Task set persistence modulates word reading following resolution of picture-word interference

We extend the finding that word reading slows following successful responses to a color-word Stroop interference task (Masson, Bub, Woodward, & Chan, 2003). Word reading was assessed in a picture-word interference task in which subjects alternated between naming a picture (with either a word or a row of Xs superimposed on it) and reading a word. For the word-reading task, words were presented either in isolation or superimposed on a picture. Word reading was slower after subjects responded to a bivalent stimulus that required resolution of conflict (naming a picture with a word superimposed on it) than after they responded to a stimulus that involved no conflict (naming a picture with Xs superimposed on it), indicating modulation of dominant task performance. This effect was found when word-reading targets were superimposed on pictures but not when those targets were presented in isolation. Modulation of word reading, therefore, appears to be the result of interference from a persistent picture-naming task set, cued by a stimulus configuration that invites execution of both competing tasks.     

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。     

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.     

Material-specific perceptual interference for visual words and faces: implications for models of capacity limitations, attention, and laterality

Four experiments were conducted to test the hypothesis that perceptual interference effects would be greatest among items that are processed by the same hemisphere than among items processed by different hemispheres. Recognition of two peripheral faces, flanked on either side of a central item that also had to be identified, was worse when the item was a face than when the item was a word. The opposite results were obtained for peripheral word identification by naming (Experiment 1). Identical results were obtained when a nonsense form was substituted for the central face (Experiment 2). Since unfamiliar faces and nonsense forms are processed primarily by the right hemisphere and words are processed by the left, the results are consistent with the hypothesis. The interference effect was the same even when the central nonsense shape was identified by naming, suggesting that the locus of the effect is not at response selection (Experiment 3). Ignoring the central item only reduces the interference effects but does not eliminate it (Experiment 4). Although in general words were perceived better in the right visual field, and faces were perceived better in the left, small fluctuations in the magnitude but not in the direction of perceptual asymmetries were sometimes noted with changes in the central item. The fluctuations were usually opposite to those predicted by attentional models of perceptual asymmetries.     

Visual-field differences in picture-word interference

Picture-word interference refers to the fact that if a picture (i.e., line drawing) is presented centrally with a word superimposed, picture-naming latency is longer than if that same picture is presented alone. This phenomenon, like the Stroop phenomenon, seems to be strongly influenced by the nature of the to-be-ignored word. That is, if the word names a member of the picture's semantic category additional interference is observed; however, if the word is replaced by a phonetically unviable consonant string interference is reduced. In the present experiments these effects were examined in the situation where the picture-word stimuli were presented unilaterally in either the left or right visual field. For right-visual-field presentations, phonetic and semantic factors both influenced performance just as in central presentations. As such, these results can be satisfactorily explained in terms of response competition processes. However, the results for the left-visual-field presentations were quite different. Although substantial interference was observed for all types of stimuli, the amount of interference was essentially independent of the linguistic nature of the superimposed letter string. These results do not appear to be explainable in terms of response competition processes. Instead, it is suggested that the best way to explain these results is in terms of the perceptual capabilities of the right hemisphere.     

The lateralized stroop: a meta-analysis and its implications for models of semantic processing

The prevailing theory in the literature concerning the lateralization of Stroop effects involves a speed of processing account (see ). Because the left hemisphere (LH) demonstrates an overall advantage relative to the right hemisphere (RH) on most verbal tasks, interference effects are hypothesized to be greater in the LH than in the RH. Inspection of the data, however, reveals that many studies find no difference in magnitude of Stroop interference between the hemispheres. Given findings within the lateralized semantic priming literature, this is not surprising. A meta-analysis on a subset of lateralized Stroop experiments was conducted to determine whether or not the LH produces significantly more interference than the RH in this paradigm. Based on a number of exclusionary criteria, a total of 19 different studies were included, representing a potential 26 effect size estimates of differential interference. The effect size representing interference using congruent conditions as the baseline (d+=.06) reveals that there is no significant difference between the hemispheres in magnitude of the Stroop interference effect. The LH interference effect was d+=.73, which is significant. Likewise, the RH interference effect, d+=.67, was significant. In summary, while there was no significant difference between the hemispheres, each hemisphere, when examined independently, did exhibit significant within hemisphere interference effects. These findings are presented in light of the lateralized semantic priming literature.     

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.     

An Hebrew language version of the Stroop test

We present normative data from a Hebrew language version of the Stroop color-word test. In this sample of college-educated Israeli young adults, 18 women and 28 men with a mean age of 28.4 yr. completed a Hebrew language Stroop test. When compared with 1978 English language norms of Golden, Hebrew speakers were slower on color-word reading and color naming, similar on naming the color of incongruently colored names of colors, and showed less interference. Slowed color-word reading and color-naming may reflect the two-syllable length of the Hebrew names for one-syllable length English language colors; reduced interference may reflect the exclusion of vowels in much Hebrew printing and subjects' ability to provide competing, nonconflicting words while naming the color of words in which the hue and the lexical content do not match.     

Semantic component of a cross-modal Stroop-like task

Three experiments showed that the pattern of interference of single-modality Stroop tests also exists cross-modally. Distractors and targets were either pictures or auditory words. In a naming task (Experiment 1), word distractors from the same semantic category as picture targets interfered with picture naming more than did semantically unrelated distractors; the semantic category of picture distractors did not differentially affect word naming. In a categorization task (Experiment 2), this Stroop-like effect was reversed: Picture distractors from the same semantic category as word targets interfered less with word categorization than picture distractors that were semantically unrelated; the semantic category of word distractors did not differentially affect picture categorization. Experiment 3 replicated these effects when each subject performed both tasks; the task, naming or categorizing, determined the pattern of interference between pictures and auditory words. The results thus support the existence of a semantic component of a cross-modal Stroop-like effect.     

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.     

Right-hemisphere interactions in picture-word processing

The processing of pictures was investigated in three experiments which eliminated the response effects involved in naming. When a categorization task was used, clear advantages in response latency and accuracy were observed for left visual-field (LVF) presentations. This was in contrast to previous investigations which have used a naming task and which have reported right visual-field (RVF) advantages. When a distracting word was added to the display, the pattern of influence also changed from that reported previously. The use of naming tasks has indicated predominantly left-hemisphere effects, with demonstrations of interactions between pictures and words in the RVF. With a categorization task in Experiment 2, however, the only effective words were those related in meaning to the picture, and only when they were projected to the right hemisphere. The third experiment confirmed the LVF advantage for picture processing with masked displays, but found no reliable asymmetry with unmasked presentations. The pattern of semantic facilitation was also confirmed with the masked displays, but when the mask was removed an inhibition effect replaced the facilitation effect. These effects are interpreted as indicating that picture recognition is localized within the right cerebral hemisphere. It is suggested that the facilitating effect of related words is restricted to the left hemisphere because it is an effect upon recognition processes, whereas the inhibition effect reflects response competition. It is also suggested that previous reports of left-hemisphere interference effects are due to effects of response competition in naming tasks.     

Stroop interference: Hemispheric difference in Chinese speakers

Some recent studies have demonstrated that the processing of color is favored by the nondominant hemisphere in English-speaking subjects. Single Chinese logographs in Japanese- as well as Chinese-speaking subjects are similarly favored. In the present study, it was hypothesized that more Stroop interference would occur in the nondominant hemisphere because the two processes involved in the Stroop effect (i.e., reading logographs and naming colors) are possibly localized in that hemisphere in Chinese-speaking subjects. Eighteen right-handed Chinese-English bilinguals were used as subjects. There were three conditions in each visual field: Interference, reading, and naming. Each slide was presented for 150 msec preceded by a fixation dot. Subjects were asked to verbally report as fast and as accurately as possible either the color words or the color names, depending upon the condition. Reaction times and error rates were analyzed. As expected, more Stroop interference was obtained when color words were presented in the left visual field. This result is in direct contrast with that of Y-C. Tsao, T. Feustel, and C. Soseos 1979, Brain and Language, 8, 367–371. In that study, more Stroop interference was obtained when the materials were presented in the right visual field in English-speaking subjects.     

Naming reaction times to tachistoscopically presented pictures: some evidence of right hemisphere encoding

The present study measured naming reaction times by normal subjects to unilaterally presented picture stimuli. Significant differences in picture-naming reaction time did not exist between left and right visual-field stimulations. The right hemisphere in the intact brain is capable of generating a verbal label for pictured stimuli. A psychological model suggests that a possible processing synergy between the two hemispheres may be tied to spatial processing and elementary linguistics.     

Stroop interference in the left and right visual fields

The Stroop Color-Word test was employed to study the amount of interference in naming colors when stimuli were presented in either visual field. It was hypothesized that more Stroop interference would occur in the dominant hemisphere. The subjects were 24 right-handed college students, between 18 and 25 years old. There were three conditions in each visual field: Interference, Reading, and Naming. Each slide was presented for 150 msec preceded by a fixation dot. Subjects were asked to verbally report as fast and as accurately as they could either the color words or the color names, depending upon the conditions. Reaction times and error rates were analyzed. As expected, significantly higher error rates were obtained when color words were presented in the right visual field under the Stroop interference condition. Under this same condition, reaction time analysis yielded no significant differences between hemispheres.     

Interference control in children with reading difficulties

Two studies investigated whether the greater Stroop interference reported in children with reading difficulties compared to typical readers of the same age represents a generalized deficit in interference control or a consequence of their reading problems. In Study 1, a color-word Stroop task and a nonverbal task involving responses to locations associated with pictures were administered to 23 children with single word reading difficulties and 22 typically developing children matched for age and nonverbal ability. Children with reading difficulties showed disproportionate interference effects in the color-word Stroop but not the nonverbal task. In Study 2, groups of poor and typical readers completed a spatial Stroop task with printed input that did not require a verbal response and a nonverbal analogue. Both groups showed comparable interference in these two tasks. Thus, the reported problems in the color-word Stroop task in children with reading difficulties do not appear to entail general impairments in interference control.     

Picture-name priming in the cerebral hemispheres: evidence for phonological access in the right hemisphere

This study investigated right hemisphere involvement in access to phonology, using a picture-naming priming paradigm where pictures and names of common objects printed in Japanese Kana were presented in succession to the same visual field or different visual fields with a stimulus onset asynchrony of 250 msec. A naming task was used for this purpose. The result showed that, when primes and targets were presented to the same visual field, facilitation for related pairs was observed in each hemisphere, with overall naming latencies being slower in the right hemisphere than in the left hemisphere. This result indicates that the prior access to phonology for a picture in the right hemisphere facilitates phonological activation of a word that names the picture in this hemisphere, suggesting that the right hemisphere is involved in access to phonology. On the other hand, when primes and targets were presented to different visual fields, there was no facilitation for related pairs with inhibition for unrelated pairs, irrespective of prime and target visual fields. It is suggested that this inhibition-dominant pattern of priming may occur due to homotopic inhibition processes proposed by N. D. Cook.     

Rhyming and the right hemisphere

Subjects determined whether two successively presented and orthographically different words rhymed with each other. The first word was presented at fixation and the second was presented either to the left or to the right of fixation, either alone (unilateral presentation) or accompanied by a distractor word in the other visual hemifield (bilateral presentation). Subjects were more accurate when the words did not rhyme, when presentation was unilateral, and when the target was flashed to the right visual hemifield. It was predicted that bilateral presentation would produce interference when information from both visual fields was processed by one hemisphere (callosal relay), but not when each of the two hemispheres performed a task independently (direct access). That is, callosal relay tasks should show greater laterality effects with bilateral presentations, whereas direct access tasks should show similar laterality effects with both bilateral and unilateral presentations. Greater laterality effects were observed for bilaterally presented rhyming words, but nonrhyming words showed similar laterality effects for both bilateral and unilateral presentations. These results suggest that judgment of nonrhyming words can be performed by either hemisphere, but that judgment of rhyming words requires callosal relay to the left hemisphere. The absence of a visual field difference with nonrhyming word pairs suggests further that judgment of nonrhyming word pairs may be accomplished by the right hemisphere when presentation is to the left visual field.     

Context effects in stroop-like word and picture processing

Presents a series of 6 experiments in which Stroop-like effects were generated by modally pure color-color, picture-picture, and word-word stimuli instead of the usual modally mixed color-word or picture-word stimuli. Naming, reading, and categorization tasks were applied. The Stroop inhibition was preserved with these stimuli but unexpectedly showed a semantic gradient only in the naming and not in the reading task. Word categorizing was slower and more interference prone than picture categorizing. These and other results can be captured by a model with two main assumptions: (a) semantic memory and the lexicon are separate, and (b) words have privileged access to the lexicon, whereas pictures and colors have privileged access to the semantic network. Such a model is developed and put to an initial test.     

Hemispheric specialization in reading and word recognition

Three experiments dealing with hemispheric specialization are presented. In Experiment 1, words and/or faces were presented tachistoscopically to the left or right of fixation. Words were more accurately identified in the right visual field and faces were more accurately identified in the left visual field. A forced choice error analysis for words indicated that errors made for word stimuli were most frequently visually similar words and this effect was particularly pronounced in the left visual field. Two additional experiments supported this finding. On the basis of the results, it was argued that word identification is a multistage process, with visual feature analysis carried out by the right hemisphere and identification and naming by the left hemisphere. In addition, Kinsbourne's attentional model of brain function was rejected in favor of an anatomical model which suggests that simultaneous processing of verbal and nonverbal information does not constrict the attention of either hemisphere.     

Effects of a concurrent memory task on hemispheric asymmetries in categorization

Recent research on the division of processing between the two cerebral hemispheres has often employed two concurrent tasks to investigate the dynamic nature of hemispheric asymmetries. The experiment reported here explored the effects of two concurrent high-level cognitive tasks (memory retention and semantic categorization) on the direction and magnitude of hemispheric differences in the processing of words and pictures. Subjects were required to categorize words and pictures presented to either the left visual field-right hemisphere (LVF-RH) or the right visual field-left hemisphere (RVF-LH). The categorization could be performed while holding either verbal material in memory (digit span), pictorial material in memory (serial nonsense figure recognition), or with no concurrent memory task. The effects produced hemisphere-specific, material-nonspecific interference. The verbal task removed a RVF-LH advantage at word categorization and enhanced a LVF-RH advantage on picture categorization; the pictorial task interfered with picture categorization in the LVF-RH, while enhancing a RVF-LH advantage at word categorization. The results are discussed in terms of multiple resource models of hemisphere function, capacity limitations, and the functional locus of processing required to produce various dynamic hemispheric effects.