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Spontaneous decay of response-code activation
Abstract
Two experiments investigated whether the
Two experiments investigated whether the Simon effect (i. e.., faster responses to spatially corresponding than to noncorresponding stimuli, with stimulus location being irrelevant) is affected by the frequency of noncorrespondence trials. Stimulus discriminability (Experiment 1) and immediate or delayed stimulus formation (Experiment 2) was varied in order to manipulate the temporal relationship between coding of the relevant stimulus information and of stimulus location. As was expected, the Simon effect decreased from high to low discriminability and from immediate- to delayed-stimulus formation. This is consistent with the notion of a gradual decay of location-induced response-code activation. Moreover, the Simon effect decreased with increasing frequency of noncorrespondence trials and was even reversed with higher frequency. This demonstrates strategic preparation of stimulus processing and/or response selection based on irrelevant location information. However, frequency did not modify the interaction between S-R correspondence and stimulus discriminability or stimulus formation, this suggesting that code decay is not a result of a strategy, but an automatic process.
... The goal of the present study was to investigate whether and how target-related perceptual processes modulate the superimposition of target-based and distractor-based activations (and, with that, the observable conflict effects) in one of the most prominent conflict paradigms, the visual Simon task (e.g., Hoffmann et al., 2023;Hübner & Töbel, 2019;Luo & Proctor, 2018;Mittelstädt & Miller, 2018;Pratte et al., 2010;Simon, 1969;Wühr & Ansorge, 2005; reviews given by Hommel, 2011;Lu & Proctor, 1995). Specifically, we tested the predictions of fading activation accounts, which assume that changes in target-related processes affect Simon effects solely by altering the absolute contribution of fading distractor-based activation (e.g., Hommel, 1993aHommel, , 1994. As detailed below, these accounts are strongly supported by distributional analyses, specifically delta plots (DPs), revealing that the Simon effect in response times tends to be more pronounced for faster responses compared to slower ones (De Jong et al., 1994;Ellinghaus et al., 2018;Mittelstädt, Miller, Leuthold, et al., 2022;Pratte et al., 2010;Servant et al., 2014). ...
... This pattern is predicted when distractor-based activation fades over time, and several conflict task models implement this notion by assuming that target-based activation is superimposed with fading (i.e., time-varying) distractor-based activation (e.g., De Jong et al., 1994;Heuer et al., 2023;Ulrich et al., 2015;Wühr & Heuer, 2018). Critically, it is not well understood to what extent experimental manipulations modulating the Simon effect, such as the perceptual difficulty of the target (Hommel, 1993a(Hommel, , 1994Mittelstädt & Miller, 2020), are actually driven by fading activation alone (Mittelstädt & Miller, 2020). To address concerns when interpreting previous findings, the present study employed fine-grained DPs and modeling analyses to examine whether fading activation alone can entirely explain the observed differences in the Simon effect resulting from a perceptual difficulty manipulation. ...
... For example, Panel B of Figure 1 provides a schematic illustration of such decreasing DPs. Thus, DPs seem to indicate that activation fades out over time, either because it passively decays (Hommel, 1994) and/or is actively inhibited (Ridderinkhof, 2002). Crucially, according to fading activation accounts, conditions with faster perceptual processing speed should exhibit a larger mean Simon effect because the impact of location-based activation decreases for slower responses. ...
The visual Simon task is widely employed to explore the underlying mechanisms of sensorimotor processing in the presence of task-relevant (targets) and task-irrelevant (distracting) location information. Critically, the Simon effect is considered as an indicator of action-related interference resulting from distractor-based activation, which fades out over time. In this study, we tested whether attenuated Simon effects with slower task processing may be fully explained by the fading of distractor-based response activation. To that end, we selectively manipulated perceptual target discriminability by varying the ratio of differently colored dots within (Experiment 1) and between blocks (Experiment 2). According to pure fading activation accounts, the negative-going delta plots of the two discriminability conditions should overlap across the entire reaction time (RT) distribution. In contrast to this prediction, the negative-going DPs for the two discriminability conditions did not overlap in either experiment. Instead, the Simon effect was either consistently smaller (Experiment 1) or larger (Experiment 2) across the entire RT distribution in the easy condition compared to the hard condition. This result pattern indicates that perceptual target discriminability affected conflict resolution beyond the mere fading of distractor-based activation. Exploratory model-based analyses suggest a stronger processing of relevant perceptual information with more discriminable targets, which may counteract the influence of distracting location information. However, as the exact effects of discriminability on conflict processing seem to depend on variation mode (trialwise vs. blockwise), the importance of global strategic effects is also highlighted.
... By varying the relative percentages of trials of different types, it is possible to cause participants to form expectancies about the likely trial types. Several studies have shown that the effect of irrelevant location can be reversed by increasing the percentage of corresponding and noncorresponding trials in variations of the Simon and spatial Stroop tasks (e.g., Greenwald & Rosenberg, 1978;Hommel, 1994;Logan, 1980). Logan and Zbrodoff (1979) demonstrated this reversal using a Stroop-like task in which the words ABOVE and BELOW were presented above or below a fixation point, and responses were a left or right keypress to the word. ...
... However, when the majority of trials were noncorresponding, a reversal of 42 ms was found, such that responses were faster when the word and location did not correspond than when they did. Hommel (1994) obtained similar results using the typical Simon task. In his Experiment 1, when the stimulus location did not correspond with response location on 75% of the trials, a 14-ms reversal of the Simon effect was found. ...
... In other words, as participants learn or are told about the validity of a stimulus dimension, they assign to it a value that reflects that understanding. However, in Logan and Zbrodoff s (1979) study, as well as in those of Hommel (1994) and Toth et al. (1995), the location correspondence effects were asymmetric. The positive effects obtained when the majority of trials were corresponding were much larger than the reversed effects obtained when the majority of trials were noncorresponding. ...
The Simon effect refers to the finding that reaction times are faster when stimulus and response locations correspond than when they do not in tasks where stimulus location is defined as irrelevant. The authors examined the Simon effect for situations in which location-irrelevant trials were intermixed with trials for which stimulus location was relevant. Compatible mapping of the location-relevant trials enhanced the Simon effect relative to an unmixed condition, whereas incompatible mapping reversed the Simon effect. The reversal with incompatible mapping remained evident when task uncertainty was removed by use of a precue and was larger than the reversed effect produced by making incongruent trials more frequent than congruent trials. This result suggests that both attentional biases and task-defined associations contribute to the reversal of the Simon effect.
... Thus, if the response codes elicited by the task-relevant target feature and the task-irrelevant spatial feature differ, response selection is delayed compared to when they are identical. Because the spatial code for the task-irrelevant spatial information rapidly decays over time (Hommel, 1994) or is actively suppressed (Ridderinkhof, 2002), response time (RT)-based distributional analyses have shown a decreasing function of the Simon effect, with a smaller Simon effect for slower than for faster responses (De Jong et al., 1994; for a review, see Proctor et al., 2011). However, this decreasing delta function has only been consistently found for the horizontal location-based Simon effect. ...
... Ellinghaus et al. (2018) specified the patterns of delta functions as a pulse-like function, tracking the time-courses of the automatic activation of the task-irrelevant spatial information followed by dissipation. In their diffusion model for conflict tasks, the output of the automatic process decreases after reaching its maximum due to active inhibition (Ridderinkhof, 2002) or spontaneous decay (Hommel, 1994). Thus, if the rapid automatic activation of spatial codes is followed by the rapid dissipation of activation, a decreasing function of the Simon effect is formed (De Jong et al., 1994). ...
Simon effects have been observed to arise from different modes of spatial information (e.g., physical location, arrow direction, and location word). The present study investigated whether different modes of spatial information elicit a unitary set of spatial codes when triggering a spatially corresponding response code. A pair of two different Simon tasks was presented in alternation: location- and arrow-based Simon tasks in Experiments 1 and 2, word- and location-based Simon tasks in Experiment 3, and arrow- and word-based Simon tasks in Experiment 4. Responses were collected using unimanual aimed-movement responses. Cross-task congruency sequence effects (CSEs) were found in Experiments 1 and 2, indicating a shared set of spatial codes between physical locations and arrow directions. Conversely, the absence of CSEs in Experiment 3 suggested that physical locations and location words elicited different sets of spatial codes. In Experiment 4, a CSE was evident in the arrow-based Simon task but not in the word-based one, implying an overlap in the spatial attributes of arrow directions with those of location words. Distributional analyses of the Simon effects revealed that different modes of spatial information yielded distinct temporal patterns of its activation and dissipation, implying quantitative differences in the Simon effects. The cross-comparisons of the CSE and delta function data indicated that the quantitative similarities in spatial modes did not correspond to the qualitative similarities, suggesting a crucial finding that each set of data reflects different aspects of the nature of the spatial codes.
... However, delta functions displaying the time course of the compatibility effect show distinguishable patterns of the horizontal and vertical dimension (De Jong et al., 1994;Proctor et al., 2011;Sturmer et al., 2002;Wascher et al., 2001). In the horizontal Simon task, the RT difference between compatible and incompatible trials usually decreases with increasing response times indicating a fast and transient automatic response activation whereby the irrelevant target location decays or is suppressed over time (De Jong et al., 1994;Hommel, 1994;Ridderinkhof et al., 2004). In the vertical Simon task or crossed-hands horizontal Simon tasks where the anatomical representation is lacking, the delta functions show the opposite pattern of a constant or positive slope, that is, the compatibility delta is constant or increases with RT (Sturmer et al., 2002;Vallesi et al., 2005;Wascher et al., 2001;Wiegand & Wascher, 2005. ...
... Such an oscillating attentional filter could interfere with the perception of external stimuli resulting in decreased perceptual sensitivity . However, such a general attenuation seems unlikely to underlie our results since decreasing the salience or discriminability of target stimuli in a Simon task does not increase compatibility effects (Hommel, 1993(Hommel, , 1994. Nevertheless, predictive coding and conflict monitoring are closely related constructs since prediction errors constitute conflict signals (Botvinick et al., 2001;Carter & van Veen, 2007). ...
Variations in cardioafferent traffic are relayed to the brain via arterial baroreceptors and have been shown to modulate perceptual processing. However, less is known about the cognitive‐behavioral consequences of these effects and their role during stress. Here, we investigated in how far automatic responses during the Simon task were modulated by exposure to a laboratory stressor and the different phases of the cardiac cycle. In this study, 30 participants performed three blocks of a combined horizontal and vertical Simon task, which is characterized by either sensorimotor or cognitive response conflicts, respectively. Before each block, subjects were exposed to both the cold pressor test (CPT) and a control condition according to a within‐subjects design. Target stimuli were presented during either systole or diastole. Behavioral and EEG‐correlates of task processing were assessed along with subjective, cardiovascular, and endocrine measures of stress. The stress induction was successful yielding significant increases in all these measures compared to control. Moreover, we found the expected Simon effects: in incompatible compared to compatible trials performance was decreased and LRP latency as well as anterior N2 area increased. Importantly, accuracy was improved in compatible but reduced in incompatible trials during systole vs. diastole but only in the horizontal Simon condition. Stress dampened N2 area, however, no interactions with cardiac cycle were evident. These results indicate a faciliatory effect of cardioafferent traffic on automated sensorimotor processes.
... When there are more incongruent trials in the Simon task, the frequency of spatially incompatible S-R associations is temporarily high. It has been shown that the brain can learn the spatially incompatible S-R associations and use them to prepare responses, as suggested by the reversed Simon effect (faster RTs in the incongruent than in the congruent trials; e.g., Hommel, 1994;Marble & Proctor, 2000;Stürmer et al., 2002). A recent modeling study has shown that these short-term-memory irrelevant S-R associations are represented by bias in the starting point in the DMC (J. ...
... The behavioral results are consistent with previous findings in three aspects. First, the Simon effect was reversed in both normal sleep and SD conditions, indicating that participants used learned short-term-memory spatially incompatible S-R associations to predict responses (Hommel, 1994(Hommel, , 2011J. Luo et al., 2023). ...
Previous studies suggest that interference control may be unaffected by sleep deprivation based on the unchanged interference effects (reaction time [RT] differences between incongruent and congruent conditions), while ignoring the overall slower RTs after sleep deprivation. In the present study, we interpreted these results from a new angle using a variant of diffusion model, diffusion model for conflict tasks (DMC), and investigated whether and how interference control is affected by sleep deprivation. Mathematical derivations and model simulations showed that unchanged task-irrelevant information processing (i.e., unaffected interference control) may not lead to the observed unchanged interference effects when considering the overall slower RTs after sleep deprivation (due to either decreased drift rate of task-relevant information or increased decision boundary). Therefore, the unchanged interference effects do not necessarily indicate unchanged interference control. We then conducted a Simon task following one night of sleep deprivation or normal sleep, and fitted the DMC to the data. Experimental results showed that the Simon effect was reversed when most of the trials were incongruent, indicating that participants used learned spatially incompatible stimulus–response associations to predict responses. However, the Simon effects in both mean RTs and RT distributions were not significantly modulated by sleep deprivation. Model fits showed that the drift rate of task-relevant information decreased and the time-to-peak of task-irrelevant activation increased after sleep deprivation. These results suggest that central information processing was degraded after sleep loss, and most importantly, task-irrelevant activation increased after sleep deprivation as interference control was impaired.
... Activation of the position nodes is presumed to be rapid and automatic. However, being task irrelevant, it decreases over time as a result of either passive decay or active inhibition (see Hommel, 1994, andZorzi &Umilta, 1995, for discussion). In the model, position nodes are activated at stimulus onset, and the activation leaks over time through a simple decay function: ...
... The initial activation of the incorrect response node in the noncorresponding condition (due to priming from the position node) is the equivalent of event-related potential recordings showing activity related to the incorrect response (De Jong et al., 1994;Eimer, 1995). Finally, the Z&U model accounts for the finding that the Simon effect decreases as a function of task difficulty (i.e., as overall RT becomes slower; Hommel, 1994;Rubichi, Nicoletti, lani, & Umilta, 1997). Because activation of the position nodes decays over time, the subthreshold activity generated by the spatial code eventually dies off (see Figure 4 in Zorzi & Umilta, 1995). ...
In Experiment 1, children performed a Simon task after a spatially compatible or incompatible task. Results showed a Simon effect after the spatially compatible task and a reversed Simon effect after the spatially incompatible task. In Experiments 2–5, an identical procedure was adopted with adult participants, who performed the Simon task immediately after, a day after, or a week after the spatial compatibility task. Experiment 6 established a baseline for the Simon effect. Results showed a Simon effect after the spatially compatible task and no Simon effect or a reversed Simon effect after the spatially incompatible task. A modified version of the computational model of M. Zorzi and C. Umiltà (1995) was used to compare possible accounts of the findings. The best account exploits 2 types of short-term-memory links between stimulus and response and their interaction with long-term-memory links.
... Interestingly, this time-course of T2 response activation seems to be a marked difference to the temporal development of task-irrelevant information in classical conflict tasks, such as the Simon or flanker task (B. A. Eriksen & Eriksen, 1974;Simon, 1969). In these tasks, where participants are required to respond to a task-relevant feature (e.g., a central stimulus in the flanker task) while ignoring a task-irrelevant feature (e.g., some flanking/surrounding stimuli), the activation induced by the task-irrelevant feature is rather transient (e.g., Hübner & Töbel, 2019;Miller & Schwarz, 2021;Pratte, 2021;Ulrich et al., 2015): After a relatively early peak, the activation induced by the task-irrelevant feature declines again, either due to active suppression (Ridderinkhof, 2002) or passive decay (Hommel, 1994). In contrast, for the BCE, a decline of T2 response activation was not observed, likely because T2 eventually becomes response-relevant ; see also Mittelstädt et al., 2023, for related results). ...
When two speeded tasks have spatially overlapping responses, preactivated Task 2 (T2) response information influences Task 1 (T1) response selection, a phenomenon known as the backward crosstalk effect (BCE). Current models of the BCE implicitly assume that T2 response information is equally present in trials requiring compatible or incompatible responses, such that T1 performance improves when T2 requires a compatible response and deteriorates when T2 requires an incompatible response. Thus, T2 response information should have a facilitatory and an interfering effect on T1. Interestingly, this hypothesis has never been tested, and the present study (conducted between 2021 and 2023) attempts to fill this gap by using neutral trials in which T2 responses did not spatially overlap with those in T1. The results suggest that the BCE (in T1) reflects both facilitation and interference effects of comparable magnitude, thus corroborating current conceptualizations of the BCE. We also observed an unexpected pattern of effects for T2, with only an interference effect, but no facilitation effect. Additional experiments led us to conclude that the T2 result was sensitive to the specific task characteristics. Conclusions about how the crosstalk transfers from T1 to T2 when switching tasks are therefore not possible.
Research has established that two cognitive processes, cognitive control and irrelevant stimulus-response (S-R) learning, may underlie the proportion congruency effect, which refers to the findings that the size of interference effects (e.g., the Stroop, Simon, or Eriksen flanker effect) reduces with increasing the proportion of incongruent trials. Further studies have begun to investigate the interaction between these two cognitive processes, which not only provide more plausible accounts for empirical data, but also advance theories. The present study set out to investigate whether cognitive control can modulate the effect of irrelevant S-R learning. In two experiments, we combined a color-letter contingency task, in which we manipulated the contingencies (low vs. high) of irrelevant S-R associations, with a color-Chinese character Stroop task, in which we manipulated the ratio of neutral to incongruent trials (mostly neutral (MN) versus mostly incongruent (MI)). Experiment 1 showed a proportion neutral effect (the Stroop effect was smaller in the MI than in the MN condition), suggesting changes in control demand. Critically, the contingency effect (faster responses in the high- than in the low-contingency condition) reduced in the MI than in the MN condition. Experiment 2 (preregistered) increased the number of Chinese characters to exclude a familiarity account for the proportion neutral effect, which replicated the findings of Experiment 1. These results suggest that cognitive control induced in the Stroop task transferred to the contingency task and modulated the contingency effect. Thus, this study provides clear evidence that cognitive control can modulate the effect of irrelevant S-R learning.
Designing auditory displays requires understanding how different attributes of sound are processed. Operators must often listen to a particular stimulus dimension and make control actions contingent on the auditory information. Three experiments used a selective-listening paradigm to examine interactions between auditory dimensions. Participants were instructed to attend to either relative pitch or direction of pitch change of dynamic stimuli. With vertically arranged keypress responses, reactions to both dimensions showed stimulus–response compatibility effects, indicating that pitch is treated spatially. Direction of pitch change affected responses to pitch; level of pitch more strongly affected responses to pitch change. To reduce deleterious effects of irrelevant pitch information, auditory display designers can restrict the pitch range used to display dynamic data.
Limbic and motor integration is enabled by a mesial temporal to motor cortex network. Parkinson's disease (PD) is characterized by a loss of dorsal striatal dopamine but relative preservation of mesolimbic dopamine early in disease, along with changes to motor action control. Here, we studied 47 patients with PD using the Simon conflict task and [18F]fallypride PET imaging. Additionally, a cohort of 16 patients participated in a single-blinded dextroamphetamine (dAMPH) study. Task performance was evaluated using the diffusion model for conflict tasks, which allows for an assessment of interpretable action control processes. First, a voxel-wise examination disclosed a negative relationship, such that longer non-decision time is associated with reduced D2-like binding potential (BPND) in the bilateral putamen, left globus pallidus, and right insula. Second, an ROI analysis revealed a positive relationship, such that shorter non-decision time is associated with reduced D2-like BPND in the amygdala and ventromedial OFC. The difference in non-decision time between off-dAMPH and on-dAMPH trials was positively associated with D2-like BPND in the globus pallidus. These findings support the idea that dysfunction of the traditional striatal–motor loop underlies action control deficits but also suggest that a compensatory parallel limbic–motor loop regulates motor output.
The classic problem of stimulus-response (S-R) compatibility (SRC) is addressed. A cognitive model is proposed that views the stimulus and response sets in S-R ensembles as categories with dimensions that may or may not overlap. If they do overlap, the task may be compatible or incompatible , depending on the assigned S-R mapping. If they do not overlap, the task is noncompatible regardless of the assigned mapping. The overlapping dimensions may be relevant or not. The model provides a systematic account of SRC effects, a taxonomy of simple performance tasks that were hitherto thought to be unrelated, and suggestive parallels between these tasks and the experimental paradigms that have traditionally been used to study attentional, controlled, and automatic processes. In this article, we address the classic problem of stimulus-response (S-R) compatibility (SRC). A model is proposed that attempts to provide a systematic account of performance in highly compatible, incompatible, and noncompatible tasks. At the core of our model is the idea that when a particular S-R ensemble produces either high or low compatibility effects, it is because the stimulus and response sets in the ensemble have properties in common, and elements in the stimulus set automatically activate corresponding elements in the response set. Noncompatible tasks are those in which the stimulus and response sets have nothing in common. If the activated response is the required one, it will be executed rapidly and correctly; if it is not, then it will be relatively slow and error prone. Whether a particular S-R ensemble will produce compatibility effects is often quite easy to determine because of the relationship between the stimulus and response sets. In the part of the model that treats the representational aspects of the problem, we postulate that this relationship is based on the commonality, simi-or GBDV @umichum.bitnet. larity, or correspondence of the sets in the ensemble. We call this the dimensional overlap of the ensemble. The automatic response activation mechanisms, as well as the response identification processes underlying SRC effects, are the processing aspect of the model. Even though the model is still in its qualitative development phase, it is able to make ordinal predictions concerning several different SRC effects, such as the effects of mapping, irrelevant dimensions, and number of alternatives. These effects had been viewed as unrelated empirical phenomena , and most of the work on SRC has dealt with them as manifestations of unique, nongeneralizable properties of particular dimensions or specific tasks. This approach has led to different accounts being proposed for "spatial," "symbolic," "sensori-motor," and "semantic" tasks. Our model attempts to break with such past approaches in a fundamental way by proposing to account for most major SRC effects in terms of common basic cognitive mechanisms. This unitary approach leads to a taxonomy of SRC tasks that reveals striking similarities between them and suggestive parallels with the experimental paradigms that have traditionally been used to investigate atten-tional, controlled, and automatic processes. Background on SRC
Two experiments used the locus-of-cognitive-slack method to determine whether dual-task interference occurs before or after the response selection stage. The experiments used the overlapping tasks paradigm, in which two signals, each requiring a different speeded choice response, are presented in rapid succession. In Experiment 1, stimulus-response (S-R) compatibility was manipulated by varying whether Task 2 stimuli were mapped onto their responses by a rule or arbitrarily. Compatibility effects were additive with the effects of degree of task overlap, manipulated by varying the stimulus onset asynchrony between the signals. Experiment 2 examined 2 additional forms of S-R compatibility: symbolic compatibility (arrows vs. letters) and spatial compatibility (the "Simon" effect). Effects of symbolic compatibility were additive with effects of degree of task overlap, whereas the effects of spatial compatibility and degree of task overlap were underadditive. It is argued that only a central-bottleneck model provides a consistent account of these results. The nature of the central bottleneck is considered.
Do perception and action share some of the same cognitive structures? What is the relationship between cognitive processes for sequencing, timing, and error detection in perception and action? Such issues form the basis for this fresh and absorbing study of the perception and production of language and other cognitive skills such as chess and piano playing. The Organization of Perception and Action provides a coherent and innovative synthesis of available data, challenges classical theories, and offers new insights into relations between language, thought, and action. Its broad, interdisciplinary approach and wealth of detailed examples extend from the motor control of typing to the role of attention in perception and action and the flexibility of conscious vs. unconscious processes. Not only researchers, but anyone with a general interest in the cognitive and brain sciences will find in this book new and interesting insights into topics long considered fundamental to psychology and related disciplines.
Theories of perception and action must account for three basic aspects of skilled behavior, and so far, the book has examined only the first two: What components underlie the organization of everyday action and perception, and what mechanisms activate these components in proper sequence?
When this title was originally published in 1981, the information processing approach to perception and memory was dominant in experimental psychology, and the research reported here had major implications for future development. After exploring the shortcomings of earlier work in this field, the author develops a new model which he shows to be capable of accounting for a variety of experimental data connected with human information processing, visual perception and attention. The central theme which is discussed is how we select relevant and discard irrelevant information. The basic assumption is that all incoming information is identified, that is, it reaches and activates the appropriate lexical entries. A piece of identified information is described as a unit consisting of three distinguishable codes: a visual code, a lexical or semantic code and a motor or action code. Identified information decays fast, so selective attention operates by selecting those units which have to be saved from this rapid decay. In a sense, therefore, the human information processor is described as struggling against forgetting.
Examined the ability of 36 undergraduates to strategically influence interference from conflicting color words while naming colors on the Stroop Color and Word Test in 3 experiments. Exps I and II involved 2 colors presented for every word, a compatible color and a conflicting color; thus, words could predict the colors. Exp III involved 4 colors, and like Exp II, required vocal responses. Results show that contingencies introduced between words and colors allowed Ss to predict the value of the reported (color) dimension when given the value of the unreported (word) dimension and thereby to speed processing. Strategies to exploit these contingencies were adopted when 2 colors were used and buttonpress responses (Exp I) and vocal responses (Exp II) were required. When 4 colors were used (Exp III), there was no evidence of the strategy. Implications for the interpretation of existing Stroop data are discussed. (10 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
It has been shown that spatial compatibility is due to a comparison between the spatial codes that describe stimulus and response positions. Such codes are often defined in right-left terms. There are, however, two types of right-left codes that can be used for describing a position in space. One is formed with relation to the egocentric axes and can be termed side, whereas the other is formed with relation to an external reference location and can be termed relative position. Five experiments were conducted to determine the role of these different codes in producing spatial compatibility effects. In Experiments 1 and 2 the position of the stimulus provided the relevant cue for choosing the correct response (i.e., the situation was typical of spatial compability proper), whereas in Experiments 3, 4, and 5 the stimulus provided a locational cue that was not necessary for choosing the correct response (i.e., the situation was typical of the Simon effect). The experimental manipulations concerned the task demands and the time elapsing between availability of the stimulus code and availability of the response code. The results showed that upon stimulus presentation, both stimulus codes (that concerning side and that concerning relative position) were formed, but experimental manipulations determined the one that was effective in yielding compatibility effects. When the task required the use of one type of code, then spatial compatibility depended on that code alone. When the two coding processes were separated in time, then spatial compatibility depended only on the code that was formed simultaneously with the response code.
Three experiments are reported that involve responding to the meaning or position of a word (Above or Below) presented above
or below a fixation point. Position and word meaning conflicted (Above/below or Below/above) or were compatible (Above/above
or Below/below), and the relative frequency of conflicting trials was varied. Experiment 1 required responses to the word
and its position. Compatibility and frequency had no effect in the spatial task, but interacted strongly in the word task:
Compatible stimuli were processed faster when conflicting trials were rare (20% conflicting), but conflicting stimuli were
processed faster when they were frequent (80% conflicting). Experiments 2 and 3 used the word task only and extended these
findings to intermediate (20%, 40%, 60%, and 80% conflicting) and more extreme (10%, 20%, 80%, and 90% conflicting) frequencies,
respectively. The advantage for conflicting stimuli when they were frequent was taken as evidence for a strategy involving
dividing attention between reported and unreported dimensions.