Unconsciously Controlled Processing: the Stroop Effect Reconsidered

Psychonomic Bulletin & Review 1999. 6 (3). 449-455

Unconsciously controlled processing: The Stroop effect reconsidered

DEREKBESNERand JENNIFER A. STOLZ University ojWaterloo, Waterloo, Ontario, Canada

The Stroop effect is widely consideredto be compelling evidence that an acquired skill such as read ing 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 ofthe 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 char acterized better as contextually controlled, rather than "automatic."

It is well established that, for skilled readers who are Stolz, 1999, for related findings). Iflexical/semantic pro explicitly told to refrain from reading a word, it takes cessing associated with word recognition is not control more time to identify the word's color ifthe word and its lable, as much ofa Stroop effect should have been found color are incongruent (e.g., red letters spelling the word in the single-colored-letter condition as in the all-letters green) than it does to identify the color ofthe word ifthe colored condition. Given that there is little or no Stroop word and its color are congruent (e.g., green letters effect in the former condition, characterizing word recog spelling the word green). Many variants ofthis phenom nition as automatic in the sense defined above does not enon have been explored empirically, theoretically, and provide an adequate account. computationally by cognitive scientists in more than 500 The purpose of the present paper is twofold. First, it papers since the publication of Stroop's (1935) seminal demonstrates that a Stroop effect is present when the color work (see MacLeod's, 1991, review). A core assumption carrier stimulus and the color word are spatially separated. ofmost ofthe theoretical accounts is that skilled readers Variations on this theme have ofcourse been reported be process the irrelevant word without consciousness or in fore (e.g., by Brown, Roos-Gilbert, & Carr, 1995). What tent. Reading the word is said to be automatic in the sense is new is that this variant ofthe Stroop effect can be largely that readers cannot refrain from computing the meaning of eliminated through a manipulation of the target's color the word despite explicit instructions that they should not, extent (whole/part) despite the fact that all the letters in and despite the fact that such computation impairs color the irrelevant and spatially distinct color word always ap identification performance.' The Stroop effect is thus pear in white (a color that is not in the response set). The seen as the "gold standard" ofautomatized performance second purpose ofthe paper is theoretical; we argue that (MacLeod, 1992). This view has been expressed in a va the results of the experiments distinguish between sev riety of sources, including journal articles, specialized eral competing accounts ofhow the reduction/elimination books on reading, and introductory and cognitive psy ofthe Stroop effect in this preparation comes about. chology textbooks. There is, however, a problem with the widespread Levels ofProcessing view that the word recognition processes that produce Stolz and Besner (1996, 1998; see also Bauer & Besner, "the" Stroop effect are not open to control.? Although a 1997; Besner & Stolz, 1999; Besner et al., 1997; Chiappe, Stroop effect is observed when the entire word is colored Smith, & Besner, 1996) have suggested that instead of (the standard condition), it can be eliminated when only word recognition being characterized as "automatic," the a single letter in the word is colored (Besner, Stolz, & mental set adopted by subjects exerts a powerful influence Boutilier, 1997; see also Bauer & Besner, 1997; Besner & on performance. The default set is to process words to the semantic level, a useful set outside the laboratory where important information is often conveyed by print This work was supported by Grants A0998, OGP018390, and (e.g., STOP, BAR, RESTAURANT, BANK, and BATHROOM). EQPOI87220 from the Natural Sciences and Engineering Research Nonetheless, this default mental set can be overridden by Council of Canada. Some of these data were presented at CSAIL (1996) the context in such a way that semantic activation is cur and at the annual meeting ofthe Psychonomic Society (1997). Corre spondence should be addressed to D. Besner, Psychology Department, tailed. For example, the well-documented "semantic University of Waterloo, ON N2L 3Gl, Canada (e-mail: dbesner@ priming" effect in lexical decision can be eliminated watarts.uwaterloo.ca). when subjects search the prime display for a letter target

(see, e.g., Chiappe et al., 1996; Friedrich, Strayer, & Neely, 1991, for reviews). This view therefore predicts Christensen, 1997; Smith, Theodor, & Franklin, 1983; that the two conditions should produce the same-sized Stolz & Besner, 1996, 1998). Coloring only a single let Stroop effect. In contrast, the levels hypothesis advanced ter instead ofall letters in a Stroop task may also serve to by Besner et al. (1997) to account for the data from the override the default mental set, the consequence being a paradigm where word and color are integral predicts that reduction or elimination ofsemantic activation and thus the single-colored-letter condition in the present para the reduction or elimination ofthe Stroop effect. digm should produce little or no Stroop effect in compar This description is not incompatible with the account of ison with the all-colored-letters condition, provided that fered by Kahneman and Henik (1981). In their view, col one additional assumption is made-namely, that sub oring only a single letter in a word renders a letter (rather jects find it difficult to maintain two different mental sets than the word) the perceptual object, thus making it less simultaneously. One ofthese sets is the normally opera susceptible to a Stroop effect, which arises through higher tive default set that processes words in such a way that level processing.' Yet another way ofdescribing Kahne semantics are activated. This set will dominate when the man and Henik's account is to suppose that coloring a sin target stimulus is a word in which all the letters are col gle letter changes the distribution ofspatial attention from ored, and it is therefore applied to reading both the target the default value of broad beam (distributed across the stimulus and the irrelevant color word. The other set is word) to narrow beam (focused on the space occupied by the one needed to process the single colored letter in the a letter). The effect ofchanges in the distribution ofspa target (where semantic activation does not occur, or occurs tial attention has largely been ignored in both the visual in very reduced form), and it is also applied to the pro word recognition and Stroop literatures, but a number of cessing ofthe irrelevant color word. reports strongly suggest that spatial attention plays a crit A version ofthis assumption has been examined before ical role (e.g., Besner & Stolz, 1999; Johnston & Me in the context ofthe so-called global/local processing lit Clelland, 1974; LaBerge, 1983; McCann, Folk, & John erature, although it is not referred to as "set" there, but ston, 1992; Stolz & McCann, 1999). In particular, ifspatial rather as the ability to focus "attention," and it is not clear attention needs to be distributed across the word as a pre whether semantics is involved or not. In the context of liminary to visual word recognition, then narrowing the processing pairs oflocal/globalletters (large letters com beam ofspatial attention so that it is focused on an indi posed ofsmall letters), where one object is attended (the vidual letter should make word recognition problematic. target) and the other not, Paquet and Merikle (1988) re In that vein, Johnston (1981) reported that the word supe port that interference from the unattended object depends riority effect in Reicher's (1969) perceptual identification on the level ofprocessing of the attended object. When task is eliminated ifsubjects are told to attend to a spatial the attended object required local level processing, there position that will be occupied by a particular letter when was little interference from the global level of the unat the word display is subsequently presented. Relatedly, tended object, but there was a large amount ofinterference Besner and Stolz (1999) reported that the Stroop effect can from the locallevei. Similarly, when the attended object be reduced in magnitude or eliminated when a single let required global level processing, there was more interfer ter position in a colored word is precued as compared to ence from the global level ofthe unattended object than when all the letter positions are precued. from the locallevei. Although not interpreted in quite this Is it possible to discriminate between any ofthese ac way, Paquet and Merikle's findings are consistent with counts, or are they just different verbal descriptions that the idea that it is difficult to hold two different mental reduce to the same operation in this context? Imagine a sets simultaneously. When two objects are in the visual paradigm in which two words appear on the screen. One, field, one relevant and the other not, processing can be the color carrier, appears at fixation and consists of a done at the local level on both, or at the global level on neutral word (i.e., one that is not color related). The sec both, but it is difficult to combine local processing of ond is an irrelevant color word, always printed in white, one object with global processing ofthe other. that appears half the time above the colored target and Experiments 1 and 2 ofthe present series demonstrate halfthe time below it. Halfthe time the meaning ofthis that different target conditions (all colored letters in the word is congruent with the displayed color ofthe neutral neutral word vs. only one colored letter in the neutral word at fixation, and halfthe time it is incongruent. Sub word) lead to differences in the size ofthe Stroop effect jects are instructed to identify the color ofthe neutral word despite the spatially distinct and irrelevant color word al at fixation and to ignore both words. On halfthe trials, the ways appearing in white. The single-letter condition word at fixation is all colored, and on the remaining trials, largely eliminates the Stroop effect that is observed when a single letter chosen at random is colored. What effect all letters in the neutral word are colored. This result is should the irrelevant color word have on performancev- consistent with the levels account offered by Besner and The standard account in the word recognition and colleagues, but also with both the perceptual object ac Stroop literatures holds that words are processed auto count offered by Kahneman and Henik (1981) and the matically to the semantic level (see, e.g., MacLeod, 1991; spatial attention account which supposes that narrowed THE STROOP EFFECT RECONSIDERED 451 spatial attention makes word recognition problematic METHOD (e.g., Besner & Stolz, 1999; Johnston, 1981; LaBerge, 1983). In Experiment 3, we therefore explored the issue Research Participants University of Waterloo psychology undergraduates volunteered ofwhether the results ofExperiments 1 and 2 generally to participate in exchange for $5. All participants had normal or cor reflected attention to a level below semantics as supposed rected-to-normal vision and normal color vision, and all were native by both the perceptual object and spatial attention ac English speakers. No participant took part in more than one of the counts, or whether they would be betterunderstood, in this following experiments. Forty-six undergraduates participated in Ex context, as reflecting domain-specific processing, as pre periment I, 18 in Experiment 2, and 55 in Experiment 3. ferred here. Design All three experiments consisted of a 2 (portion of word/object Domain-Specific Processing colored: whole vs. part) X 2 (color-word congruency: congruent Domain-specific processing refers here to the idea vs. incongruent) within-subjects design. that the mind develops specialized algorithms for the processing ofdifferent kinds of stimuli (a standard idea Stimulus Materials and Test List Construction in cognitive psychology and neuropsychology; see, e.g., All three experiments consisted of 144 trials in which the partic ipant was asked to respond to the color of a stimulus presented at Allport, 1980; Shallice, 1988). It is assumed that the al fixation. In Experiments 1 and 2, the stimulus at fixation was pre gorithm associated with the processing ofwell-structured sented inside a bounding box. Because geometric shapes were used alphabetic material (printed words) is different from the in Experiment 3, no bounding box was used in order to prevent con algorithm associated with the processing offamiliar geo fusion between box and shape. Distractor color words were always metric forms. When the color carrier stimulus and the ir presented either 3 mm above or 3 mm below the side of the bound relevant color word are processed by different algorithms, ing box in Experiments 1 and 2, and 3 mm above/below the top/bot the subject can maintain two different mental sets simul tom ofthe shapes in Experiment 3. The distractors words used were the words red (9 mm long X 5 mm high), blue (12 mm long X 5 mm taneously because they belong to different domains and high), green (15 mm long X 4 mm high), and yellow (18 mm long therefore do not make demands on common mental ma X 6 mm high). The words were presented in Micro Experimental chinery. The consequence is that the algorithm used to Lab (MEL; Schneider, 1988) romantri.fnt font, which is a graphi process the color carrier geometric form when only a sin cal version ofthe standard MEL font. All color words were always gle element is colored should not interfere with the de presented in white (RGB: 63, 63, 63). fault set ofprocessing the irrelevant color word to the se Across experiments, what varied was the stimulus at fixation. In Experiment 1, 144 five-letter, color-neutral words were used as mantic level. In contrast to the results ofExperiments 1 stimuli. A single word was presented inside a 56 X 25 pixel bound and 2, then, the domain-specific processing hypothesis ing box at fixation; the word had either all-letters-colored, or only predicts that Experiment 3 should produce a Stroop effect one letter colored. In the one-letter condition, the colored letter was that is as large in the single-colored-element condition as chosen from the beginning (Position 1), middle (Position 3), and in the all-colored-elements condition. end (Position 5) of the word equally often. Each neutral word ap In contrast to the domain-specific processing hy peared only once in the experiment. The assignment of neutral words to conditions was made randomly without replacement. pothesis, ifall that matters is whether spatial attention is In Experiment 2, three shape words-circle, triangle, square generally broad or narrow (i.e., focused on an individual were used as stimuli. A single word was presented inside a 74 X 25 element or on the object as a whole; Besner & Stolz, 1999; pixel bounding box at fixation. According to condition, the shape Kahneman & Henik, 1981; Johnston, 1981; LaBerge, word would appear either entirely colored or with only one letter 1983; Paquet & Merikle, 1988), then it should not mat colored. In the one-letter condition, the colored letter was chosen ter whether the material at fixation belongs to the same from the beginning, middle, and end ofthe word equally often. The domain as does the irrelevant color word. All three ex assignment of shape words to conditions was made randomly with out replacement until all the shape words were selected once. periments should produce the same interaction. In Experiment 3, the stimuli at fixation consisted of a circle, tri In summary, three experiments are reported here. In angle, or square. All were constructed to fit into an imaginary 30 X each experiment, a colored target appeared at fixation, and 30 pixel bounding box; all sides were 4 pixels thick. From a view an irrelevant color word, displayed in white, appeared ing distance ofapproximately 45 ern, the objects subtended a max above or below the target. Either the target was all colored, imal visual angle of 1.7° X 1.7°. According to condition, the shape or only a single element was colored. What varies across was presented either entirely colored or with only one segment col ored. The one-segment-colored condition was constructed as fol these experiments is the relation between the stimulus dis lows: For the circle, a 120° arc was colored; for the triangle, one of played at fixation and the irrelevant color word. In Ex three sides was colored; for the square, one of four sides was col periments 1 and 2 both were words and therefore belonged ored. The location of the colored portion varied randomly across to the same domain. In Experiment 3, the color carrier at trials and was distributed equally across all possible positions. fixation consisted ofa geometric form and therefore be The colors used on the stimuli at fixation were red (RGB: 42, 0, longed to a different domain from that of the irrelevant 0), blue (RGB: 0, 0,42), green (RGB: 0,42,0), and yellow (RGB: 63, 63, 21). In the part-stimulus-colored condition, the uncolored color word. The outcome ofthese experiments will allow stimulus parts were presented in MEL white (RGB: 63, 63, 63). us to discriminate among several competing accounts re All experiments consisted of 144 experimental trials-9 in each garding the nature ofprocessing underlying performance ofthe 16 trial types formed by crossing the portion of stimulus col in a variant of Stroop's paradigm. ored factor and the congruency factor with the four ink colors. 452 BESNER AND STOLZ

Table 1 sive trimming procedure in which the criterion cutofffor Mean Response Times (in Milliseconds) and Percent outlier removal was established independently for each Errors (%E) According to Conditions in Experiments 1-3 participant, in each condition, with reference to the sam Color Level ple size in that condition (Van Selst & Jolicoeur, 1994). All Elements Colored One Element Colored This trimming procedure resulted in 3.3% ofthe correct Display Type RT %E RT %E RT data's being discarded in Experiment 1,2.5% in Ex Experiment I: Neutral Words(n = 46) periment 2, and 2.7% in Experiment 3. The trimmed Incongruent 753 2.0 762 2.0 means and percent error data for each condition for each Congruent 722 2.0 755 2.0 experiment are displayed in Table I. Difference 31 0 7 0 Experiment 2: Shape Words(n = 18) Experiment 1: Neutral Words Incongruent 772 3.0 782 2.0 Responses were faster when the entire word was colored Congruent 733 4.0 787 3.0 (737 msec) than when one letter was colored (759 msec) Difference 39 -1.0 -5 -1.0 [F(1,45) = 12.43, MSe = 1,677, P < .0001]. There was Experiment 3: Geometric Shapes (n = 55) also a main effect of congruency, with responses being Incongruent 680 4.1 703 3.6 faster on congruent (739 msec) than on incongruent Congruent 650 2.8 683 3.4 (758 msec) trials [F(1,45) = 5.49, MS = 3,040,p < .05]. Difference 30 1.3 20 .2 e Most importantly, the magnitude ofthe Stroop effect dif fered for the whole-word-colored and single-letter colored conditions [F(I,45) = 3.90, MSe = 1,822,p < .05]. There were equal numbers of congruent and incongruent trials in Subsequent analyses showed that although the Stroop ef each experiment. All conditions were randomly intermixed in each experiment, and each subject received a different random order of fect was significant in the whole-word-colored (31 msec) trials. A set of48 practice trials was also constructed to meet the ex condition [t(45) = 2.58, P < .01], it was not significant perimenta trial constraints. Administration of the practice trials in the single-letter-colored (7 msec) condition [t(45) = preceded the experiment proper. .83,p = .4]. None ofthe error effects were significant (all Fs < 1). Procedure The participants were tested individually, seated approximately 45 ern from a computer monitor. The task instructions were dis Experiment 2: Shape Words played on the monitor and were also relayed verbally by the exper Responses were faster when the entire word was colored imenter. The stimuli were displayed on a Microscan 4V/ADI color (752 msec) than when one letter was colored (785 msec) monitor controlled by MEL software implemented in a Vault Pen [F(1,17) = 7.36, MSe = 2,61l,p < .01]. There was also a tium 100 computer. main effect ofcongruency, with responses being faster on Each trial began with the appearance ofa centrally located white congruent (760 msec) than on incongruent (777 msec) fixation box (see above for the exact sizes, which fit the stimuli trials [F(I,17) = 5.54, MS = 954,p .05]. Most impor used in the three experiments). Following a 500-msec stimulus e < onset asynchrony, the colored (whole stimulus or part stimulus) tantly, the effects of portion of word colored and color stimulus was presented in the fixation box simultaneously with the congruency interacted [F(I,17) = 8.81, MSe = 934,p < presentation ofthe distractor word above or below the fixation box. .01]. Subsequent analyses revealed a significant Stroop The distractor word appeared above the box on halfofthe trials and effect in the whole-word-colored (39 msec) condition below the box on halfofthe trials. Distractor word location was dis [t(17) = 3.26, p < .01], and no significant congruency tributed equally across all conditions. effect in the single-letter-colored (-4 msec) condition The participants were instructed to ignore the distractor word and to respond to the ink color of the stimulus at fixation. Responses [t(17) = .51, P > .6]. The error data revealed a tendency were made with the left and right hands by depressing a key covered toward a main effect of congruency [F(1,17) = 2.68, with an appropriately colored piece of paper. The colored paper MSe = 6.76, p > .12]. No other error effect approached covered the "z,'~"x," ">," and "I" keys and were red, blue, yellow, significance (all Fs < 1). and green, respectively. A response terminated the stimulus display and initiated a 500-msec intertrial interval, during which time the Experiment 3: Geometric Shapes screen remained blank. The MEL software recorded reaction time to the nearest milliseconds, as well as response accuracy. Responses were faster when the entire shape was col The participants were given the opportunity to ask questions fol ored (665 msec) than when only a part was colored lowing the practice phase and were instructed to perform the task (693 msec) [F(1,54) = 16.21, MSe = 2,704, p < .001]. as quickly and as accurately as possible. The error difference was not significant (F < 1). There was also a main effect of congruency, with responses RESULTS being faster and more accurate on trials in which the shape color and distractor word were congruent (666 msec, Only response time (RT) data from correct responses 3.1%) than when they were incongruent (691 msec, 3.8%) were entered into the analyses. A 2 X 2 within-subjects [for RTs, F(1,54) = 14.07, MSe = 2,503,p < .0001; the analysis of variance was performed on both the RT and error difference was only marginally significant, F( 1,54) = the error data from each experiment. Before the analyses 2.71, MSe = 13,p < .11]. Most importantly, the magnitude were conducted, the RT data were subjected to a recur- ofthe Stroop effect was equivalent for the whole-shape- THE STROOP EFFECT RECONSIDERED 453

colored (30 msec) and part-shape-colored (20 msec) con this interaction, it would seem that the spatial attention ditions (F < I). Although there was a tendency toward a account does not provide a sufficient account ofprocess difference in the magnitude ofthe Stroop effect in error ing in this context. rates for whole-colored (1.3%) versus part-colored (.2%) In contrast, the domain-specific processing account shapes, this was not significant [F(I,54) = 1.8, MSe = 9, provides a simple explanation for the results ofall three P > .17]. The individual subject data were also perused in experiments. The default mental set is to process words to search ofa trend; 28 subjects yielded a larger RT Stroop the semantic level, which produces a Stroop effect. How effect in the all-colored condition, and 26 subjects yielded ever, when the processing algorithm applied to the stim a larger difference in the part-colored condition. The re ulus at fixation changes in order to process the single maining subject produced tied scores. Finally,the 20-msec colored letter, this new algorithm is also applied to the pro congruency effect in the part-colored condition was mar cessing ofthe irrelevant and spatially distinct color word ginal [t(54) = 1.962,p < .0548]. because the two stimuli belong to the same domain. This algorithm does not easily activate semantics, so little in DISCUSSION the way ofa Stroop effect is seen. When the color carrier stimulus is analyzed by an algorithm that does not belong The results ofthese three experiments can be summa to the same domain as does the irrelevant color word, little rized easily. When the color carrier stimulus and the spa common mental machinery is involved. This was the case tially distinct color word belonged to the same domain in Experiment 3, where the color carrier was a geometric (i.e., when they were both words), the single-colored form rather than a printed word. The consequence is that element manipulation largely eliminated the Stroop effect the default mental set that processes words to the seman (Experiments 1-2). In contrast, when the color carrier tic level holds sway and is applied to the spatially dis stimulus and the spatially distinct color word belonged to tinct and irrelevant color word. The Stroop effect is con different domains (i.e., when the target was a familiar geo sequently as large in the single-colored-element condition metric shape), the single-colored-element manipulation as in the all-colored-elements condition.> produced a Stroop effect that was as large as when the color carrier stimulus was all colored (Experiment 3). Control ofProcessing The received idea that words are processed automati Given the outcome ofthese experiments, how should cally to the semantic level predicts that the same pattern control of processing be understood in this context? In would be seen across all three experiments, and that the many accounts, control ofmental processes is associated pattern would take a particular form. That is, there should with consciousness, and lack of control, with uncon have been as much ofa Stroop effect in the single-colored sciousness. In the same accounts, consciousness is used element condition as in the all-colored-elements condition. as though it is synonymous with "attention" and uncon The data from Experiments I and 2 are inconsistent with sciousness with the absence of"attention." Unconscious this prediction, as are data from related experiments processes are therefore said to be automatic (see, e.g., (Besner & Stolz, 1999; Besner et aI., 1997). This would Jacoby, Lindsay. & Toth, 1992; Posner & Snyder, 1975). seem to pose a problem for any account ofthe Stroop ef These ideas are very influential in cognitive psychology, fect in which it is assumed that semantic level analyses and rightly so; it would be odd for such ideas to have held ofwords are automatic in the sense that they cannot be pre sway for so long, had they no merit. That said, a difficulty vented in skilled readers (e.g., Anderson, 1995; Ashcraft, here is the assumption that levels of consciousness and 1994; Cohen, Dunbar, & McClelland, 1990; LaBerge & control are tightly, and necessarily, linked. Consciousness Samuels, 1974; Marcel, 1983;Medin & Ross, 1997;Neely, (ofsomething) need not imply that control is an inevitable 1977, 1991; Posner & Snyder, 1975; Rayner & Pollatsek, consequence ofsuch a state. Obsessional thoughts, for ex 1989; Reisberg, 1997; Shaffer & LaBerge, 1979, among ample, are manifestly conscious, but not, by definition, many others). easily controllable. By the same token, unconscious men The spatial attention account (Besner & Stolz, 1999; tal processes such as word recognition are not automatic Johnston, 1981; Kahneman & Henik, 1981; LaBerge, in the sense ofinevitably computing lexical/semantic rep 1983), in which it is supposed that whether processing is resentations (contrary to the claims by Marcel, 1983, and done at the semantic level or not depends on whether at Neely, 1977, 1991, among many others). Instead, they are tention is focused on an individual component or distrib strongly affected (controlled) by context (e.g., Bauer & uted across the entire object also appears problematic in Besner, 1997; Besner et aI., 1997; Smith et aI., 1983; Stolz this context. Iflocal-level processing (which does not eas & Besner, 1996, 1998) and by the distribution ofspatial ily activate the semantic level) is invoked whenever a attention (e.g., Besner & Stolz, 1999; Johnston, 1981; single-colored-element appears in the target, and this Johnston & McClelland, 1974). We have no quarrel with kind of processing is also applied to the irrelevant and the idea that many mental processes are unconscious, but spatially distinct color word, the interaction observed in we do take issue with the assumption that such uncon Experiments I and 2 should also have been observed in sciousness implies a lack ofcontrol (see, e.g., Neumann, Experiment 3. Given that Experiment 3 failed to produce 1984) or a lack of attention (e.g., McCormick, 1997). 454 BESNER AND STOLZ

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NOTES 4. This design is embedded in an experiment reported by Kahneman and Henik (1981), but they do not comment on it. Their results are un 1. The present paper addresses the issue ofwhether processing can be usual (i.e., there is no Stroop effect in the all-colored-target condition). said to be automatic in the restricted sense that semantic activation can 5. It is tempting to describe the "domains" here as linguistic versus not be prevented. We do not question the claim that (attentional) strat nonlinguistic; this is certainly a sufficient account ofthese data. How egy effects can be overlaid on the standard Stroop effect (e.g., ever, our speculation is that domain refers to more specialized algo Cheesman & Merikle, 1985; Logan, Zbrodoff, & Williamson, 1984). rithms. For example, one prediction is that since the algorithms typi 2. Exactly what is meant by "control" is an important issue in its own cally used to read Japanese Kanji (the ideographic script) differ from the right. Cognitive psychologists are too sophisticated to say that they algorithms used to read Japanese Kana (the syllabic script), the inter mean that "the subject" controls processing x or y or z, because this in action observed here in Experiments 1 and 2 will not be observed when vites the argument that "the subject" is just a homunculus. It is prefer the target and irrelevant color word appear in Kana and Kanji, respec able to suppose that control exists as an interaction between internal tively. In contrast, when both items appear in Kana or in Kanji, the inter goals, specialized processors (a committee rather than a homunculus), action observed here should occur, because the stimuli belong to a com and the external context. We return to this issue briefly in the Discus mondomain. sion. 3. Kahneman and Henik's (1981) account is clear. The data that pur port to support this account are less so (see Besner et al., 1997, for (Manuscript received April 14, 1998; discussion). revision accepted for publication August 3, 1998.)