Effects of laterality and pitch height of an auditory accessory stimulus on horizontal response selection: The Simon effect and the SMARC effect

In the present article, we investigated the effects of pitch height and the presented ear (laterality) of an auditory stimulus, irrelevant to the ongoing visual task, on horizontal response selection. Performance was better when the response and the stimulated ear spatially corresponded (Simon effect), and when the spatial—musical association of response codes (SMARC) correspondence was maintained—that is, right (left) response with a high-pitched (low-pitched) tone. These findings reveal an automatic activation of spatially and musically associated responses by task-irrelevant auditory accessory stimuli. Pitch height is strong enough to influence the horizontal responses despite modality differences with task target.     

S-R compatibility effects due to context-dependent spatial stimulus coding

Responses are faster with spatial S-R correspondence than with noncorrespondence (spatial compatibility effect), even if stimulus location is irrelevant (Simon effect). In two experiments, we sought to determine whether stimuli located above and below a fixation point are coded as left and right (and thus affect the selection of left and right responses) if the visual context suggests such a coding. So, stimuli appeared on the left or right eye of a face’s image that was tilted by 90° to one side or the other (Experiment 1) or varied between upright and 45° or 90° tilting (Experiment 2). Whether stimulus location was relevant (Experiment 1) or not (Experiment 2), responses were faster with correspondence of (face-based) stimulus location and (egocentrically defined) response location, even if stimulus and response locations varied on physically orthogonal dimensions. This suggests that object-based spatial stimulus codes are formed automatically and thus influence the speed of response selection.     

Simon effect with and without awareness of the accessory stimulus

The authors investigated whether a Simon effect could be observed in an accessory-stimulus Simon task when participants were unaware of the task-irrelevant accessory cue. In Experiment 1A a central visual target was accompanied by a suprathreshold visual lateral cue. A regular Simon effect (i.e., faster cue-response corresponding reaction times [RTs]) was found. Experiment 1B demonstrated that this effect cannot be attributed to perceptual grouping of the target and cue. Experiments 2A, 2B, and 2C showed a reverse Simon effect (i.e., faster noncorresponding RTs) when participants were not aware of the cue. In this condition, the Simon effect would occur relative to the reorientation of attention from the cue, which would initially capture attention, toward the target. This conclusion is supported by the results of Experiments 3A and 3B, in which the reorientation of attention was induced by having the target flash after its onset. With suprathreshold cues either a reverse or regular Simon effect was observed by using a 100-ms or > or = 200-ms onset flashing interval, respectively, whereas with subthreshold cues a reverse Simon effect was found irrespective of the interval length.     

Spatial correspondence between onsets and offsets of stimuli and responses

The Simon effect denotes faster responses when the task-irrelevant stimulus position corresponds to response position than when it does not. A common explanation is that a spatial stimulus code is formed automatically and activates a spatially corresponding response code. Previous research on stimulus–response (S–R) compatibility has focused on the ability to initiate movements to stimulus onsets. The present study investigates spatial-compatibility effects (i.e., the Simon effect) in the ability to initiate and to terminate actions both to stimulus onsets and to stimulus offsets. There were four major results. Firstly, offset stimuli produced normal Simon effects suggesting that stimulus offsets can automatically produce spatial codes. Secondly, onset stimuli produced larger Simon effects than offset stimuli, which is consistent with the attention-shift account of spatial coding. Thirdly, Simon effects were also observed in action termination. Fourthly, Simon effects in action initiation and in action termination were of similar size.     

The SNARC effect: an instance of the Simon effect?

Our aim was to investigate the relations between the Spatial-Numerical Association of Response Codes (SNARC) effect and the Simon effect. In Experiment 1 participants were required to make a parity judgment to numbers from 1 to 9 (without 5), by pressing a left or a right key. The numbers were presented to either the left or right side of fixation. Results showed the Simon effect (left-side stimuli were responded to faster with the left hand than with the right hand whereas right-side stimuli were responded to faster with the right hand), and the SNARC effect (smaller numbers were responded to faster with the left hand than with the right hand, whereas larger numbers were responded to faster with the right hand). No interaction was found between the Simon and SNARC effects, suggesting that they combine additively. In Experiment 2 the temporal distance between formation of the task-relevant non-spatial stimulus code and the task-irrelevant stimulus spatial code was increased. As in Experiment 1, results showed the presence of the Simon and SNARC effects but no interaction between them. Moreover, we found a regular Simon effect for faster RTs, and a reversed Simon effect for longer RTs. In contrast, the SNARC effect did not vary as a function of RT. Taken together, the results of the two experiments show that the SNARC effect does not simply constitute a variant of the Simon effect. This is considered to be evidence that number representation and space representation rest on different neural (likely parietal) circuits.     

Transfer effects of incompatible location-relevant mappings on a subsequent visual or auditory Simon task

Two experiments investigated the influence of practice with an incompatible mapping of left and right stimuli to keypress responses on performance of a subsequent Simon task, for which stimulus location was irrelevant, after a delay of 5 min or 1 week. In Experiment 1, the visual Simon effect was eliminated when the practice modality was auditory and reversed to favor noncorresponding responses when it was visual, and there was no significant effect of delay interval. In Experiment 2, significant auditory Simon effects were obtained that did not vary as a function of practice modality, with delay having only a marginal effect on the magnitude of the Simon effect. The elimination of the visual Simon effect in the transfer session is most likely due to the short-term stimulus-response associations defined for the incompatible spatial mapping remaining active during the transfer session. Because the auditory Simon effect is stronger than the visual one, more practice with the incompatible mapping may be necessary to produce reliable transfer effects for it.     

The Simon effect and visual motion

Summary S-R compatibility and Simon effects were studied for real visual motion. In Experiment 1, two small stimulus lights were constantly visible, 5° to the left and right of fixation; after a random delay, one began to move at 2°/s. In Experiment 2, a single stimulus light moving at 2°/s suddenly appeared 5° to the left or right of fixation, i. e., motion onset and stimulus onset coincided. In both experiments, subjects responded by a key press with their left or right index finger as soon as they detected motion. In Condition A responses were made to the position (left or right) from which the motion started, irrespective of its direction (position compatibility); in Condition B responses were made to the direction of motion (leftward or rightward) irrespective of whether motion started to the left or to the right of fixation (direction compatibility). The results show strong compatibility effects for both position and direction of motion in both experiments. A Simon effect, however, occurred only when position was task irrelevant in Experiment 1; no Simon effect was found in Experiment 2. The data only partly confirm previous results obtained with apparent motion. The selective lack of a Simon effect supports the integrated model of Umiltá and Nicoletti (1992), which requires orienting of attention for the Simon effect to occur. It is specifically assumed that this attention-orienting is triggered only by the saccade program and does not extend to the pursuit program that is initiated by smooth stimulus motion.     

Flowers and spiders in spatial stimulus-response compatibility: does affective valence influence selection of task-sets or selection of responses?

The present study examined the effect of stimulus valence on two levels of selection in the cognitive system, selection of a task-set and selection of a response. In the first experiment, participants performed a spatial compatibility task (pressing left and right keys according to the locations of stimuli) in which stimulus-response mappings were determined by stimulus valence. There was a standard spatial stimulus-response compatibility (SRC) effect for positive stimuli (flowers) and a reversed SRC effect for negative stimuli (spiders), but the same data could be interpreted as showing faster responses when positive and negative stimuli were assigned to compatible and incompatible mappings, respectively, than when the assignment was opposite. Experiment 2 disentangled these interpretations, showing that valence did not influence a spatial SRC effect (Simon effect) when task-set retrieval was unnecessary. Experiments 3 and 4 replaced keypress responses with joystick deflections that afforded approach/avoidance action coding. Stimulus valence modulated the Simon effect (but did not reverse it) when the valence was task-relevant (Experiment 3) as well as when it was task-irrelevant (Experiment 4). Therefore, stimulus valence influences task-set selection and response selection, but the influence on the latter is limited to conditions where responses afford approach/avoidance action coding.     

Display-control arrangement correspondence and logical recoding in the Hedge and Marsh reversal of the Simon effect

When left and right keypresses are made to stimuli in left and right locations, and stimulus location is irrelevant to the task, responses are typically faster when stimulus location corresponds with response location than when it does not (the Simon effect). This effect reverses when the relevant stimulus-response mapping is incompatible, with responses being slower when stimulus and response locations correspond (the Hedge and Marsh reversal). Simon et al. (Acta Psychol. 47 (1981) 63) reported an exception to the Hedge and Marsh reversal for a situation in which the relevant stimulus dimension was the color of a centered visual stimulus and the irrelevant location information was left or right tone location. In contrast, similar experiments have found a reversal of the Simon effect for tone location when relevant visual locations were mapped incompatibly to responses. We conducted four experiments to investigate this discrepancy. Both results were replicated. With an incompatible mapping, irrelevant tone location showed a small reverse Simon effect when the relevant visual dimension was physical location but not when the color of a centered stimulus or the direction in which an arrow pointed conveyed the visual location information. The reversal occurred in a more standard Hedge and Marsh task in which the irrelevant dimension was location of the colored stimulus, but only when the response keys were visibly labeled. Several of the results suggest that display-control arrangement correspondence is the primary cause of the Hedge and Marsh reversal, with logical recoding playing only a secondary role.     

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.     

The role of attention in the occurrence of the affordance effect

It has been demonstrated that visual objects activate responses spatially corresponding to the orientation (left or right) of their graspable parts. To investigate the role of attention orienting in the generation of this effect, which we will refer to as affordance effect, we ran three experiments in which the target stimulus could either correspond or not with a dynamic event capturing attention. Participants were required to press a left or right key according to the vertical orientation (upward or inverted) of objects presented with their handles oriented to the right or to the left. In Experiments 1 and 2, the objects were located above or below fixation, while in Experiment 3, to assess the contemporary presence of the affordance and Simon effects, the objects were located to the left or right of fixation. The results showed that while the affordance effect, when evident, was always relative to the target object, irrespective of its attentional capturing properties, the Simon effect occurred relative to the event capturing attention. These findings suggest that automatic and controlled processes of visual attention may play a differential role in the occurrence of the two effects.     

Stimulus congruence and stimulus-response compatibility: Two variables disentangled in an auditory reaction time task

Abstract

Stimulus—response (S-R) compatibility was a tem fmt used by Wtts and Seeger (1953) to describe effcts observed on reaction time (RT) when the stimulus—response relationship was varied, as in the following instructions: “move to tbe right when the stimulus appears on the right” (compatible) or “move to the left when the stimulus appears on the right” (incompatible). This term was later employed in a broader sense (Simon & Rudell, 1967) with paradigms involving elaborate stimuli, such as the verbal command ‘RIGHT’ delivered to the right tar (compatible) or to the left ear (incompatible). In such paradigms. subjects respond faster when the response is delivered on the same side as the stimulus (the so-called “Simon effect”). It has been shown, however, that this effect could be reversed under some circumstanas in the visual domain. In this paper, we report data showing that it can also be reversed in the auditory domain when using the above-mentioned verbal commands. This brings further evidence that stimulus-response compatibility and the Simon effect difier in essence, with the latter effect reflecting the influence of stimulus congruence, the correspondence relationship borne by the two simultaneous characteristics of the stimulus. Stimulus congruence and stimulus-response compatibility had indeed independent influences on RT, which in a serially connected information-processing modcl would imply that they act upon independent stages.     

Cross-modal links in exogenous covert spatial orienting between touch, audition, and vision

Three experiments investigated cross-modal links between touch, audition, and vision in the control of covert exogenous orienting. In the first two experiments, participants made speeded discrimination responses (continuous vs. pulsed) for tactile targets presented randomly to the index finger of either hand. Targets were preceded at a variable stimulus onset asynchrony (150,200, or 300 msec) by a spatially uninformative cue that was either auditory (Experiment 1) or visual (Experiment 2) on the same or opposite side as the tactile target. Tactile discriminations were more rapid and accurate when cue and target occurred on the same side, revealing cross-modal covert orienting. In Experiment 3, spatially uninformative tactile cues were presented prior to randomly intermingled auditory and visual targets requiring an elevation discrimination response (up vs. down). Responses were significantly faster for targets in both modalities when presented ipsilateral to the tactile cue. These findings demonstrate that the peripheral presentation of spatially uninforrnative auditory and visual cues produces cross-modal orienting that affects touch, and that tactile cues can also produce cross-modal covert orienting that affects audition and vision.     

Irrelevant auditory attention shifts prime corresponding responses

In this paper we investigate whether an attention shift towards an auditory signal, while performing a two-choice serial reaction time task, primes responses in the direction of the auditory signal. In Experiment 1, subjects had to react to the pitch of the signal, which was randomly presented to the left or right ear. A short (50-ms) and a long (1000-ms) response-stimulus interval (RSI) was used. In Experiment 2 with an RSI of 2000 ms, subjects had to respond to the color of a centrally presented visual stimulus, while a sound was presented to one of the ears. In the short RSI condition of Experiment 1, there was a Simon effect for location alternations only. In the long RSI condition, there was a Simon effect for location repetitions and alternations. Experiment 2 showed a Simon effect in relation to the accessory sound. The results of this study suggest that an attention shift is a sufficient and necessary condition in order to observe a Simon effect. Preparation of this article was supported by a grant from the National Fund for Scientific Research, Flanders, Belgium (FWO-VL G.0009.99)     

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.     

Mechanisms underlying spatial coding in a multiple-item Simon task

Choice responses are faster when target position and response side correspond than when they do not, even if target position is response-irrelevant. This "Simon effect" has also been observed in case of multi-item arrays. Generally, it is assumed that an automatically generated spatial response code is responsible for the effect. The referential-coding account assumes that this code is directly related to the target, although the moment of production of the code is not fully clear. The attention-shift account assumes that the code is directly related to the direction of the most recent attentional shift. An experiment was performed in which left or right target locations were indicated by arrows occurring before (precue), simultaneous with (simcue), or after (postcue) six-element arrays. Overt responses and EEG potentials were recorded. The Simon effect was present in all conditions, and decreased when responses were slower. No relation was found between amplitude of posterior lateralized components and the magnitude of the Simon effect. A posterior contralateral negativity was also found after presenting the arrays in the precue condition, which might reflect the reorienting of attention toward the target position. The results are more favorable to the referential-coding account although this account becomes very similar to the attention-shift hypothesis as the moment of formation of the spatial response code is related to effective target onset rather than to stimulus onset.     

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.     

A Simon effect for stimulus-response duration

A non-spatial variant of the Simon effect for the stimulus-response (S-R) feature of duration is reported. In Experiment 1 subjects were required to press a single response key either briefly or longer in response to the colour of a visual stimulus that varied in its presentation duration. Short keypresses were initiated faster with short than with long stimulus duration whereas the inverse was observed with long keypresses. In Experiment 2 subjects were required to press a left or right key (according to stimulus form) either briefly or longer (according to stimulus colour). The stimuli concurrently varied in their location (left or right) and duration (short or long), which were both task irrelevant. Approximately additive correspondence effects for S-R location and S-R duration were observed. To summarize, the results suggest that the irrelevant stimulus features of location and duration are processed automatically and prime corresponding responses in an independent manner.     

Facilitation of responses by task-irrelevant complex deviant stimuli

Novel stimuli reliably attract attention, suggesting that novelty may disrupt performance when it is task-irrelevant. However, under certain circumstances novel stimuli can also elicit a general alerting response having beneficial effects on performance. In a series of experiments we investigated whether different aspects of novelty – stimulus novelty, contextual novelty, surprise, deviance, and relative complexity – lead to distraction or facilitation. We used a version of the visual oddball paradigm in which participants responded to an occasional auditory target. Participants responded faster to this auditory target when it occurred during the presentation of novel visual stimuli than of standard stimuli, especially at SOAs of 0 and 200 ms (Experiment 1). Facilitation was absent for both infrequent simple deviants and frequent complex images (Experiment 2). However, repeated complex deviant images did facilitate responses to the auditory target at the 200 ms SOA (Experiment 3). These findings suggest that task-irrelevant deviant visual stimuli can facilitate responses to an unrelated auditory target in a short 0–200 millisecond time-window after presentation. This only occurs when the deviant stimuli are complex relative to standard stimuli. We link our findings to the novelty P3, which is generated under the same circumstances, and to the adaptive gain theory of the locus coeruleus–norepinephrine system (Aston-Jones and Cohen, 2005), which may explain the timing of the effects.     

Crossmodal spatial attention shift produced by centrally presented gaze cues1

Abstract: Despite previous failures to identify visual‐upon‐auditory spatial‐cuing effects, recent studies have demonstrated that the abrupt onset of a lateralized visual stimulus triggers a shift of spatial attention in response to auditory judgment. Nevertheless, whether a centrally presented visual stimulus orients auditory attention remained unclear. The present study investigated whether centrally presented gaze cues trigger a reflexive shift of attention in response to auditory judgment. Participants fixated on a schematic face in which the eyes looked left or right (the cue). A target sound was then presented to the left or right of the cue. Participants judged the direction of the target as quickly as possible. Even though participants were told that the gaze direction did not predict the direction of the target, the response time was significantly faster when the gaze was in the target direction than when it was in the non‐target direction. These findings provide initial evidence for visual‐upon‐auditory spatial‐cuing effects produced by centrally presented cues, suggesting that a reflexive crossmodal shift of attention does occur with a centrally presented visual stimulus.