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.     

Self-monitoring,need for cognition,and the Stroop effect: a preliminary study

The color-word Stroop task requires an individual to ignore one piece of information (word) while responding to another (color). Since self-monitors are good at adapting their responses to fit a situation and those high in need for cognition carefully think through information before responding, this study explored the relationship between self-monitoring and need for cognition using Stroop interference. It was anticipated that self-monitoring would reduce Stroop interference, while need for cognition would increase Stroop interference. 23 General Psychology students (10 men, 13 women, M(age) = 18.8 yr.) participated. Participants were given the Self-monitoring Scale, the Need for Cognition Scale, and the Stroop Color-Word Test. Analysis indicated that Need for Cognition was not correlated with Stroop interference (r = .31) but higher scores on Self-monitoring were correlated with lower Stroop interference (r = .43). Implications for research are suggested.     

A horse race of a different color: Stroop interference patterns with transformed words

Four experiments investigated Stroop interference using geometrically transformed words. Over experiments, reading was made increasingly difficult by manipulating orientation uncertainty and the number of noncolor words. As a consequence, time to read color words aloud increased dramatically. Yet, even when reading a color word was considerably slower than naming the color of ink in which the word was printed, Stroop interference persisted virtually unaltered. This result is incompatible with the simple horse race model widely used to explain color-word interference. When reading became extremely slow, a reversed Stroop effect--interference in reading the word due to an incongruent ink color--appeared for one transformation together with the standard Stroop interference. Whether or not the concept of automaticity is invoked, relative speed of processing the word versus the color does not provide an adequate overall explanation of the Stroop phenomenon.     

Semantic processing in auditory lexical decision: Ear-of-presentation and sex differences

In this study we examined the interplay between appetitive (approach) and defensive (avoid) responses in spoken word recognition. Ninety-two right-handed participants (half women) took part in an auditory lexical decision experiment in which speech was presented to only one ear. The danger and usefulness of the word referents interacted in predicting RTs, as in previous (binaural) studies with poorer control of psycholinguistic covariates. Specifically, higher danger ratings were associated with faster RTs for words rated low on usefulness; but higher danger ratings were associated with slower RTs for words rated high on usefulness. In addition to this primary finding, men showed more lateralised performance, as indicated by significant interactions of sex and ear of presentation with word frequency, and with the animacy of the word referents. For both sexes, word frequency had a stronger effect on accuracy for speech presented to the right ear. Finally, men's but not women's RTs were related to the danger dimension. This last finding provides an intriguing avenue for future research in the area of sex differences and emotion.     

The Effects of Procedural Variations on Lateralized Stroop Effects

Several issues in the classic Stroop effect remain open, including (i) the stage of processing which gives rise to the effect, (ii) the effect of some procedural manipulations, (iii) the effect of hemispheric specialization and of interhemispheric interactions, and (iv) the existence of individual differences. In this paper, we investigate these issues using a series of experiments with central, lateral, and bilateral presentations of the Stroop stimuli. A total of 146 right-handed subjects took part in a multiexperiment study with relatively equal numbers of the two sexes participating in each experiment. We found that manual responses diluted but did not abolish the Stroop interference relative to vocal responses, arguing for a late processing stage account of the effect. However, separating the color patch from the color word either unilaterally or bilaterally did not significantly change the magnitude of the Stroop interference, arguing against a cost of interhemispheric transfer in the Stroop effect in normal subjects. We did, however, find evidence for hemispheric specialization in Stroop interference, greater in the left hemisphere than in the right hemisphere. Color words in the RVF produced the greatest Stroop effects regardless of the location of the color patch. In most cases, this laterality effect interacted with the sex of the subject, such that only males and a subgroup of females (i.e., those tested during a low estrogen phase in the menstrual cycle) showed evidence for greater Stroop effects when a color word projected to the left hemisphere than when it projected to the right hemisphere, regardless of the placement of the color patch.     

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

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.     

The Stroop congruency effect is more observable under a speed strategy than an accuracy strategy

Naming the ink color of an incongruent color word (e.g., RED printed in green) usually takes longer than naming the ink color of a color bar. However, when the ink matches the word (e.g., RED printed in red), naming tends to be faster. These phenomena are known as the STroop interference effect and the Stroop congruency effect, respectively. Although the interference effect has been robust and reliable across studies, the congruency effect tends to be elusive. It was hypothesized that this variation in outcomes might be related to subjects' response strategy. The experiment conducted to test this hypothesis induced either a speed or an accuracy strategy in two separate groups of subjects. Significant interference effects were found for both groups and the magnitudes did not differ. At the same time, the congruency effect was observed in the speed group but not in the accuracy group. These results suggest that researchers who wish to observe and study the Stroop congruency and interference effects should place special emphasis on speed. Implications of the study for a model of the Stroop effect are also discussed.     

Stroop dilution depends on the nature of the color carrier but not on its location

Stroop dilution is the reduction of the Stroop effect in the presence of a neutral word. It has been attributed to competition for attention between the color word and neutral word, to competition between all stimuli in the visual field, and to perceptual interference. Five experiments tested these accounts. The critical manipulation was whether the color to be named was carried by the color word or the neutral word. Neutral words diluted the Stroop effect when they were the color carrier, but not when the color word was the color carrier. We argue that Stroop dilution is due to attentional competition between the color word and neutral word, with priority given to the color carrier.     

Abstracts

Slower colour-naming reaction times (RTs) for negatively valenced Stroop words (e.g. SELFISH printed in green ink) than for positively valenced words (e.g. TOLERANT printed in blue ink) have been taken as evidence of an automatic vigilance mechanism that directs attention towards undesirable events and objects. These findings were replicated when words were shown at fixation but not when they were shown away from the locus of fixation. The failure of negative word valence to capture spatial attention is compared with the capture that has been found with angry and threatening facial expressions. From an ecological view of social perception both findings are unsurprising. Unlike words, facial expressions have evolved to provide the species with adaptively important information.     

Stroop and picture—word interference are two sides of the same coin

This article presents a cognitive model that reconciles a surprising observation in the picture—word interference (PWI) paradigm with the general notion that PWI is a form of Stroop interference. Dell’Acqua, Job, Peressotti, and Pascali (2007) assessed PWI using a psychological refractory period (PRP) paradigm, and concluded that the locus of interference in PWI is during the perceptual encoding stage. Stroop interference, on the other hand, is generally attributed to response selection. Based on these findings it was argued that PWI is not a Stroop effect. The present article discusses an alternative interpretation of these results. We assume that both effects are caused by the same interference mechanism, but that the processing speed associated with the different stimuli (colors vs. words) accounts for the previously reported differences. We support this argument by presenting a single computational model that accounts for both PWI and Stroop phenomena in single task and PRP settings.     

Semantic Competition as the Basis of Stroop Interference:Evidence From Color-Word Matching Tasks

Abstract—A color-word matching task was used to investigate the basis of Stroop interference. Subjects were shown a pair of stimuli: an ink color (e.g., a red bar) and a colored word (e.g., RED printed in red or blue) and decided whether the two items had the same meaning (meaning decisions) or whether they had the same surface color (visual decisions). In Experiment 1, the two stimuli were shown simultaneously, and conflicting visual information of the word (e.g., RED printed in blue, against a red bar) led to interference in meaning decisions, whereas conflicting verbal information (e.g., BLUE printed in red, against a red bar) produced no interference in visual decisions. In Experiment 2, as an increasing time interval was imposed between presentation of the color bar and the colored word, interference in meaning decisions diminished, whereas interference in visual decisions was established. These results suggest that semantic competition, not response competition, is the major source of Stroop and Stroop-like interference.     

What is the nature of increased Stroop interference in schizophrenia?

In comparison to controls, patients with schizophrenia classically display (1) an overall slowing in response times (RTs) and (2) a disproportionate slowing in RTs in the conflict condition of the Stroop color/word interference task. These two effects appear repeatedly in the card version of the Stroop task but were not replicated in a number of studies using a computer item-by-item version of the task. The present study was aimed at understanding the exact nature of the increased interference classically found in the performance of patients with schizophrenia in the card version of the Stroop task. We used a computer trial-by-trial version in which we investigated the effects of two major methodological differences between the two versions: (1) blocked (card version) versus mixed (computer version) presentation of the neutral, congruent and conflict conditions and (2) presence (card version) versus absence (computer version) of distractors in the spatial surrounding of the target. We found an overall slowing in performance and a disproportionate slowing in the conflict condition for patients with schizophrenia but only when the target was surrounded by distractors (in Experiments 2 and 3). The data are discussed in terms of a deficit in selective attention and inhibitory processes in schizophrenia.     

Verbal coding and the elimination of Stroop interference in a matching task

Translational models of the Stroop effect (Virzi & Egeth, 1985) predict that Stroop interference can be eliminated if subjects can be induced to process target colors using a coding system separate from the coding system used to process distractors. This hypothesis was tested in two experiments. In the first experiment, we attempted to eliminate the need for subjects to translate target colors to verbal codes when responding to Stroop stimuli. Before responding to verbal incongruent color word distractors, subjects practiced matching colors to irregular shapes. It was expected that subjects would use nonverbal codes to mediate responding in this task. After practice, subjects continued the matching task in the presence of incongruent color words. Stroop interference persisted, contrary to predictions. Because subjects reported adopting verbal strategies to perform the matching task, Experiment 2 was designed to control the verbal coding strategies that subjects employed. Before responding to Stroop distractor stimuli, subjects in the nonsense name group practiced using nonsense names to mediate the matching of shapes to colors; subjects in the actual name group used actual color names to mediate performance in the matching task. When incongruent color word distractors were introduced, Stroop interference was eliminated for subjects in the nonsense name group, but persisted for subjects in the actual name group. The results are interpreted as consistent with an outcome conflict (Navon & Miller, 1987) or a modified translational model of the Stroop effect.     

SEPARATING SPEED FROM AUTOMATICITY IN A PATIENT WITH FOCAL BRAIN ATROPHY

Abstract— Automatic processes are characterized as being rapid, as requiring little attentional effort, and as obligatory (once initialed, the activity cannot be inhibited or controlled). In contrast, controlled processes are slower, require attention, and are non-obligatory. This distinction appears in the Stroop effect the interference that appears when a person tries to name the color of the ink in which a word is printed when the word spells the name of a different color. This effect has historically been attributed to an automatic reading of the color name interfering with the slower, less automatic, naming of the ink color (MacLeod, 1991, Stroop, 1935). In this report, we describe a patient with focal brain atrophy whose speed of reading was no faster than his speed of naming colors, but who still showed the classic Stroop effect. This finding critically challenges the traditional identification of automaticity with processing speed.     

Sex differences in memory estimates for pictures and words with multiple recall trials

Undergraduate students (23 men and 23 women) provided memory performance estimates before and after each of three recall trials involving 80 stimuli (40 pictures and 40 words). No sex differences were found across trials for the total recall of items or for the recall of pictures and words separately. A significant increase in recall for pictures (not words) was found for both sexes across trials. The previous results of Ionescu were replicated on the first and second recall trials: men underestimated their performance on the pictures and women underestimated their performance on the word items. These differences in postrecall estimates were not found after the third recall trial: men and women alike underestimated their performance on both the picture and word items. The disappearance of item-specific sex differences in postrecall estimates for the third recall trial does not imply that men and women become more accurate at estimating their actual performance with multiple recall trials.     

Nonconscious control mimics a purposeful strategy: strength of Stroop-like interference is automatically modulated by proportion of compatible trials

The magnitude of the Stroop effect is known to be modulated by the proportion of trials on which the irrelevant word and relevant ink color correspond. This has often been attributed to a conscious strategy of increased (or decreased) reliance on the irrelevant words when these are more likely (or less likely) to correspond to the ink colors. However, the present data from a Stroop-like task involving successively presented arrows indicate instead that this type of modulation can be automatic because it can occur even if the irrelevant stimuli are not phenomenally visible. In this case participants cannot determine the proportion of compatible trials to direct their strategy. An automatic, item-specific associative interpretation can account for these findings.     

Attention, temporal predictability, and the time course of context effects in naming performance

Models of attention and context effects in naming performance should be able to account for the time course of color-word Stroop interference revealed by manipulations of the stimulus onset asynchrony (SOA) between color and word. Prominent models of Stroop task performance ( [Cohen et al., 1990], [Cohen and Huston, 1994] and [Phaf et al., 1990]) fail to account for the fact that response time (RT) and Stroop interference peak at zero SOA and diminish with word preexposure. The models may be saved by assuming that the time course of interference is determined by a strategic orienting of attention to color onsets when SOA is predictable. To test this temporal predictability hypothesis, SOA was blocked or randomly mixed in Experiment 1. In addition, the time interval between color onsets was randomly variable in Experiment 2. Although RTs were affected, none of the randomization manipulations influenced the typical shape of the time course of Stroop effects. These findings provide evidence against the temporal predictability hypothesis and thereby against prominent models of the Stroop task.     

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.     

Objective assessment of gender roles: Gender Roles Test (GRT-36)

This study was designed to develop a computerized test to assess gender roles. This test is presented as a decision-making task to mask its purpose. Each item displays a picture representing an activity and a brief sentence that describes it. Participants have to choose the most suitable sex to perform each activity: man or woman. The test (Gender Roles Test, GRT-36) consists of 36 items/activities. The program registers both the choices made and their response times (RTs). Responses are considered as stereotyped when the chosen sex fits stereotyped roles and non-stereotyped when the chosen sex does not fit stereotyped roles. Individual means (RTs) were computed for stereotyped and non-stereotyped responses, differentiating between domestic and work spheres. A "D" score, reflecting the strength of association between activities and sex, was calculated for each sphere and sex. The study incorporated 78 participants (69% women and 31% men) ranging from 19 to 59 years old. The results show that: (a) reading speed does not explain the variability in the RTs; (b) RTs show good internal consistency; (c) RTs are shorter for stereotyped than for neutral stimuli; (d) RTs are shorter for stereotyped than for non-stereotyped responses. Intended goals are supported by obtained results. Scores provided by the task facilitate both group and individual detailed analysis of gender role, differentiating the gender role assigned to men from that assigned to women, at the domestic and work spheres. Obtained data fall within the scope of the genderology and their implications are discussed.     

The effects of amount of information in the Stroop color word test

The processing time of the relevant (color) and irrelevant (word) stimulus dimensions in a Stroop color word test were each varied by manipulating the amount of information in the color and word sets from which the stimuli were obtained. Interference in the Stroop task was found to increase with increases in relevant and irrelevant stimulus information. It was concluded that the findings of increased interference with increases in both word and color processing time supported a perceptual conflict interpretation of Stroop task interference.