Enhancing the Believability of Positive Cognitions in EMDR

Eye Movement Desensitization and Reprocessing (EMDR) is an evidence based treatment for posttraumatic stress disorder (PTSD) (Shapiro, 2018). Its effectiveness is supported by multiple systematic reviews and meta analyses (Cuijpers et al., 2020; Cusack et al., 2016; Lee & Cuijpers, 2013; Wilson et al., 2018; Wright et al., 2024). EMDR aims to reduce PTSD symptoms by decreasing the emotional intensity of distressing memories and modifying dysfunctional beliefs into more adaptive, functional ones, referred to as positive cognitions (Shapiro, 2018). According to Working Memory (WM) theory, engaging working memory during memory retrieval, such as through eye movements, reduces the vividness and emotional intensity of mental images, as working memory has limited capacity (Baddeley, 2012; Van den Hout & Engelhard, 2012). When a secondary task is added during memory recall, fewer working memory resources remain available for maintaining the memory representation, resulting in reduced emotional intensity and vividness upon reconsolidation (Engelhard et al., 2010). This mechanism has been widely supported in EMDR research (Andrade et al., 1997; Gunter & Bodner, 2008; Lee & Cuijpers, 2013; Mertens et al., 2021). While the effect of dual working memory tasks on the processing of distressing memories is well established, their role in strengthening positive cognitions during EMDR’s installation phase remains unclear. From a WM theory perspective, dual tasks would be expected to weaken rather than strengthen mental representations, raising questions about their presumed reinforcing effect on positive cognitions. Matthijssen and Van den Hout (2016) found that dual working memory tasks did not enhance the believability of positive verbal statements during EMDR’s positive closure phase. Although their study did not include mental imagery and did not focus on the installation phase, the findings suggest that dual working memory tasks may not support the strengthening of positive cognitions. In response, protocol adaptations have been proposed in which dual working memory tasks are replaced by embodied techniques, such as powerful postures and positive facial expressions, applied as one integrated embodied imagination technique during the EMDR closure phase (de Jongh & Ten Broeke, 2019). These adaptations are consistent with embodiment research indicating that open and upright postures can enhance feelings of power, confidence, and positive affect (Carney et al., 2010; Cuddy et al., 2015; Körner et al., 2022). The present study examines, in a non-clinical adult sample, whether three installation phase conditions differ in enhancing the believability of positive cognitions: (1) a positive cognition–only condition without a dual working-memory task (control condition), (2) a positive cognition condition combined with a dual working-memory task (comparison condition), and (3) a positive cognition condition combined with an embodied imagination technique. Believability of positive cognitions is assessed using the Believability of Cognition (BoC) scale at multiple time points during the installation phase.