The perception of number from the separability of the stimulus: The Stroop effect revisited

The literature on numerical perception is reviewed from the standpoint of research on selective attention, and predictions are made concerning the dimensional interaction between physical and numerical size of numerals. We manipulated stimulus differences to make the classification of numerical value slightly better (Experiment 1), substantially better (Experiment 2), or worse (Experiments 3–4) than classification of physical size. Garner, Stroop, and redundancy effects were used to gauge the degree of interactive processing. For nearly matched discriminability, both number and size appeared separable when the dimensions were varied orthogonally, but showed Stroop interference and redundancy gain when the dimensions were varied in a correlative fashion. When mismatched, asymmetric Garner and Stroop effects emerged in orthogonal contexts along with Stroop and redundancy gains in correlative contexts. These findings define a unique relation: Numerical value and physical size were optionally separable dimensions. We conclude that a magnitude representation is not mandatory for the perception of numerals. Our conclusions offer a new perspective for understanding both numerical perception and the Stroop phenomenon itself.     

The stroop effect: It is not the robust phenomenon that you have thought it to be

Five experiments demonstrate that context has a powerful effect on the ease with which people can name (Experiments 1-3) or categorize (Experiments 4-5) a stimulus while ignoring another stimulus, irrelevant or conflicting with the target. Selectivity of attention to the target dimension was gauged through Stroop and Garner effects. When the stimulus values along the target dimension and the to-be-ignored dimension were correlated over the experimental trials, large effects of Stroop and Garner influenced performance. However, when random allocation of values created zero dimensional correlation, the Stroop effects vanished. These results imply that when the nominally irrelevant dimension is in fact correlated with the relevant dimension, participants then attend to the irrelevant dimension and thus open themselves up to Stroop interference. Another variable of context, the relative salience of the constituent dimensions, also affected performance with the more discriminable dimension disrupting selective attention to the less discriminable dimension. The results demonstrate the importance of context in engendering the failure of selective attention and challenge traditional automaticity accounts of the Stroop effect.     

Does intermodal equivalence exist between heteromodal stimulus dimensions or between stimulus values on those dimensions?

In a same--different judgement task with successively presented signals, subjects matched dots in different vertical positions and tones of different frequencies intramodally and intermodally. The first and second stimuli of trials in each of the four modality conditions were drawn from a set consisting of two, three or five alternatives. In all intermodal set size conditions, the dimensions of pitch and vertical position were related by the same equivalence rule. While intramodal performance improvement depended only on the total number of practice trials at matching on the relevant dimensions, intermodal performance improvement appeared to be related to the number of trials practice with each heteromodal stimulus pairing in a particular set. After performance had approached asymptotic level neither intramodal nor intermodal matching reaction time depended on set size. Mean “same” reaction time was less than mean “different” reaction time, and this difference was greater for intermodal matching than for intramodal matching. The results indicated that intermodal equivalence exists between discrete stimulus values on heteromodal dimensions rather than between the dimensons themselves.     

Effects of context in judgments of sweetness and pleasantness

Dramatic effects of the immediate stimulus context were demonstrated for ratings of sweetness and also for ratings of pleasantness of soft drinks containing different concentrations of sucrose. The same drinks were rated sweeter when the lower concentrations were presented more frequently, less sweet when the higher concentrations were presented more frequently. A quasi-normal distribution of frequencies yielded ratings falling between the two skewed distributions. Ratings of sweetness were accurately predicted by Parducci’s (1974) range-frequency model of judgment, which was originally developed to explain contextual effects in other psychophysical dimensions. Ratings of pleasantness were also affected by context; the highest ratings were assigned to concentrations of intermediate sweetness in their respective contexts.     

Driven by information: a tectonic theory of Stroop effects

The goal of avoiding distraction (e.g., ignoring words when naming their print colors in a Stroop task) is opposed intrinsically by the penchant to process conspicuous and correlated characteristics of the environment (e.g., noticing trial-to-trial associations between the colors and the words). To reconcile these opposing forces, the authors propose a tectonic theory of selective attention in which 2 memory-based structures--dimensional imbalance and dimensional uncertainty--drive selection by processing salient, surprising, and/or correlated information contained within and across stimulus dimensions. Each structure modulates the buildup of excitation to targets and the buildup of inhibition to distractors and to memories of previous stimuli. Tectonic theory is implemented to simulate the impact of 4 types of context on the presence, magnitude, and direction of congruity effects and task effects in the Stroop paradigm. The tectonic model is shown to surpass other formal models in explaining the range and diversity of Sroop effects.     

Working-memory capacity and the control of attention: the contributions of goal neglect,response competition,and task set to Stroop interference

Individual differences in working-memory (WM) capacity predicted performance on the Stroop task in 5 experiments, indicating the importance of executive control and goal maintenance to selective attention. When the Stroop task encouraged goal neglect by including large numbers of congruent trials (RED presented in red), low WM individuals committed more errors than did high WM individuals on the rare incongruent trials (BLUE in red) that required maintaining access to the "ignore-the-word" goal for accurate responding. In contrast, in tasks with no or few congruent trials, or in high-congruency tasks that followed low-congruency tasks, WM predicted response-time interference. WM was related to latency, not accuracy, in contexts that reinforced the task goal and so minimized the difficulty of actively maintaining it. The data and a literature review suggest that Stroop interference is jointly determined by 2 mechanisms, goal maintenance and competition resolution, and that the dominance of each depends on WM capacity, as well as the task set induced by current and previous contexts.     

Range and regression, loudness scales, and loudness processing: toward a context-bound psychophysics

How does context affect basic processes of sensory integration and the implicit psychophysical scales that underlie those processes? Five experiments examined how stimulus range and response regression determine characteristics of (a) psychophysical scales for loudness and (b) 3 kinds of intensity summation: binaural loudness summation, summation of loudness between tones widely spaced in frequency, and temporal loudness summation. Context affected the overt loudness scales in that smaller power-function exponents characterized larger versus smaller range of stimulation and characterized magnitude estimation versus magnitude production. More important, however, context simultaneously affected the degree of loudness integration as measured in terms of matching stimulus levels. Thus, stimulus range and scaling procedure influence not only overt response scales, but measures of underlying intensity processing.     

Context-specific learning and control: the roles of awareness, task relevance, and relative salience

The processes mediating dynamic and flexible responding to rapidly changing task-environments are not well understood. In the present research we employ a Stroop procedure to clarify the contribution of context-sensitive control processes to online performance. In prior work Stroop interference varied as a function of probe location context, with larger Stroop interference occurring for contexts associated with a high proportion of congruent items [Crump, M. J., Gong, Z., & Milliken, B. (2006). The context-specific proportion congruent stroop effect: location as a contextual cue. Psychonomic Bulletin &Review, 13, 316-321.] Here, we demonstrate that this effect does not depend on awareness of the context manipulation, but that it can depend on attention to the predictive context dimension, and on the relative salience of the target and predictive context dimensions. We discuss the implications of our results for current theories of cognitive control.     

Nonconcurrently presented auditory tones reduce distraction

Recent research has demonstrated that task-irrelevant stimuli presented simultaneously with a target-distractor stimulus reduce distraction and improve selective attention. In studies examining this reduced interference effect, visual selective attention tasks and concurrently presented task-irrelevant stimuli are used. We report first evidence for a similar effect in the auditory domain and with nonconcurrent stimuli (i.e., the task-irrelevant stimuli are presented before the target). The effect of nonconcurrently presented auditory tones on an auditory Stroop task developed by Leboe and Mondor (Psychological Research, 71, 568--575, 2007) was investigated. Stroop interference was reduced when task-irrelevant tones were presented before the Stroop stimulus. We conclude that task-irrelevant stimuli can improve selective attention not only when presented concurrently, but also when presented before the selective attention task. Our results are consistent with the hypothesis that interference reduction is due to perceptual dilution caused by task-irrelevant stimuli.     

Information processing in chronic pain disorder: A preliminary analysis

Researchers have alternately suggested selective attention, impaired stimulus filtering, and affective language deficiency models as accounting for multiple somatic complaints in persons with chronic pain disorder. The purpose of the present study was to establish the comparative usefulness of these three models for explaining somatic focus in a chronic pain population. Nine chronic pain patients evidencing high somatic focus (somatizing chronic pain patients), 10 chronic pain patients evidencing low somatic focus (nonsomatizing chronic pain patients), and 10 healthy control subjects were administered a computerized version of the emotional Stroop test as a test of these models. A total of 105 pain-, depression-, and neutral-content words were used as Stroop test stimuli. Stroop test color-naming response latencies were submitted to a two-way Group × Word Type mixed-model ANOVA, with Word Type as the repeated measure. Results reveal that neither the selective attention model nor the affective language deficiency model adequately explain Stroop test performance in somatizing chronic pain patients. Findings provide tentative support for the impaired stimulus filtering model, with somatizing chronic pain patients evidencing similar Stroop test response delays across all words. These results suggest that chronic pain sufferers misinterpret bodily sensations. Findings are discussed in terms of a bilevel approach for treatment of somatizing chronic pain patients that would include assisting the patient in accurate appraisal and interpretation of physical symptoms.     

Contextual influences on the sequential congruency effect

The sequential congruency effect (SCE) refers to the reduction in the size of the congruency effect following incongruent, relative to congruent, trials. Prior evidence indicated that the SCE does not generalize across tasks or different conflict-producing feature dimensions. We present results from a Stroop task showing that when the local list context is such that all colors and words appear in the same proportion of congruent trials, the SCE is present, but when those same items vary in the proportions congruent, the SCE is absent. We suggest that if stimuli are sufficiently consistent in the informativeness of their dimensions for the responses, individuals will attempt to track such information and weight the dimensions accordingly. In this way, the SCE reflects sequential adjustments to the weights given to individual stimulus dimensions in an attempt to track this information.     

Modeling geometric–optical illusions: A variational approach

Visual distortions of perceived lengths, angles, or forms, are generally known as “geometric–optical illusions” (goi). In the present paper we focus on a class of gois where the distortion of a straight line segment (the “target” stimulus) is induced by an array of non-intersecting curvilinear elements (“context” stimulus). Assuming local target–context interactions in a vector field representation of the context, we propose to model the perceptual distortion of the target as the solution to a minimization problem in the calculus of variations. We discuss properties of the solutions and reproduction of the respective form of the perceptual distortion for several types of contexts. Moreover, we draw a connection between the interactionist model of gois and Riemannian geometry: the context stimulus is understood as perturbing the geometry of the visual field from which the illusory distortion naturally arises. The approach is illustrated by data from a psychophysical experiment with nine subjects and six different contexts.     

Automatic access of the meanings of ambiguous words in context: Some limitations of knowledge-based processing

Five experiments are described on the processing of ambiguous words in sentences. Two classes of ambiguous words (noun-noun and noun-verb) and two types of context (priming and nonpriming) were investigated using a variable stimulus onset asynchrony (SOA) priming paradigm. Noun-noun ambiguities have two semantically unrelated readings that are nouns (e.g., PEN, ORGAN); noun-verb ambiguities have both noun and verb readings that are unrelated (e.g., TIRE, WATCH). Priming contexts contain a word highly semantically or associatively related to one meaning of the ambiguous word; nonpriming contexts favor one meaning of the word through other types of information (e.g., syntactic or pragmatic). In nonpriming contexts, subjects consistently access multiple meanings of words and select one reading within 200 msec. Lexical priming differentially affects the processing of subsequent noun-noun and noun-verb ambiguities, yielding selective access of meaning only in the former case. The results suggest that meaning access is an automatic process which is unaffected by knowledge-based (“top-down”) processing. Whether selective or multiple access of meaning is observed largely depends on the structure of the ambiguous word, not the nature of the context.     

Computerized stroop test to assess selective attention in children with attention deficit hyperactivity disorder

Research shows abnormal function of the pre-frontal cortex in Attention Deficit Hyperactivity Disorder (ADHD). This cortex is involved in the control of executive functions related to planning and execution of goal-oriented strategies, working memory, inhibitions, cognitive flexibility, and selective attention. Selective attention involves focus on the target stimulus, ignoring competing distractions. The Stroop Test (Stroop, 1935) is usually used to evaluate selective attention. This study investigated whether children with ADHD could exhibit modified performance in the Stroop Test. Using a computerized version of this test (Capovilla, Montiel, Macedo, & Charin, 2005), the study compared the reaction times (RTs) of 62 Brazilian children, between 8 and 12 years of age, 31 of whom were diagnosed with ADHD and sent to psychiatric clinics, and 31 without ADHD studying in regular schools. All children with ADHD satisfied the criteria of the DSM-IV-TR and were evaluated with the Conners Abbreviated Questionnaire (Goyette, Conners, & Ulrich, 1978), completed by parents and teachers. The results revealed that children with ADHD exhibit greater interference in RT than children without ADHD. This corroborated the hypothesis that children with ADHD exhibit a deficit in selective attention, consisting in augmented RTs, as measured by the Computerized Stroop Test.     

A functional model to localize the conflict underlying the stroop phenomenon

Summary A new functional response competition model to describe the cognitive processes underlying the Stroop phenomenon is proposed. The main challenge for any explanation is the asymmetry of the conflict, i.e. the fact that the meaning of the color word disturbs naming the color of an incongruent color-word-color stimulus far more than the irrelevant color disturbs reading the word. The model proposes that the organism processes both competing verbal responses by priming the relevant set and inhibiting the irrelevant set if both responses belong to different sets, and by computing internal delay-time differences if both responses belong to the same set. The model explains most of the existing data about the Stroop phenomenon and is in full accordance with present knowledge on selective attention, stimulus encoding, response selection, and psychological refractory period. It is confirmed by data of a Stroop experiment using a set of verbal color responses disjoint from the set of the stimulus color words. This experiment is based on the strategy often used in Stroop research to try to obtain a reversed Stroop effect in order to find an explanation of the Stroop effect. The data show full symmetry of competition, that is a Stroop effect and a reversed Stroop effect of about the same amount of increased reaction time.This paper is based on an experimental study conducted by Dipl.-Psych. Margrit O. Dolt under the supervision of Dr. W.R. Glaser and submitted as Diplomarbeit.     

刺激呈现时间对汉字语义加工脑偏侧化的影响

以往关于汉字字词识别脑功能偏侧化的研究发现了左半球优势、右半球优势或者大脑两半球均势三种不同的结果。该研究采用一侧化Stroop范式(刺激分别只呈现于左视野、中央视野或右视野中),通过系统地改变刺激呈现时间以期探讨刺激呈现时间是可以解释这些不一致结果的可能因素之一。结果显示:对于右利手被试,在刺激呈现时间为60 ms时右半球出现了较强的Stroop效应,在刺激呈现200 ms时左右半球的Stroop效应没有表现出差异,在刺激呈现时间较长时左半球表现出较强的Stroop效应。该结果提示,随着刺激呈现时间的延长,语义优势发生了从右半球到左半球的转换。     

Age differences in stroop-like interference as a function of semantic relatedness

Abstract

The disinhibition hypothesis advanced by Hasher and Zacks (1988) predicts a faulty inhibitory mechanism resulting in “increased breadth of activation of nongoal path ideas” with aging (p. 213, Fig. 1). to assess this prediction, we tested young and older adults with a modified Stroop paradigm in which the semantic relationship between the words and ink colors was varied. Items were presented in five conditions: Stroop words (BLUE), related color words (NAVY), related words (SKY), neutral words (REFER), and asterisks (???). We found an age difference in interference for the Stroop words only; that is, when the response set was the same as the stimulus set, older adults' color-naming performance was jeopardized. In contrast, young and older adults did not differ in proportional slowing when related colors, related words, neutral words, or asterisks were presented. the findings are discussed in terms of three explanations: (a) a developmental dissociation between response suppression and semantic suppression; (b) weaker semantic activation; and (c) the effect of paradigm differences.     

What kind of attention modulates the Stroop effect?

An intersection of three literatures (skilled word recognition, spatial attention, and the Stroop effect) is addressed in a series of four experiments. The results, in conjunction with other observations, are taken to suggest that (1) thedefault value for spatial attention in visual word recognition is distributed across the word, (2) precuing a single letter position serves to narrow the focus of spatial attention, and (3) this reduces or prevents activation in the word recognition system. Consequently, the Stroop effect is reduced in magnitude or eliminated, depending on details of the context. Contrary to the widespread view that it reflects automatic processing, the Stroop effect is better conceptualized as reflecting the action of default settings in the word recognition and attentional systems. Some relations between consciousness, context, and control are noted.     

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.     

Effects of exposure to psychophysical scaling on lingual vibrotactile magnitude estimation and magnitude production

The purpose of the present study was to determine if the results obtained by the scaling methods of magnitude estimation and magnitude production could be influenced by providing subjects with prior exposure to psychophysical scaling in the form of magnitude estimation or magnitude production. Group 1 (n = 10, Mage = 21.1 yr.) performed lingual vibrotactile-magnitude estimation followed by lingual vibrotactile magnitude production. Group 2 (n = 10, Mage = 19.7 yr.) performed lingual vibrotactile-magnitude production (using the magnitude-estimation responses provided by Group 1), followed by lingual vibrotactile-magnitude estimation. For the magnitude estimations there was no over-all statistically significant difference between the two groups, but there was for the magnitude-production values. Magnitude-estimation scaling was apparently not influenced by prior exposure to magnitude production, while magnitude-production scaling was influenced by prior exposure to magnitude estimation. The results are discussed in terms of how subjective scaling behavior in psychophysical experimentation may be influenced by the interaction between an absolute internal scaling mechanism and parameters set by the experimenter, such as scaling method and range of stimulus intensity.