As social beings, humans are continually required to act in combination with others. This joint action can only be successful if we are able to predict and integrate our predictions about the co-actors actions into our own action representation. These abilities are combined in a shared representation of the task, considering a joint task as one task, as opposed to two individual tasks for each actor. Research in joint action has focussed on the social Simon task, and numerous social manipulations have been carried out through this task. The shared-Stroop task is a fairly novel task designed to determine if linguistic tasks can be shared in the same way as spatial tasks can, through the generation of shared mental representations of the task. The current study draws upon the notion of social manipulation from the social Simon studies, and intergroup relationships as a focus based upon its significance in social psychological literature. It is expected that intergroup pairs will demonstrate less interference in the shared-Stroop task compared to intra-group pairs, and there will be greater interference when both partners responds to a (different) colour (joint response) compared to when only one partner responds to a colour (single response). The results did not support either expectation, however further analysis of participant ratings of group affiliation and group closeness found a significant difference in interference between the levels of group affiliation indicated by the participants, F(2,33)=3.928, p<0.05, r=0.48. This result indicate that physical pairings are less important to participants in terms of their reaction times on the shared-Stroop task, their perceptions of group affiliation and between group closeness are more influential on shared representations, and therefore reaction times. Furthermore a number of trends are noted, despite being non significant when tested. A number of limitations, and potential fixes for future research are discussed, along with some possible explanations for the lack of findings.