotional events induce image-like memories more often than non-emotional events.     

The locus of semantic interference in the “Stroop” color-naming task

In two experiments, introductory psychology students responded in two ways to three lists of 60 words printed in different colors. The lists consisted of color words and two sets of words associated with the colors (e.g., SKY, BLOOD, etc.). When the subjects responded by naming the color in which each word was printed, it took longer for the color word list than for either list of associates, i.e., the classical Stroop interference effect. The other response required the subjects to say words from one of the association lists which corresponded to the color in which each word was printed, e.g., they saw the word BLACK (or NIGHT, or COAL) printed inred ink, and had to respond by saying “blood.” Using this response, it took longest for the subjects to complete the list of words which were the same as those required as responses. Color words were somewhat less difficult, and the other association words were completed most quickly. The results do not pinpoint the locus of interference, but clarify additional assumptions which must be accepted to maintain alternative hypotheses.     

Selective processing of threat cues in panic disorder

A computerized Stroop color-naming paradigm was used to investigate attentional biases for selectively processing threat information in panic-disordered patients. Subjects named the colors of neutral words (e.g. TYPICAL), fear words (e.g. PANIC), bodily sensation words (e.g. HEARTBEAT), and catastrophe words (e.g. HEART ATTACK). To control for familiarity with threat concepts, we used clinicians who treat panic disorder as normal control subjects. In contrast to normal controls, panic patients exhibited greater Stroop interference for all threat words, especially those associated with catastrophe. Stroop interference waned during the course of the experiment, thereby indicating habituation to the semantic content of the cues. These findings suggest that panic disorder, like other anxiety disorders, is associated with an attentional bias for processing threatening information.     

Is attention needed for word identification? Evidence from the Stroop paradigm

One of the most robust findings in attention research is that the time to name a color is lengthened markedly in the presence of an irrelevant word that spells a different color name: the Stroop effect. The Stroop effect is found even when the word is physically separated from the color, apparently indicating that words can be read outside the focus of spatial attention. The present study critically evaluated this claim. We employed several stringent measures within a Stroop paradigm to prevent participants from attending to the irrelevant words (e.g., limiting exposure duration to prevent attention capture). Nonetheless, residual Stroop effects were obtained for both color words and semantic associates (e.g., sky to blue). These data suggest that lexical processing can sometimes occur outside the focus of spatial attention.     

Interactions between color and word processing in a flanker task

To examine interactions between color and word attributes, participants responded, either manually or vocally, to a central target (color patch or word) flanked by a Stroop stimulus. Color and word attributes of the flanker affected both vocal and manual responding to color patches. Color and word flankers also affected manual responding to word targets, but only word flanker affected vocal responding to word targets. These results are not consistent with models (e.g., translational models) of Stroop tasks, which posit that interactions between colors and words occur only when vocal responding is required.     

Reduced Stroop interference for opponent colors may be due to input factors: evidence from individual differences and a neural network simulation

Sensory or input factors can influence the strength of interference in the classic Stroop color-word task. Specifically, in a single-trial computerized version of the Stroop task, when color-word pairs were incongruent, opponent color pairs (e.g., the word BLUE in yellow) showed reduced Stroop interference compared with nonopponent color pairs (e.g., BLUE in red). In addition, participants' color discrimination ability was measured by standard color vision tests (i.e., Farnsworth-Munsell 100-Hue Test and Ishihara plates). Error rates in the Farnsworth-Munsell test correlated positively with the amount of Stroop interference. Neural network simulations (variants of J. D. Cohen, K. Dunbar, & J. L. McClelland's, 1990, model) showed that only a distributed trichromatic input layer was able to simulate these findings. Thus, sensory input from the color system needs to be incorporated into current accounts of the Stroop effect.     

Dissociating stimulus-stimulus and response-response effects in the Stroop task.

The separate semantic and response competition interactions between colour and word processing in a manual Stroop task were evaluated by comparing three trial types. Identity trials are both semantically compatible and response compatible (e.g., BLUE in the colour blue), different response trials are both semantically incompatible and response incompatible (e.g., BLUE in the colour green, where blue and green have different response keys), and same response trials are semantically incompatible and response compatible (e.g., the word BLUE in the colour red, where blue and red have the same key press response). Ink colours were embedded in two different word types, colour words, and colour associates. The results using colour words replicated the findings of De Houwer (2003) and demonstrated both a semantic effect (a difference between same response trials and identity trials) and response competition (a difference between same response trials and different response trials). In contrast, the results using colour associates provided evidence for only a semantic effect. These findings support interpretations of the colour associate Stroop effect that attribute the effect to semantics, but challenge Klein's (1964) response competition account and Sharma and McKenna's (1998) claim that the effect of colour associates is dependent on verbal responding. The results confirm that the Stroop colour-word task appears to involve at least two mechanisms, a semantic mechanism and a response competition mechanism.     

A rational look at the emotional stroop phenomenon: a generic slowdown, not a stroop effect

The role of Stroop processes in the emotional Stroop effect was subjected to a conceptual scrutiny augmented by a series of experiments entailing reading or lexical decision as well as color naming. The analysis showed that the Stroop effect is not defined in the emotional Stroop task. The experiments showed that reading, lexical decision, and color naming all are slower with emotional words and that this delay is immune to task-irrelevant variation and to changes in the relative salience of the words and the colors. The delay was absent when emotional and neutral words appeared in a single block. A threat-driven generic slowdown is implicated, not a selective attention mechanism associated with the classic Stroop effect.     

学习材料的背景颜色对认知负荷及学习的影响

本研究采用2×2的多因素混合实验设计,探讨了物理学习环境之一的学习材料背景颜色对认知负荷及学习的影响。结果发现：（1）背景颜色在对认知负荷的影响上与任务类型产生交互作用,在解决创造性问题时,暖色调（如红色）背景下的认知负荷显著高于冷色调（如蓝色）。（2）从学习成绩上看,暖色调（如红色）更有利于记忆测试问题的解决,冷色调（如蓝色）更有利于创造性问题的解决。（3）认知负荷与任务绩效呈一定程度相关。