The prevalence effect in two-dimensional stimulus-response compatibility is a function of the relative salience of the dimensions

When stimulus-response (S-R) sets vary along horizontal and vertical dimensions, a right-left prevalence effect is often obtained in which the horizontal compatibility effect is larger than the vertical compatibility effect. Vu and Proctor (2001) showed that the prevalence effect varies as a function of the dimension made salient by the response configuration. A salient features coding interpretation of this result implies that manipulating the salience of the stimulus display should produce similar results and that S-R translation should be fastest when salient features of the stimulus and the response sets correspond. Experiment 1 manipulated spatial proximity to make the vertical or the horizontal stimulus dimension salient. Neutral displays yielded a typical right-left prevalence effect, and this effect was enhanced by horizontal-salient displays and eliminated by vertical-salient displays. Experiments 2 and 3 showed that the benefit for horizontal (or vertical) compatibility was larger when the salient features of both the stimulus and the response sets emphasized the horizontal (or the vertical) dimension than when only one did. The results support salient features coding as an explanation for the prevalence effect obtained with two-dimensional S-R arrangements.     

Vertical versus horizontal spatial compatibility: Right-left prevalence with bimanual responses

For two-choice tasks in which stimulus and response locations vary along horizontal and vertical dimensions, the spatial compatibility effect is often stronger on the horizontal than vertical dimension. Umiltà and Nicoletti [(1990) Spatial stimulus-response compatibility (pp. 89–116). Amsterdam: North-Holland] attributed this right-left prevalence effect to an inability to code vertical location when horizontal codes are present simultaneously. Hommel [(1996) Perception & Psychophysics, 43, 102–110] suggested instead that it reflects a voluntary strategy. This study reports four experiments that examine this issue. Experiment 1 was a conceptual replication of Hommel's Experiment 1, with responses made on a numeric keypad and subjects instructed in terms of the vertical or horizontal dimension. The results replicated Hommel's findings that showed a right-left advantage with horizontal instructions; however, with vertical instructions, we found a benefit of vertical compatibility alone that he did not. This benefit for vertical compatibility alone was eliminated in Experiment 2 using a varied practice schedule similar to that used by Hommel. Experiment 3 showed right-left prevalence and a benefit of vertical compatibility alone, even with varied practice and vertical instructions, when subjects responded on perpendicularly arranged handgrips. These benefits were eliminated in Experiment 4 using Hommel's method of urging subjects to respond only in terms of the instructed dimension. With bimanual responses, right-left prevalence is a robust phenomenon that is evident when comparing across vertical and horizontal instructions and, when the right-left distinction is relatively salient, within the vertical instructions condition alone. Received: 4 February 2000 / Accepted: 5 May 2000     

Determinants of right-left and top-bottom prevalence for two-dimensional spatial compatibility

When stimulus and response sets vary along horizontal and vertical dimensions, the horizontal dimension is more dominant than the vertical one, an effect called right-left prevalence. Three accounts have been proposed that attribute the effect to a reduced ability to code vertical locations when horizontal codes are also present, the use of right-left effectors, or a difference in salience of the 2 dimensions. The accounts differ in terms of whether the ability to code and process the 2 dimensions is of limited capacity and whether the prevalence effect is a consequence of the effectors used for responding. The authors report 4 experiments that evaluated these issues. Results indicate that use of right-left effectors is important to the right-left prevalence effect because it increases the salience of the horizontal dimension. However, a top-bottom prevalence effect can be obtained if the vertical dimension is made more salient.     

Does right-left prevalence occur for the Simon effect?

In four experiments, we investigated whether a right-left prevalence effect occurs for the Simon task, in which stimulus location is irrelevant, when the stimulus and the response sets vary along horizontal and vertical dimensions simultaneously. Simon effects were evident for both dimensions, and they were of similar magnitude, indicating no prevalence effect. Manipulations of the relative salience of the dimensions for the stimulus and the response sets resulted in a larger Simon effect for the more salient dimension than for the less salient one, but there was no overall prevalence effect. The results indicate that manipulations of salience affect the relative magnitudes of automatic response activation for the vertical and the horizontal dimensions but that the right-left prevalence effect is due to a coding bias in intentional response selection processes when stimulus location is relevant.     

Effects of precuing horizontal and vertical dimensions on right—left prevalence

When stimuli and responses can be coded along horizontal and vertical dimensions simultaneously, a right-left prevalence effect is often obtained for which the advantage for a compatible mapping is larger on the horizontal dimension than on the vertical dimension. The present study investigated the role of preparatory processes in this right-left prevalence effect using a method in which the relevant dimension was cued at short and long intervals prior to presentation of the target stimulus. In three experiments, the right-left prevalence effect did not vary significantly in magnitude as a function of cue-target interval, suggesting that the effect is due primarily to relative salience of the horizontal and vertical codes, as determined by the task structure, and not to a greater ease of attending to the horizontal dimension.     

No overall right-left prevalence for horizontal and vertical Simon effects

The present study confirmed that there is no overall right-left prevalence effect for Simon tasks, in which stimulus location is irrelevant, when (1) the stimulus and response sets vary along both horizontal and vertical dimensions simultaneously, (2) the stimulus set varies along both dimensions, but the response set varies along only one dimension, and (3) the stimuli and responses vary in one of four possible locations and responses are made by a unimanual joystick movement. In all experiments, Simon effects of similar magnitude were evident for both the horizontal and the vertical dimensions. The findings suggest that the right-left prevalence effect observed with two-dimensional location-relevant tasks is not due to stronger overall automatic activation of horizontal codes but to different translation efficiencies in intentional response selection processes.     

Right—left prevalence effect with horizontal and vertical effectors

We investigated the right-left prevalence effect in spatial compatibility tasks by assessing subjects’ performance on a two-dimensional task in which both the horizontal and vertical spatial dimensions were task relevant. Two experiments were performed, in which stimulus-response mappings were one-dimensional (Experiment 1) and two-dimensional (Experiment 2). The subjects responded by using either horizontal or vertical effectors to stimuli appearing in four possible locations. With the one-dimensional mapping, the spatial compatibility effect was present only in the dimension relevant to the mapping. With the two-dimensional mapping, the horizontal compatibility effect was always present, whereas the vertical compatibility effect was present only when vertical effectors were used. This pattern of results indicates that horizontal coding takes place with either horizontal or vertical effectors, whereas vertical coding takes place only when vertical effectors are used.     

Right-left prevalence effect with horizontal and vertical effectors

We investigated the right-left prevalence effect in spatial compatibility tasks by assessing subjects' performance on a two-dimensional task in which both the horizontal and vertical spatial dimensions were task relevant. Two experiments were performed, in which stimulus-response mappings were one-dimensional (Experiment 1) and two-dimensional (Experiment 2). The subjects responded by using either horizontal or vertical effectors to stimuli appearing in four possible locations. With the one-dimensional mapping, the spatial compatibility effect was present only in the dimension relevant to the mapping. With the two-dimensional mapping, the horizontal compatibility effect was always present, whereas the vertical compatibility effect was present only when vertical effectors were used. This pattern of results indicates that horizontal coding takes place with either horizontal or vertical effectors, whereas vertical coding takes place only when vertical effectors are used.     

Right-left prevalence with task-irrelevant spatial codes

The present work investigated the right-left prevalence effect caused by the automatic activation of horizontal and vertical spatial codes in a task (Simon task) in which spatial information is task-irrelevant. Experiment 1 showed a horizontal Simon effect and a vertical Simon effect with a two-dimensional stimulus-response set. In Experiments 2 and 3, the right-left prevalence was obtained in two-dimensional Simon tasks with two contralateral effectors and four effectors respectively. Experiment 4 showed that horizontal coding is based on multiple spatial codes, whereas only one spatial code was formed for vertical coding. On the whole, these results support the notion that the right-left prevalence effect is a general phenomenon affecting spatial coding, and suggest that the horizontal dimension is prevalent because it is based on multiple spatial codes.     

Influence of auditory and audiovisual stimuli on the right–left prevalence effect

When auditory stimuli are used in two-dimensional spatial compatibility tasks, where the stimulus and response configurations vary along the horizontal and vertical dimensions simultaneously, a right–left prevalence effect occurs in which horizontal compatibility dominates over vertical compatibility. The right–left prevalence effects obtained with auditory stimuli are typically larger than that obtained with visual stimuli even though less attention should be demanded from the horizontal dimension in auditory processing. In the present study, we examined whether auditory or visual dominance occurs when the two-dimensional stimuli are audiovisual, as well as whether there will be cross-modal facilitation of response selection for the horizontal and vertical dimensions. We also examined whether there is an additional benefit of adding a pitch dimension to the auditory stimulus to facilitate vertical coding through use of the spatial-musical association of response codes (SMARC) effect, where pitch is coded in terms of height in space. In Experiment 1, we found a larger right–left prevalence effect for unimodal auditory than visual stimuli. Neutral, non-pitch coded, audiovisual stimuli did not result in cross-modal facilitation, but did show evidence of visual dominance. The right–left prevalence effect was eliminated in the presence of SMARC audiovisual stimuli, but the effect influenced horizontal rather than vertical coding. Experiment 2 showed that the influence of the pitch dimension was not in terms of influencing response selection on a trial-to-trial basis, but in terms of altering the salience of the task environment. Taken together, these findings indicate that in the absence of salient vertical cues, auditory and audiovisual stimuli tend to be coded along the horizontal dimension and vision tends to dominate audition in this two-dimensional spatial stimulus–response task.     

No prevalence of right-left over top-bottom spatial codes

Reaction time is known to depend on spatial stimulus-response compatibility in both the horizontal and the vertical dimensions. However, if both dimensions are varied in the same task, horizontal but not vertical compatibility affects performance, even if subjects are instructed to attend to the vertical dimension only (Nicoletti & Umiltà, 1984). Experiment 1 compared the effect of horizontal and vertical instructions in a task with left- versus right-handed key responses placed at a top versus bottom location. A horizontal-prevalence effect was observed only with a horizontal, and not with a vertical, instruction. This suggests that subjects might not have heeded the vertical instruction in the Nicoletti and Umiltà study but instead attended to the horizontal dimension. Experiment 2 did not yield any horizontal prevalence with one-handed responses (joystick movements). This indicates that top-bottom codes become ineffective only if the responses suggest an exclusively horizontal response coding. In sum, results demonstrated multiple spatial coding of stimuli and responses under appropriate conditions and suggest that the right-left codes do not dominate the top-bottom spatial codes.     

Orthogonal stimulus–response compatibility effects emerge even when the stimulus position is task irrelevant

The above-right/below-left mapping advantage with vertical stimuli and horizontal responses is known as the orthogonal stimulus–response compatibility (SRC) effect. We investigated whether the orthogonal SRC effect emerges with irrelevant stimulus dimensions. In Experiment 1, participants responded with a right or left key press to the colour of the stimulus presented above or below the fixation. We observed an above-right/below-left advantage (orthogonal Simon effect). In Experiment 2, we manipulated the polarity in the response dimension by varying the horizontal location of the response set. The orthogonal Simon effect decreased and even reversed as the left response code became more positive. This result provides evidence for the automatic activation of the positive and negative response codes by the corresponding positive and negative stimulus codes. These findings extended the orthogonal SRC effect based on coding asymmetry to an irrelevant stimulus dimension.     

Orthogonal stimulus-response compatibility effects emerge even when the stimulus position is task irrelevant

The above-right/below-left mapping advantage with vertical stimuli and horizontal responses is known as the orthogonal stimulus-response compatibility (SRC) effect. We investigated whether the orthogonal SRC effect emerges with irrelevant stimulus dimensions. In Experiment 1, participants responded with a right or left key press to the colour of the stimulus presented above or below the fixation. We observed an above-right/below-left advantage (orthogonal Simon effect). In Experiment 2, we manipulated the polarity in the response dimension by varying the horizontal location of the response set. The orthogonal Simon effect decreased and even reversed as the left response code became more positive. This result provides evidence for the automatic activation of the positive and negative response codes by the corresponding positive and negative stimulus codes. These findings extended the orthogonal SRC effect based on coding asymmetry to an irrelevant stimulus dimension.     

汉语背景下横纵轴上的心理时间线

采用反应区分范式, 以表示过去和未来的时间词为刺激, 对汉语背景下横、纵两轴上的时间表征情况进行了探讨。结果发现, (1)横、纵轴方向上都出现了STEARC效应; (2)右对角线方向上, 出现了服从横轴的减弱的STEARC效应, 且STEARC效应值呈正态分布。以上结果表明, 汉语背景下既存在从左向右的心理时间线, 也存在从上到下的心理时间线, 两种时间表征同时存在, 且横轴表征倾向于占优势。     

No overall right-left prevalence for horizontal

The present study confirmed that there is no overall right—left prevalence effect for Simon tasks, in which stimulus location is irrelevant, when (1) the stimulus and response sets vary along both horizontal and vertical dimensions simultaneously, (2) the stimulus set varies along both dimensions, but the response set varies along only one dimension, and (3) the stimuli and responses vary in one of four possible locations and responses are made by a unimanual joystick movement. In all experiments, Simon effects of similar magnitude were evident for both the horizontal and the vertical dimensions. The findings suggest that the right—left prevalence effect observed with two-dimensional location-relevant tasks is not due to stronger overall automatic activation of horizontal codes but to different translation efficiencies in intentional response selection processes.     

Congruency sequence effect in cross-task context: Evidence for dimension-specific modulation

The congruency sequence effect refers to a reduced congruency effect after incongruent trials relative to congruent trials. This modulation is thought to be, at least in part, due to the control mechanisms resolving conflict. The present study examined the nature of the control mechanisms by having participants perform two different tasks in an alternating way. When participants performed horizontal and vertical Simon tasks in Experiment 1A, and horizontal and vertical spatial Stroop task in Experiment 1B, no congruency sequence effect was obtained between the task congruencies. When the Simon task and spatial Stroop task were performed with different response sets in Experiment 2, no congruency sequence effect was obtained. However, in Experiment 3, in which the participants performed the horizontal Simon and spatial Stroop tasks with an identical response set, a significant congruency sequence effect was obtained between the task congruencies. In Experiment 4, no congruency sequence effect was obtained when participants performed two tasks having different task-irrelevant dimensions with the identical response set. The findings suggest inhibitory processing between the task-irrelevant dimension and response mode after conflict.     

The prioritization of perceptual processing in categorization

In three experiments, the effects of selective attention on perceptual processes in a complex multidimensional object categorization task were investigated. In each experiment, participants completed a perceptual-matching task to gain estimates of the perceptual salience of each stimulus dimension, then a categorization task using the same stimuli. In Experiments 1 and 2, the perceptual processing of stimulus dimensions was faster when dimensions were more diagnostic of category membership, regardless of their perceptual salience. Experiment 3 demonstrated that this prioritization of perceptual processing was evident even when stimuli were presented in unpredictable locations during categorization, indicating that the physical characteristics of the stimulus guide selective attention to diagnostic stimulus dimensions.     

Transfer of noncorresponding spatial associations to the auditory Simon task

Four experiments examined transfer of noncorresponding spatial stimulus-response associations to an auditory Simon task for which stimulus location was irrelevant. Experiment 1 established that, for a horizontal auditory Simon task, transfer of spatial associations occurs after 300 trials of practice with an incompatible mapping of auditory stimuli to keypress responses. Experiments 2-4 examined transfer effects within the auditory modality when the stimuli and responses were varied along vertical and horizontal dimensions. Transfer occurred when the stimuli and responses were arrayed along the same dimension in practice and transfer but not when they were arrayed along orthogonal dimensions. These findings indicate that prior task-defined associations have less influence on the auditory Simon effect than on the visual Simon effect, possibly because of the stronger tendency for an auditory stimulus to activate its corresponding response.     

Writing words from pictures: What representations are activated, and when?

In three experiments, the nature of the representations involved in written picture naming and the time course of their activation were investigated. French participants had to produce picture names while hearing distractors. In Experiment 1, distractors semantically related to the picture names yielded a semantic interference effect when a stimulus onset asynchrony (SOA) of--150 msec, but not when a SOA of 0 msec, was used, in both spoken and written picture naming. Experiment 2 showed that the semantic interference effect was not located at the conceptual level. In Experiment 3, participants wrote down picture names while hearing semantically related, phonologically related, both semantically and phonologically related, or unrelated distractors, presented at both SOAs. A semantic interference effect was obtained with phonologically unrelated distractors but was eliminated with phonologically related distractors. Facilitatory effects of phonologically related distractors were found at both SOAs. The implications of the findings for written picture naming are discussed.     

Goal relevance and artificial grammar learning

This investigation used a newly developed artificial grammar learning (AGL) paradigm in which participants were exposed to sequences of stimuli that varied in two dimensions (colours and letters) that were superimposed on each other. Variation within each dimension was determined by a different grammar. The results of two studies strongly suggest that implicit learning in AGL depends on the goal relevance of the to-be-learned dimension. Specifically, when only one of the two stimulus dimensions was relevant for their task (Experiment 1) participants learned the structure underlying the relevant, but not that of the irrelevant dimension. However, when both dimensions were relevant, both structures were learned (Experiment 2). These findings suggest that implicit learning occurs only in dimensions to which we are attuned. Based on the present results and on those of Eitam, Hassin, and Schul (2008) we suggest that focusing on goal relevance may provide new insights into the mechanisms underlying implicit learning.