The Joint Flanker Effect and the Joint Simon Effect: On the Comparability of Processes Underlying Joint Compatibility Effects

Abstract

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.

Drawn together: When motor representations ground joint actions

“…In a series of experiments, Dolk et al (2011), Liepelt (2013, 2014) have proposed that effects which appear to be specific to joint action are actually merely a consequence of mechanisms for distinguishing one's own actions from other events (see further Dittrich, Bossert, Rothe-Wulf, & Klauer, 2017;Wenke et al, 2011). On this account, what matters are relations between one's own actions and other events rather than between one's own actions and a co-actor's actions.…”

Theory of mind and joint action in Parkinson’s disease

“…Nevertheless, the different performances in the joint and individual Flanker task could also be explained according to the attentional-focus account (Dittrich et al, 2017;Doneva & Cole, 2014;Fabbri et al, 2017Fabbri et al, , 2018Porcu et al, 2016;Shteynberg, 2015). Conversely from PCC/TPJ patients, the frontal patients, who failed in the ToM task, had difficulty involving enough processing resources to code both their own action and the actions of the co-actor.…”

“…However, the action co-representation account for the joint compatibility effect has recently been challenged (Dittrich, Bossert, Rothe-Wulf, & Klauer, 2017;Dittrich, Dolk, Rothe-Wulf, et al, 2013;Dittrich, Rothe, & Klauer, 2012;Dolk, Hommel, Prinz, & Liepelt, 2013, 2014aDoneva & Cole, 2014;Guagnano, Rusconi, & Umiltà, 2010;Hommel, Colzato, & van den Wildenberg, 2009;Klempova & Liepelt, 2015;Liepelt, Wenke, Fischer, & Prinz, 2011;Müller, Brass, Kühn, et al, 2011a;Porcu, Bölling, Lappe, & Liepelt, 2016;Puffe, Dittrich, & Klauer, 2017;Sellaro, Dolk, Colzato, et al, 2015;Stenzel & Liepelt, 2016; see Dolk, Hommel, Colzato et al, 2011, 2014b. One of these recent alternative accounts is the referential coding account (Dolk et al, 2011(Dolk et al, , 2013(Dolk et al, , 2014a, which offers a plausible explanation for modulations of the joint Simon effect in a number of observations, such as group membership (i.e., in-group vs. out-group; Müller, Kühn, van Baaren et al, 2011b) or the presence of a joint Simon effect in presence of nonhuman co-actors (e.g., Japanese waving cat: Dolk et al, 2013) compared with the action co-representation account.…”

“…When a salient (human or nonhuman) event is introduced, a greater response discrimination is induced, and thus the impact of all flankers in the response competition increases (Peterburs et al, 2017). Recently, Dittrich et al (2017) proposed a new explanation of the joint Flanker effect, after finding that joint Simon and Flanker effects were not driven by the same underlying processes. Manipulating the visibility of the co-actor (i.e., participants performed both tasks with or without a partition panel between them) in joint and individual conditions, the authors found a larger joint Flanker effect when participants were not separated by a partition panel, whereas the joint Simon effect was not affected by visibility manipulation.…”

“…Manipulating the visibility of the co-actor (i.e., participants performed both tasks with or without a partition panel between them) in joint and individual conditions, the authors found a larger joint Flanker effect when participants were not separated by a partition panel, whereas the joint Simon effect was not affected by visibility manipulation. Dittrich et al (2017) explained the joint Flanker effect as the result of less spatial attention in the joint task condition because of the presence and visibility of another person. This attentional-focus account can explain how the Flanker effect is modulated by the size of the focus of spatial attention (see Hübner, Steinhauser, & Lehle, 2010, for a review) and can be considered an alternative interpretation of the results observed by Dolk et al (2014a).…”