Thirty-six participants (18 female, 18 male) viewed affective pictures to investigate the coupling between emotional reactions and motivated behavior. Framed within the biphasic theory of emotion, the three systems approach was employed by collecting measures of subjective report, expressive physiology, and motivated behavior. Postural adjustments associated with viewing affective pictures were measured. Results indicated sex-differences for postural responses to unpleasant pictures; an effect not found for pleasant and neutral picture contents. Females exhibited increased postural movement in the posterior direction, and males exhibited increased movement in the anterior direction, for unpleasant pictures. Subjective report of valence and arousal using the self-assessment manikin (SAM), and the startle eye-blink reflex were collected during a separate session, which replicated previous picture-viewing research. Specifically, participants rated pleasant pictures higher in valence and exhibited smaller startle responses compared to unpleasant pictures. Females also reported lower valence ratings compared to males across all picture contents. These findings extend our knowledge of motivated engagement with affective stimuli and indicate that postural responses may provide insight into sex-related differences in withdrawal behavior.