Theories that formally describe decision-making have traditionally posited that decisions are made by rational actors. However, it is generally accepted that humans often make irrational decisions because of quick emotional judgements. In order to reconcile these two inconsistent ideas psychologists have developed two-system theories that hypothesize decisions are made by two opposing cognitive systems, representing the rational and emotional processing of decisions. Evidence for a two-system model of decision-making can be observed in ultimatum game responder decisions. It is thought that rational processing of these choices will produce acceptance of unfair offers and emotional processing will encourage rejection of unfair offers. Emotional priming has been shown to decrease ultimatum game acceptances and trans-cranial magnetic stimulation of rational brain areas, i.e. DLPFC, show increases in ultimatum game acceptances. This study investigated the possibility of using behavioral tasks that are known to activate rational brain areas to promote/disrupt ultimatum game acceptances. The possible relationship between ultimatum game acceptances and executive functions was also examined. Although there were promising indications that working memory loading may increase ultimatum game acceptances in between-subject experiments, a within-subject investigation found little support for this method of promoting/disrupting rational ultimatum game decisions. There were also no relationships found between switching or inhibition executive functions and ultimatum game responder decisions. A moderate positive relationship was found between updating executive function and ultimatum game acceptance rates but this relationship was dependent on working memory task feedback, a within-subject design and active loading of the working memory system. However, its possible that these findings only apply to within-subject paradigms and future between-subject studies are advised.