No evidence of task co-representation in a joint Stroop task

Cooperation and competition have same benefits but different costs

Cooperation and competition shape everyday human interactions and impact individuals' chances of success in different domains. Using a virtual Stroop test, classically employed to assess general cognitive interference, we examined the impact of social context (cooperation and competition) and other's ability (higher and lower performers) on performance, perceived stress, and autonomic activity. In Experiment 1, we found that both cooperation with a lower performer and competition with a higher performer led to similar enhancement in performance. However, only competition with a more skilled opponent induced an increase in perceived stress and physiological activity. Experiment 2 further demonstrated that these effects persisted even with prolonged exposure to these contexts. In summary, cooperation can be just as effective as competition in improving individuals' performance. However, cooperation does not carry the same level of stress and physiological burden as the competitive context, representing a healthier and more optimal way to boost individual performance.

Co-actors represent each other's task regularity through social statistical learning

Numerous joint action studies have demonstrated that certain low-level aspects (e.g., stimuli and responses) of a co-actor's task can be automatically and implicitly represented by us as actors, biasing our own task performance in a joint action setup. However, it remains unclear whether individuals also represent more abstract, high-level aspects of a co-actor's task, such as regularity. In the first five experiments, participants participated alongside their co-actors and responded to a mixed shape sequence generated by randomly interleaving two fixed order sequences of shapes in both the pre- and post-test sessions. But different intermediate practice sessions were undergone by participants across experiments. When practicing their own fixed order sequences in a mixed shape sequence, either together with another person (Experiment 1) or alone but informed that their partner was performing the same practice task in a different room (Experiment 4), participants exhibited a learning effect on their co-actors' practiced sequences. This indirect learning effect was absent when one of the co-actors did not participate due to either being removed from the practice (Experiment 2) or sitting still without offering responses (Experiment 3), as well as when the two co-actors practiced together but responded to two distinct properties of stimuli (e.g., colour and shape, respectively), with one having regularity and the other not. Finally, participants exhibited comparable direct learning effects on their own practiced sequences for Experiments 1-5 as when performing the pre-test, practice, and post-test sessions alone for Experiment 6. These results demonstrate that, when practicing together, or even when believing that they are acting together with a partner, co-actors do represent the task regularity of one another through social statistical learning and transfer this learned regularity to subsequent task performances. The present study extends our understanding of co-representation in the joint action context in terms of the more abstract and high-level task features people co-represent, such as a co-actor's task regularity.

Interference in the shared-Stroop task: a comparison of self- and other-monitoring

Co-actors represent and integrate each other's actions, even when they need not monitor one another. However, monitoring is important for successful interactions, particularly those involving language, and monitoring others' utterances probably relies on similar mechanisms as monitoring one's own. We investigated the effect of monitoring on the integration of self- and other-generated utterances in the shared-Stroop task. In a solo version of the Stroop task (with a single participant responding to all stimuli; Experiment 1), participants named the ink colour of mismatching colour words (incongruent stimuli) more slowly than matching colour words (congruent). In the shared-Stroop task, one participant named the ink colour of words in one colour (e.g. red), while ignoring stimuli in the other colour (e.g. green); the other participant either named the other ink colour or did not respond. Crucially, participants either provided feedback about the correctness of their partner's response (Experiment 3) or did not (Experiment 2). Interference was greater when both participants responded than when they did not, but only when their partners provided feedback. We argue that feedback increased interference because monitoring one's partner enhanced representations of the partner's target utterance, which in turn interfered with self-monitoring of the participant's own utterance.

A Simon-like effect in Go/No-Go tasks performed in isolation

The present study was conducted to decipher whether a spatial correspondence effect can emerge in Go/No-Go tasks (cSE, in reference to Donders' type c task) performed in isolation (participant alone in the cubicle). To this aim, a single participant was centrally positioned in front of a device and was required to respond by a hand key-press to the color of the stimulus. Half the participants were seated in front of a table equipped with only one response key and the other half in front of a table equipped with two response keys (one active and the other one useless). Using a substantial number of subjects (48) and trials (960), the present study revealed a numerically small but statistically reliable cSE. This result contrasts with referential coding predictions and suggests that the representation of a concurrently active response is not a prerequisite for the cSE to emerge. Moreover, the presence of a second response button in the participant's peripersonal space exerted no measurable influence on the cSE. The lack of statistical power of numerous previous studies may explain why the cSE has often been considered to be nil.

Is Your Color My Color? Dividing the Labor of the Stroop Task Between Co-actors

Performing a task with other actors involves two opposing forces, division of labor between co-acting individuals and integration of divided parts of the task into a shared mental representation (co-representation). Previous studies have focused primarily on the integration of task representations and limited attention has paid to the division of labor. The present study devised a test of the integration and the division in a joint task setting. A joint version of the Stroop task was developed, in which pairs of actors were assigned different sets of target colors. If the actors integrate their co-actor’s task, the colors assigned to their co-actor should be represented as if they were the actor’s own target colors; the Stroop effect should be as large when distractor color words denote their co-actor’s target colors as when these words denote the actor’s own target colors. If the actors divide the labor of the Stroop task, the colors assigned to their partner should be represented as non-target colors; the Stroop effect should be smaller when the distractor color words denote the co-actor’s target colors than when these words denote the actor’s own target colors. The results of response time did not provide clear support for either position, while those of response accuracy supported the division of labor. Possible cognitive mechanisms that support the division of labor and the integration of task representation are discussed.

When task sharing reduces interference: evidence for division-of-labour in Stroop-like tasks

Performing a task with another person may either enhance or reduce the interference produced by task-irrelevant information. In three experiments, we employed the joint version of a Stroop-like task (i.e., the picture-word interference-PWI-task) to investigate some of the task features that seem to be critical in determining the effect of task-irrelevant information when the task is shared between two individuals. Participants were asked to perform a PWI task, which required to name a picture while ignoring a distractor word, first individually (in a baseline block of trials) and then co-acting with an alleged partner. Results showed that, compared to the baseline and to a condition in which participants continued to perform the PWI task individually, the belief of co-acting with another individual who was thought to be in charge of the distractor words suppressed the semantic interference effect when these words were in case alternation letters (e.g., "mOuSe"). Conversely, the semantic interference effect persisted when the co-actor was thought to be in charge of the same task as the participant, that is, the co-actor was thought to respond to the pictures. These results are accounted for by assuming that, when the participant knows that another person is in charge of the task-irrelevant information, a division-of-labour between participant and co-actor can be established. Such a division-of-labour may provide the participant with a strategy to oppose the semantic interference effect. Our findings, therefore, suggest that sharing a task with another person in charge of potentially interfering information can enable people to filter out this information from their own task representation.