Sexual interest and sexual fantasy are intricately linked. The target of someone’s sexual interest (whether a person, object, or behaviour) is typically represented within the content of their sexual fantasies (Noorishad, Levaque, Byers, & Shaughnessy, 2019). As such, sexual fantasies provide a source of sexual arousal (Gee, Ward, & Eccleston, 2003). In addition, conditioning-based theories propose that the repeated pairing of sexual arousal (via masturbation) with a sexual fantasy can produce a sexual interest (Laws & Marshall, 1990; McGuire, Carlisle, & Young, 1964; Storms, 1981). While this is unlikely to be the case for broad categories of sexual orientation, it is conceivable that specific targets/behaviours can acquire erotic value via conditioning processes, especially considering the range of sexual interests, fetishes, and kinks that people report (Imhoff, Banse, & Schmidt, 2017; Smid & Wever, 2019).
It is crucial, therefore, to have a clear understanding of sexual fantasy. However, there is little to no theoretical work on the topic. Fortunately, a plethora of research exists, covering the content (Arndt, Foehl, & Good, 1985; Rokach, 1990), frequency (Harvey & Jeglic, 2020; Joyal, Cossette, & Lapierre, 2015), function (Davidson & Hoffman, 1986; Gee et al., 2003), and appraisal of sexual fantasies (Renaud & Byers, 2001), along with its link to other factors, such as personality (Baughman, Jonason, Veselka, & Vernon, 2014), attachment (Birnbaum, 2007), attitudes/beliefs (Zurbriggen & Yost, 2004), and corresponding behaviour (Bouchard, Dawson, & Lalumière, 2017; Noorishad et al., 2019). In addition, there is a vast literature base on mental imagery and episodic simulation that provides valuable insight into human thought. Synthesising key aspects of this literature, we recently developed a theoretical account of sexual thoughts and fantasising termed the Dual-Process Model of Sexual Thinking (DPM-ST). This theory was first presented at professional conferences (Bartels, Beech, & Harkins, 2014), before being outlined in a book chapter on theories of deviant sexual fantasy (Bartels & Beech, 2016). In the present chapter, we provide a more focused and updated account of the DPM-ST.