Background: While research indicates cognitive biases in individuals vulnerable to bipolar symptoms, the specificity of these biases to the self and others, and to low or high activation states, is underexplored. Method: These biases were investigated using individuals with high (n = 24) and low levels (n = 24) of hypomanic personality (HPS) during word rating and free recall of a list of trait words after a positive versus neutral mood induction. Results: The mood induction was not successful. Also, in contrast to the predicted self-serving bias, there was a self-denigratory bias in self-ratings relative to ratings of another person. In post hoc analyses, the study succeeded in producing a rating task of trait words that differentiated between high and low hypomania-prone individuals, as the high HPS group made higher ratings of high activation trait words (e.g. dynamic) to describe positive and neutral attributes regardless of whether it referred to themselves or another person. The high HPS group also showed a negative recall bias, but it was not specific to the self, questioning assumptions made about negative biases in existing research. Furthermore, a strong relationship emerged between greater use of imagery at encoding and greater recall of self-referent, positive, high activation words, suggesting a role for the intensity of images associated with the amplification of emotions in people with bipolar disorder (Holmes et al., 2008). Conclusions: It seems important to consider various multiple factors in memory bias research in people vulnerable to bipolar disorder, including self versus other encoding, high versus low activated states and the role of mental imagery. Further research is needed to spell out their interactive contribution.