Effects of S-R and R-R compatibility on bimanual movement time

Bimanual asymmetrical movements are generally found to be slower than symmetrical movements but asymmetrical movement normally involves visual separation of targets which might account for the effect. By using a system in which the subject controls two cursors on an oscilloscope screen by moving two levers the S-R relationship on either hand can be reversed, thus providing an asymmetrical movement task without visual separation of targets. Movement times for five right-handed subjects were recorded on four unimanual and six bimanual conditions varying with respect to both S-R and R-R compatibility. In the unimanual conditions, the left hand was found to be as fast as the right when the opposite S-R relationship was used. In the bimanual tasks visual separation of targets was a relatively minor factor movement time being strongly influenced by S-R compatibility and to a lesser degree by R-R compatibility. The results suggest that compatibility, rather than being a property of a single central channel, differs, as between the two cerebral hemispheres.     

Is automatic imitation a specialized form of stimulus–response compatibility? Dissociating imitative and spatial compatibilities

In recent years research on automatic imitation has received considerable attention because it represents an experimental platform for investigating a number of interrelated theories suggesting that the perception of action automatically activates corresponding motor programs. A key debate within this research centers on whether automatic imitation is any different than other long-term S-R associations, such as spatial stimulus-response compatibility. One approach to resolving this issue is to examine whether automatic imitation shows similar response characteristics as other classes of stimulus-response compatibility. This hypothesis was tested by comparing imitative and spatial compatibility effects with a two alternative forced-choice stimulus-response compatibility paradigm. The stimulus on each trial was a left or right hand with either the index or middle finger tapping down. Speeded responses were performed with the index or middle finger of the right hand in response to the identity or the left-right spatial position of the stimulus finger. Two different tasks were administered: one that involved responding to the stimulus (S-R) and one that involved responding to the opposite stimulus (OS-R; i.e., the one not presented on that trial). Based on previous research and a connectionist model, we predicted standard compatibility effects for both spatial and imitative compatibility in the S-R task, and a reverse compatibility effect for spatial compatibility, but not for imitative compatibility, in the OS-R task. The results from the mean response times, mean percentage of errors, and response time distributions all converged to support these predictions. A second noteworthy result was that the recoding of the finger identity in the OS-R task required significantly more time than the recoding of the left-right spatial position, but the encoding time for the two stimuli in the S-R task was equivalent. In sum, this evidence suggests that the processing of spatial and imitative compatibility is dissociable with regard to two different processes in dual processing models of stimulus-response compatibility.     

A role for set in the control of automatic spatial response activation

Spatial stimulus-response (S-R) compatibility effects are widely assumed to reflect the automatic activation of a spatial response by the spatial attributes of a stimulus. The experiments reported here investigate the role of the participant's set in enabling or interacting with this putatively automatic spatial response activation. Participants performed a color discrimination task (Experiment 1) or a localization task (Experiment 2). In each experiment, two different S-R mappings were used and a task-cue indicated the appropriate mapping on each trial. S-R compatibility and the time between the task-cue and target were manipulated, and compatibility effects were assessed as a function of (a) the time between the task-cue and the stimulus, and (b) whether the S-R mapping repeated or switched on consecutive trials. Critically, whether response mappings repeated or switched on consecutive trials determined the relation between compatibility effects and the time between task-cue and stimulus. These results are discussed in terms of an interaction between automatic spatial response activation and the participant's set.     

Persistence of stimulus-response compatibility effects with extended practice.

The influence of extended practice on stimulus-response (S-R) compatibility effects was investigated. Three experiments, each extending over a period of 8 sessions, were conducted. The nature and degree of compatibility was manipulated across experiments. In all experiments, a persistent effect of S-R compatibility on reaction times was observed. Thus, the lower bound for reaction times appears to be less for compatible assignments than for incompatible assignments. This persistence of S-R compatibility indicates that the initial codings used to perform a novel task continue to exert an influence on later performance.     

Effects of stimulus-response uncertainty on watchkeeping performance and choice reactions

The present study was conducted to assess the effects of S-R uncertainty on performance in watchkeeping and typical type-b choice-reaction situations. The assessment was based in part on measurements of S-R compatibility effects in the two performance conditions. Four levels of S-R uncertainty (1, 2, 3 and 4 bits/S-R event) were combined factorially with two levels of S-R compatibility (high and low) and the two kinds of tasks (watchkeeping and choice-reaction); 12 Ss were assigned at random to each of the 16 conditions. A matrix of lights was used as stimuli in the choice-reaction condition; Ss monitored the matrix for a I-h duration in the watchkeeping condition. In both tasks, Ss responded by pressing a corresponding key after the presentation of a stimulus or “critical signal.” Reaction time (RT) was found to be an increas ing linear function of S-R uncertainty in both tasks. and the effects of S-R compatibility were essentially identical in the two. However, choice reactions were significantly faster than watchkeeping responses, and the rate of gain of information in watchkeeping was greater than in the comparable choice-reaction situations. The results are interpreted as supporting the hypothesis that watchkeeping differs from the simpler choice-reaction task principally in presenting an additional source of (temporal) uncertainty for information processing.     

Stimulus-Response Compatibility and Motor-Programming Effects: A Test of Theoretical Accounts of Compatibility

Traditional mental coding accounts of stimulus-response (S-R) compatibility suggest that the S-R translation stage is the locus for the effect (Umilta & Nicoletti, 1990; Wallace, 1971). However, recent response-priming accounts have suggested that the S-R translation and response-programming stages may interact to produce S-R compatibility effects (Kornblum, Hasbroucq, & Osman, 1990; Wickens. 1984; Zelaznik & Franz, 1990). Our study investigated the nature of the relation between these two stages relative to the S-R compat- ibility effect. Subjects performed a choice reaction-time task in response to visual stimuli. The critical manipulations in the study were of compatibility and response programming. The analysis revealed a significant compatibility effect but no interaction between the factors affecting compatibility and those affect- ing response programming. The results were consistent with the notion that the S-R translation stage of information processing is the locus of S-R compatibility effects. Thus S-R compatibility is an effect of the mental operations that occur within the S-R translation stage of human information processing.     

Control of stimulus-response translation in dual-task performance

In contradiction to stimulus-response- (S-R-) translation bottleneck models of dual-task control, stimulus processing in a primary task is affected by its compatibility with the response in a secondary, later performed task (Hommel, 1998a)- an indication of parallel S-R translation. Here we show that this backward-compatibility effect is independent of working-memory load, whether this is induced by an extra memory task (Experiment 1) or by increasing the number of S-R alternatives in the primary task (Experiment 2). However, backward effects occur even when the secondary task is no longer carried out (Experiment 3) and they are strongly affected by the inconsistency of previously used S-R mappings (Experiment 4). These findings suggest that S-R translation is (or can be) capacity-independent and automatic even under multiple-task conditions, and that it is mediated by direct S-R associations that emerge after only little practice.     

Selective effects of barbiturate and amphetamine on information processing and response execution

In a 3 × 2 × 2 factoral experiment, 12 subjects carried out a choice reaction task with reaction time (RT) and movement time (MT) as response measures.Independent variables were drug treatment (amphetamine, barbiturate, placebo), visual stimulus degradation and S-R compatibility. Visual stimulus degradation and S-R compatibility showed additive effect on the RT, but did not affect the MT. This confirms that stimulus encoding, response selection and response execution represent independent processing stages. The two drugs had selective effects on the RT and the MT. Barbiturate (as compared to placebo) had no effect on the MT, but it lengthened the RT, and this effect was additive with the effects of S-R compatibility but showed an interaction with the effects of stimulus degradation. Amphetamine (as compared to placebo) shortened the MT, but there was no significant main effect of amphetamine on the RT although the interaction with the effect of S— compatibility was significant. These results suggest that barbiturate affects stimulus encoding whereas amphetamine affects response-related processes..     

Dual-task interference as a function of cognitive processing load

Sixteen subjects from the Naval Submarine Medical Research Laboratory participated in a dual-task study designed to measure processing requirements of a choice reaction time (RT) task. Two levels of choice RT stimulus-response (S-R)compatibility were tested with each of two tracking tasks to provide different levels of dual-task loading. In one tracking task, the target's temporal-spatial pattern was fixed; in the other, the target's path was a function of the subject's performance. In the choice RT task, compatibility was treated as a between-subjects factor, while the number of alternatives (set size) within a sequence was a within-subjects variable. Choice RT results indicated that compatibility and set size interacted; the increase in response latency as a function of set size was much greater when compatibility was low. An increase in choice RT response latency occurred when the secondary tracking task was added. Within a given compatibility level, this dual-task decrement was constant for all levels of set size; however, the magnitude of the dual-task decrement varied as a function of S-R compatibility, being greater when compatibility was low than when it was high. For these data, a model like Sternberg's (1969) stages model is seen to have more explanatory value than a pooled processing capacity model (e.g., Norman and Bobrow 1975).     

Error-detection and correction latencies as a function of S-R compatibility

In choice-response tasks employing correction-procedure, error-correcting responses are typically found to be faster than equivalent correct responses. An experiment was made to compare error-correction RT under conditions of good and poor S-R compatibility in a two-choice task. After practice, variations in S-R compatibility producing significant variations in mean correct RT nevertheless have no effect on error-correction time. The contrast between this result, and one previously reported (Burns, 1965) leads to a re-discussion of the processes of error detection and correction.     

Effect of compatibility of S-R mapping on reactions toward the stimulus source

This research was concerned with separating the effects of three varieties of S-R compatibility: reactions toward the stimulus source, compatibility of S-R mapping, and display-control arrangement correspondence. In experiments 1 and 2, subjects pressed a green or red key located on the left and right in response to the onset of a green or red stimulus presented in a left or right window. Half of the subjects pressed the key which corresponded to the color of the stimulus (compatible S-R mapping) while the other half pressed the alternate colored key (incompatible S-R mapping). In the compatible mapping task, reactions were faster when location of stimulus and response corresponded than when they did not while, in the incompatible task, reactions were faster when location of stimulus and response did not correspond. This apparent reversal in the tendency to react toward the stimulus source was attributed to display- control arrangement correspondence rather than to logical recoding of the directional cue. Experiment 3 established that faster reactions toward the stimulus source occured only under compatible mapping instructions.     

Dilution of compatibility effects in Simon-type tasks depends on categorical similarity between distractors and diluters

The presence of a distracting stimulus during performance of the Stroop color-naming task leads to dilution of the Stroop effect. Because the automatic activation of word meaning may interfere with the task-relevant stimulus feature (text color; stimulus-stimulus [S-S] interference) and the response (saying the text color; stimulus-response [S-R] interference), it is unclear which of these types of interference is diluted. We introduce a new dilution paradigm using word- and arrow-based Simon tasks, in which only S-R interference is present. Participants made a left or right response to a central color target. A task-irrelevant location-word (Experiment 1) or arrow (Experiment 2) distractor adjacent to the target produced S-R compatibility effects. An additional neutral word or symbol series (diluter) was sometimes presented on the opposite side of the target from the distractor. The compatibility effect was smaller when the distractor and diluter category domains matched than when they mismatched. This result provides evidence that S-R compatibility effects are susceptible to the presence of diluters that are categorically similar to the distractors.     

Dimensional overlap: cognitive basis for stimulus-response compatibility--a model and taxonomy

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.     

A suppressing effect of response selection on immediate arousal in a choice reaction task

A clear conflict exists between experiments showing either additive or interactive effects of foreperiod duration and S-R compatibility on choice reaction time. It is hypothesized that in principle S-R compatibility and foreperiod duration have additive effects but that the effect of foreperiod duration is reduced in conditions where a signal is immediately arousing and where the S-R relations are highly compatible. In the case of low S-R compatibility the effect of immediate arousal is supposed to be ineffective.This hypothesis is tested and confirmed in an experiment in which the combined effects of foreperiod duration and S-R compatibility were studied with either loud (85 dBA) or weak (45 dBA) auditory signals. As predicted, additive effects were found in the latter case, while an interaction was observed with 85 dBA signals.     

Sequence learning at optimal stimulus-response mapping: evidence from a serial reaction time task

We propose a new version of the serial reaction time (SRT) task in which participants merely looked at the target instead of responding manually. As response locations were identical to target locations, stimulus-response compatibility was maximal in this task. We demonstrated that saccadic response times decreased during training and increased again when a new sequence was presented. It is unlikely that this effect was caused by stimulus-response (S-R) learning because bonds between (visual) stimuli and (oculomotor) responses were already well established before the experiment started. Thus, the finding shows that the building of S-R bonds is not essential for learning in the SRT task.     

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.     

Transfer of orthogonal stimulus-response mappings to an orthogonal Simon task

When up-down stimulus locations are mapped to left-right keypresses, an overall advantage for the up-right/down-left mapping is often obtained that varies as a function of response eccentricity. This orthogonal stimulus-response compatibility (SRC) effect also occurs when stimulus location is irrelevant, a phenomenon called the orthogonal Simon effect, and has been attributed to correspondence of stimulus and response code polarities. The Simon effect for horizontal stimulus-response (S-R) arrangements has been shown to be affected by short-term S-R associations established through the mapping used for a prior SRC task in which stimulus location was relevant. We examined whether such associations also transfer between orthogonal SRC and Simon tasks and whether correspondence of code polarities continues to contribute to performance in the Simon task. In Experiment 1, the orthogonal Simon effect was larger after practising with an up-right/down-left mapping of visual stimuli to responses than with the alternative mapping, for which the orthogonal Simon effect tended to reverse. Experiment 2 showed similar results when practice was with high (up) and low (down) pitch tones, though the influence of practice mapping was not as large as that in Experiment 1, implying that the short-term S-R associations acquired in practice are at least in part not modality specific. In Experiment 3, response eccentricity and practice mapping were shown to have separate influences on the orthogonal Simon effect, as expected if both code polarity and acquired S-R associations contribute to performance.     

Separating mental transformations and spatial compatibility effects in the own body transformation task

Laterality judgments about the left or right hand of a schematic human figure, made from the perspective of the figure, are faster and more accurate when the figure is presented in back-facing view as compared to front-facing view. Mental perspective transformation accounts of this finding have recently been challenged on grounds of a confounding of facing direction with spatial stimulus-response (S-R) compatibility (Gardner and Potts in Acta Psychol 137: 371-381, 2011). We report two experiments that introduced stimulus figures in an orientation that was neutral in terms of spatial S-R compatibility. Results revealed a stable back-facing advantage that cannot be explained by compatibility conflicts. Comparisons of these neutral stimuli and conditions with figures presented in upright or upside-down orientation, however, confirmed a substantial impact of spatial S-R compatibility in the latter conditions. The present experiments show that it is possible to distinguish between mental transformation and incompatibility costs allowing future work to focus on the specialized mental spatial transformation processes.     

Spatial compatibility of signal-response position in pointing

Two experiments are reported in which, by means of a pointing task, we studied the stimulus-position effect, i.e. the inverted U-shape form of the reaction-time function in relation to stimulus position in tasks in which stimuli and/or responses are arranged in a horizontal array. The response consisted of aiming the index finger from a central starting point at a target area on a screen. Reaction time was the main dependent variable. The spatial relation between the position of the imperative signal and the position of the response was manipulated by varying the spatial S-R compatibility and physical distance that separated the positions of stimulus and response. The stimulus-position effect was shown to depend on the compatibility of the S-R relation (Exp. 1). In Exp. 2 it was found that the modulation of the stimulus-position effect by spatial compatibility disappeared completely when the distance between the positions of stimulus and response was reduced. None of the experiments revealed that the stimulus position effect depended on signal discriminability, which renders an interpretation of this effect in terms of perceptual processes unlikely. We argue that the attentional model of spatial coding provides the most reasonable explanation of the obtained reaction-time patterns.     

Effects of mixed versus blocked design on stimulus evaluation: combining underadditive effects

According to the asynchronous discrete coding model of Miller, two manipulations should display underadditive effects on reaction time if they slow down noncontingent stages associated with the processing of two separable dimensions of a stimulus. Underadditive effects are also predicted by a dual route model when a task variable is factorially varied with design type (mixed vs blocked). Interpretations of both underadditive effects and their combination were evaluated. Intact and degraded stimuli were presented to 18 young adults either in a single block (mixed) or in separate blocks (blocked). Spatial stimulus-response (S-R) compatibility was manipulated in all conditions. Stimulus degradation and S-R compatibility interacted underadditively, but only in blocked presentations. Both interpretations of underadditive effects were supported. Eye-movement registrations provided additional support for the alternative routes model.