Previous studies have brought conflicting results regarding the effects of valence and arousal in visual word processing. Some authors have pointed to participants’ individual differences as one of the possible explanations for these inconsistencies. The main aim of the present research was to examine whether participants’ individual differences in the level of epistemically unwarranted beliefs (EUB) contribute to these conflicting results. Therefore, participants who varied in their level of paranormal, pseudoscientific and conspiracy beliefs (assessed by self-report measures) performed a lexical decision task (LDT) and a recognition memory task. Linear mixed-effects models over LDT response times revealed that the effects of words’ emotional content (both valence and arousal) were modulated by the degree of individuals’ EUB. In addition, signal detection theory analyses showed that in the recognition task (but not in the LDT) response bias became more liberal as individuals’ EUB increased. These patterns of effects were not general to all EUB instances. The obtained results highlight the need to consider participants’ individual differences in affective word processing and signal detection. In addition, this study reveals some basic psychological mechanisms that would underlie EUB, a fact that has both theoretical and applied relevance.