Multidimensional vector model of stimulus-response compatibility

Generalisation of unpredictable action-effect features: Large individual differences with little on-average effect

Ideomotor theory suggests that selecting a response is achieved by anticipating the consequences of that response. Evidence for this is the response-effect compatibility (REC) effect, that is, responding tends to be faster when the (anticipated) predictable consequences of a response (the action effects) are compatible rather than incompatible with the response. The present experiments investigated the extent to which the consequences must be exactly versus categorically predictable. According to the latter, an abstraction from particular instances to the categories of dimensional overlap might take place. For participants in one group of Experiment 1, left-hand and right-hand responses produced compatible or incompatible action effects in perfectly predictable positions to the left or right of fixation, and a standard REC effect was observed. For participants in another group of Experiment 1, as well as in Experiments 2 and 3, the responses also produced action effects to the left or right of fixation, but the eccentricity of the action effects (and thus their precise location) was unpredictable. On average, the data from the latter groups suggest that there is little, if any, tendency for participants to abstract the critical left/right features from spatially somewhat unpredictable action effects and use them for action selection, although there were large individual differences in these groups. Thus, at least on average across participants, it appears that the spatial locations of action effects must be perfectly predictable for these effects to have a strong influence on the response time.

Effects of a neutral warning signal under increased temporal uncertainty

Han and Proctor (2022a, Quarterly Journal of Experimental Psychology, 75[4], 754-764) reported that in a visual two-choice task, compared with a no-warning condition, a neutral warning tone caused shorter reaction times (RTs) but at the expense of an increase in error percentages (a speed-accuracy trade-off) at a constant 50-ms foreperiod but shorter RTs without an increase in error percentages at a 200-ms foreperiod. Also, the spatial compatibility of stimulus-response mappings was found to interact with the foreperiod effect on RT. We conducted three experiments to investigate whether these findings can be replicated without the constancy of foreperiod within a trial block. In Experiments 1 and 2, participants performed the same two-choice task as in Han and Proctor's study but with the foreperiod randomly varied among 50, 100, and 200 ms and RT feedback provided after each response. Results showed that as the foreperiod increased, RT decreased while EP increased, demonstrating a consistent speed-accuracy trade-off. Also, the mapping effect was found to be largest at the 100-ms foreperiod. In Experiment 3, RT feedback was not provided, and the warning tone speeded responses without evidence of an increase in error percentage. We conclude that the enhanced information processing at a 200-ms foreperiod depends on constancy of foreperiod within a trial block, whereas the mapping-foreperiod interaction found in Han and Proctor is relatively unaffected by increased temporal uncertainty.

Positive Impacts of a Four-Week Neuro-Meditation Program on Cognitive Function in Post-Acute Sequelae of COVID-19 Patients: A Randomized Controlled Trial

Study objective: Long COVID patients can experience high levels of impairment in their cognitive function and mental health. Using a parallel randomized control trial, we evaluated the effectiveness of a neuro-meditation program to reduce cognitive impairment in patients with long COVID. Methods: A total of 34 patients with long COVID were randomized to an intervention group (G-Int; n = 17) or a control group (G-Con; n = 17) and 15 healthy participants were constitutive of a normative group (G-Nor). The intervention consisted of ten 30-min sessions of Rebalance® over a period of five weeks. Each session included sound therapy and coach-guided meditation associated with light stimulations (i.e., chromotherapy). Primary outcomes were performance on five computerized cognitive tasks (choice response time, pattern comparison, Simon, pursuit rotor task, and Corsi block-tapping task), mental and physical fatigue (Chalder fatigue scale), perceived stress (perceived stress scale) and mood (profiles of mood states). Secondary outcomes were anxiety and depressive symptoms (hospital anxiety and depression scale), muscular pain, joint pain, and headaches using visual analog scales (VAS) as well as sleep quality (Spiegel sleep questionnaire). Assessments were conducted at baseline and at 1−2 and 7−8 days of follow-up. Results: Compared to healthy subjects, long COVID patients showed significant differences at baseline on all the self-report questionnaires, and a Rebalance® program improved all the subjective reports, as well as cognitive performances, especially on reaction time-based tasks. In particular, only the G-Int group revealed shortened reaction times in the choice reaction time (RTbaseline = 593 ± 121 ms vs. RTpost2 = 521 ± 86 ms, p < 0.001), Simon (RTbaseline = 539 ± 123 ms vs. RTpost2 = 494 ± 134 ms, p < 0.01), and pattern comparison tasks (RTbaseline = 1244 ± 315 ms vs. RTpost2 = 1079 ± 213 ms, p < 0.001). Conclusions) Initial evidence suggests that neuro-meditation reduces cognitive impairment and improves physical and mental fatigue, muscle and joint pain, symptoms of depression and anxiety, mood disturbances as well as sleep quality. The Rebalance® program hence constitutes a promising non-pharmacological intervention for the treatment of long-term psychological/cognitive outcomes of COVID-19.

The Simon Effect Asymmetry for Left- and Right-Dominant Persons

When participants respond to a task-relevant stimulus attribute by pressing a left or right key with the respective index finger, reaction time is shorter if task-irrelevant left-right stimulus location corresponds to that of the response key than if it does not. For right-handers, this Simon effect is larger for right-located than left-located stimuli; for left-handers this Simon-effect asymmetry is reversed. A similar asymmetry has been found for right-footers pressing pedals with their feet. For analyses that separate stimulus- and response-location factors, these asymmetries appear as a main effect of response location, with responses being faster with the dominant effector. If the Simon-effect asymmetry is strictly a function of effector dominance, it should reverse for left-footers responding with their feet. In Experiment 1, left-dominant persons showed faster responses with the left than right hand but with the right than left foot, a finding consistent with prior research on tapping actions. Right-dominant persons also showed the right-foot asymmetry but, unexpectedly, not the typical asymmetry with hand responses. To evaluate whether hand-presses yield results distinct from finger-presses, in Experiment 2 participants performed the Simon task with finger-presses and hand-presses. The opposing asymmetries for right- and left-dominant persons were evident for both response modes. Our results are consistent with the view that the Simon effect asymmetry is primarily due to differences in effector efficiency, usually but not always favoring the dominant effector.

A diffusion model for the congruency sequence effect

Two-choice reaction tasks for which stimuli differ on irrelevant and relevant dimensions (e.g., Simon, flanker, and Stroop tasks) show congruency effects. The diffusion model for conflict tasks (DMC) has provided a quantitative account of the mechanisms underlying decisions in such conflict tasks, but it has not been applied to the congruency sequence effect (CSE) for which the congruency on the prior trial influences performance on the current trial. The present study expands analysis of the reaction time (RT) distributions reflected by delta plots to the CSE, and then extends the DMC to simulate the results. With increasing RT: (1) the spatial Simon effect was almost unchanged following congruent trials but initially became smaller and finally reversed following incongruent trials; (2) the arrow-based Simon effects increased following both congruent and incongruent trials, but more so for the former than the latter; (3) the flanker congruency effect varied quadratically following congruent trials but increased linearly following incongruent trials. These results were modeled by the CSE-DMC, extended from the DMC with two additional assumptions: (1) feature integration influences only the controlled processes; (2) following incongruent trials, the automatic process is weakened. The results fit better with the CSE-DMC than with two variants that separately had only one of the two additional assumptions. These findings indicate that the CSEs for different conflict tasks have disparate RT distributions and that these disparities are likely due to the controlled and automatic processes being influenced differently for each trial sequence.

The effect of irrelevant response dimension on stimulus response compatibility

The well-known Stroop, Simon, and Eriksen flanker effects reflect the influence of an irrelevant dimension of a stimulus on task performance. In contrast, this study investigated the effect of an irrelevant (color) dimension of a response on performance. In Experiment 1, participants performed a color-discrimination Simon task with left and right responses. The novel feature of the experiment was that two-colored labels were presented at the bottom of the display, on the left and right side respectively, which were irrelevant to the task and had nothing to do with response keys. The results revealed a Color Compatibility effect. Participants responded faster and more accurately when the color of the label appearing on the same side (left or right) as the correct response matched the color of the stimulus than when it did not. Experiment 2A replicated the Color Compatibility effect. Experiment 2B showed that the Color Compatibility effect in reaction times disappeared when color was irrelevant to both the stimulus and the response. The results suggest that the presence of an irrelevant color dimension at response may result in a stimulus-response compatibility (SRC) effect as long as the color is represented in working memory. These studies have implications for the dimensional overlap model and the broader understanding of stimulus-response compatibility effects.

Your action does matter to me: Examining the role of the co-actor's action-effects in resolving the self-other discrimination problem

Sharing a task with another person can introduce the need to discriminate representations that refer to our own action from that of the other person's. The current understanding is that information about the stimulus event drives the self-other discrimination process, as it promotes (via the reactivation of feature codes) the representation that encodes the corresponding action. However, this mechanistic explanation relies on experimental situations in which stimulus event information (e.g., spatial location) is always and directly available. Thus, it remains unclear whether and how we could successfully discriminate between self- and other related action representations in the absence of such information. The present study addressed this unanswered question using a novel joint Simon task-based paradigm. We report the results of three experiments in which we manipulated the availability of stimulus event information into the contralateral space. Our findings demonstrate that participants are able to compensate for the absence of stimulus event information by relying on temporal features of their co-actor's action-effects (Experiment 1). Even more surprising was that participants continued to monitor the temporal features of their co-actor's actions even when given a verbal signal by their co-actor (Experiments 2a), or full access to the common workspace (Experiment 2b). Our results are strong evidence that the representation of actions is not purely stimulus driven. They suggest that the temporal dimension of the other person's actions is able to drive the self-other discrimination process, in the same way as other perceptual dimensions and feature codes that are shared with the stimulus event.

Interaction mechanism between location and sequence in letter cognition

A previous study used days as a sequence symbol to investigate the interaction mechanism between location and sequence in sequence symbol cognition; the study findings suggested that the spatial stimulus-response compatibility effect and the Simon effect could not co-exist with the SNARC-like effect when processing sequence symbols. The previous study did not include the influence of the difficulty of identifying sequence symbols on the Simon effect in the investigation, so it is unclear whether the conclusion about processing sequence symbols with considerable identification difficulty can be extended to the processing of sequence symbols with less identification difficulty. Therefore, the present study explored letters that have a low level of identification difficulty to investigate the interaction mechanism between location and sequence in sequence symbol cognition. Participants were asked to classify a probe letter, which was randomly displayed on the left or right side of the screen, according to its location (Experiment 1), its sequence (Experiment 2) or its colour (Experiment 3). The results indicated that (1) only the spatial stimulus-response compatibility effect and Simon effect were present in the letter location classification task and letter colour classification task, respectively. (2) The Simon effect co-existed with the SNARC-like effect, and these two effects interacted with each other in the letter sequence classification task. From these results, it can be concluded that the task determines whether the Simon effect and the SNARC-like effect can co-exist, with differences presented across sequence symbols.

Word- and arrow-based Simon effects emerge for eccentrically presented location words and arrows

Two experiments examined whether the location-based Simon effect and word- or arrow-based Simon effects, and their interaction, emerge in the same task situations by presenting location words and (left and right, Experiment 1) or single-headed arrows (left and right pointing, Experiment 2) in the left-right visual field. These tasks include two attributes of task-irrelevant location information, physical location and either location word (Experiment 1) or arrow direction (Experiment 2), when they vary jointly for a single stimulus. Moreover, the location-based Simon effect in these tasks was compared to that obtained in a pure location-based Simon task. Results showed that (1) the location-, word- and arrow-based Simon effects occurred on both mean RT and delta plots; (2) the word- and arrow-based Simon effects interacted with the location-based Simon effect on mean RT; (3) the Simon effect in the pure location-based Simon task differed little from the location-based Simon effect in the two joint Simon tasks. These results indicate that different task-irrelevant spatial attributes can influence responses in the same task, and that one of them can influence the effect of the other on responses. This latter result offers evidence that the different attributes do not provide separate sources of activation.

The influence of the location of ordered symbols on the ordinal position effect: The involvement of the task performed

Since the ordinal position effect was identified, several studies have investigated its mechanism in various contexts; however, how the space location of ordinal symbols influences this effect remains unclear. Thus, the present study explored Chinese words representing the day before yesterday, yesterday, tomorrow, and the day after tomorrow as ordinal symbols to investigate how the stimulus space location influences the ordinal position effect across different task contexts. We randomly and equally presented days on the left or right location of a display and asked participants to perform a stimulus space location, a stimulus colour and a stimulus order classification task in three consecutive experiments, respectively. The results revealed that the spatial stimulus-response compatibility effect and Simon effect prevailed in the stimulus space location and colour classification task. Conversely, the ordinal position effect prevailed in the stimulus order classification task. These results suggested that (1) the spatial stimulus-response compatibility effect (or Simon effect) and the ordinal position effect cannot appear simultaneously in some experimental contexts and that (2) the task context predicted which of these effects prevailed. From these results, we conclude that the ordinal symbols could be coded depending on multiple reference frames, including spatial and non-spatial reference frame, and the use of the reference frame was mediated by the task context.

The location-based Simon effect: Reliability of ex-Gaussian analysis

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.

Shared mechanisms underlying the location-, word- and arrow-based Simon effects

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.

How different direct association routes influence the indirect route in the same Simon-like task

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.

Vertically arrayed stimuli and responses: transfer of incompatible spatial mapping to Simon task occurs regardless of response-device orientation

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.

No evidence for shared representations of task sets in joint task switching

It has been suggested that actors co-represent a shared task context when they perform a task in a joint fashion. The present study examined the possibility of co-representation in joint task switching, in which two actors shared two tasks that switched randomly across trials. Experiment 1 showed that when an actor performed the tasks individually, switch costs were obtained if the actors responded on the previous trial (go trial), but not if they did not respond (no-go trial). When two actors performed the tasks jointly, switch costs were obtained if the actor responded on the previous trial (actor-repeat trials) but not if the co-actor responded (actor-switch trials). In Experiment 2, a single actor performed both tasks of the joint condition to test whether the findings of Experiment 1 were due to the use of different response sets by the two actors. Switch costs were obtained for both repetitions and alternations of the response set, which rules out this possibility. Taken together, our findings provided little support for the idea that actors co-represent the task sets of their co-actors.

Do silhouettes and photographs produce fundamentally different object-based correspondence effects?

When participants classify pictures of objects as upright or inverted with a left or right keypress, responses are faster if the response location (left/right) corresponds with the location of a handle (left/right) than if it does not. This result has typically been attributed to a grasping affordance (automatic activation of muscles associated with grasping the object with the ipsilateral hand), but several findings have indicated instead that the effect is a spatial correspondence effect, much like the Simon effect for object location. Pappas (2014) reported evidence he interpreted as showing that spatial coding predominates with silhouettes of objects, whereas photographs of objects yield affordance-based effects. We conducted two experiments similar to those of Pappas, using frying pans as stimuli, with our two experiments differing in whether the entire object was centered on the display screen or the base was centered. When the objects were centered, a positive correspondence effect relative to the handle was evident for the silhouettes but a negative correspondence effect for the photographs. When the base was centered, the handle was clearly located to the left or right side of the display, and both silhouettes and photographs produced correspondence effects of similar size relative to the handle location. Despite the main results being counter to the grasping affordance hypothesis, response-time distribution analyses suggest that, instead of activating automatically at fast responses, an effector-specific component of the hypothesized type may come into play for responses that are selected after the handle location has been identified.

Transcranial direct current stimulation (tDCS) reveals a dissociation between SNARC and MARC effects: Implication for the polarity correspondence account

The concept of stimulus response compatibility (SRC) refers to the existence of a privileged association between a specific stimulus feature and a specific response feature. Two examples of SRC are the Spatial Numerical Association of Response Codes (SNARC) and the Markedness Association of Response Codes (MARC) effects. According to the polarity correspondence principle, these two SRC effects occur because of a match between the most salient dimensions of stimulus and response. Specifically, the SNARC effect would be caused by a match between right-sided responses and large numbers, while a match between right-sided responses and even numbers would give rise to the MARC effect. The aim of the present study was to test the validity of the polarity correspondence principle in explaining these two SRC effects. To this end, we applied transcranial direct current stimulation (tDCS) over left and right posterior parietal cortex (PPC), which is thought to be the neural basis of salience processing, during a parity judgement task. Results showed that cathodal tDCS over the PPC significantly reduced the MARC effect but did not affect the SNARC effect, suggesting a dissociation between the two effects. That is, the MARC would rely on a salience processing mechanism, whereas the SNARC would not. Despite this interpretation is in need of further experimental confirmations (i.e., testing different tasks or using different tDCS montages), our results suggest that the polarity correspondence principle can be a plausible explanation only for the MARC effect but not for the SNARC effect.

Action-effect sharing induces task-set sharing in joint task switching

A central issue in the study of joint task performance has been one of whether co-acting individuals perform their partner's part of the task as if it were their own. The present study addressed this issue by using joint task switching. A pair of actors shared two tasks that were presented in a random order, whereby the relevant task and actor were cued on each trial. Responses produced action effects that were either shared or separate between co-actors. When co-actors produced separate action effects, switch costs were obtained within the same actor (i.e., when the same actor performed consecutive trials) but not between co-actors (when different actors performed consecutive trials), implying that actors did not perform their co-actor's part. When the same action effects were shared between co-actors, however, switch costs were also obtained between co-actors, implying that actors did perform their co-actor's part. The results indicated that shared action effects induce task-set sharing between co-acting individuals.

Sharing tasks or sharing actions? Evidence from the joint Simon task

In a joint Simon task, a pair of co-acting individuals divide labors of performing a choice-reaction task in such a way that each actor responds to one type of stimuli and ignores the other type that is assigned to the co-actor. It has been suggested that the actors share the mental representation of the joint task and perform the co-actor’s trials as if they were their own. However, it remains unclear exactly which aspects of co-actor’s task-set the actors share in the joint Simon task. The present study addressed this issue by manipulating the proportions of compatible and incompatible trials for one actor (inducer actor) and observing its influences on the performance of the other actor (diagnostic actor) for whom there were always an equal proportion of compatible and incompatible trials. The design of the present study disentangled the effect of trial proportion from the confounding effect of compatibility on the preceding trial. The results showed that the trial proportions for the inducer actor had strong influences on the inducer actor’s own performance, but it had little influence on the diagnostic actor’s performance. Thus, the diagnostic actor did not represent aspects of the inducer actor’s task-set beyond stimuli and responses of the inducer actor. We propose a new account of the effect of preceding compatibility on the joint Simon effect.

Observed bodies generate object-based spatial codes

Contemporary studies of spatial and social cognition frequently use human figures as stimuli. The interpretation of such studies may be complicated by spatial compatibility effects that emerge when researchers employ spatial responses, and participants spontaneously code spatial relationships about an observed body. Yet, the nature of these spatial codes - whether they are location- or object-based, and coded from the perspective of the observer or the figure - has not been determined. Here, we investigated this issue by exploring spatial compatibility effects arising for objects held by a visually presented whole-bodied schematic human figure. In three experiments, participants responded to the colour of the object held in the figure's left or right hand, using left or right key presses. Left-right compatibility effects were found relative to the participant's egocentric perspective, rather than the figure's. These effects occurred even when the figure was rotated by 90° to the left or to the right, and the coloured objects were aligned with the participant's midline. These findings are consistent with spontaneous spatial coding from the participant's perspective and relative to the normal upright orientation of the body. This evidence for object-based spatial coding implies that the domain general cognitive mechanisms that result in spatial compatibility effects may contribute to certain spatial perspective-taking and social cognition phenomena.

Polarity Correspondence as a General Compatibility Principle

Proctor and Cho (2006) proposed that, when making binary decisions, people code the stimulus and response alternatives asymmetrically (positive and negative polarities), with performance being best when the codes of the corresponding polarities are paired. They presented evidence that polarity correspondence could explain many results associated with orthogonal compatibility, the Implicit Association Test, and numerical judgments. We review and evaluate literature on these topics and on polarity coding in the context of metaphorical relations published during the ensuing 10 years. Our conclusion is that the results have supported polarity correspondence as a contributor to binary decisions. We consider issues concerning the principle and topics in need of research.

Transfer of learning in choice reactions: The roles of stimulus type, response mode, and set-level compatibility

The Simon effect refers to the advantage of responding to spatially compatible stimuli. This effect can be eliminated or even reversed to favor spatially incompatible stimuli after participants practice a choice-reaction task with spatially incompatible mappings (e.g., pressing left and right keys to stimuli on the right and left, respectively). This transfer of incompatible spatial associations has been observed under conditions in which responses were made manually (e.g., keypresses, moving a joystick). The present study used vocal responses to reveal the primary determinants of the transfer effect, dissociating the influences of stimulus type, response mode, and their interaction (set-level compatibility). The results suggest that contextual match between the practice and transfer tasks with respect to stimulus type and response mode determined transfer of incompatible associations to the Simon task, and stimulus type determined the efficiency of acquiring new associations. However, there was little evidence that set-level compatibility plays any major role in either acquisition or transfer of spatial associations.

Electrophysiological dynamics reveal distinct processing of stimulus-stimulus and stimulus-response conflicts

The present study examined electroencephalogram profiles on a novel stimulus-response compatibility (SRC) task in order to elucidate the distinct brain mechanisms of stimulus-stimulus (S-S) and stimulus-response (S-R) conflict processing. The results showed that the SRC effects on reaction times (RTs) and N2 amplitudes were additive when both S-S and S-R conflicts existed. We also observed that, for both RTs and N2 amplitudes, the conflict adaptation effects-the reduced SRC effect following an incongruent trial versus a congruent trial-were present only when two consecutive trials involved the same type of conflict. Time-frequency analysis revealed that both S-S and S-R conflicts modulated power in the theta band, whereas S-S conflict additionally modulated power in the alpha and beta bands. In summary, our findings provide insight into the domain-specific conflict processing and the modular organization of cognitive control.

Modeling graded response congruency effects in task switching

Compound cue retrieval is a computational model of a mediated route for response selection in task-switching situations. In previous studies, the model has been shown to account for response congruency effects when switching between two tasks, where response congruency reflects the degree of match between relevant and irrelevant task responses associated with a target stimulus. In the present study, the author derived a model prediction of graded response congruency effects in situations involving three tasks. The predicted pattern was observed for both response time and error rate in an experiment in which numerical categorization tasks were performed on single-digit targets. Implications for understanding response congruency effects and for developing models of task-switching performance are discussed.

The joint Simon effect: a review and theoretical integration

The social or joint Simon effect has been developed to investigate how and to what extent people mentally represent their own and other persons' action/task and how these cognitive representations influence an individual's own behavior when interacting with another person. Here, we provide a review of the available evidence and theoretical frameworks. Based on this review, we suggest a comprehensive theory that integrates aspects of earlier approaches–the Referential Coding Account. This account provides an alternative to the social interpretation of the (joint) go-nogo Simon effect (aka the social Simon effect) and is able to integrate seemingly opposite findings on joint action.

Correspondence Effects with Torches: Grasping Affordance or Visual Feature Asymmetry?

Three experiments were conducted to determine whether an object-based correspondence effect for torch (flashlight) stimuli reported by Pellicano et al. [(2010). Simon-like and functional affordance effects with tools: The effects of object perceptual discrimination and object action state. Quarterly Journal of Experimental Psychology, 63, 2190–2201] is due to a grasping affordance provided by the handle or asymmetry of feature markings on the torch. In Experiment 1 the stimuli were the same as those from Pellicano et al.'s Experiment 2, whereas in Experiments 2 and 3 the stimuli were modified versions with the graspable handle removed. Participants in all experiments performed upright/inverted orientation judgements on the torch stimuli. The results of Experiment 1 replicated those of Pellicano et al.: A small but significant object-based correspondence effect was evident, mainly when the torch was in an active state. With the handle of the torch removed in Experiment 2, making the barrel markings more asymmetric in the display, the correspondence effect was larger. Experiment 3 directly demonstrated an effect of barrel-marking asymmetry on the correspondence effect: When only the half of the markings nearest the light end of the torch was included, the correspondence effect reversed to favour the light end. The results are in agreement with a visual feature-asymmetry account and are difficult to reconcile with a grasping-affordance account.

Independent processing of stimulus-stimulus and stimulus-response conflicts

The dimensional overlap (DO) model proposes distinct mechanisms for stimulus-stimulus (S-S) and stimulus-response (S-R) conflict effects. Many studies have examined the independence of S-S and S-R conflict effects in the color-word Stroop and Simon tasks. However, confounds exist between the distinction of DO (i.e., S-S dimensional overlap compared with S-R dimensional overlap) and the distinction of stimulus attributes (e.g., color compared with spatial location; semantic compared with nonsemantic information), which may hinder interpretation of the independence of S-S and S-R conflicts. A spatial Stroop (word) task and a spatial Stroop (arrow) task were combined with a Simon task in Experiments 1 and 2, respectively to eliminate these confounds of stimulus attributes. The results showed that S-S and S-R conflicts affected performance additively. There was no significant correlation across participants. These findings lend further support to independent processing of S-S and S-R conflicts as it is outlined in the taxonomy of DO.

The Psychology Experiment Building Language (PEBL) and PEBL Test Battery

BACKGROUND

We briefly describe the Psychology Experiment Building Language (PEBL), an open source software system for designing and running psychological experiments.

NEW METHOD

We describe the PEBL Test Battery, a set of approximately 70 behavioral tests which can be freely used, shared, and modified. Included is a comprehensive set of past research upon which tests in the battery are based.

RESULTS

We report the results of benchmark tests that establish the timing precision of PEBL.

COMPARISON WITH EXISTING METHOD

We consider alternatives to the PEBL system and battery tests.

CONCLUSIONS

We conclude with a discussion of the ethical factors involved in the open source testing movement.

How Task Goals Mediate the Interplay between Perception and Action

Theories of embodied cognition suppose that perception, action, and cognition are tightly intertwined and share common representations and processes. Indeed, numerous empirical studies demonstrate interaction between stimulus perception, response planning, and response execution. In this paper, we present an experiment and a connectionist model that show how the Simon effect, a canonical example of perception–action congruency, can be moderated by the (cognitive representation of the) task instruction. To date, no representational account of this influence exists. In the experiment, a two-dimensional Simon task was used, with critical stimuli being colored arrows pointing in one of four directions (backward, forward, left, or right). Participants stood on a Wii balance board, oriented diagonally toward the screen displaying the stimuli. They were either instructed to imagine standing on a snowboard or on a pair of skis and to respond to the stimulus color by leaning toward either the left or right foot. We expected that participants in the snowboard condition would encode these movements as forward or backward, resulting in a Simon effect on this dimension. This was confirmed by the results. The left–right congruency effect was larger in the ski condition, whereas the forward–backward congruency effect appeared only in the snowboard condition. The results can be readily accounted for by HiTEC, a connectionist model that aims at capturing the interaction between perception and action at the level of representations, and the way this interaction is mediated by cognitive control. Together, the empirical work and the connectionist model contribute to a better understanding of the complex interaction between perception, cognition, and action.

Intentional weighting: a basic principle in cognitive control

Human perception and action are tailored to the situation at hand, and thus reflect the current intentions of the perceiver/actor. We suggest that this is achieved by an "intentional-weighting" mechanism. It operates on the cognitive representations of the features of perceived events and produced event--perceptions and actions that is. Intention- or goal-related feature dimensions are weighted more strongly, so that feature values defined on the respective dimension have a stronger impact on information processing, and stimulus and response selection in particular. This article discusses what intentional weighting is, how such a mechanism may work, and how it relates to available research on attention, action planning, and executive control.

Dissociating influences of key and hand separation on the Stroop color-identification effect

Three experiments examined the influence of distance between response keys (and hands) on the Stroop effect obtained for two-choice tasks in which stimulus colors were identified with keypresses. The Stroop effect was larger when the response locations were close together than when they were far apart, replicating a previous finding. Although this result was obtained only in the initial 30 trials, it was evident in a between-subject design as well as a within-subject design. With more practice, the Stroop effect was of similar size for the close and far separation conditions. Also, when the keys were close together, the Stroop effect was of similar size regardless of whether they were actuated by fingers from one or two hands, providing evidence against anatomical discriminability as a critical factor. Finally, the Stroop effect was numerically larger when the close keys were pressed by sticks held at the far separation than when the far keys were pressed by sticks held at the close separation, implicating distance between the keys rather than the hands as the main factor. The initially larger Stroop effect in RT for close keys could be due to lower spatial discriminability or to an accuracy bias in response thresholds, as suggested by the finding that it was accompanied by a numerically smaller effect in percent error.