An act of betrayal, defined as an intentional undermining of one’s trust or expectations, is believed to have potential to affect one’s level of co-representation, a construct that posits that those in a dyad share mental representations with one another. The construct results in one’s actions being represented and having impact on the other’s actions, which is important for interdependent tasks that require cooperation or competition. Although there has been extensive research into co-representation, very few studies have investigated the influence of social effects on the cognitive construct, and even fewer have explored standardized betrayal manipulations. The current study examined whether betrayal would facilitate or diminish one’s level of co-representation, using an asymmetrical multiplayer game to elicit feelings of betrayal and negative moods. We tested the level of co-representation with an established go/no-go task. Although our findings were not statistically significant, the observed trends corresponded to previous claims that negative moods have a reducing effect on one’s level of co-representation.