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.     

Attention,instruction, and response representation

A two-dimensional Simon-type task was devised to investigate the impact of task requirements and explicit instructions on spatial action coding. Subjects performed actions that were defined on two spatial dimensions: horizontal (left-right) or vertical (top-bottom). The relevant stimulus feature was nonspatial but the stimuli varied on the horizontal and the vertical dimension, so that horizontal and vertical S-R compatibility effects could be measured separately. Implicit task requirements were manipulated by having the subjects perform an unrelated task before the Simon task—a task in which only one of the two spatial dimensions was relevant. Instructions were varied by describing the responses in the unrelated priming task and/or in the Simon task in spatial terms or by referring to nonspatial features of the response keys. Priming a particular dimension increased the Simon effect on that dimension, whereas instructions had no differential effect. These findings suggest that, first, drawing attention to a particular dimension leads to a stronger contribution to event representation of those features defined on that dimension (intentional weighting) and, second, that instructions do not affect action coding if the manipulation does not change the task goal.     

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.     

Attentional focussing and spatial stimulus-response compatibility

Summary The relative functional significance of attention shifts and attentional zooming for the coding of stimulus position in spatial compatibility tasks is demonstrated by proposing and testing experimentally a tentative explanation of the absence of a Simon effect in Experiment 3 of Umiltà and Liotti (1987). It is assumed that the neutral point of the spatial frame of reference for coding spatial position is at the position where attention is focussed immediately before exposition of the stimulus pattern. If a stimulus pattern is exposed to the right or the left of this position a spatial compatibility effect can be observed when the stimulus-response pairing is incompatible. Generalizing from this, one can say that a spatial compatibility effect will be observed if the last step in attentional focussing of the stimulus attribute specifying the response is a horizontal or a vertical attention shift. If the last step in focussing is attentional zooming (change in the representational level attended to), the stimulus pattern is localized at the horizontal and the vertical positions where the last attention shift had positioned the focus. In this case the spatial code is neutral on these dimensions and so no spatial compatibility effect should result. To test this model we conducted two experiments. Experiment 1 replicated the finding of Umiltà and Liotti that there is no Simon effect in the condition with no delay between a positional cue (two small boxes on the left or right of a fixation cross) and the imperative stimulus, whereas in the condition with a delay of 500 ms a Simon effect was observed. In a comparison condition with a single, rather large cue instead of two small boxes (forcing attention to zoom in), no Simon effect was observed under either delay condition. Experiment 2 used a spatial compatibility task proper with the same experimental conditions as Experiment 1. But in contrast to those of Experiment 1, the results show strong compatibility effects in all cue and delay conditions. The absence of a Simon effect in some experimental conditions in Experiment 1 and the presence of a spatial compatibility effect proper in all conditions in Experiment 2 are consistently accounted for with the proposed attentional explanation of spatial coding and spatial compatibility effects.     

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.     

Between-task transfer of learning from spatial compatibility to a color stroop task

Responses to a relevant stimulus dimension are faster and more accurate when the stimulus and response spatially correspond compared to when they do not, even though stimulus position is irrelevant (Simon effect). It has been demonstrated that practicing with an incompatible spatial stimulus-response (S-R) mapping before performing a Simon task can eliminate this effect. In the present study we assessed whether a learned spatially incompatible S-R mapping can be transferred to a nonspatial conflict task, hence supporting the view that transfer effects are due to acquisition of a general "respond to the opposite stimulus value" rule. To this aim, we ran two experiments in which participants performed a spatial compatibility task with either a compatible or an incompatible mapping and then transferred, after a 5 min delay, to a color Stroop task. In Experiment 1, responses were executed by pressing one of two keys on the keyboard in both practice and transfer tasks. In Experiment 2, responses were manual in the practice task and vocal in the transfer task. The spatially incompatible practice significantly reduced the color Stroop effect only when responses were manual in both tasks. These results suggest that during practice participants develop a response-selection strategy of emitting the alternative spatial response.     

Referential coding contributes to the horizontal SMARC effect

The present study tested whether coding of tone pitch relative to a referent contributes to the correspondence effect between the pitch height of an auditory stimulus and the location of a lateralized response. When left-right responses are mapped to high or low pitch tones, performance is better with the high-right/low-left mapping than with the opposite mapping, a phenomenon called the horizontal SMARC effect. However, when pitch height is task irrelevant, the horizontal SMARC effect occurs only for musicians. In Experiment 1, nonmusicians performed a pitch discrimination task, and the SMARC effect was evident regardless of whether a referent tone was presented. However, in Experiment 2, for a timbre-judgment task, nonmusicians showed a SMARC effect only when a referent tone was presented, whereas musicians showed a SMARC effect that did not interact with presence/absence of the referent. Dependence of the SMARC effect for nonmusicians on a reference tone was replicated in Experiment 3, in which judgments of the color of a visual stimulus were made in the presence of a concurrent high- or low-pitched pure tone. These results suggest that referential coding of pitch height is a key determinant for the horizontal SMARC effect when pitch height is irrelevant to the task.     

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。     

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     

Preparation for horizontal or vertical dimensions affects the right-left prevalence effect

When stimulus and response simultaneously vary in both horizontal and vertical dimensions, the stimulus-response compatibility effect is often larger for the horizontal dimension. We investigated the role of preparation for each dimension in this right-left prevalence. In Experiment 1, tasks based on horizontal and vertical dimensions were mixed in random order, and the relevant dimension in each trial was cued with a variable cue-target stimulus onset asynchrony (SOA). A right-left prevalence effect was observed only when participants prepared for the upcoming task. Experiment 2 replicated the absence of the prevalence effect for the simultaneous presentation of cue and target using a fixed SOA of 0 msec. In Experiment 3, the right-left prevalence emerged with a 0-msec SOA when participants prepared for e achdimension basedon its frequency. These resultssuggest that participants' internal set can be greater for the horizontal dimension, leading to the right-left prevalence effect.     

Shared learning shapes human performance: Transfer effects in task sharing

We investigated whether performing a task with a co-actor shapes the way a subsequent task is performed. In four experiments participants were administered a Simon task after practicing a spatial compatibility task with an incompatible S-R mapping. In Experiment 1 they performed both tasks alongside another person; in Experiment 2 they performed the spatial compatibility task alone, responding to only one stimulus position, and the Simon task with another person; in Experiment 3, they performed the spatial compatibility task with another person and the Simon task alone; finally, in Experiment 4, they performed the spatial compatibility task alone and the Simon task with another person. The incompatible practice eliminated the Simon effect in Experiments 1 and 4. These results indicate that when a task is distributed between two participants with each one performing a different part of it, they tend to represent the whole task rather than their own part of it. This experience can influence the way a subsequent task is performed, as long as this latter occurs in a social context.     

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.     

A response-discrimination account of the Simon effect

Simon effects might partly reflect stimulus-triggered response activation. According to the response-discrimination hypothesis, however, stimulus-triggered response activation shows up in Simon effects only when stimulus locations match the top-down selected spatial codes used to discriminate between alternative responses. Five experiments support this hypothesis. In Experiment 1, spatial codes of each response differed by horizontal and vertical axis position, yet one axis discriminated between alternative responses, whereas the other did not. Simon effects resulted for targets on discriminating axes only. In Experiment 2, both spatial axes discriminated between responses, and targets on both axes produced Simon effects. In Experiment 3, Simon effects resulted for a spatial choice-reaction task but not for a go/no-go task. Even in the go/no-go task, a Simon effect was restored when a two-choice reaction task preceded the go/no-go task (Experiment 4) or when participants initiated trials with responses spatially discriminated from the go response (Experiment 5).     

Role of gravitational cues in the haptic perception of orientation

The haptic perception of vertical, horizontal, +45°-oblique, and +135°-oblique orientations was studied in adults. The purpose was to establish whether the gravitational cues provided by the scanning arm—hand system were involved in the haptic oblique effect (lower performances in oblique orientations than in vertical—horizontal ones) and more generally in the haptic coding of orientation. The magnitude of these cues was manipulated by changing gravity constraints, and their variability was manipulated by changing the planes in which the task was performed (horizontal, frontal, and sagittal). In Experiment 1, only the horizontal plane was tested, either with the forearm resting on the disk supporting the rod (“supported forearm” condition) or with the forearm unsupported in the air. In the latter case, antigravitational forces were elicited during scanning. The oblique effect was present in the “unsupported” condition and was absent in the “supported” condition. In Experiment 2, the three planes were tested, either in a “natural” or in a “lightened forearm” condition in which the gravitational cues were reduced by lightening the subject’s forearm. The magnitude of the oblique effect was lower in the “lightened” condition than in the “natural” one, and there was no plane effect. In Experiment 3, the subject’s forearm was loaded with either a 500- or a 1,000-g bracelet, or it was not loaded. The oblique effect was the same in the three conditions, and the plane effect (lower performances in the horizontal plane than in the frontal and sagittal ones) was present only when the forearm was loaded. Taken together, these results suggested that gravitational cues may play a role in haptic coding of orientation, although the effects of decreasing or increasing these cues are not symmetrical.     

Response coding in the Simon task

Recent findings indicate that two distinct mechanisms can contribute to a Simon effect: a visuomotor information transmission on the one hand and a cognitive code interference on the other hand (see for e.g., Wiegand & Wascher, in Journal of Experimental Psychology: Human Perception and Performance 2005a). Furthermore, it was proposed that the occurrence of one or the other mechanism strongly depends on the way responses are coded. Visuomotor information transmission seems to depend on a correspondence between stimulus position and spatial anatomical status of the effector, whereas cognitive code interference is thought to be based on relative response location codes. To further test the spatial anatomic coding hypothesis, three experiments were conducted, in which the Simon effect with unimanual responses was investigated for horizontal (Experiment 1 and 2) and vertical (Experiment 3) stimulus-response (S-R) relations. Based on the finding of a decreasing effect function (indicating the presence of visuomotor information transmission) for horizontal and vertical S-R relations, it was concluded that visuomotor information transmission occurs whenever there is an overlap between the spatial stimulus feature and parameters of the motor representation of the response. Furthermore, the specific motor representation seems to be task dependent, that is, it entails those response parameters that clearly differentiate between the two response alternatives in a given task situation.     

Task-set inertia and memory-consolidation bottleneck in dual tasks

Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations (“ignore” trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC → BC vs. BC → BC) in Experiment 3.     

Influences on the Simon effect of prior practice with spatially incompatible mappings: Transfer within and between horizontal and vertical dimensions

The Simon effect refers to the fact that for tasks in which stimulus location is irrelevant and a nonspatial attribute is relevant, responses are typically faster when stimulus and response locations correspond than when they do not. Two experiments examined the influence of prior practice with an incompatible relevant spatial mapping on the Simon effect as a function of the dimension (vertical or horizontal) along which the stimuli and responses varied in practice and transfer sessions. With 72 practice trials, the Simon effect in the transfer session was eliminated only when the spatial dimension was horizontal for both practice and transfer. With 600 practice trials, the Simon effect was eliminated for all combinations of practice and transfer dimensions, with noncorresponding responses showing an advantage when the dimension was horizontal for both practice and transfer. Within-dimension transfer effects for the horizontal dimension after a small amount of practice can be attributed to reactivation of specific stimulus-response associations defined for the practice task. However, the between-dimension transfer effects evident after a larger amount of practice cannot be explained in this manner and suggest that the subjects acquired a general procedure of responding opposite to the stimulus location.     

Effects of stimulus-stimulus compatibility and stimulus-response compatibility on response inhibition

Previous studies demonstrated that interference control in stimulus–stimulus compatibility tasks slowed down stopping in the stop signal task (e.g., Kramer, A. F., Humphrey, D. G., Larish, J. F., Logan, G. D., & Strayer, D. L. (1994). Aging and inhibition: beyond a unitary view of inhibitory processing in attention. psychology and aging, 9, 491–512). In the present study, the impact of stimulus–stimulus compatibility and stimulus–response compatibility on response inhibition is further investigated. In Experiment 1, the stop signal task was combined with a traditional horizontal Simon task and with a vertical variant. For both dimensions, stopping responses was prolonged in incompatible trials, but only when the previous trial was compatible. In Experiment 2, the Simon task was combined with a spatial Stroop task in order to compare the effects of stimulus–stimulus and stimulus–response compatibility. The results demonstrated that both types of compatibility influenced stopping in a similar way. These findings are in favor of the hypothesis that response inhibition in the stop signal task and interference control in conflict tasks rely on similar mechanisms.