It is well established that an observer will automatically follow the eye gaze of another person. Whether this automatic behaviour is influenced by the emotion displayed on the face has been a topic of intense interest yet previous research on healthy adults has failed to provide a consistent account. To address these inconsistencies, research has largely focused on examining the contribution of external factors and has ignored the relative, and perhaps critical, contribution of various internal factors. This ---thesis examines the contribution of a number of potentially important factors that might influence attention to the eye gaze of emotional facial expressions, with particular emphasis on biological and psychological internal factors. The first three experiments provide a baseline measure of gaze following of various facial expressions by healthy adults, and suggest that under standard conditions, and when a more ecologically valid target is included, gaze following is not influenced by the expression displayed on the face. Four further experiments highlight the importance of internal factors such as concurrent mood, the female menstrual cycle, and trait anxiety, in investigating emotional gaze following. Most significantly, it is apparent that in healthy adults, gaze following occurs more readily in positive contexts, and that this bias might be dysfunctional in individuals with high trait anxiety. These experiments provide an important insight into conditions under which rapid gaze following of emotional expressions proceeds. This thesis also serves to highlight the need for further gaze following research to take such individual differences into account.