Joint action changes valence-based action coding in an implicit attitude task

Social affiliation is sufficient to provoke the partner-advantage

The partner-advantage is a type of identity-priority processing that we afford to a person with whom we perform a task together ¹. The partner-advantage has been revealed by shortened reaction time (RT) and enhanced accuracy when participants learned to match a shape with an associated name. It is distinguished from other long-lasting and robust identity advantages (e.g., self-advantage and friend-advantage) by its instantaneous build-up and quick reduction; however, its characteristics and enabling factors remain unknown. The present study addresses these questions. In Experiment 1, we replicated the partner-advantage in a solo shape-name matching task (i.e., without a social component) in which other identity biases are usually reported. In Experiment 2, an absent partner (who did not appear physically) was sufficient to induce beneficial partner-related processing, with a temporary partner enjoying a benefit similar to that of significant others. In Experiment 3, an identity low in socially affiliated significance (e.g., another participant in the same experiment) did not automatically enjoy a priority bias. Taken together, our results suggest that the bias toward partners, similar to other known identity biases, does not require physical presence to build and maintain a referential advantage. The partner-advantage does not automatically extend to other social affiliations, and a joint task is not a pre-requisite to produce the bias. Our study offers new insights on identity-referential processing and its underlying mechanisms.

Saliency at first sight: instant identity referential advantage toward a newly met partner

Neutral information enjoys beneficial processing when it is associated with self and significant others, but less is known about how the identity referential advantage is constructed in the initial stages of a relationship. We offer a novel solution by asking if a newly met stranger could provide a processing advantage in a shape-identity matching task where shapes were associated with the names of different identities. Each participant was paired with a newly met partner in a joint shape-identity matching task in which three shapes were associated with the names of the participant or his/her best friend, the partner, and a stranger, respectively. The participants judged whether or not the shape and name correctly matched.

Intriguingly, the trials related to a newly met partner exhibited instant referential saliency, which was more accurate and faster than that related to the stranger’s name (baseline) when the partner was physically present (experiments 1, 2, 4, 5), but not when the partner was absent (experiment 3). Self-advantage, however, was robust and lasting. The precursor of physical presence when forming referential saliency toward a stranger and its distinct temporal dynamics imply a novel referential benefit unendowed with familiarity, which is qualitatively different from the well-documented self/friend-advantage effect.

When a Social Experimenter Overwrites Effects of Salient Objects in an Individual Go/No-Go Simon Task - An ERP Study

When two persons share a Simon task, a joint Simon effect occurs. The task co-representation account assumes that the joint Simon effect is the product of a vicarious representation of the co-actor's task. In contrast, recent studies show that even (non-human) event-producing objects could elicit a Simon effect in an individual go/no-go Simon task arguing in favor of the referential coding account. For the human-induced Simon effect, a modulation of the P300 component in Electroencephalography (EEG) is typically considered as a neural indicator of the joint Simon effect and task co-representation. Showing that the object-induced Simon effects also modulates the P300 would lead to a re-evaluation of the interpretation of the P300 in individual go/no-go and joint Simon task contexts. To do so, the present study conceptually replicated Experiment 1 from Dolk et al. (2013a) adding EEG recordings and an experimenter controlling the EEG computer to test whether a modulation of the P300 can also be elicited by adding a Japanese waving cat to the task context. Subjects performed an individual go/no-go Simon task with or without a cat placed next to them. Results show an overall Simon effect regardless of the cat's presence and no modulatory influence of the cat on the P300 (Experiment 1), even when conceivably interfering context factors are diminished (Experiment 2). These findings may suggest that the presence of a spatially aligned experimenter in the laboratory may produce an overall Simon effect overwriting a possible modulation of the Japanese waving cat.

It's not me, it's you - Differential neural processing of social and non-social nogo cues in joint action

This study used a joint flanker task to investigate differences in processing of social and non-social nogo cues, i.e., between cues indicating that a co-actor should respond and cues signaling that neither actor nor co-actor should respond, using event-related potentials (ERPs) and trial-to-trial response times (RTs). It was hypothesized that a social co-actor's response should be reflected in stronger modulation (slower RTs on subsequent trials; augmented neural responses) for social compared to non-social nogo. RTs and ERPs replicated flanker compatibility effects, with faster responses and increased P3a on compatible trials. In line with the hypotheses, ERPs revealed distinct coding of social and non-social nogo in the conflict-sensitive N2 which showed a compatibility effect only for social nogo, and in the attention/memory-related P3b which was larger for social relative to non-social nogo. The P3a did not distinguish between social and non-social nogo, but was larger for compatible and smaller for go trials. Contrary to our hypotheses, RTs were faster after social relative to non-social nogo. Hence, the representation of the co-actor's response in joint action modulates conflict processing reflected in the N2 and response discrimination and evaluation reflected in the P3b and may facilitate subsequent responses in the context of social versus non-social nogo.