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Background Car accidents due to unexpected forward or backward runaway by older drivers are a serious social problem. Although the cause of these accidents is often attributed to stepping on the accelerator instead of the brake, it is difficult to induce such pedal application errors systematically with usual drive simulators. We developed a simple personal computer system that induces the pedal errors, and investigate the effects of age on the error behaviors. Methods The system consisted of a laptop computer and a three-pedal foot mouse. It measured response time, accuracy, and flexibility of pedal operation to visual stimuli. The system displayed two open circles on the computer display, lighting one of the circles in a random order and interval. Subjects were instructed to press the foot pedal with their right foot as quickly as possible when the circle was lit; the ipsilateral pedal to the lit circle in a parallel mode and the contralateral pedal in a cross mode. When the correct pedal was pressed, the light went off immediately, but when the wrong pedal was pressed, the buzzer sounded and the light remained on until the correct pedal was pressed. During a 6-min trial, the mode was switched between parallel and cross every 2 min. During the cross mode, a cross mark appears on the display. The pedal responses were evaluated in 52 subjects divided into young (20–29 years), middle-aged (30–64 years), and older (65–84 years) groups. Additionally, the repeatability of the pedal response characteristic indicators was examined in 14 subjects who performed this test twice. Results The mean response time was 95 ms (17%) longer in the older group than in the young group. More characteristically, however, the older group showed 2.1 times more frequent pedal errors, fell into long hesitations (response freezing > 3 s) 16 times more often, and took 1.8 times longer period to correct the wrong pedal than the young groups. The indicators of pedal response characteristics showed within-individual repeatability to the extent that can identify the age-dependent changes. Conclusions Hesitations and extended error correction time can be associated with increased crash risk due to unexpected runaway by older drivers. The system we have developed may help to uncover and evaluate physiological characteristics related to crash risk in the elderly population.

Selection and effort are central to attention, yet it is unclear whether they draw on a common pool of cognitive resources, and if so, whether there are differences for early versus later stages of cognitive processing. This study assessed effort by quantifying the vigilance decrement, and spatial processing at early and later stages as a function of time-on-task. Participants performed an auditory spatial attention task, with occasional "catch" trials requiring no response. Psychophysiological measures included bilateral cerebral blood flow (transcranial Doppler), pupil dilation, and blink rate. The shape of attention gradients using reaction time indexed early processing, and did not significantly vary over time. Later stimulus-response conflict was comparable over time, except for a reduction to left hemispace stimuli. Target and catch trial accuracy decreased with time, with a more abrupt decrease for catch versus target trials. Diffusion decision modeling found progressive decreases in information accumulation rate and non-decision time, and the adoption of more liberal response criteria. Cerebral blood flow increased from baseline and then decreased over time, particularly in the left hemisphere. Blink rate steadily increased over time, while pupil dilation increased only at the beginning and then returned towards baseline. The findings suggest dissociations between resources for selectivity and effort. Measures of high subjective effort and temporal declines in catch trial accuracy and cerebral blood flow velocity suggest a standard vigilance decrement was evident in parallel with preserved selection. Different attentional systems and classes of computations that may account for dissociations between selectivity versus effort are discussed.

Evidence is currently mixed regarding the way in which cognitive conflict modulates the effect of emotion on task performance. The present study aimed to address methodological differences across previous studies and investigate the conditions under which interference from emotional stimuli can either be elicited or eliminated under high cognitive conflict. Four behavioural experiments were conducted with a university sample using a gender-discrimination stimulus-response compatibility task. In line with our previous findings, Experiment 1 found that when emotion and cognitive conflict conditions were blocked, emotional faces increased reaction time interference during response compatible trials (low conflict) but not response incompatible trials (high conflict). However, when conflict and emotion conditions were randomised in different configurations across Experiments 2 (all trials randomised), 3 (emotion blocked, compatibility randomised) and 4 (compatibility blocked, emotion randomised), emotion interfered with task performance across both high and low conflict trials. These results suggest that predictability of both compatibility and emotion is required in order to obtain reduced emotional interference under high cognitive conflict. Consistent with prior reports, a top-down anticipatory control mechanism seems to be engaged in the presence of negative emotion when there are incompatible stimulus-response mappings.

The Simon effect, that is the advantage of the spatial correspondence between stimulus and response locations when stimulus location is task irrelevant, occurs even when the task is performed by two participants, each performing a go/no-go task. This effect, known as the joint Simon effect, does not emerge when participants sit outside each other's peripersonal space, thus suggesting that the presence of an active confederate in peripersonal space might provide a reference for response coding. The present study investigated whether this finding is due to the distance separating the participants and/or to the distance separating each participant and the other agent's response. In two experiments, pairs of participants performed a social detection task sitting outside each other's arm reach, with response keys located close to the participants or outside arm reach. When the response key was located outside the participant's arm reach, he/she could reach it by means of a tool. In Experiment 1, by means of a tool, participants could reach their response key only, while in Experiment 2, they could reach also their co-agent's response key. The joint Simon effect did not emerge when participants could not reach the co-actor's response, while it emerged when they could potentially reach the other participant's response using the tool, but only when turn taking was required. These results may be taken as evidence that the possibility to reach and act upon the co-actor's response key may be at the bases of compatibility effects observed in joint action contexts requiring complementary responses.

Although the joint Simon task (JST) has been investigated for more than a decade, its cause is still unclear. According to ideomotor views of action control, action effects are a commonly cited explanation. However, action effects are usually confounded with the actions producing such effects. We combined a JST with eye tracking and asked participants to respond by performing specific saccades. Saccades were followed by visual feedback (central vs. lateral feedback), serving as the action effect. This arrangement allowed us to isolate actions from action effects and, also to prevent each actor from seeing the reciprocal actions of the other actor. In this saccadic JST, we found a significant compatibility effect in the individual setting. The typical enhanced compatibility effect in the joint setting of the JST was absent with central action feedback and even when lateralized visual action feedback was provided. Our findings suggest that the perception of action effects alone might not be sufficient to modulate compatibility effects for eye movements. The presence of a compatibility effect in the individual setting shows the specific requirements of a saccadic compatibility task - the requirement to perform prosaccades to compatible and antisaccades to incompatible target locations. The lack of a difference between compatibility effects in joint and individual settings and the lack of a modulation of the compatibility effect through lateralized visual action feedback shows that the finding of a joint Simon effect that has frequently been reported for manual responses is absent for saccadic responses.

Deciding what information we attend to has implications on our ability to remain valuable and productive in our respective academic and economic domains. This study investigated if attentional switching due to information technology interruptions would deplete resources in a unique way and impair performance on a response inhibition task. Three groups (120 women, 57 men

Task-irrelevant stimulus location can influence the response performance to task-relevant attributes, generating the location-based Simon effect. Using a Monte Carlo study and other methods, we examined whether the ex-Gaussian distribution provides a good fit to empirical reaction time (RT) distributions in the Simon task and whether reliable Simon effects occur on the ex-Gaussian parameters: (a) the mean (μ), (b) the standard deviation (σ) of the normal distribution, and (c) the tail (τ). Results showed that the ex-Gaussian function fits well to empirical RT distributions, and that these ex-Gaussian parameters are reliable between two trial blocks at the group level. At the individual level, correlation analysis showed that the Simon effect was reliable on the μ parameter but not on σ and τ. Moreover, a partial correlation analysis, with μs of the two blocks as controlling variables, showed that the Simon effect on τ was reliable. These results provide evidence that the ex-Gaussian function is a valuable tool for analyzing the Simon effect and can be considered as an alternative for analyzing RT distributions in Simon-type tasks.

According to the conflict monitoring theory (CMT), one of the most prominent theories of cognitive control, the exertion of cognitive control is triggered by the detection of conflicting response tendencies in the anterior cingulate cortex (ACC). Recent research has challenged this emphasis of response conflicts and has debated whether in addition to shielding after incongruent trials the relaxation after congruent trials also contributes to the sequential adaptation of control. To investigate the functionality of facilitative congruent trials in sequential adaptation of control, we conducted two experiments using a visual (Experiment 1) and an auditory (Experiment 2, preregistered) Simon task with stimuli presented laterally to the left or right (creating response congruent and incongruent trials) or without any particular spatial information (creating neutral trials). Both experiments showed converging results: in the error and reaction time data, the Simon effect was smaller following incongruent trials, larger following congruent trials, and the Simon effect following neutral trials was in-between. Results thus suggest that sequential control adaptations can originate from two processes: Increased shielding in response to incongruent trials and relaxation in response to congruent trials. Argumentations for a functional role of congruent and incongruent trials in the sequential adaptation of control suggest a more general theory of fluency monitoring instead of mere conflict monitoring. In addition, such extensions of the CMT provide theoretical explanations of how control is ever relaxed in response conflict tasks after being enhanced by conflict in the first place. Last but not least, the results may also be taken as a further hint that congruent stimuli may provide a positive affective signal for control relaxation just it has already been shown for incongruent stimuli as aversive signals for the up-regulation of control (shielding).

Lateralized responses to central targets are facilitated when distractors are presented ipsilaterally (congruent trials) compared with contralaterally (incongruent trials) to the response. This accessory Simon effect is explained by assuming that distractors generate a spatial code that conforms to, or conflicts with, the response. The effect typically diminishes as the distractor-target interval increases. However, it is unclear whether irrelevant spatial codes passively decay or are actively inhibited. Given that inhibition takes time to develop, its operation may reverse the Simon effect-indicated by impaired performance in congruent compared with incongruent trials-when the distractor is presented prior to the target. In the present study, the temporal separation between distractor and target was systematically manipulated. Participants responded to a centrally presented visual (Experiments 1 and 2) or auditory (Experiments 3 and 4) target. A lateralized auditory distractor either occurred prior to, or simultaneously with, the target. A Simon effect occurred when distractor and target were presented simultaneously or in close temporal proximity. The effect was reversed with longer distractor-target intervals, but only when targets and distractors were presented in the same modality (Experiments 3 and 4), suggesting that an inhibition process operates on distractor events, which is stronger in the case of matching target and distractor modalities. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Visual snow syndrome (VSS) is a poorly understood neurological disorder that features a range of disabling sensory changes. Visual processing changes revealed previously in VSS appear consistent with poor attentional control, specifically, with difficulty controlling environmentally driven shifts of attention. This study sought to confirm this proposal by determining whether these changes were similarly evident where attention is internally driven. Sixty seven VSS patients and 37 controls completed two saccade tasks: the endogenously cued saccade task and saccadic Simon task. The endogenously cued saccade task correctly (valid trial) or incorrectly (invalid trial) pre-cues a target location using a centrally presented arrow. VSS patients generated significantly shorter saccade latencies for valid trials (p = 0.03), resulting in a greater magnitude cue effect (p = 0.02), i.e. the difference in latency between valid and invalid trials. The saccadic Simon task presents a peripheral cue which may be spatially congruent or incongruent with the subsequent target location. Latencies on this task were comparable for VSS patients and controls, with a normal Simon effect, i.e. shorter latencies for saccades to targets spatially congruent with the preceding cue. On both tasks, VSS patients generated more erroneous saccades than controls towards non-target locations (Endogenously cued saccade task: p = 0.02, saccadic Simon task: p = 0.04). These results demonstrate that cued shifts of attention differentially affect saccade generation in VSS patients. We propose that these changes are not due to impairment of frontally-mediated inhibitory control, but to heightened saccade-related activity in visual regions. These results contribute to a VSS ocular motor signature that may provide clinical utility as well as an objective measure of dysfunction to facilitate future research.

It is crucial for humans to coordinate between behavioural tendencies that can lead to reward but are in conflict with each other. This response conflict can be measured in a reward-modulated Simon task, in which a discriminative response to the identity of a lateral target is required and the target is associated with either high- or low-reward. Critically, the lateral target is presented either congruent or incongruent with the location of the responding hand. It has been shown that relative to the low-reward target, the high-reward target induced a larger response conflict when the target was incongruent with the position of the task-required, reward-obtaining hand. Here we investigated how this response conflict is resolved by acquiring 24 healthy participants' electromyography (EMG) signals from both the task-required responding hand (i.e., goal-directed effector) and the alternative hand (i.e., inappropriate effector). During the coping with the response conflict, motor inhibition (indexed by reduction in EMG signals between conditions) was observed not only at the inappropriate effector but also at the goal-directed effector. Individuals who showed stronger inhibition on the inappropriate effector suffered less from the inhibition on the goal-directed effector, and had more efficient implementation of the reward-obtaining response. Our findings suggest a global motor inhibition that may function to increase the signal-noise ratio in the motor system so as to implement reward-guided behavior.

Visual processing near the hands is altered compared with stimuli far from the hands. Here, we aimed to test whether this alteration can be found in auditory processing. Participants were required to perform an auditory Simon task either with their hands close to the loudspeakers or far from the loudspeakers. Two experiments consistently showed that the auditory Simon effect was enhanced when the hands were close to the speakers compared with far from the speakers. This is consistent with previous findings of an enhanced visual Simon effect near the hands. Furthermore, the hand-proximity effects in auditory and visual Simon tasks (an enhanced Simon effect near hands compared with far from hands) were comparable, indicating hand-proximity effect is reliable across visual and auditory modalities. Thus, the present study extended the hand-proximity effect from vision to audition by showing that the auditory Simon effect was enhanced near the hands compared with far from the hands.

Schlaghecken, F., Blagrove, E., Mantantzis, K., Maylor, E. A., & Watson, D. G. [(2017). Look on the bright side: Positivity bias modulates interference effects in the Simon task. Journal of Experim...

An accumulating body of evidence highlights the contribution of general cognitive processes, such as attention, to language-related skills.Objective:The purpose of the present study was to explore how interference control (a subcomponent of selective attention) is affected in developmental dyslexia (DD) by means of control over simple stimulus-response mappings. Furthermore, we aimed to examine interference control in adults with DD across sensory modalities.Methods:The performance of 14 dyslexic adults and 14 matched controls was compared on visual/auditory Simon tasks, in which conflict was presented in terms of an incongruent mapping between the location of a visual/auditory stimulus and the appropriate motor response.Results:In the auditory task, dyslexic participants exhibited larger Simon effect costs; namely, they showed disproportionately larger reaction times (RTs)/errors costs when the auditory stimulus and response were incongruent relative to RT/errors costs of non-impaired readers. In the visual Simon task, both groups presented Simon effect costs to the same extent.Conclusion:These results indicate that the ability to control auditory selective attention is carried out less effectively in those with DD compared with visually controlled processing. The implications of this impaired process for the language-related skills of individuals with DD are discussed.

Two experiments examined whether practicing discrete key pressing sequences eventually leads to a disregard of the key-specific stimuli, as suggested by sequence learning models, or whether these stimuli continue to be relied upon because the associated luminance increase attracts visuospatial attention. Participants practiced two sequences by reacting to two fixed series of seven letter stimuli, each displayed at a location that did or did not correspond with the required response location. Stimulus use was indicated by a Simon effect in that key presses were slowed when stimulus and key locations did not correspond. Experiment 1 demonstrated that letter stimuli continued to be used as the Simon effect occurred with each sequence element, and this remained quite stable across practice and did not differ for familiar and unfamiliar sequences. Experiment 2 showed that the Simon effect remained present even with meaningless stimuli that were often even harmful. These findings suggest that even in motor sequences that can be executed without element-specific stimuli attention attraction enforces stimulus use. The data further supported the assumptions that S-R translation and sequencing systems are racing to trigger individual responses, and that explicit sequence representations include spatial and verbal knowledge.

Exerting cognitive control is an effortful endeavor that is strongly modulated by the availability of dopamine (DA) and norepinephrine (NE), which are both synthesized from the amino acid precursor tyrosine. Supplementing tyrosine may increase the synthesis of both catecholamines. This has been suggested to improve executive functioning and potentially even counteract depletion effects in this domain. Yet, it has remained unclear whether tyrosine also improves interference control and whether subliminally and consciously triggered response conflicts are subject to the same modulation. We investigated this question in a double-blind intra-individual study design. N = 26 young healthy subjects performed two consecutive cognitive control tasks that triggered automatic incorrect response tendencies; once with tyrosine supplementation and once with a placebo. The results show that tyrosine decreased the size of consciously perceived conflicts in a Simon Task, but not a Flanker task, thus suggesting that stimulus–response conflicts might be modulated differently from stimulus–stimulus conflicts. At the same time, tyrosine supplementation increased the size of subliminally triggered conflicts whenever a different, consciously perceived conflict was also present. This suggests that control-related DA and NE release may increase visuo-motor priming, especially when no conflict-specific top-down control may be triggered to counteract subliminal priming effects. Also, these subliminal conflicts might be aggravated by concurrent control investments in other kinds of conflict. Taken together, our data suggest that beneficial effects of tyrosine supplementation do not require depletion effects, but may be limited to situations where we consciously perceive a conflict and the associated need for conflict-specific control.

The Dimension-Action model maintains that response selection in the visual system is modular, such that response selection based on a target’s feature occurs within modules. This study suggests that response selection processes based on a target’s spatial location occur within modules as well, where spatial locations are coded along with the feature information. From this perspective, the typical Simon effect, in which interference occurs between a target’s feature and its spatial location, occurs within modules. This study explored whether the unique characteristic of the spatial Simon, namely, its reduction with increased reaction time is typical of spatial intra-dimension but not of spatial cross-dimension Simon effects, using the accessory Simon task. Experiment 1 demonstrated that intra-dimension Simon effects were reduced with increased reaction time, a reduction that was modulated by the task relevance of the distractor. In contrast, cross-dimension accessory Simon effects were positive and increased with reaction time. Experiment 2 demonstrated that intra-dimension Simon effects were not reduced when space was conveyed symbolically by arrows. Overall, the study suggests that interference in the accessory Simon task is influenced not only by the nature of the irrelevant spatial information but also by the modular locus of the targets and distractors.

The location-, word-, and arrow-based Simon effects are usually attributed to the result of a direct route (the spatially corresponding stimulus-response association, activated automatically) that interferes with an indirect route (the association of task-relevant information and response, activated in accordance with the instructed stimulus-response mapping). We examined whether and how distinct direct routes (stimulus-location-response position and location word-response position or arrow direction-response position associations) affect responding on the basis of the same indirect route (a stimulus color-response association) in a Simon-like task. For this task, left-right keypresses were made to indicate the ink colors of location words or left- or right-pointing arrows, presented eccentrically in left or right locations. The location-based Simon effect occurred at the levels of mean reaction time (RT) and RT distribution in the word Simon-like task, whereas the word-based Simon effect only occurred at the level of RT distribution. In the arrow Simon-like task, the location-based Simon effect did not occur at the level of mean RT, but did at the level of RT distribution, whereas the opposite pattern occurred for the arrow-based Simon effect. These results could imply that one direct route influences the effects of the other direct route on the responses, depending on the task context.

Behavioral coordination is a fundamental element of human cooperation. It is facilitated when individuals represent not only their own actions but also those of their partner. Identifying whether action corepresentation is unique to humans or also present in other species is therefore necessary to fully understand the evolution of human cooperation. We used the auditory joint Simon task to assess whether action corepresentation occurs in common marmosets, a monkey species that engages extensively in coordinated action during cooperative infant care. We found that marmosets indeed show a joint Simon effect. Furthermore, when coordinating their behavior in the joint task, they were more likely to look at their partner than in a joint control condition. Corepresentation is thus not unique to humans but also present in the cooperatively breeding marmosets. Since marmosets are small-brained monkeys, our results suggest that routine coordination in space and time, rather than complex cognitive abilities, plays a role in the evolution of corepresentation.

Task-irrelevant spatial information, conveyed by stimulus location, location word, or arrow direction, can influence the response to task-relevant attributes, generating the location-, word-, and arrow-based Simon effects. We examined whether different mechanisms are involved in the generation of these Simon effects by fitting a mathematical ex-Gaussian function to empirical response time (RT) distributions. Specifically, we tested whether which ex-Gaussian parameters (μ, σ, and τ) show Simon effects and whether the location-, word, and arrow-based effects are on different parameters. Results show that the location-based Simon effect occurred on mean RT and μ but not on τ, and a reverse Simon effect occurred on σ. In contrast, a positive word-based Simon effect was obtained on all these measures (including σ), and a positive arrow-based Simon effect was evident on mean RT, σ, and τ but not μ. The arrow-based Simon effect was not different from the word-based Simon effect on τ or σ but was on μ and mean RT. These distinct results on mean RT and ex-Gaussian parameters provide evidence that spatial information conveyed by the various location modes are different in the time-course of activation.

Conde et al. (Exp Brain Res 233:3313-3321, 2015) found that the Simon effect for vertically arrayed stimuli and responses was reduced after 100 prior practice trials with an incompatible mapping of the stimulus locations and responses. This finding was contrary to Vu's (Mem Cognit 35:1463-1471, 2007) finding of no transfer effect with 72 trials of prior practice. Conde et al. proposed that the different results were due to their responses being coded as top and bottom in the frontal plane, whereas Vu's were coded as far and near in the transverse plane. We conducted four experiments to test this possibility in which participants responded with keypresses using their thumbs on a numeric keypad held vertically (upright in the frontal plane) or horizontally (flat in the transverse plane). Experiment 1 showed that, without any prior practice, a similar sized Simon effect was obtained when the response device was oriented in the transverse plane as when it was oriented in the frontal plane. In Experiments 2 and 3 participants performed with the same device orientation in the incompatible practice and Simon transfer tasks, with orientation manipulated between-subjects in the former and within-subjects in the latter. The Simon effect was reduced in both cases, with no significant difference in transfer effect for transverse and frontal planes. In Experiment 4, the device orientation differed between the incompatible practice and Simon transfer tasks, and the Simon effect was reduced similarly across both response-device orientations. Thus, the differences between Conde et al.'s and Vu's findings cannot be attributed to the response-device orientation. Our results are consistent with the view that people code response locations in the transverse plane as top and bottom, rather than far and near, in agreement with the terminology of "top row" and "bottom row" for computer keyboards.

Inhibition of irrelevant and conflicting information and responses is crucial for goal-directed behaviour and adaptive functioning. In the Simon task, for example, responses are slowed if their mappings are spatially incongruent with stimuli that must be discriminated on a nonspatial dimension. Previous work has shown that practice with incongruent spatial mappings can reduce or even reverse the Simon effect. We asked whether such practice transfers between the manual and oculomotor systems and if so to what extent this occurs across a range of behavioural tasks. In two experiments, one cohort of participants underwent anti-saccade training, during which they repeatedly inhibited the reflexive impulse to look toward a briefly presented target. Additionally, two active-control training groups were included, in which participants either trained on Pro-saccade or Fixation training regimens. In Experiment 1, we probed whether the Simon effect and another inhibitory paradigm, the Stroop task, showed differential effects after training. In Experiment 2, we included a larger battery of inhibitory tasks (Simon, Stroop, flanker and stop-signal) and noninhibitory control measures (multitasking and visual search) to assess the limits of transfer. All three training regimens led to behavioural improvements in the trained-upon task, but only the anti-saccade training group displayed benefits that transferred to the manual response modality. This transfer of training benefit replicated across the two experiments but was restricted to the Simon effect. Evidence for transfer of inhibition training across motor systems offers important insights into the nature of stimulus-response representations and their malleability.

Previous studies observed compatibility effects in different interference paradigms such as the Simon and flanker task even when the task was distributed across two co-actors. In both Simon and flanker tasks, performance is improved in compatible trials relative to incompatible trials if one actor works on the task alone as well as if two co-actors share the task. These findings have been taken to indicate that actors automatically co-represent their co-actor's task. However, recent research on the joint Simon and joint flanker effect suggests alternative non-social interpretations. To which degree both joint effects are driven by the same underlying processes is the question of the present study, and it was scrutinized by manipulating the visibility of the co-actor. While the joint Simon effect was not affected by the visibility of the co-actor, the joint flanker effect was reduced when participants did not see their co-actors but knew where the co-actors were seated. These findings provide further evidence for a spatial interpretation of the joint Simon effect. In contrast to recent claims, however, we propose a new explanation of the joint flanker effect that attributes the effect to an impairment in the focusing of spatial attention contingent on the visibility of the co-actor.

When a two-choice "Simon task" is distributed between two people, performance in the shared go/no-go task resembles performance in the whole task alone. This finding has been described as the joint Simon effect (JSE). Unlike the individual go/no-go task, not only is the typical joint Simon task shared with another person, but also the imperative stimuli dictate whose turn it is to respond. Therefore, in the current study, we asked whether removing the agent discrimination component of the joint Simon task influences co-representation. Participants performed the typical joint Simon task, which was compared to two turn-taking versions of the task. For these turn-taking tasks, pairs predictably alternated turns on consecutive trials, with their respective imperative stimulus presented either on 100% of their turns (fully predictable group) or on 83% of their turns (response-uncertainty group, 17% no-go catch trials). The JSE was absent in the fully predictable, turn-taking task, but emerged similarly under the response-uncertainty condition and the typical joint Simon task condition where there is both turn and response-execution-related uncertainty. These results demonstrate that conflict related to agent discrimination is likely not a critical factor driving the JSE, whereas conflict surrounding the need to execute a response (and hence the degree of preparation) appears fundamental to co-representation.

Sharing tasks with other persons can simplify our work and life, but seeing and hearing other people's actions may also be very distracting. The joint Simon effect (JSE) is a standard measure of referential response coding when two persons share a Simon task. Sequential modulations of the joint Simon effect (smJSE) are interpreted as a measure of event-file processing containing stimulus information, response information and information about the just relevant control-state active in a given social situation. This study tested effects of physical (Experiment 1) and virtual (Experiment 2) separation of shared workspaces on referential coding and event-file processing using a joint Simon task. In Experiment 1, participants performed this task in individual (go-nogo), joint and standard Simon task conditions with and without a transparent curtain (physical separation) placed along the imagined vertical midline of the monitor. In Experiment 2, participants performed the same tasks with and without receiving background music (virtual separation). For response times, physical separation enhanced event-file retrieval indicated by an enlarged smJSE in the joint Simon task with curtain than without curtain (Experiment1), but did not change referential response coding. In line with this, we also found evidence for enhanced event-file processing through physical separation in the joint Simon task for error rates. Virtual separation did neither impact event-file processing, nor referential coding, but generally slowed down response times in the joint Simon task. For errors, virtual separation hampered event-file processing in the joint Simon task. For the cognitively more demanding standard two-choice Simon task, we found music to have a degrading effect on event-file retrieval for response times. Our findings suggest that adding a physical separation optimizes event-file processing in shared workspaces, while music seems to lead to a more relaxed task processing mode under shared task conditions. In addition, music had an interfering impact on joint error processing and more generally when dealing with a more complex task in isolation.

Simon tasks reveal implicit processing conflicts that arise when the abstract coding of stimulus position is incongruent with coding for location of the output response. Participants were tested with two versions of a Simon task in a counterbalanced order to examine a potential female bias for attending to object characteristics versus object location. Both tasks used a triangle pointing to the left or right. A simple version presented the triangle in an inner or outer position relative to central fixation. A more complex version included a frame surrounding the inner-outer triangle presentation area in order to introduce additional visual elements for left/right visual processing. When the No Frame version was the first presented, there were no sex differences in the Simon effect in either version, which is consistent with results from other studies that did not provide feedback regarding accuracy. When the initial test was the Frame version, we observed a reverse Simon effect for incongruent triangles presented in the left inner position, with females faster than males to identify the incongruent condition versus the congruent (-59 vs -5 msec). In the No Frame condition that followed, females showed a carryover effect from the previous Frame condition, exhibiting positive Simon effects that were two fold larger than males for identifying incongruent stimuli presented in the left and right outer positions. Similar to previous Simon studies, females showed longer overall reaction times than males (~15%). The difference was not related to the Simon effect and is also found in other types of tasks involving early visual processing of objects with location. Based on sex differences in the Simon effect that emerged following initial experience of the triangle adjoining the frame, the present results support a female bias toward broader integration of objects within the context of location.

Here, we explored the role of perceived interpersonal closeness in joint action using the joint Simon task in adolescents and adults. In a two-choice reaction time task, spatially assigned responses to non-spatial stimulus features are faster when the stimulus and response are in congruent locations than not. This phenomenon is called Simon effect and is absent or strongly attenuated when a participant responds to only one of the stimuli. However, the effect reappears when two participants carry out the same go/no-go tasks cooperatively. This re-emergence of the Simon effect in joint action is called the joint Simon effect (JSE). In this study, we first replicated the standard and joint Simon effects in adolescents (n = 43), as well as adults (n = 39) with similar magnitude of the effects in the two age groups. The magnitude of the JSE was positively correlated with the level of closeness as measured by Inclusion of Other in the Self scale. This correlation was not significantly different in adolescents (n = 73) compared to adults (n = 71). Our findings show that joint action is sensitive to the social factor such as interpersonal closeness, and the underlying mechanisms are already mature by adolescence.

In Simon-type interference tasks, participants are asked to perform a 2-choice reaction on a stimulus dimension while ignoring the stimulus position. Commonly, robust congruency effects are found; that is, reactions are faster when the relevant stimulus attribute and the assigned response match the location of the stimulus. Simon congruency effects are regularly attributed to a fast, nonverbal processing route. In 3 experiments, we tested the importance of verbal representations in the Simon effect by manipulating the format of representations (verbal vs. nonverbal) with stimulus material (i.e., words vs. gratings) and stimulus arrangement (i.e., horizontally vs. vertically). Results of the first experiment point to a modulation of the Simon effects by both factors when they were manipulated between subjects, up to an inversion of the Simon effect for words presented in vertical arrangement. We replicated the inverse congruency effect for verbal material in vertical arrangement when a within-participant design was used (Experiment 2) and when the impact of reading processes was ruled out (Experiment 3). One cause for this inversion might be the construction of language-based representations that counteract automatic processing given the stimulus arrangement. To investigate this, we assessed individual differences in the use of inner speech for self-instruction. Using hierarchical linear modeling analysis, we found that self-rated evaluative and motivational inner speech processes accounted for a significant portion of the Simon effect. This supports claims that individual differences predict performance even in simple cognitive tasks such as the Simon task and highlights the flexibility of basic cognitive processes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

We combined analyses of reaction time (RT) distributions with experimental manipulations of different processing stages (perception, decision, motor execution) in a Simon task to investigate which changes in Simon effects could be explained entirely by fading irrelevant response activation. Consistent with fading activation accounts, the Simon effect on mean RT was usually smaller for conditions with slower responses (Expts. 1–3 but not Expt. 4), and delta plot analyses revealed that it was always smaller for the slower responses within each condition. Critically, however, these analyses also revealed that some experimental manipulations produced upward or downward shifts in the RT delta plots, thus altering the Simon effect on mean RT in ways that could not be explained by fading activation. The results demonstrate the power of combining RT distributional analyses with experimental manipulations to reveal mechanisms contributing to the Simon effect that would not be revealed using only mean RT. We consider alternatives to fading activation accounts of decreasing delta plots and discuss the contribution of different cognitive stages in modulating Simon effects.

Although domain-specificity is prevalent in models of human cognition, its presence is not always easy to verify. For example, according to one prominent model, experiencing conflict from an incongruent distractor in a Stroop-like task triggers an upregulation of domain-specific control that facilitates the resolution of the same, but not a different, type of conflict in the next trial. The only evidence for this view, however, comes from tasks wherein confounds can mimic the effects of domain-specific control. In the present study, I report that Stroop-incongruent and Simon-incongruent distractors in a hybrid Stroop-Simon task trigger selective reductions of the Stroop and Simon effects in the next trial (i.e., distractor-specific congruency sequence effects [CSEs]), regardless of whether confounds are absent (Experiment 1) or present (Experiment 2). However, I also report that the Stroop and Simon effects interact when confounds are absent (Experiment 1) and in trials with slow reaction times when confounds are present (Experiment 2). These within-trial interactions suggest that the Stroop and Simon effects index overlapping conflicts, rather than independent conflicts. Thus, they prevent one from drawing any conclusions about whether the distractor-specific CSEs index domain-specific (i.e., conflict-specific) or domain-general (i.e., conflict-general) control. This outcome challenges prior data suggesting domain-specific control in the hybrid Stroop-Simon task. However, it fits with recent findings suggesting independent within- and across-trial conflict control processes. It also fits with an emerging view wherein across-trial conflict control processes engender CSEs by retrieving an episodic memory of previous-trial control settings. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

International audience; This study seeks to investigate whether users activate cognitive representations of their partner’s action when they are involved in tactile collaborative tasks. The social Simon effect is a spatial stimulus–response interference induced by the mere presence of a partner in a go/nogo task. It has been extensively studied in the visual and auditory sensory modalities, but never before in the tactile modality. We compared the performances of 28 participants in three tasks: (1) a standard Simon task where participants responded to two different tactile stimuli applied to their fingertips with either their left or right foot, (2) an individual go/nogo task where participants responded to only one stimulus and (3) a social go/nogo task where they again responded to only one stimulus, but were partnered with another person who responded to the complementary stimulus. The interference effect due to spatial incongruence between the side where participants received the stimulus and the foot used to answer increased significantly in the standard Simon task compared to the social go/nogo task. Such a difference was not observed between the social and individual go/nogo tasks. Performances were nevertheless enhanced in the social go/nogo task, but irrespectively of the stimulus–response congruency. This study is the first to report a negative result for the social Simon effect in the tactile modality. Results suggest that cognitive representation of the co-actor is weaker in this modality.

The avatar-Simon task demonstrates that even task irrelevant avatars cause compatibility effects from their point of view, a result that can be interpreted within the frameworks of spontaneous spatial perspective taking and referential coding. In the present study, we used an avatar-Simon task with rapidly changing avatar positions and with simultaneous and non-simultaneous presentations to investigate the time course of this phenomenon. The results showed that participants took the avatar's perspective into account even when the avatar's position was randomized on a trial-by-trial basis. This avatar-compatibility effect was also observed when avatar and stimulus were presented simultaneously, even though the participants had no time to adopt the avatar's perspective in advance. However, the effect was much more pronounced when a delay between avatar and stimulus presentation was in place.

We examined the possible dissociation between two modes of valence: affective valence (valence of e emotional response) and semantic valence (stored knowledge about valence of an object or event). In Experiment 1, 50 participants viewed affective pictures that were repeatedly presented while their facial electromyography (EMG) activation and heart rate response were continuously recorded. Half of the participants provided self-report ratings about the valence of their feelings and half about the valence of the stimulus. Next, all participants performed an affective Simon task. In Experiment 2, 30 new participants performed the affective Simon task with the repeated exposure embedded within the task. The results showed that measures related to affective valence (feelings-focused self-reports, heart rate, and facial EMG activations) attenuated with repeated exposure to pleasant and unpleasant pictures, whereas measures related to semantic valence (knowledge-focused self-reports and congruency effect of affective Simon task) did not. These findings strongly suggest that affective and semantic valence represent two distinct psychological constructs. (PsycINFO Database Record

It is assumed that we recruit cognitive control (i.e., attentional adjustment and/or inhibition) to resolve 2 conflicts at a time, such as driving toward a red traffic light and taking care of a near-by ambulance car. A few studies have addressed this issue by combining a Simon task (that required responding with left or right key-press to a stimulus presented on the left or right side of the screen) with either a Stroop task (that required identifying the color of color words) or a Flanker task (that required identifying the target character among flankers). In most studies, the results revealed no interaction between the conflict tasks. However, these studies include a small stimulus set, and participants might have learned the stimulus-response mappings for each stimulus. Thus, it is possible that participants have more relied on episodic memory than on cognitive control to perform the task. In 5 experiments, we combined the 3 tasks pairwise, and we increased the stimulus set size to circumvent episodic memory contributions. The results revealed an interaction between the conflict tasks: Irrespective of task combination, the congruency effect of 1 task was smaller when the stimulus was incongruent for the other task. This suggests that when 2 conflicts are presented concurrently, the control processes induced by 1 conflict source can affect the control processes induced by the other conflict source. (PsycINFO Database Record

In the Simon effect (SE), choice reactions are fast if the location of the stimulus and the response correspond when stimulus location is task-irrelevant; therefore, the SE reflects the automatic processing of space. Priming of social concepts was found to affect automatic processing in the Stroop effect. We investigated whether spatial coding measured by the SE can be affected by the observer’s mental state. We used two social priming manipulations of impairments: one involving spatial processing - hemispatial neglect (HN) and another involving color perception - achromatopsia (ACHM). In two experiments the SE was reduced in the “neglected” visual field (VF) under the HN, but not under the ACHM manipulation. Our results show that spatial coding is sensitive to spatial representations that are not derived from task-relevant parameters, but from the observer’s cognitive state. These findings dispute stimulus-response interference models grounded on the idea of the automaticity of spatial processing.

In object perception studies, a response advantage arises when the handle of an object is congruent with the responding hand. This handle effect is thought to reflect increased motor activation of the hand most suited to grasp the object, consistent with affordance theories of object representation. An alternative explanation has been proposed, however, which suggests that the handle effect is related to a simple spatial compatibility effect (the Simon effect). In 3 experiments, we determined whether the handle effect would emerge in the absence of explicit spatial compatibility between handle and response. Stimulus and response location was varied vertically and participants made horizontally orthogonal, bimanual responses to objects' kitchen/garage category, color (as in a traditional Simon effect) or upright/inverted orientation. Categorization and inversion tasks, which relied on object knowledge, elicited a handle effect and a vertical Simon effect regarding stimulus and response locations. When participants judged object color, as per standard Simon effect paradigms, the handle effect disappeared but the Simon effect strengthened. These data demonstrate a dissociation between affordance and spatial compatibility effects and prove that affordance plays an important role in the handle effect. Models that incorporate both affordance and spatial compatibility mechanisms are discussed. (PsycINFO Database Record

Spatial information can be conveyed not only by stimulus position but by the meaning of a location word or direction of an arrow. We examined whether all the location-, arrow- and word-based Simon effects or some of them can be observed when a location word or an arrow is presented eccentrically and a left-right keypress is made to indicate its ink color. Results showed that only the location-based Simon effect was observed for location words, whereas an additional smaller arrow-based Simon effect, compared to the location-based Simon effect was observed, for arrows. These results showed spatial location, arrow direction, and location word stimulus dimensions affect response position codes in a spatial-to-verbal priority order, consistent with the possibility that they can activate mode-specific spatial representations.

Proportion congruency effects are the observation that the magnitude of the Stroop effect increases as the proportion of congruent trials in a block increases. Contemporary work shows that proportion effects can be specific to a particular context. For example, in a Simon task in which items appearing above fixation are mostly congruent and items appearing below fixation are mostly incongruent, the Simon effect is larger for the items appearing at the top. There is disagreement as to whether these context-specific effects result from simple associative learning or, instead, a type of conflict-mediated associative learning. Here, we address this question in an ERP study using a Simon task in which the proportion congruency effect was context-specific, manipulating the proportion of congruent trials based on location (upper vs. lower visual field). We found significant behavioral proportion congruency effects that varied with the specific contexts. In addition, we observed that the N2 response of the ERPs to the stimuli was larger in amplitude for the high congruent (high conflict) versus low congruent (low conflict) conditions/contexts. Because the N2 is known to be greater in amplitude also for trials where conflict is high and is believed to be an electrical signal related to conflict detection in the medial frontal cortex, this supports the idea that conflict-mediated associative learning is involved in the proportion congruency effect.

Cognitive control has been classically considered as a flexible process engaged to pursue intentional behaviors, as distinct from automatic processes, which are unintentional, inflexible, and triggered by unconscious mechanisms. Our study challenged this view, showing that such a distinction may not be so clear-cut. We analyzed motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation to investigate the neurocognitive mechanisms occurring in a conflict task during trials that either required or did not require a response. We observed a Simon effect on MEPs and sequential modulations of such effects on both kinds of trials. Sequential modulations are usually explained as resulting from the engagement of intentional control mechanisms. Our findings rule against this idea, suggesting that these effects are the result of a mechanism that detects and resolves conflict even when there is no intention to select any response. Accordingly, cognitive control also seems to operate without intention, acting in an automatic fashion.

In the last decade, a number of studies have reported sex differences in selective attention, but a unified explanation for these effects is still missing. This study aims to better understand these differences and put them in an evolutionary psychological context. 418 adult participants performed a computer-based Simon task, in which they responded to the direction of a left or right pointing arrow appearing left or right from a fixation point. Women were more strongly influenced by task-irrelevant spatial information than men (i.e., the Simon effect was larger in women, Cohen’s d = 0.39). Further, the analysis of sex differences in behavioral adjustment to errors revealed that women slow down more than men following mistakes (d = 0.53). Based on the combined results of previous studies and the current data, it is proposed that sex differences in selective attention are caused by underlying sex differences in core abilities, such as spatial or verbal cognition.

When location words left and right are presented in left and right locations and mapped to left and right keypress responses in the Hedge and Marsh (1975) task (Arend & Wandmacher, 1987), a compatible mapping of words to responses yields a benefit for stimulus -response location correspondence (sometimes called the Simon effect), whereas an incompatible mapping yields a benefit for noncorrespondence (called the Hedge and Marsh reversal). Experiment 1 replicated the correspondence benefit and its reversal by using Chinese location words a (left) and (right) in the Hedge and Marsh task. Experiments 2 and 3 examined whether the tendency to-respond with the noncorresponding response when the mapping is incompatible transfers to the task version in which the mapping is compatible, and Experiment 4 examined whether transfer similarly occurs from the compatible mapping to the task version with incompatible mapping. Transfer of the incompatible relation was apparent in a lack of correspondence benefit when the mapping was changed to compatible, but transfer of the compatible relation to the incompatible mapping did not occur. The results suggest that an association between noncorresponding stimulus -response locations is acquired when the word -response mapping is incompatible, even though this relation is only implicit, regardless of whether through misapplication of a logical recoding rule or spatial representations shared by the locations and words. These associations then continue to affect processing of location when the mapping is compatible. (C) 2015 Elsevier B.V. All rights reserved.

Recent findings suggested that the orienting of attention towards gazed at locations (i.e., the gaze cueing effect) could result from the conflict emerging in incongruent trials between the spatial information conveyed by gaze direction and the target spatial position. In two experiments, we assessed this hypothesis by investigating whether this effect is influenced by the same trial-by-trial modulations that are reported in a spatial conflict task, i.e., the Simon task. In Experiment 1, we compared the trial-by-trial modulations emerging in the Simon task with those emerging in a gaze cueing task, while in Experiment 2, we compared gaze and arrows cues. Trial-by-trial modulations were evident in both tasks. In the Simon task, correspondence sequence affected both corresponding and noncorresponding responses, this resulting in a larger Simon effect when the preceding trial was corresponding and an absent effect when the preceding trial was noncorresponding. Differently, in the gaze cueing task, congruence sequence affected only congruent responses with faster responses when the preceding trial was congruent compared to when it was incongruent, resulting in a larger gaze cuing effect when the preceding trial was congruent. Same results were evident with nonpredictive arrow cues. These findings speak against a spatial conflict account.

International audience; Recent studies have suggested that individuals are not able to develop a sense of joint agency during joint actions with automata. We sought to examine whether this lack of joint agency is linked to individuals’ inability to co-represent the automaton-generated actions. Fifteen participants observed or performed a Simon response time task either individually, or jointly with another human or a computer. Participants reported the time interval between their response (or the co-actor response) and a subsequent auditory stimulus, which served as an implicit measure of participants’ sense of agency. Participants’ reaction times showed a classical Simon effect when they were partnered with another human, but not when they collaborated with a computer. Furthermore, participants showed a vicarious sense of agency when co-acting with another human agent but not with a computer. This absence of vicarious sense of agency during human-computer interactions and the relation with action co-representation are discussed.; Des études récentes ont suggéré que les individus ne sont pas en mesure de développer un sens d'agentivité conjoint lors de leurs interactions avec des automates. Nous avons cherché à examiner si ce manque d'agentivité conjointe est lié à l'incapacité des individus à représenter des actions générées par un automate. Quinze participants ont observé ou effectué une tâche de détection de cible (e.g. tâche de Simon) soit individuellement, soit conjointement avec un autre humain ou un ordinateur. Les participants ont estimé l'intervalle de temps entre leur détection (ou la détection du co-acteur) et un stimulus auditif ultérieur, ce qui a servi de mesure implicite du sens d'agentivité des participants. Les temps de réaction des participants ont montré que les participants se représentaient au sein de leur propre système moteur les actions de leur partenaire quand ils étaient en partenariat avec un autre humain mais pas quand ils ont collaboraient avec un ordinateur. De plus, les participants ont montré un sens d'agentivité conjoint lors des interactions avec un autre agent humain mais pas avec lors des interactions avec un ordinateur. Cette absence de sens d'agentivité conjoint lors des interactions homme-ordinateur et la relation avec le concept de représentation de l'action sont discutées.

A left or right keypress response to a relevant stimulus attribute (e.g., color) is faster when irrelevant left or right stimulus-location information corresponds with the correct response than when it does not. This phenomenon, known as the Simon effect, is obtained not only for physical locations, but also location words “left” and “right” and left- or right-pointing arrows. However, these location-, word-, and arrow-based Simon effects show different patterns in the reaction-time (RT) distributions, as evident in delta plots. In the present study, we employed procedures, analysis of survival curves and divergence point analysis, which have not previously been applied to the Simon effect, to investigate differences in time course of these various Simon effects in more detail. Also, we examined whether the diffusion model for conflict tasks (DMC), which assumes that automatic activation of task-irrelevant information occurs in a pulse-like function, can capture not only features of the RT distributions for the location-based Simon effect, to which it has been fit previously, but also features of the word- and arrow-based Simon effects, to which it has not. Results showed different survival curves and earliest, maximum, and latest divergence points for the three Simon effects, but DMC was able to capture the basic features of the RT distributions reflected by delta plot and survival curves for all effects. The results imply that the location-, word-, and arrow-based Simon effects have shared mechanisms, although they have different RT distributions.

The Simon effect represents a phenomenon in which the location of the stimuli affects the speed and accuracy of the response, despite being irrelevant for the task demands. This is believed to be due to an automatic activation of a response corresponding to the location of the stimuli, which conflicts with the controlled decision process based on relevant stimuli features. Previously, differences in the nature of the Simon effect (i.e., the pattern of change of the effect across the distribution of response times) between visual and somatosensory stimuli were reported. We hypothesize that the temporal dynamics of visual and somatosensory automatic and controlled processes vary, thus driving the reported behavioral differences. While most studies have used response times to study the underlying mechanisms involved, in this study we had participants reach out to touch the targets and recorded their arm movements using a motion capture system. Importantly, the participants started their movements before a final decision was made. In this way, we could analyze the movements to gain insights into the competition between the automatic and controlled processes. We used this technique to describe the results in terms of a model assuming automatic activation due to location-based evidence, followed by inhibition. We found that for the somatosensory Simon effect, the decay of the automatic process is significantly slower than for the visual Simon effect, suggesting quantitative differences in this automatic process between the visual and somatosensory modalities.

In the present study, we tested the idea that relevant and irrelevant location-based activations are combined when selecting a response in the Simon task. For this purpose, we manipulated the strength of the relevant activation by using single versus redundant relevant stimuli to indicate the correct response. Assuming that relevant and irrelevant activations are summed during the decision process, the Simon effect should be reduced in the presence of the stronger relevant activation produced by redundant stimuli. Contrary to this expectation, the results revealed that the Simon effect was larger overall with redundant stimuli than with single stimuli. Importantly, distributional analyses indicated that the Simon effect was not reduced for redundant stimuli even when controlling for the opportunity for irrelevant location activation to dissipate after stimulus onset. These results are thus inconsistent with accounts in which the summation of decision-level activations is the cause of the Simon effect. Instead, these results are consistent with the idea that redundancy and irrelevant location information influence activations at different levels. Considering the findings of previous studies, the most likely account is that redundancy affects decision-level activations whereas relevant and irrelevant activation are integrated at the motor level to produce the Simon effect (i.e., decision locus of redundancy gain and motor locus of Simon effect). (PsycINFO Database Record

In experimental psychology, a unique model of general processing is often sought to represent the behaviors of all individuals. We address the question of whether seeking this objective - a unique model - is the most fruitful scientific strategy by studying a specific case example. In order to approach an answer to such a question, we compared the conventional approach in experimental psychology with analyses at the individual level by applying a specific mathematical modeling approach. A sample of 1159 individuals completed an experimental task based on managing conflict (a type of Simon task). Key findings revealed that at least four models are required to properly account for individuals' performance. Interestingly, four out of ten participants failed to show stimulus-response congruency effects in the experimental task, whereas the remaining 60% followed distinguishable theoretical models (consistent with conflict-monitoring theory and/or priming and episodic memory effects). The reported findings suggest that individuals' psychological characteristics might help to explain some of the reproducibility issues that are currently of great concern in psychology. These findings, along with further recent research, support the view that general and differential psychological approaches work better together for addressing relevant theoretical issues in psychological research.

Most actions we perform in daily life consist of multiple movement elements. In two Simon task experiments, we investigated the impact of stimulus-response compatibility on planning and execution of action sequences. A total of 38 participants were instructed to perform action sequences consisting of multiple key presses (two to four key presses) as response to a left- or right-presented colored stimulus. Within one block, the requested action sequences were of the same length but differed in their spatial features. The results show Simon effects in reaction time for up to four-element long action sequences. The effects became especially apparent when participants were forced to finish action planning before action execution by the implementation of a no-go condition (Experiment 2). Simon effects in movement time emerged for two movement element actions, only. That is, dimensional overlap between spatial features embedded in an action sequence as well as in an imperative stimulus can affect action initiation.

The reversal logical recoding rule (i.e., "respond opposite") induced by an incompatible task (e.g., a task requiring to respond to red or green stimuli by pressing a key of the alternative colour compared to that of the stimulus) can be transferred to another task when the two tasks are combined in a task-switching paradigm. When the task to which the rule is transferred is a Simon task, this causes the disappearance of the typical advantage for responses that spatially correspond to the stimulus, or even results in an advantage for spatially noncorresponding responses. The present study aimed at investigating whether the transferred rule is independent of the specific stimulus and response dimensions for which it has been created. Previous studies suggest that when a Simon task is coupled with a colour incompatible task, the Simon effect may disappear or reverse even when stimuli in the two tasks, apart from being both visual and appearing on the same computer screen, have no other features in common. Results of the present study corroborate the hypothesis that feature overlap between stimuli is not necessary for the between-task transfer of the logical rule. However, an overlap between the representations of responses appears to be crucial. No modulation of the Simon effect was observed when the Simon task required bimanual responses while the colour-compatibility task required either vocal responses or responses executed with the two feet. In contrast, we did observe such a modulation when the discriminative response dimension and the effectors/response device were the same in the two tasks, even though these two tasks provided for different stimuli.

The present study explored how response preparation, varied by relative response frequency, affects response conflict as expressed in the Simon effect. Previous studies showed that valid response cues, when presented before the imperative stimulus, increase rather than decrease the Simon effect. This finding was explained by the hypothesis that response cues trigger shifts of attention to the side of the prepared response, and that these attention shifts modulate processing of the imperative stimulus. We investigated whether cues are necessary for inducing shifts of attention and thereby modulating the Simon effect, or whether response preparation without cues is sufficient. In two experiments, participants performed a Simon task with one response being more frequent than the other. Results showed larger Simon effects for the more frequent (i.e. prepared) response than for the less frequent (i.e. unprepared) response. These results suggest that response preparation (rather than the cue that induces the preparation) triggers a shift of spatial attention which modulates the Simon effect.