The spatial Stroop effect: A comparison of color-word and position-word interference

The Stroop effect is one of the most famous examples of interference in human perception. The present study demonstrates that a position Stroop paradigm, comparable to the classical color-word interference paradigm, resulted in the same pattern of interference for the spatial dimension; however, the interference was significantly weaker. By exchanging the original oral response for a manual response in the spatial paradigm, we showed that the verbal component is crucial for the Stroop effect: Manual responses lead to a disappearance of the interference effect. Moreover, with manual responses word position was recognized at the same speed for the baseline condition and for words that were incongruent as well as congruent with the spatial position. The results indicate (1) that the Stoop effect depends heavily on verbal components and (2) that differing processing speeds between reading and position recognition do not serve as a proper explanation for the effect. In addition, the provided paradigm plausibly transfers the classical color-word interference to the spatial dimension.     

The reverse Stroop effect

In classic Stroop interference, manual or oral identification of sensory colors presented as incongruent color words is delayed relative to simple color naming. In the experiment reported here, this effect was shown to all but disappear when the response was simply to point to a matching patch of color. Conversely, strong reverse Stroop interference occurred with the pointing task. That is, when the sensory color of a color word was incongruent with that word, responses to color words were delayed by an average of 69 msec relative to a word presented in gray. Thus, incongruently colored words interfere strongly with pointing to a color patch named by the words, but little interference from incongruent color words is found when the goal is to match the color of the word. These results suggest that Stroop effects arise from response compatibility of irrelevant information rather than automatic processing or habit strength.     

A developmental study of the auditory Stroop effect

A pediatric auditory version of the Stroop procedure was developed and administered to 48 normal children from 3 to 6 years of age. Our purpose was to define the developmental course characterizing interaction between auditory and semantic speech dimensions in young children. The procedure was a reaction time (RT) task that required children to respond as quickly and as accurately as possible to words spoken by a male or a female voice. Children were instructed to ignore what was said and to push the "Mommy" button if Mommy was talking or the "Daddy" button if Daddy was talking. Performance was obtained for words with neutral, congruent, and conflicting semantic content. Preschool children manifested processing dependencies that were similar to those observed in adults on the visual Stroop procedure. Conflict between semantic and auditory dimensions significantly increased RT and congruence between the two dimensions significantly decreased RT relative to the neutral condition. The pattern of results indicated that the meaning of words was processed automatically in the normal children. The magnitude of the Stroop effect reflected developmental change with increasing age.     

Single letter coloring and spatial cuing eliminates a semantic contribution to the Stroop effect

Previous work has shown that the Stroop effect is reduced in size when a single letter is colored and spatially precued. The present experiment addresses a number of criticisms of this work by (1) providing a direct measure of semantic processing, (2) using a vocal response instead of a manual one, and (3) using a more appropriate baseline. A semantically based Stroop effect (slower color naming for color-associated words than for color-neutral words) is observed when all letters in the display are precued and appear in a homogeneous color. This Stroop effect is statistically eliminated when a single letter is precued and is the “odd man out” in terms of its color. Two explanations are considered. In one, single-letter coloring and cuing serve to curtail semantic processing. In the other, single-letter coloring and cuing help to keep the informational sources (i.e, color, word) separate and hence reduce interference, but semantic analysis is not curtailed. The latter account provides a more complete account of existing data.     

Stroop interference in naming and verifying spatial locations

Two experiments are reported that were designed to assess effects of semantic similarity on naming and verification of spatial locations. In Experiment I, the wordsabove, below, left, andright occurred as distractors when Ss named the location of the word relative to a dot, or the location of a dot relative to the word. In Experiment II. the same dot-word displays were used, but Ss reported whether or not the word correctly specified its own location relative to the dot or the location of the dot relative to itself. The naming task showed some within-dimension facilitation and interference effects, most notably when Ss named the location occupied by the distractor word. The verification tasks showed quite substantial retardation of “no” responses when the word and location represented different values on either the horizontal or the vertical dimension.     

A dissociation between object manipulation spatial ability and spatial orientation ability

We developed psychometric tests of spatial orientation ability, in which people are shown a two-dimensional array of objects, imagine taking a perspective within the array, and indicate the direction to a target object from this perspective. Patterns of errors on these tests were consistent with experimental studies of perspective taking. Characteristic errors and verbal protocols supported the validity of the perspective-taking tests, suggesting that people encoded the objects in the display with respect to a body-centered coordinate system when the imagined perspective was more than 90 degrees different from the orientation of the display. By comparing alternative models in a confirmatory factor analysis, we found that the ability to mentally rotate and manipulate an imagined object (as measured by tests of spatial visualization and spatial relations) and the ability to reorient the imagined self (as measured by the perspective-taking tests) are separable spatial abilities.     

Evidence for task conflict in the Stroop effect

C. M. MacLeod and P. A. MacDonald (2000) suggested that congruent and incongruent Stroop stimuli cause more task conflict than neutral stimuli because the anterior cingulate cortex is more activated with these stimuli. This study investigated behavioral expression for this pattern. Experiment 1 reduced task conflict control by increasing the proportion of nonword neutrals. Additionally, half the trials had conflict or neutral cues. The control reduction revealed the task conflict. For noncued trials, response time was longer for congruent stimuli than for neutral stimuli (reverse facilitation effect). In addition, response time for congruent stimuli was longer when stimuli were uncued vs. cued. Experiment 2 increased task conflict control by changing the neutral stimuli to noncolor words. Consequently, the task conflict expression disappeared.     

Decomposing the emotional Stroop effect

The emotional Stroop effect refers to the phenomenon that participants are faster in responding to the ink colour of neutral than of negative word stimuli, possibly reflecting fast and automatic allocation of attention towards negative stimuli. However, this interpretation was challenged by McKenna and Sharma (2004) McKenna, F. P. and Sharma, D. 2004. Reversing the emotional Stroop effect reveals that it is not what it seems: The role of fast and slow components. Journal of Experimental Psychology: Learning, Memory, and Cognition, 30: 382–392. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] who found that the emotional Stroop effect reflected a generic slowdown after negative stimuli. In fact, they even found reversed effects in a design in which neutral stimuli more often followed negative stimuli and vice versa. Yet, besides reversing the emotional Stroop effect this contingency might in fact have counteracted the fast effect, which was usually interpreted as the emotional Stroop effect. To decompose the emotional Stroop effect we used a design in which the foregoing and the current valence were uncorrelated and in which the fast and slow effects could be computed independently from each other. We found evidence for both fast and slow effects and discuss the practical implications for researchers using the emotional Stroop task as a measurement and the theoretical implications for researchers interested in the underlying cognitive mechanisms that contribute to the emotional Stroop effect.     

A reverse Stroop effect without translation or reading difficulty

It is well known that irrelevant color words affect the time needed to identify the color they are displayed in (the Stroop effect). One major view is that a reverse Stroop effect (RSE)—in which the irrelevant color affects the time needed to identify the word—does not occur unless a translation is needed between domain-specific memory codes. In the present article, we report an experiment in which the reverse Stroop effect was investigated by having subjects identify a colored word at fixation by pointing to a location on the screen containing that word. Although the response was untranslated, an RSE was observed. An account is provided in which the strength of association between a stimulus and a specific response plays a central role.     

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.     

The effect of spatial orientation on the perception of moving tactile stimuli

Previous studies have shown that the perception of spatial patterns, such as letters, presented to the hand is affected by the spatial orientation of the hand. The present study investigated how the perception of direction of motion across the fingerpads changes with the position of the hand in space. The moving stimuli were generated on two displays. In one condition, the displays were placed horizontally in front of the subject, with the subject’s thumb (target site) and index finger (nontarget site) placed flat on the displays. In a second condition, the displays were vertically oriented and gripped between the thumb and index finger. Using a selective-attention paradigm in which subjects are instructed to respond only to the direction of motion at the target site, performance was still affected by the direction of motion at the nontarget site. Changing the orientation of the displays changed the effectiveness of the nontarget in interfering with the identification of the target movement. Nontarget stimuli that produced no interference in the horizontal orientation did so in the vertical, and vice versa. It appears that subjects are not using the local direction of movement across the fingerpads to judge the relative direction of movement at the two sites; rather, they are using the external direction of movement.     

Single-letter coloring and spatial cuing do not eliminate or reduce a semantic contribution to the Stroop effect

The automaticity of semantic activation in the Stroop task is still the subject of considerable debate (Augustinova & Ferrand, 2007; Manwell, Roberts, & Besner, 2004). The present experiments were designed to assess whether coloring and cuing a single letter (vs. all letters) in the Stroop task reliably eliminates semantically based Stroop interference or whether the elimination observed by Manwell et al. was due to insufficient statistical power. Experiment 1 was an exact replication of the experiment conducted by Manwell and colleagues and involved a large population. Experiment 2 replicated and extended Experiment 1 by controlling for initial fixation. In line with previous findings obtained by Augustinova and Ferrand, both experiments indicated that coloring and cuing a single letter failed to eliminate or even reduce the semantically based Stroop effect. Thus, these results add to the growing body of evidence suggesting that semantic activation in the Stroop task is automatic.     

A position-sensitive Stroop effect: further evidence for a left-to-right component in print-to-speech conversion

In the classical Stroop effect, response times for naming the color in which a word is printed are affected by the presence of semantic, phonological, or orthographic relationships between the stimulus word and the response word. We show that color naming responses are faster when the printed word shares a phoneme with the color name to be produced than when it does not, in conditions where there is no semantic relationship between the printed word and the color name. This result is compatible with a variety of computational models of reading. However, we also found that these effects are much larger when it is the first phoneme that the stimulus and response share than when it is the last. Our data are incompatible with computational models of reading in which the computation of phonology from print is purely parallel. The dual route cascaded model computational model of reading, which has a lexical route that operates in parallel and a nonlexical route that operates serially letter by letter, successfully simulates this position-sensitive Stroop effect. The model also successfully simulates the “onset effect” in masked priming (Forster & Davis, 1991) and the interaction between the regularity effect and the position in a word of a grapheme-phoneme irregularity (Rastle & Coltheart, 1999b)-effects which, we argue, arise for the same reason as the position-sensitive Stroop effect we report.     

Sexual orientation and spatial memory

The present study aimed at determining the influence of sexual orientation in human spatial learning and memory. Participants performed the Boxes Room, a virtual reality version of the Holeboard. In Experiment I, a reference memory task, the position of the hidden rewards remained constant during the whole experiment. In Experiment II, a working memory task, the position of rewards changed between blocks. Each block consisted of two trials: One trial for acquisition and another for retrieval. The results of Experiment I showed that heterosexual men performed better than homosexual men and heterosexual women. They found the rewarded boxes faster. Moreover, homosexual participants committed more errors than heterosexuals. Experiment II showed that working memory abilities are the same in groups of different sexual orientation. These results suggest that sexual orientation is related to spatial navigation abilities, but mostly in men, and limited to reference memory, which depends more on the function of the hippocampal system.     

A reversal of the Stroop interference effect,through scanning:

Interference on the Stroop test has been explained on the basis of a stronger habit (word reading) interfering with a weaker one (color naming) on an incongruous color-word (CW) card. Since scanning for words is slower (weaker) than scanning for colors, it was predicted that making the Stroop a scanning task would produce more interference with scanning for words rather than colors on the CW card. This prediction was confirmed. In addition, analyses of individual differences offered some support for differential habit-strength theories of Stroop interference. However, differences between the standard and scanning Stroop tests suggested that some kind of information-processing analysis would be more fruitful.     

The picture-word interference effect is not a Stroop effect

A psychological refractory period (PRP) paradigm was used to isolate the locus of the picture-word interference effect along the chain of processes subtended in name production. Two stimuli were presented sequentially on each trial, separated by a varying stimulus onset asynchrony (SOA). The first stimulus, SI, was a tone that required a manual response. The second stimulus, S2, was a picture-word stimulus associated with picture naming. The distractor word was conceptually related to the picture on half of the trials, and unrelated in the other trials. A picture-word interference effect was found at long SOA, but not at short SOA. Such underadditive interaction between SOA and semantic relatedness suggests strongly that the locus of the picture-word interference effect is functionally earlier than the PRP effect locus. The results are discussed in relation to models of word production suggesting the involvement of central mechanisms in the selection of lexical output.     

Developmental change in the cross-modal Stroop effect

E. M. Elliott, Cowan, and Valle-Inclan (1998) reported a cross-modal Stroop-like interference effect in adults when an auditory distractor (a color or noncolor word) occurred simultaneously with a color patch to be named. Response times were slower with color as opposed to noncolor distractors. To distinguish two accounts of this phenomenon, we tested 4- to 11-year-olds and adults. The suppression hypothesis posits that the irrelevant word enters a phonological buffer and is injurious to color naming if the participant is unable to suppress its representation in time. The concurrent processing hypothesis states that interference occurs when the distractor and the color name are lexically accessed at the same time. Our finding that the cross-modal Stroop effect occurred in young children even with a distractor presented 500 msec in advance of the color patch favors the suppression account. Development in executive functioning may also contribute to the interference effect's becoming progressively weaker with age.     

Wheel chairs and arm chairs: A novel experimental design for the emotional Stroop effect

The emotional Stroop effect demonstrates that people are slower to name the ink colour of emotionally charged words than that of neutral words. Attributing this slowdown to emotionality or threat requires that the emotion and neutral words presented are equal on all extraneous variables. However, it is impossible in principle to match the two types of words on all conceivable variables. To address the problem, we presented the same set of words, polarised to be negative in one condition and neutral in another by using appropriate prime words that produced the desired valence through idiomatic two-word expressions. Across two studies, participants took longer to name the colour of the same words when they were rendered negative than when they were rendered neutral. This difference reflects a true emotional Stroop effect given the control provided for all potentially confounding variables tied to the target stimuli. The new procedure also enables researchers to calculate item-specific emotional Stroop effects for the first time.     

Asymmetry of congruency effects in spatial Stroop tasks can be eliminated

Three experiments examined whether asymmetry in interference can be eliminated in spatial Stroop tasks. In Experiment 1, responding to arrows or location words written in Chinese and to their locations created spatial Stroop effects of similar sizes. In Experiment 2, responding to a location word embedded in an outline drawing of arrow did not yield a spatial Stroop effect, but responding to the arrow's direction did yield an effect. In Experiment 3, responding to a location word flanked by an arrow and to the arrow rather than the word produced similar sizes of spatial Stroop effects. These results show that asymmetry in spatial Stroop interference can be eliminated in some situations. Although aspects of the results are consistent with predictions of translation and dimensional overlap models, they are in closest agreement overall with an account in terms of the relative strengths of the relevant and irrelevant stimulus–response associations.