Selective attention and priming: Inhibitory and facilitatory effects of ignored primes

The priming effects of ignored information have been studied in Stroop displays (Neill, 1977) and with spatially superimposed drawings (Tipper, in this issue); naming of probes related to ignored primes is delayed in these experiments (“negative priming”). This negative priming effect is confirmed in a list reading task in Experiment 1, which used partially superimposed letters, and Experiment 2, which used spatially separated letters. Furthermore, Lowe (1979) using Stroop colour words observed that changing the nature of the probe such that it did not require selection from a competing word reversed the priming effects of the ignored word from inhibition to facilitation. Experiment 3 confirmed this observation when subjects selected a red letter from a green letter. Two models are suggested to account for this result. In the first, negative priming is a product of the ignored prime and subsequent probe being encoded both as a stimulus to be ignored and one to be named (Allport, Tipper and Chmiel, in press; Lowe, in press). This dual encoding is ambiguous, requiring further processing before response can be output. The other model suggests that negative priming reflects inhibition of response to ignored information, slowing naming latencies to probe stimuli that require the same response. Experiment 4 attempts to differentiate between the models, and the latter inhibition view is preferred.     

Effects of stimulus-stimulus compatibility and stimulus-response compatibility on response inhibition

Previous studies demonstrated that interference control in stimulus–stimulus compatibility tasks slowed down stopping in the stop signal task (e.g., Kramer, A. F., Humphrey, D. G., Larish, J. F., Logan, G. D., & Strayer, D. L. (1994). Aging and inhibition: beyond a unitary view of inhibitory processing in attention. psychology and aging, 9, 491–512). In the present study, the impact of stimulus–stimulus compatibility and stimulus–response compatibility on response inhibition is further investigated. In Experiment 1, the stop signal task was combined with a traditional horizontal Simon task and with a vertical variant. For both dimensions, stopping responses was prolonged in incompatible trials, but only when the previous trial was compatible. In Experiment 2, the Simon task was combined with a spatial Stroop task in order to compare the effects of stimulus–stimulus and stimulus–response compatibility. The results demonstrated that both types of compatibility influenced stopping in a similar way. These findings are in favor of the hypothesis that response inhibition in the stop signal task and interference control in conflict tasks rely on similar mechanisms.     

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.     

Articulatory duration in single-word speech production

Three different speech production paradigms assessed C. T. Kello, D. C. Plaut, and B. MacWhinney's (2000) claim that the characteristics of speech production flexibly vary between staged and cascaded modes depending on task demand. All experiments measured response latencies and durations of single words without and with a response deadline. Experiment 1 used a picture-word interference task; Experiment 2 blocked pictures either by semantic category or by word-initial overlap; and Experiment 3 used a Stroop paradigm. In all cases, systematic effects of semantic and form relatedness were obtained on latencies but not on response durations. These results support the assumption that articulation, as assessed by response duration, is never influenced by central cognitive processes once a response has been initiated.     

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.     

Identity primes produce facilitation in a colour naming task

Five experiments examined associative or identity priming effects in a colour-naming task with colour-neutral words. In Experiment 1, subjects instructed to read the prime silently showed no associative priming effect but a colour-naming facilitation with identity priming. In Experiment 2, the typical associative priming interference in colour naming was demonstrated in subjects recalling the prime word, but not in subjects reading the prime silently, whereas associative primes facilitated word naming regardless of the prime response requirement. The remaining studies investigated the colour-naming facilitation observed with identity primes. Experiment 3 showed no effects on the facilitation of colour naming from varying the letter case of a silently read prime. Experiment 4 showed facilitation when subjects recalled the prime, and a target frequency effect, with faster colour-naming latencies for high- and medium- than low-frequency targets. In Experiment 5, there was no facilitation for naming the colour of target words paired with non-word primes differing in their initial letter from the target. Taken together, the results suggest that the facilitation of colour naming following identical primes reflects faster target word recognition, whereas the associative priming interference reflects an attentional effect.     

The effect of cognitive load on saccadic eye movements

The present study tested the hypothesis that, unlike prosaccades, antisaccades require controlled processing, due to the prepotent response that needs to be inhibited. The effect of the Random time Interval Generation (RIG) task (Vandierendonck, A., De Vooght, G., & Van der Goten, K. (1998). European Journal of Cognitive Psychology, 10, 413-444) on these saccade latencies and errors was studied. This task has the advantage that it loads executive processes, with only minimal interference with verbal or visuo-spatial components. A first experiment compared saccade performance within the prosaccade and the antisaccade task, executed alone and in combination with the RIG task and fixed tapping (added to exclude possible motor component interference explanations). A second experiment investigated the influence of task characteristics on the effects found. Although it was shown that antisaccades are more prone to interference of an executive interference task, it seems that prosaccades are also vulnerable. Interference on prosaccades could originate from a controlled execution of these saccades. A third experiment confirmed that endogenously generated prosaccades are susceptible to dual-task interference and showed that controlled saccade execution, without the need to inhibit a prepotent response, is sufficient to produce interference.     

Red-hot: How colour and semantic temperature processing interact in a Stroop-like paradigm

Temperature concepts and colour are commonly associated (i.e., red is “hot” and blue is “cold”), although their direction of influence (unidirectional, bidirectional) is unknown. Semantic Stroop effects, whereby words like fire influence colour categorization, suggest automatic semantic processing influences colour processing. The experiential framework of language comprehension indicates abstract concepts like temperature words simulate concrete experiences in their representation, where expressions like “red-hot” suggest colour processing influences conceptual processing. Participants categorized both colour (Experiment 1: red, blue; Experiment 2: red, green, blue) and word-meaning with matched lists of hot and cold meaning words in each colour. In Experiments 1 and 2, semantic categorization showed congruency effects across hot and cold words, while colour categorization showed facilitation only with hot words in Experiment 2. This asymmetry reflects a more consistent influence of colour categorization on semantic categorization than the reverse, suggesting experiential grounding effects may be more robust than the effects of semantic processing on colour processing.     

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.     

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

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

冲突观察能诱发冲突适应

重复启动效应和一致试次所占的比例都会影响冲突适应效应。采用词-色Stroop任务, 本研究在控制了重复启动效应和一致试次的比例之后, 通过三个实验共同探讨反应执行和冲突观察对冲突适应效应的影响。实验一发现当前试次的Stroop干扰效应, 但没有得到冲突适应效应; 在实验二中, 先前试次为四选一的选择反应时任务, 当前试次为词-色Stroop任务, 得到反转的冲突适应效应; 实验三和实验一程序相似, 但在先前试次上不执行反应, 得到了稳定的冲突适应效应。这些结果证明, 冲突观察能够诱发冲突适应机制, 提升当前的操作表现。     

Stroop interference is a composite phenomenon: Evidence from distinct developmental trajectories of its components

Only one previous developmental study of Stroop task performance (Schiller, 1966) has controlled for differences in processing speed that exist both within and between age groups. Therefore, the question of whether the early developmental change in the magnitude of Stroop interference actually persists after controlling for processing speed needs further investigation; work that is further motivated by the possibility that any remaining differences would be caused by process(es) other than processing speed. Analysis of data from two experiments revealed that, even after controlling for processing speed using z‐transformed reaction times, early developmental change persists such that the magnitude of overall Stroop interference is larger in 3rd‐ and 5th graders as compared to 1st graders. This pattern indicates that the magnitude of overall Stroop interference peaks after 2 or 3 years of reading practice (Schadler & Thissen, 1981). Furthermore, this peak is shown to be due to distinct components of Stroop interference (resulting from specific conflicts) progressively falling into place. Experiment 2 revealed that the change in the magnitude of Stroop interference specifically results from joint contributions of task, semantic and response conflicts in 3rd‐ and 5th graders as compared to a sole contribution of task conflict in 1st graders. The specific developmental trajectories of different conflicts presented in the present work provide unique evidence for multiple loci of Stroop interference in the processing stream (respectively task, semantic and response conflict) as opposed to a single (i.e. response) locus predicted by historically – favored response competition accounts.     

The specificity of the Stroop interference score of errors to ADHD in boys

The Stroop Interference Test is widely used to assess the inhibition function; however, divergent results have emerged from meta-analyses in children with ADHD. This has led to conflicting results as to whether the Stroop test detects the level of inhibition in these children. We hypothesized that the general approach to include interference scores depending on response time causes conflicting results, whereas recordings of errors may prove a superior measure of the inhibition function in children with ADHD. In the present study, 39 children with an ADHD diagnosis, two subgroups with and without another comorbid mental health disorder, were compared with respect to their interference scores of response time and errors with two subgroups of children with no ADHD. The two subgroups comprised 33 children with another mental health disorder other than ADHD and 56 children with no psychiatric disorder. The between-group analyses detected a multivariate, marginal main effect of an ADHD diagnosis on the Stroop interference scores, and a univariate main effect of an ADHD diagnosis on the interference score of errors. Further, only the interference score of errors predicted significantly the parent reported scores on the Inhibit scale from the Behavior Rating Inventory of Executive Function. These findings support that a Stroop interference score of errors is sensitive for inhibition problems in children with ADHD and encourages the use of Stroop versions including error recordings independent of response time.     

Control over the time course of cognition in the tempo-naming task

Five experiments are reported in which standard naming and tempo-naming tasks were used to investigate mechanisms of control over the time course of lexical processing. The time course of processing was manipulated by asking participants to time their responses with an audiovisual metronome. As the tempo of the metronome increased, results showed that (a) the rate of lexical errors increased, whereas the rate of regularization errors remained constant; (b) onset errors increased at a faster rate than body errors; (c) stimulus effects weakened on latencies, whereas they strengthened on durations and errors; and (d) naming durations decreased more slowly when stimuli were presented prior to the response cue. These results constitute evidence that time pressure in the tempo-naming task caused a compression in the time course of lexical processing. Compression is discussed in terms of threshold mechanisms and rate mechanisms of control.     

Attentional strategic control over nonlexical and lexical processing in written spelling to dictation in adults

We conducted four experiments to investigate whether adults can exert attentional strategic control over nonlexical and lexical processing in written spelling to dictation. In Experiment 1, regular and irregular words were produced either in a nonword context (regular and irregular nonwords) or in a word context (high-frequency regular and irregular words), whereas in Experiment 2, the same set of words was produced either in a regular nonword or in an irregular low-frequency word context. Experiment 3 was a replication of Experiment 2 but with increased manipulation of the context. In Experiment 4, participants had to produce either under time pressure or in response to standard written spelling instructions. Regularity effects were found in all the experiments, but their size was not reliably affected by manipulations intended to increase or decrease reliance on nonlexical processing. More particularly, the results from Experiment 4 show that adults can speed up the initialization of their writing responses to a substantial degree without altering regularity effects on either latencies or spelling errors. Our findings suggest that, although adults are able to generate an internal deadline criterion of when to initialize the writing responses, nonlexical processing is a mandatory process that is not subject to attentional strategic control in written spelling to dictation.     

Age differences in Stroop interference: contributions of general slowing and task-specific deficits

This study examined the contributions of general slowing and task-specific deficits to age-related changes in Stroop interference. Nine hundred thirty-eight participants aged 20 to 89 years completed an abbreviated Stroop color-naming task and a subset of 281 participants also completed card-sorting, simple reaction time, and choice reaction time tasks. Age-related increases in incongruent color-naming latency and card-sorting perseverative errors were observed. Hierarchical regression analyses showed that the processing speed measures accounted for significant variance on both dependent measures, but that there was also a significant residual effect of age. An additional regression analysis showed that some of the variance in incongruent color-naming, after controlling for processing speed, was shared with the variance in perseverative errors. Overall, findings suggest that the age difference in Stroop interference is partially attributable to general slowing, but is also attributable to age-related changes in task-specific processes such as inhibitory control.     

About the unidirectionality of interference: Insight from the musical Stroop effect

The asymmetry of interference in a Stroop task usually refers to the well-documented result that incongruent colour words slow colour naming (Stroop effect) but incongruent colours do not slow colour word reading (no reverse Stroop effect). A few other studies have suggested that, more generally, a reverse Stroop effect can be occasionally observed but at the expense of the Stroop effect itself, as if interference was inherently unidirectional, from the stronger to the weaker of the two competing processes. We describe here a situation conducive to a pervasive mutual interference effect. Musicians were exposed to congruent and incongruent note name/note position patterns, and they were asked either to read the word while ignoring the location of the note within the staff, or to name the note while ignoring the note name written inside the note picture. Most of the participants exhibited interference in the two tasks. Overall, this result pattern runs against the still prevalent model of the Stroop phenomenon [Cohen, J. D., Dunbar, K., & McClelland, J. L. (1990). On the control of automatic processes: A parallel distributed processing account of the Stroop effect. Psychological Review, 97(3), 332–361]. However, further analyses lend support to one of the key tenets of the model, namely that the pattern of interference depends on the relative strength of the two competing pathways. The reasons for the impressive differences between the results collected in the present study and in the standard colour–word (or picture–word) paradigms are also examined. We suggest that these differences reveal the importance of stimulus–response contingency in the formation of automatisms.     

The impact of threat and cognitive stress on speech motor control in people who stutter

PurposeIn the present study, an Emotional Stroop and Classical Stroop task were used to separate the effect of threat content and cognitive stress from the phonetic features of words on motor preparation and execution processes.MethodA group of 10 people who stutter (PWS) and 10 matched people who do not stutter (PNS) repeated colour names for threat content words and neutral words, as well as for traditional Stroop stimuli. Data collection included speech acoustics and movement data from upper lip and lower lip using 3D EMA.ResultsPWS in both tasks were slower to respond and showed smaller upper lip movement ranges than PNS. For the Emotional Stroop task only, PWS were found to show larger inter-lip phase differences compared to PNS. General threat words were executed with faster lower lip movements (larger range and shorter duration) in both groups, but only PWS showed a change in upper lip movements. For stutter specific threat words, both groups showed a more variable lip coordination pattern, but only PWS showed a delay in reaction time compared to neutral words. Individual stuttered words showed no effects. Both groups showed a classical Stroop interference effect in reaction time but no changes in motor variables.ConclusionThis study shows differential motor responses in PWS compared to controls for specific threat words. Cognitive stress was not found to affect stuttering individuals differently than controls or that its impact spreads to motor execution processes.Educational objectives: After reading this article, the reader will be able to: (1) discuss the importance of understanding how threat content influences speech motor control in people who stutter and non-stuttering speakers; (2) discuss the need to use tasks like the Emotional Stroop and Regular Stroop to separate phonetic (word-bound) based impact on fluency from other factors in people who stutter; and (3) describe the role of anxiety and cognitive stress on speech motor processes.     

An investigation into some of the underlying associative verbal processes of the stroop colour effect

The Stroop test was examined to throw some light on the verbal basis of the test. When words are presented printed in the wrong colour it is found that the written word provides more interference with response to the colour of print than occurs the other way round (the Stroop effect). It was shown that, by allowing subjects to match the colour of the print with colour patches instead of words, the interference due to the written word can be considerably reduced. In a further experiment, associations were formed by the subjects between nonsense syllables and colours in the course of a paired-associate learning task. When nonsense syllables were presented printed in colours different from those associated with them, it was found that the interference effects depended upon the direction of the stimulus-response association in the paired-associate experiment. It is concluded that the underlying processes in the Stroop effect are primarily verbal and depend partly upon the directionality of previously established verbal associations.     

Seeking the source of emotional Stroop interference effects in PTSD: A study of P3s to traumatic words

We investigated the source of emotional Stroop interference effects in posttraumatic stress disorder (PTSD) by measuring reaction times and P3 latencies and amplitudes to personal traumatic, personal positive, and neutral words in a modified Stroop paradigm. Individuals with PTSD were slower to indicate word color, especially for traumatic words, thereby replicating emotional Stroop interference in PTSD. Individuals with PTSD also had significantly reduced and delayed P3 components across word types. Across diagnostic groups, frontal P3 amplitudes were larger to personal positive and traumatic words compared to standard neutral words. However, the absence of Diagnosis x Word Type interactions for P3 measures suggests that individuals with PTSD do not differ from individuals without PTSD in the encoding and recognition of the color of traumatic relative to nontraumatic words, and that Stroop interference does not occur during these early stages of processing.