Thomas Dolk

The (not so) social Simon effect: A referential coding account

The joint go-nogo Simon effect (social Simon effect, or joint cSE) has been considered as an index of automatic action/task co-representation. Recent findings, however, challenge extreme versions of this social co-representation account by suggesting that the (joint) cSE results from any sufficiently salient event that provides a reference for spatially coding ones own action. By manipulating the salient nature of reference-providing events in an auditory go-nogo Simon task, the present study indeed demonstrates that spatial reference events do not necessarily require social (Experiment 1) or movement features (Experiment 2) to induce action coding. As long as events attract attention in a bottom-up fashion (e.g., auditory rhythmic features; Experiment 3 and 4), events in an auditory go-nogo Simon task seem to be co-represented irrespective of the agent or object producing these events. This suggests that the cSE does not necessarily imply the co-representation of tasks. The theory of event coding provides a comprehensive account of the available evidence on the cSE: the presence of another salient event requires distinguishing the cognitive representation of ones own action from the representation of other events, which can be achieved by referential coding-the spatial coding of ones action relative to the other events.

How “Social” is the social Simon effect?

In the standard Simon task, participants carry out spatially defined responses to non-spatial stimulus attributes. Responses are typically faster when stimulus location and response location correspond. This effect disappears when a participant responds to only one of the two stimuli and reappears when another person carries out the other response. This social Simon effect (SSE) has been considered as providing an index for action co-representation. Here, we investigated whether joint-action effects in a social Simon task involve mechanisms of action co-representation, as measured by the amount of incorporation of another persons action. We combined an auditory social Simon task with a manipulation of the sense of ownership of another persons hand (rubber hand illusion). If the SSE is established by action co-representation, then the incorporation of the other persons hand into ones own body representation should increase the SSE (synchronous > asynchronous stroking). However, we found the SSE to be smaller in the synchronous as compared to the asynchronous stroking condition (Experiment 1), suggesting that the SSE reflects the separation of spatial action events rather than the integration of the other persons action. This effect is independent of the active involvement (Experiment 2) and the presence of another person (Experiment 3). These findings suggest that the “social” Simon effect is not really social in nature but is established when an interaction partner produces events that serve as a spatial reference for ones own actions.

The benefit of gestures during communication: Evidence from hearing and hearing-impaired individuals

There is no doubt that gestures are communicative and can be integrated online with speech. Little is known, however, about the nature of this process, for example, its automaticity and how our own communicative abilities and also our environment influence the integration of gesture and speech. In two Event Related Potential (ERP) experiments, the effects of gestures during speech comprehension were explored. In both experiments, participants performed a shallow task thereby avoiding explicit gesture-speech integration. In the first experiment, participants with normal hearing viewed videos in which a gesturing actress uttered sentences which were either embedded in multi-speaker babble noise or not. The sentences contained a homonym which was disambiguated by the information in a gesture, which was presented asynchronous to speech (1000 msec earlier). Downstream, the sentence contained a target word that was either related to the dominant or subordinate meaning of the homonym and was used to indicate the success of the disambiguation. Both the homonym and the target word position showed clear ERP evidence of gesture-speech integration and disambiguation only under babble noise. Thus, during noise, gestures were taken into account as an important communicative cue. In Experiment 2, the same asynchronous stimuli were presented to a group of hearing-impaired students and age-matched controls. Only the hearing-impaired individuals showed significant speech-gesture integration and successful disambiguation at the target word. The age-matched controls did not show any effect. Thus, individuals who chronically experience suboptimal communicative situations in daily life automatically take gestures into account. The data from both experiments indicate that gestures are beneficial in countering difficult communication conditions independent of whether the difficulties are due to external (babble noise) or internal (hearing impairment) factors.

Action blind: Disturbed self-other integration in schizophrenia

Recent research using individual task settings suggests that a major problem in schizophrenia is a dysfunctional theory of mind system leading to false mental state attributions. However, if a more low-level deficit to integrate own and others actions (action blindness) is present in schizophrenia is still unknown. Using a social Simon task, we tested if schizophrenia patients have a deficit in self-other integration. Further, we tested for a possible genetic bias of this dysfunction by studying clinically unaffected first-degree relatives of schizophrenia patients. While schizophrenia patients showed no Social Simon effect, we found a reliable social Simon effect in healthy participants and first-degree relatives of schizophrenia patients. Joint task performance differed statistically between patients and healthy controls. We did not find any differences in the size of the social Simon effects of relatives and healthy controls. The present findings suggest that schizophrenia patients have severe problems with self-other integration, which may lead to problems in social interactions. Since first-degree relatives of schizophrenia patients showed a reliable social Simon effect, the evidence for a genetic bias of this social dysfunction in schizophrenia however is weak.

Keys and seats: Spatial response coding underlying the joint spatial compatibility effect.

Spatial compatibility effects (SCEs) are typically observed when participants have to execute spatially defined responses to nonspatial stimulus features (e.g., the color red or green) that randomly appear to the left and the right. Whereas a spatial correspondence of stimulus and response features facilitates response execution, a noncorrespondence impairs task performance. Interestingly, the SCE is drastically reduced when a single participant responds to one stimulus feature (e.g., green) by operating only one response key (individual go/no-go task), whereas a full-blown SCE is observed when the task is distributed between two participants (joint go/no-go task). This joint SCE (a.k.a. the social Simon effect) has previously been explained by action/task co-representation, whereas alternative accounts ascribe joint SCEs to spatial components inherent in joint go/no-go tasks that allow participants to code their responses spatially. Although increasing evidence supports the idea that spatial rather than social aspects are responsible for joint SCEs emerging, it is still unclear to which component(s) the spatial coding refers to: the spatial orientation of response keys, the spatial orientation of responding agents, or both. By varying the spatial orientation of the responding agents (Exp. 1) and of the response keys (Exp. 2), independent of the spatial orientation of the stimuli, in the present study we found joint SCEs only when both the seating and the response key alignment matched the stimulus alignment. These results provide evidence that spatial response coding refers not only to the response key arrangement, but also to the—often neglected—spatial orientation of the responding agents.

The joint Simon effect depends on perceived agency, but not intentionality, of the alternative action

A co-actors intentionality has been suggested to be a key modulating factor for joint action effects like the joint Simon effect (JSE). However, in previous studies intentionality has often been confounded with agency defined as perceiving the initiator of an action as being the causal source of the action. The aim of the present study was to disentangle the role of agency and intentionality as modulating factors of the JSE. In Experiment 1, participants performed a joint go/nogo Simon task next to a co-actor who either intentionally controlled a response button with own finger movements (agency+/intentionality+) or who passively placed the hand on a response button that moved up and down on its own as triggered by computer signals (agency−/intentionality−). In Experiment 2, we included a condition in which participants believed that the co-actor intentionally controlled the response button with a Brain-Computer Interface (BCI) while placing the response finger clearly besides the response button, so that the causal relationship between agent and action effect was perceptually disrupted (agency−/intentionality+). As a control condition, the response button was computer controlled while the co-actor placed the response finger besides the response button (agency−/intentionality−). Experiment 1 showed that the JSE is present with an intentional co-actor and causality between co-actor and action effect, but absent with an unintentional co-actor and a lack of causality between co-actor and action effect. Experiment 2 showed that the JSE is absent with an intentional co-actor, but no causality between co-actor and action effect. Our findings indicate an important role of the co-actors agency for the JSE. They also suggest that the attribution of agency has a strong perceptual basis.

Joint response–effect compatibility

When performing jointly on a task, human agents are assumed to represent their coactor’s share of this task, and research in various joint action paradigms has focused on representing the coactor’s stimulus–response assignments. Here we show that the response–effect (R–E) contingencies exploited by a coactor also affect performance, and thus might be represented as if they were used by oneself. Participants performed an R–E compatibility task, with keypresses producing spatially compatible or incompatible action effects. We did not observe any R–E compatibility effects when the task was performed in isolation (individual go–no-go). By contrast, small but reliable R–E compatibility effects emerged when the same task was performed in a joint setting. These results indicate that the knowledge of a coactor’s R–E contingencies can influence whether self-produced action effects are used for one’s own motor control.

The joint flanker effect: less social than previously thought.

Research on joint action has been taken to suggest that actors automatically co-represent the tasks and/or actions of co-actors. However, recent findings on the joint Simon effect have provided evidence for a nonsocial account, which renders automatic co-representation unlikely. In the present study, we aimed to test whether a nonsocial account is also feasible for the joint version of the flanker task. In particular, we manipulated the social nature of the “co-actor” who could be another human or a Japanese waving cat. Contrary to the social interpretation of the joint flanker effect, the results demonstrated a “joint” flanker effect, irrespective of whether participants shared the task with another person or with the Japanese waving cat.

Referential Coding Does Not Rely on Location Features: Evidence for a Nonspatial Joint Simon Effect

The joint Simon effect (JSE) shows that the presence of another agent can change ones representation of ones task and/or action. According to the spatial response coding approach, this is because another person in ones peri-personal space automatically induces the spatial coding of ones own action, which in turn invites spatial stimulus-response priming. According to the referential coding approach, the presence of another person or event creates response conflict, which the actor is assumed to solve by emphasizing response features that discriminate between ones own response and that of the other. The 2 approaches often make the same predictions, but the spatial response coding approach considers spatial location as the only dimension that can drive response coding, whereas the referential coding approach allows for other dimensions as well. To compare these approaches, the authors ran 2 experiments to see whether a nonspatial JSE can be demonstrated. Participants responded to the geometrical shape of a central colored stimulus by pressing a left or right button, while wearing gloves of the same or different color as the stimuli. Participants performed the task individually, either by responding to either stimulus shapes (Experiment 1) or by responding to only 1 of the 2 shapes (Experiment 2), and in the presence of a coactor. Congruence between stimulus and glove color affected performance in the 2-choice and the joint tasks but not in the individual go/no-go task. This demonstration of a nonspatial JSE is inconsistent with the spatial response coding approach but supports the referential coding approach.

Bidirectional semantic interference between action and speech

Research on embodied cognition assumes that language processing involves modal simulations that recruit the same neural systems that are usually used for action execution. If this is true, one should find evidence for bidirectional crosstalk between action and language. Using a direct matching paradigm, this study tested if action–languages interactions are bidirectional (Experiments 1 and 2), and whether the effect of crosstalk between action perception and language production is due to facilitation or interference (Experiment 3). Replicating previous findings, we found evidence for crosstalk when manual actions had to be performed simultaneously to action–word perception (Experiment 1) and also when language had to be produced during simultaneous perception of hand actions (Experiment 2). These findings suggest a clear bidirectional relationship between action and language. The latter crosstalk effect was due to interference between action and language (Experiment 3). By extending previous research of embodied cognition, the present findings provide novel evidence suggesting that bidirectional functional relations between action and language are based on similar conceptual–semantic representations.