Conceptual response distance and intervening keys distinguish action goals in the Stroop color-identification task

In previous studies, a physical response-distance effect was found in the two-choice Stroop color-identification task, with the Stroop effect being larger when the two response keys were physically close together than when they were far apart. In the present study, we found a conceptual response-distance effect, with the Stroop effect being larger when the response keys were conceptually close (labeled as “5” and “6”) than when they were conceptually far (labeled as “1” and “9”). Moreover, a response-distance effect due to pure physical distance was not evident; rather, the effect was found only when additional keys were placed between the two far response keys. These results are in agreement with a view that response keys are coded as action goals, with farther conceptual distance and additional keys helping distinguish the action goals. The results are difficult to reconcile with accounts that place emphasis on the physical separation of the effectors or their inanimate extensions.     

Dissociating stimulus-stimulus and response-response effects in the Stroop task.

The separate semantic and response competition interactions between colour and word processing in a manual Stroop task were evaluated by comparing three trial types. Identity trials are both semantically compatible and response compatible (e.g., BLUE in the colour blue), different response trials are both semantically incompatible and response incompatible (e.g., BLUE in the colour green, where blue and green have different response keys), and same response trials are semantically incompatible and response compatible (e.g., the word BLUE in the colour red, where blue and red have the same key press response). Ink colours were embedded in two different word types, colour words, and colour associates. The results using colour words replicated the findings of De Houwer (2003) and demonstrated both a semantic effect (a difference between same response trials and identity trials) and response competition (a difference between same response trials and different response trials). In contrast, the results using colour associates provided evidence for only a semantic effect. These findings support interpretations of the colour associate Stroop effect that attribute the effect to semantics, but challenge Klein's (1964) response competition account and Sharma and McKenna's (1998) claim that the effect of colour associates is dependent on verbal responding. The results confirm that the Stroop colour-word task appears to involve at least two mechanisms, a semantic mechanism and a response competition mechanism.     

Decomposing the emotional Stroop effect

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

Dissociating positive and negative influences of verbal processing on the recognition of pictures of faces and objects

Four experiments investigated the role of verbal processing in the recognition of pictures of faces and objects. We used (a) a stimulus-encoding task where participants learned sequentially presented pictures in control, articulatory suppression, and describe conditions and then engaged in an old-new picture recognition test and (b) a poststimulus-encoding task where participants learned the stimuli without any secondary task and then either described or not a single item from memory before the recognition test. The main findings were as follows: First, verbalization influenced picture recognition. Second, there were contrasting influences of verbalization on the recognition of faces, compared with objects, that were driven by (a) the stage of processing during which verbalization took place (as assessed by the stimulus-encoding and poststimulus-encoding tasks), (b) whether verbalization was subvocal (whereby one goes through the motions of speaking but without making any sound) or overt, and (c) stimulus familiarity. During stimulus encoding there was a double dissociation whereby subvocal verbalization interfered with the recognition of faces but not objects, while overt verbalization benefited the recognition of objects but not faces. In addition, stimulus familiarity provided an independent and beneficial influence on performance. Post stimulus encoding, overt verbalization interfered with the recognition of both faces and objects, and this interference was apparent for unfamiliar but not familiar stimuli. Together these findings extend work on verbalization to picture recognition and place important parameters on stimulus and task constraints that contribute to contrasting beneficial and detrimental effects of verbalization on recognition memory.     

Conceptual encoding and locus of the Stroop effect

Subjects reacted to coloured season and month names by naming the season associated with the print colour of the word, or by naming the season opposite to the one associated with the print colour. Reactions were facilitated in both tasks when the word on the display named the season associated with the colour or was a month belonging to that season. Opposite season naming was not facilitated when the word named the response which the subject made. A comparable effect of print colour was found when subjects reacted to season names by naming the colour associated with the name, or with its opposite. These results suggest that Stroop congruity and interference effects occur during conceptual encoding, and not during response production.     

Phonology in the bilingual Stroop effect

In a bilingual Stroop task, we examined between-language interference among proficient Japanese-English bilingual speakers. Participants named ink colors either in Japanese or in English. The Japanese color terms were either phonologically similar to (i.e., loan words) or dissimilar from (i.e., traditional color terms) English color terms. For both response languages, a significant between-language Stroop effect was found despite the orthographic dissimilarity between the languages. The magnitude of the between-language interference was larger with the phonologically similar terms. These findings implicate direct links connecting phonologically similar matching words in the lexicons of proficient bilingual speakers of dissimilar languages and imply that phonological processing in lexical access occurs even when the access is done unintentionally.     

Context-specific control and the Stroop negative priming effect

The present study highlights the utility of context-specific learning for different probe types in accounting for the commonly observed dependence of negative priming on probe selection. Using a Stroop priming procedure, Experiments 1a and 1b offered a demonstration that Stroop priming effects can differ qualitatively for selection and no-selection probes when probe selection is manipulated between subjects, but not when it is manipulated randomly from trial to trial within subject (see also Moore, 1994). In Experiments 2 and 3, selection and no-selection probes served as two contexts that varied randomly from trial to trial, but for which proportion repeated was manipulated separately. A context-specific proportion repeated effect was observed in Experiment 2, characterized by modest quantitative shifts in the repetition effects as a function of the context-specific proportion repeated manipulation. However, with a longer intertrial interval in Experiment 3, a context-specific proportion repeated manipulation that focused on the no-selection probes changed the repetition effect qualitatively, from negative priming when the proportion repeated was .25 to positive priming when the proportion repeated was .75. The results are discussed with reference to the role of rapid, context-specific learning processes in the integration of prior experiences with current perception and action.     

Influence of color word availability on the Stroop color-naming effect

Three experiments tested whether the Stroop color-naming effect is a consequence of word recognition's being automatic or of the color word's capturing visual attention. In Experiment 1, a color bar was presented at fixation as the color carrier, with color and neutral words presented in locations above or below the color bar; Experiment 2 was similar, except that the color carrier could occur in one of the peripheral locations and the color word at fixation. The Stroop effect increased as display duration increased, and the Stroop dilution effect (a reduced Stroop effect when a neutral word is also present) was an approximately constant proportion of the Stroop effect at all display durations, regardless of whether the color bar or color word was at fixation. In Experiment 3, the interval between the onsets of the to-be-named color and the color word was manipulated. The Stroop effect decreased with increasing delay of the color word onset, but the absolute amount of Stroop dilution produced by the neutral word increased. This study's results imply that an attention shift from the color carrier to the color word is an important factor modulating the size of the Stroop effect.     

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.     

A developmental study of the auditory Stroop effect

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

The effect of Stroop interference on the categorical perception of color

In two experiments, we examined the effects of Stroop interference on the categorical perception (CP; better cross-category than within-category discrimination) of color. Using a successive two-alternative forced choice recognition paradigm (deciding which of two stimuli was identical to a previously presented target), which combined to-be-remembered colors with congruent and incongruent Stroop words, we found that congruent color words facilitated CP, whereas incongruent color words reduced CP. However, this was the case only when Stroop interference was presented together with the target color, but not when Stroop stimuli were introduced at the test stage. This suggests that target name, but not test name generation, affects CP. Target name generation may be important for CP because it acts as a category prime, which, in turn, facilitates cross-category discrimination.     

Economic and biological influences on a pigeon's key peck

Pigeons were studied in a two-component multiple schedule. In the first phase of the experiment, key pecks were reinforced on a variable-interval 2-min schedule in both components and free food was delivered additionally during one component. When components alternated every 8 sec, all pigeons pecked at a much higher rate during the component with free food than during the other component. At a component duration of 16 min, the reverse was true: all pigeons pecked at a higher rate during the component without free food. In the second phase, the additional food during one component was made contingent on pecking. Responding during the component without the extra food remained essentially unchanged, as expected, since rate of reinforcement remained identical to that in the previous phase. However, rate of responding during the component with the extra food (now contingent on pecking) was elevated, compared to the rate in the first phase, and did not show the marked decline as component duration was increased.     

Evidence for task conflict in the Stroop effect

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

Object-based attentional selection can modulate the Stroop effect

The Stroop (1935) effect is the inability to ignore a color word when the task is to report the ink color of that word (i.e., to say "green" to the word RED in green ink). The present study investigated whether object-based processing contributes to the Stroop effect. According to this view, observers are unable to ignore irrelevant features of an attended object (Kahneman & Henik, 1981). In three experiments, participants had to name the color of one of two superimposed rectangles and to ignore words that appeared in the relevant object, in the irrelevant object, or in the background. The words were congruent, neutral, or incongruent with respect to the correct color response. Words in the irrelevant object and in the background produced significant Stroop effects, consistent with earlier findings. Importantly, however, words in the relevant object produced larger Stroop effects than did the other conditions, suggesting amplified processing of all the features of an attended object. Thus, object-based processing can modulate the Stroop effect.     

Unconsciously controlled processing: the Stroop effect reconsidered

The Stroop effect is widely considered to be compelling evidence that an acquired skill such as reading is “automatic” in the sense that lexical/semantic analyses of single words cannot be prevented, even when they are irrelevant and harmful to the task at hand. This view is challenged by a series of three experiments in which the presence/absence of a Stroop effect depends on (1) whether all of the target elements are colored or not, in conjunction with (2) whether the target and the spatially distinct color word distractor belong to the same domain or not. A framework is offered in which domain-specific encoding algorithms play a major role. Skilled word recognition is typically unconscious, but is characterized better as contextually controlled, rather than “automatic.”     

The cause of the within-language Stroop superiority effect and its implications

This study examines the causes for the within-language Stroop superiority effect (WLSSE; larger Stroop effect for words appearing in the response language than in another language). Participants named in their first language (L1) or second language (L2) the colour of colour-words or colour-associated words appearing in L1 or in L2. The WLSSE was limited for colour-words. It was concluded that for colour-words, the cause for the WLSSE is that words appearing in the within-language condition belong to the response set, whereas words in the between-language condition do not. This finding challenges previous suggestions that a nonrelevant stimulus language can be suppressed.     

The cause of the within-language Stroop superiority effect and its implications

This study examines the causes for the within-language Stroop superiority effect (WLSSE; larger Stroop effect for words appearing in the response language than in another language). Participants named in their first language (L1) or second language (L2) the colour of colour-words or colour-associated words appearing in L1 or in L2. The WLSSE was limited for colour-words. It was concluded that for colour-words, the cause for the WLSSE is that words appearing in the within-language condition belong to the response set, whereas words in the between-language condition do not. This finding challenges previous suggestions that a nonrelevant stimulus language can be suppressed.