The nature of cross-modal color-word interference effects

Crossmodal interference on counting performance: Evidence for shared attentional resources

During the act of counting, our perceptual system may rely on information coming from different sensory channels. However, when the information coming from different sources is discordant, such as in the case of a de-synchronization between visual stimuli to be counted and irrelevant auditory stimuli, the performance in a sequential counting task might deteriorate. Such deterioration may originate from two different mechanisms, both linked to exogenous attention attracted by auditory stimuli. Indeed, exogenous auditory triggers may infiltrate our internal "counter", interfering with the counting process, resulting in an overcount; alternatively, the exogenous auditory triggers may disrupt the internal "counter" by deviating participants' attention from the visual stimuli, resulting in an undercount. We tested these hypotheses by asking participants to count visual discs sequentially appearing on the screen while listening to task-irrelevant sounds, in systematically varied conditions: visual stimuli could be synchronized or de-synchronized with sounds; they could feature regular or irregular pacing; and their speed presentation could be fast (approx. 3/sec), moderate (approx. 2/sec), or slow (approx. 1.5/sec). Our results support the second hypothesis since participants tend to undercount visual stimuli in all harder conditions (de-synchronized, irregular, fast sequences). We discuss these results in detail, adding novel elements to the study of crossmodal interference.

Resisting Visual, Phonological, and Semantic Interference - Same or Different Processes? A Focused Mini-Review

The unitary nature of resistance to interference (RI) processes remains a strongly debated question: are they central cognitive processes or are they specific to the stimulus domains on which they operate? This focused mini-review examines behavioral, neuropsychological and neuroimaging evidence for and against domain-general RI processes, by distinguishing visual, verbal phonological and verbal semantic domains. Behavioral studies highlighted overall low associations between RI capacity across domains. Neuropsychological studies mainly report dissociations for RI abilities between the three domains. Neuroimaging studies highlight a left vs. right hemisphere distinction for verbal vs. visual RI, with furthermore distinct neural processes supporting phonological versus semantic RI in the left inferior frontal gyrus. While overall results appear to support the hypothesis of domain-specific RI processes, we discuss a number of methodological caveats that ask for caution in the interpretation of existing studies.

Event-Related Brain Potentials Associated With the Olfactory-Visual Stroop Effect and Its Modulation by Olfactory-Induced Emotional States

This study investigated the event-related brain potentials associated with the olfactory-visual cross-modal Stroop effect and its modulation by olfactory-induced and self-reported affective states. Eighteen healthy participants were presented with an olfactory stimulus and the image of a plant, and they had to categorize the olfactory attribute of the image as “aromatic” or “pungent” by pressing the relevant button as quickly as possible. The type of olfactory-visual stimuli (congruent or incongruent) and the valence of the olfactory-induced emotional states (positive or negative) were manipulated following a 2 × 2 factorial design. Interference effects were observed at the behavioral and the electrophysiological levels: response times recorded in the incongruent condition were higher than those observed in the congruent condition; an incongruent minus congruent negative difference component was discovered between 350 and 550 ms after stimulus onset in the negative—but not in the positive—olfactory-induced emotional state condition. This ND350-550 component was interpreted as reflecting the amount of selective attention involved in the olfactory-visual cross-modal Stroop effect. These results are also consistent with a facilitatory effect of positive emotional state on selective attention which could reduce brain potentials associated with the cross-modal interference effect.

Predicting Context-Dependent Cross-Modal Associations with Dimension-Specific Polarity Attributions Part 1 – Brightness and Aggression

Although researchers have repeatedly shown that the meaning of the same concept can vary across different contexts, it has proven difficult to predict when people will assign which meaning to a concept, and which associations will be activated by a concept. Building on the affective theory of meaning (Osgood, Suci, & Tannenbaum, 1957) and the polarity correspondence principle (Proctor & Cho, 2006), we propose the dimension-specificity hypothesis with the aim to understand and predict the context-dependency of cross-modal associations. We present three sets of experiments in which we use the dimension-specificity hypothesis to predict the cross-modal associations that should emerge between aggression-related concepts and saturation and brightness. The dimension-specificity hypothesis predicts that cross-modal associations emerge depending upon which affective dimension of meaning (i.e., the evaluation, activity, or potency dimension) is most salient in a specific context. The salience of dimensions of meaning is assumed to depend upon the relative conceptual distances between bipolar opposed concept pairs (e.g., good vs. bad). The dimension-specificity hypothesis proposes that plus and minus polarities will be attributed to the bipolar concepts, and associations between concrete and affective abstract concepts that share plus or minus polarities will become activated. Our data support the emergence of dimension-specific polarity attributions. We discuss the potential of dimension-specific polarity attributions to understand and predict how the context influences the emergence of cross-modal associations.

Spatial Integration and the Underlying Mechanisms of Cross-Modality Interference

Researchers have often utilized the classic Stroop task as a measure of selective attention processes. While it is largely agreed upon that semantic interference plays a role in the classic task, the role of attentional processes is less clear. The picture is further muddied when variations on the classic task are used. For example, the cross-modal Stroop task, in which one names the color of visual items while ignoring distracting auditory color words, typically leads to smaller sized interference effects and little or no facilitation when compared to the classic task. Furthermore, relationship(s) with working memory capacity have only been found in the classic version. We examined whether these differences are due to a methodological factor; namely, spatial integration versus separation of the target and distractor locations. We conducted four experiments manipulating the location of auditory distractors within the cross-modal Stroop task, and found that the location of the distractors had little to no impact on the size of the effect. This lack of an effect of location implies that the mechanisms contributing to the cross-modal Stroop effect are not the same as those of the classic Stroop effect, and that the role of spatial attention in cross-modal Stroop is limited. The implications of a unique role for auditory distractors is considered as well, and supports the conclusion that interference in the cross-modal Stroop effect is the result of a combination of semantic interference and modality-specific interference.

Distraction of Mental Arithmetic by Background Speech

When solving mental arithmetic problems, one can easily be distracted by someone speaking in the background and this distraction is greater if the speech comprises numbers. We explored the basis of this disruption by asking participants to solve mental addition problems (e.g., "45 + 17 = ?") in three different conditions: background speech comprising numbers in ascending order (e.g., "61, 62, 63, 64, 65"), background speech comprising numbers in descending order (e.g., "65, 64, 63, 62, 61"), and quiet. Performance was best in quiet, worse in the descending numbers condition, and poorest in the ascending numbers condition. In view of these findings, we suggest that disruption arises as a by-product of preventing the primed, but inaccurate, candidate responses from assuming the control of action. Alternative explanations are also discussed.

The Role of Visual Stimuli in Cross-Modal Stroop Interference

It has long been known that naming the color of a color word leads to what is known as the Stroop effect (Stroop, 1935). In the traditional Stroop task, when compared to naming the color of a color-neutral stimulus (e.g. an X or color patch), the presence of an incongruent color word decreases performance (Stroop interference), and a congruent color word increases performance (Stroop facilitation). Research has also shown that auditory color words can impact the color naming performance of colored items in a similar way in a variation known as cross-modal Stroop (Cowan & Barron, 1987). However, whether the item that is colored interacts with the auditory distractor to affect cross-modal Stroop interference is unclear. Research with the traditional, visual Stroop task has suggested that the amount of color the visual item displays and the semantic and phonetic components of the colored word can affect the magnitude of the resulting Stroop interference; as such, it is possible the same components could play a role in cross-modal Stroop interference. We conducted two experiments to examine the impact of the composition of the colored visual item on cross-modal Stroop interference. However, across two different experiments, three test versions, and numerous sets of trials, we were only able to find a small effect of the visual stimulus. This finding suggests that while the impact of the auditory stimuli is consistent and robust, the influence of non-word visual stimuli is quite small and unreliable and, while occasionally being statistically significant, it is not practically so.

Auditory distraction compromises random generation. Falling back into old habits?

Auditory distraction of random generation--a quintessentially executive control task--was explored in three experiments. Random number generation was impaired by the mere presence of irrelevant auditory sequences that comprise digits, but not letters, and then only if the digits were heard in a canonical order (1, 2, 3 … or 3, 2, 1 …), not in random order (Experiments 1 and 2). Random letter generation was impaired by irrelevant letters heard in alphabetical order (a, b, c …) and reversed alphabetical order (i, h, g …), but not by numbers in canonical order or letters in random order (Experiment 3). Attempting to ignore canonical sequences--with items that are members of the same category as the to-be-generated items--reduced the randomness of the generated sequence, by decreasing the tendency to change the direction of the produced sequence for random number generation, and by increasing resampling of responses for random letter generation. Like other selective attention tasks, the cost of distraction to random generation appears to stem from preventing habitual responses assuming the control of action.

Effect of perceptual load on semantic access by speech in children

PURPOSE

To examine whether semantic access by speech requires attention in children.

METHOD

Children (N = 200) named pictures and ignored distractors on a cross-modal (distractors: auditory-no face) or multimodal (distractors: auditory-static face and audiovisual-dynamic face) picture word task. The cross-modal task had a low load, and the multimodal task had a high load (i.e., respectively naming pictures displayed on a blank screen vs. below the talker's face on his T-shirt). Semantic content of distractors was manipulated to be related vs. unrelated to the picture (e.g., picture "dog" with distractors "bear" vs. "cheese"). If irrelevant semantic content manipulation influences naming times on both tasks despite variations in loads, Lavie's (2005) perceptual load model proposes that semantic access is independent of capacity-limited attentional resources; if, however, irrelevant content influences naming only on the cross-modal task (low load), the perceptual load model proposes that semantic access is dependent on attentional resources exhausted by the higher load task.

RESULTS

Irrelevant semantic content affected performance for both tasks in 6- to 9-year-olds but only on the cross-modal task in 4- to 5-year-olds. The addition of visual speech did not influence results on the multimodal task.

CONCLUSION

Younger and older children differ in dependence on attentional resources for semantic access by speech.

Making sense of age-related distractibility: the critical role of sensory modality

Older adults are known to have reduced inhibitory control and therefore to be more distractible than young adults. Recently, we have proposed that sensory modality plays a crucial role in age-related distractibility. In this study, we examined age differences in vulnerability to unimodal and cross-modal visual and auditory distraction. A group of 24 younger (mean age=21.7 years) and 22 older adults (mean age=65.4 years) performed visual and auditory n-back tasks while ignoring visual and auditory distraction. Whereas reaction time data indicated that both young and older adults are particularly affected by unimodal distraction, accuracy data revealed that older adults, but not younger adults, are vulnerable to cross-modal visual distraction. These results support the notion that age-related distractibility is modality dependent.

Irrelevant auditory and visual events induce a visual attentional blink

In the present study we investigated whether a task-irrelevant distractor can induce a visual attentional blink pattern. Participants were asked to detect only a visual target letter (A, B, or C) and to ignore the preceding auditory, visual, or audiovisual distractor. An attentional blink was observed regardless of the distractor modality. The magnitude of the attentional blink was greater when the target was preceded by a visual or an audiovisual distractor than when the target letter was preceded by an auditory distractor. The presence of a distractor-induced attentional blink regardless of the distractor modality suggests that the attentional blink phenomenon is at least partly due to an amodal processing limitation.

Goal-neglect links Stroop interference with working memory capacity

Relationships between Stroop interference and working memory capacity may reflect individual differences in resolving conflict, susceptibility to goal neglect, or both of these factors. We compared relationships between working memory capacity and three Stroop tasks: a classic, printed color-word Stroop task, a cross-modal Stroop, and a new version of cross-modal Stroop with a concurrent auditory monitoring component. Each of these tasks showed evidence of interference between the semantic meaning of the color word and the to-be-named color, suggesting these tasks each require resolution of interference. However, only Stroop interference in the print-based task with high proportions of congruent trials correlated significantly with working memory capacity. This evidence suggests that the relationships observed between Stroop interference and working memory capacity are primarily driven by individual differences in the propensity to actively maintain a goal.

Distraction by Auditory Novelty

The unexpected occurrence of an oddball auditory stimulus (novel) among an otherwise repeated stream of sounds (standards) is known to impact negatively on participants’ performance in an unrelated visual task. The present study sought to test new predictions emerging from Parmentier’s (2008) model of distraction by auditory novelty. Participants categorized the direction of visual arrows preceded by a task-irrelevant sound. Two time intervals between distractor and target were tested in separate blocks of trials. Rare auditory novels consisted of the words “left” or “right”, which were either congruent or incongruent with the upcoming target. The data confirmed the slowing of response in the face of a novel (novelty distraction) as well as, on incongruent trials, a further delay due to cross-talk interference between distractor and target (semantic effect). More importantly, and in line with our predictions, the results further showed that (1) the semantic effect, but not novelty distraction, increased with the time interval between distractor and target; and that (2) the production of a response on the first standard trial following a novel trial was slowed if that response required the activation of a recently inhibited network (post-novelty semantic effect). Overall, the data lend support to the view that behavioral distraction by auditory novelty reflects a mosaic of contributors, the effects of which can ripple across trials.

Audiovisual semantic interference and attention: evidence from the attentional blink paradigm

In the present study we investigate the role of attention in audiovisual semantic interference, by using an attentional blink paradigm. Participants were asked to make an unspeeded response to the identity of a visual target letter. This target letter was preceded at various SOAs by a synchronized audiovisual letter-pair, which was either congruent (e.g. hearing an "F" and viewing an "F") or incongruent (e.g. hearing an "F" and viewing a "Z"). In Experiment 1, participants were asked to match the members of the audiovisual letter-pair. In Experiment 2, participants were asked to ignore the synchronized audiovisual letter-pairs altogether and only report the visual target. In Experiment 3, participants were asked to identify only one of the audiovisual letters (identify the auditory letter, and ignore the synchronized visual letter, or vice versa). An attentional blink was found in all three experiments indicating that the audiovisual letter-pairs were processed. However, a congruency effect on subsequent target detection was observed in Experiments 1 and 3, but not in Experiment 2. The results indicate that attention to the semantic contents of at least one modality is necessary to establish audiovisual semantic interference.

Stroop Interference and Facilitation Effects in Kinesthetic and Haptic Tasks

Stroop interference and facilitation effects were documented in the visual, auditory, olfactory, and gustatory modalities. This study extends the Stroop phenomena also for kinesthetic and haptic tasks. In a touch-enabled computer interface, participants touched and manipulated virtual objects (cylinders, cubes, and tiles), through a pen-like stylus, and identified their haptic qualities (weight, firmness, vibrations). Similarly, participants were stimulated with a mechanical force pushing their hands lightly towards a specific direction which they had to identify. While performing these identification tasks, participants were simultaneously presented with words or symbols that were congruent, neutral, or incongruent with the experienced kinesthetic/haptic sensations. Error rates and response times were affected in the following order: congruent < neutral < incongruent. As technologies advance into multisensory systems, engineers and designers can improve human-computer interactions by ensuring optimal congruence between all the inter- and intra-sensory elements in the display.

The dog's meow: asymmetrical interaction in cross-modal object recognition

Little is known on cross-modal interaction in complex object recognition. The factors influencing this interaction were investigated using simultaneous presentation of pictures and vocalizations of animals. In separate blocks, the task was to identify either the visual or the auditory stimulus, ignoring the other modality. The pictures and the sounds were congruent (same animal), incongruent (different animals) or neutral (animal with meaningless stimulus). Performance in congruent trials was better than in incongruent trials, regardless of whether subjects attended the visual or the auditory stimuli, but the effect was larger in the latter case. This asymmetry persisted with addition of a long delay after the stimulus and before the response. Thus, the asymmetry cannot be explained by a lack of processing time for the auditory stimulus. However, the asymmetry was eliminated when low-contrast visual stimuli were used. These findings suggest that when visual stimulation is highly informative, it affects auditory recognition more than auditory stimulation affects visual recognition. Nevertheless, this modality dominance is not rigid; it is highly influenced by the quality of the presented information.

Towards a cognitive model of distraction by auditory novelty: the role of involuntary attention capture and semantic processing

Unexpected auditory stimuli are potent distractors, able to break through selective attention and disrupt performance in an unrelated visual task. This study examined the processing fate of novel sounds by examining the extent to which their semantic content is analyzed and whether the outcome of this processing can impact on subsequent behavior. This issue was investigated across five laboratory experiments in which participants categorized visual left and right arrows while instructed to ignore irrelevant sounds. The results showed that auditory novels that were incongruent with the visual target (e.g., word "left" presented before a right arrow) disrupted performance over and above congruent novels (semantic effect) while both types of novels delayed responses in the visual task compared to a standard sound (novelty effect). No semantic effect was observed for congruent and incongruent standards, suggesting that novelty detection is necessary for involuntary semantic processing to unravel. While the novelty effect augmented as the difference between novels and the standard increased, the semantic effect was immune to this variation. Furthermore, the novelty effect decreased across the task while the semantic effect did not. A general cognitive framework is proposed encompassing these new findings and previous work in an attempt to account for the behavioral impact of irrelevant auditory novels on primary task performance.

Effects of onset- and rhyme-related distractors on phonological processing in children with specific language impairment

PURPOSE

This study used the cross-modal picture-word interference task of P. J. Brooks and B. MacWhinney (2000) to compare effects of phonologically related words on lexical access in children with specific language impairment (SLI).

METHOD

Children (7;1 [years;months]-11;2) named pictures while ignoring auditory distractors. Three stimulus asynchrony conditions varied the timing of distractors relative to the pictures. Experiment 1 presented onset-related (bell-bed), unrelated (clown-bed), neutral (go-bed), and identical (bed-bed) distractors. Experiment 2 presented rhyme-related instead of onset-related distractors (clock-sock).

RESULTS

Children with SLI produced longer reaction times (RTs) and more errors than their typical language development (TLD) peers. For children with SLI, onset-related distractors led to slower RTs than unrelated distractors (inhibition) when presented before the picture, and faster RTs (facilitation) when presented after the picture. Children with TLD showed facilitation from onset-related distractors when presented after the picture but no inhibition when presented before the picture. Both groups failed to show facilitation from rhyme-related distractors.

CONCLUSIONS

The priming effects from onset-related distractors and lack of effects from rhyme-related distractors in SLI supports "just-in-time" incremental processing, similar to children with TLD. However, children with SLI experience phonological interference from members of a lexical cohort while accessing words. Results are discussed with respect to observed word finding and word learning difficulties in SLI.

From dichotic listening to the irrelevant sound effect: a behavioural and neuroimaging analysis of the processing of unattended speech

The assumption that ignoring irrelevant sound in a serial recall situation is identical to ignoring a non-target channel in dichotic listening is challenged. Dichotic listening is open to moderating effects of working memory capacity (Conway et al., 2001) whereas irrelevant sound effects (ISE) are not (Beaman, 2004). A right ear processing bias is apparent in dichotic listening, whereas the bias is to the left ear in the ISE (Hadlington et al., 2004). Positron emission tomography (PET) imaging data (Scott et al., 2004, submitted) show bilateral activation of the superior temporal gyrus (STG) in the presence of intelligible, but ignored, background speech and right hemisphere activation of the STG in the presence of unintelligible background speech. It is suggested that the right STG may be involved in the ISE and a particularly strong left ear effect might occur because of the contralateral connections in audition. It is further suggested that left STG activity is associated with dichotic listening effects and may be influenced by working memory span capacity. The relationship of this functional and neuroanatomical model to known neural correlates of working memory is considered.

Auditory short-term memory behaves like visual short-term memory

Are the information processing steps that support short-term sensory memory common to all the senses? Systematic, psychophysical comparison requires identical experimental paradigms and comparable stimuli, which can be challenging to obtain across modalities. Participants performed a recognition memory task with auditory and visual stimuli that were comparable in complexity and in their neural representations at early stages of cortical processing. The visual stimuli were static and moving Gaussian-windowed, oriented, sinusoidal gratings (Gabor patches); the auditory stimuli were broadband sounds whose frequency content varied sinusoidally over time (moving ripples). Parallel effects on recognition memory were seen for number of items to be remembered, retention interval, and serial position. Further, regardless of modality, predicting an item's recognizability requires taking account of (1) the probe's similarity to the remembered list items (summed similarity), and (2) the similarity between the items in memory (inter-item homogeneity). A model incorporating both these factors gives a good fit to recognition memory data for auditory as well as visual stimuli. In addition, we present the first demonstration of the orthogonality of summed similarity and inter-item homogeneity effects. These data imply that auditory and visual representations undergo very similar transformations while they are encoded and retrieved from memory.

Scope of attention, control of attention, and intelligence in children and adults

Recent experimentation has shown that cognitive aptitude measures are predicted by tests of the scope of an individual's attention or capacity in simple working memory tasks and also by the ability to control attention. However, these experiments do not indicate how separate or related the scope and control of attention are. An experiment with 52 children (10 to 11 years old) and 52 college students included measures of the scope and control of attention, as well as verbal and nonverbal aptitude measures. The children showed little evidence of using sophisticated attentional control, but the scope of attention predicted intelligence in that group. In adults, both the scope and control of attention varied among individuals and accounted for considerable individual variance in intelligence. About one third that variance was shared between scope an d control, and the rest was unique to one or the other. Scope and control of attention appear to be related but distinct contributors to intelligence.

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.

Coherence of the irrelevant-sound effect: individual profiles of short-term memory and susceptibility to task-irrelevant materials

We examined individual and developmental differences in the disruptive effects of irrelevant sounds on serial recall of printed lists. In Experiment 1, we examined adults (N = 205) receiving eight-item lists to be recalled. Although their susceptibility to disruption of recall by irrelevant sounds was only slightly related to memory span, regression analyses documented highly reliable individual differences in this susceptibility across speech and tone distractors, even with variance from span level removed. In Experiment 2, we examined adults (n = 64) and 8-year-old children (n = 63) receiving lists of a length equal to a predetermined span and one item shorter (span-1). We again found significant relationships between measures of span and susceptibility to irrelevant sounds, although in only two of the measures. We conclude that some of the cognitive processes helpful in performing a span task may not be beneficial in the presence of irrelevant sounds.

Contributions of response set and semantic relatedness to cross-modal Stroop-like picture–word interference in children and adults

Resistance to interference from irrelevant auditory stimuli undergoes development throughout childhood. To test whether semantic processes account for age-related changes in a Stroop-like picture-word interference effect, children (3- to 12-year-olds) and adults named pictures while listening to words varying in terms of semantic relatedness to the pictures and response set membership. In Experiments 1 and 2, with animal and clothing pictures, the interference effect observed in children, but not in adults, depended on the distractors' status as members of the response set. In Experiment 3, with unrelated pictures, adults, but not children, showed greater interference for trials with distractors in the response set. These results indicate developmental changes in picture-word interference involving the establishment of a response set in working memory.

Seeing or hearing? Perceptual independence, modality confusions, and crossmodal congruity effects with focused and divided attention

Observers were given brief presentations of pairs of simultaneous stimuli consisting of a visual and a spoken letter. In the visual focused-attention conditon, only the visual letter should be reported; in the auditory focused-attention condition, only the spoken letter should be reported; in the divided-attention condition, both letters, as well as their respective modalities, should be reported (forced choice). The proportions of correct reports were nearly the same in the three conditions (no significant divided-attention decrement), and in the divided-attention condition, the probability that the visual letter was correctly reported was independent of whether the auditory letter was correctly reported. However, with a probability much higher than chance, the observers reported hearing the visual stimulus letter or seeing the spoken stimulus letter (modality confusions). The strength of the effect was nearly the same with focused as with divided attention. We also discovered a crossmodal congruity effect: Performance was better when the two letters in a stimulus pair were the same than when they differed in type.

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.

Why do non-color words interfere with color naming?

In the non-color-word Stroop task, university students' response latencies were longer for low-frequency than for higher frequency target words. Visual identity primes facilitated color naming in groups reading the prime silently or processing it semantically (Experiment 1) but did not when participants generated a rhyme of the prime (Experiment 3). With auditory identity primes, generating an associate or a rhyme of the prime produced interference (Experiments 2 and 3). Color-naming latencies were longer for nonwords than for words (Experiment 4). There was a small long-term repetition benefit in color naming for low-frequency words that had been presented in the lexical decision task (Experiment 5). Facilitation of word recognition speeds color naming except when phonological activation of the base word increases response competition.

Cross-modal selective attention: on the difficulty of ignoring sounds at the locus of visual attention

In three experiments, we investigated whether the ease with which distracting sounds can be ignored depends on their distance from fixation and from attended visual events. In the first experiment, participants shadowed an auditory stream of words presented behind their heads, while simultaneously fixating visual lip-read information consistent with the relevant auditory stream, or meaningless "chewing" lip movements. An irrelevant auditory stream of words, which participants had to ignore, was presented either from the same side as the fixated visual stream or from the opposite side. Selective shadowing was less accurate in the former condition, implying that distracting sounds are harder to ignore when fixated. Furthermore, the impairment when fixating toward distractor sounds was greater when speaking lips were fixated than when chewing lips were fixated, suggesting that people find it particularly difficult to ignore sounds at locations that are actively attended for visual lipreading rather than merely passively fixated. Experiments 2 and 3 tested whether these results are specific to cross-modal links in speech perception by replacing the visual lip movements with a rapidly changing stream of meaningless visual shapes. The auditory task was again shadowing, but the active visual task was now monitoring for a specific visual shape at one location. A decrement in shadowing was again observed when participants passively fixated toward the irrelevant auditory stream. This decrement was larger when participants performed a difficult active visual task there versus fixating, but not for a less demanding visual task versus fixation. The implications for cross-modal links in spatial attention are discussed.