Young people aged 12-25 account for the highest prevalence and incidence of mental health disorders across the lifespan (McGorry, Bates & Birchwood, 2013). Onset of mental health disorders, of which anxiety disorders comprise a large portion (Eisenberg, Gollust, Golberstein & Hefner, 2007), are said to present shortly before or during typical college-going years (Kessler, Berglund, Demler, Merikangas & Walters, 2005). A broad body of behavioural researchers emphasize the functional role of fear and avoidance responding as central processes that may underlie and maintain anxiety in humans (Dymond, Bennett, Boyle, Roche & Schlund, in press; Luciano et al; 2014). As an alternative to experiential avoidance of undesirable psychological content, a considerable body research supports the efficacy of cognitive defusion (a behavioural technique derived from Acceptance and Commitment Therapy), as a treatment for anxiety related behaviour (Hayes et al., 2006). Despite the positive outcomes reported for defusion-based interventions, a functional account of the basic behavioural processes involved in cognitive defusion is not well established (Foody, Barnes-Holmes, Barnes-Holmes & Luciano, 2013). In attempt to expand on the extant compendium of defusion-related analogue component process studies, and shed further light on the behavioural processes that may be responsible for successful defusion outcomes, the current research examined the differential impact of a brief cognitive defusion exercise, (delivered in two distinct formats) on explicit, self-report measures of state anxiety, experiential avoidance and emotional discomfort, believability and willingness to engage with distressful thoughts. In pursuit of this goal, two experiments were conducted with a non-clinical sample of university students (N=80). Both of the experiments employed a similar procedural sequence and examined the same defusion exercise (the Hands as Thoughts exercise by Harris, (2009)), but differed in terms of the format by which the exercise was delivered, as well as the outcome measures used to assess its effects. At the beginning of both of the experiments, a stress induction paradigm was utilized to experimentally induce distress using a time-based mathematical task, paired with a deceptive statement regarding a previous cohort’s performance of the task. Immediately following the distress induction phase, participants were instructed to discriminate a single self-referential statement (i.e. a verbal stimulus) related to the dominant thought/emotion that they experienced following the math task. This self-referential statement represented the target stimulus with which the defusion exercise would be conducted. Following this, participants in the intervention condition were exposed to the defusion exercise. Alternatively, participants in the control condition were exposed to a distraction-based task. In Experiment 1 (N=55), which employed a 2 × 2 factorial design, instructions pertaining to the defusion exercise were delivered by the experimenter who modelled the exercise along with participants. Defusion impact/outcomes were assessed using pre- and post-measures of state anxiety and psychological inflexibility/experiential avoidance. Participants exposed to the defusion exercise/intervention (n=36) reported a significant reduction in state anxiety and psychological inflexibility/avoidance from pre- to post-intervention. Control group participants who were exposed to a distraction-based control task (n=19) also reported a significant reduction in state anxiety and psychological inflexibility/avoidance from pre- to post-control task. No significant difference was detected between the control and intervention groups in terms of the within-group reductions in psychological inflexibility/avoidance. However, there was a significant between-groups difference regarding the within-group reductions in state anxiety; participants in the intervention condition reported a superior reduction in state anxiety to those in the control condition. In Experiment 2 (N=35), which employed a 2 × 2 factorial design, instructions pertaining to the cognitive defusion exercise were delivered audibly via an audio-speaker. In addition to pre- and post-measures of state anxiety and psychological inflexibility/avoidance, impact was further assessed using measures of emotional discomfort, believability and willingness to engage with the self-referential thought/emotion (verbal stimulus), in an effort to further examine the potential processes of change. Participants exposed to the defusion intervention (n=19) reported a significant reduction in state anxiety from pre- to post-intervention. While a slight reduction in psychological inflexibility/avoidance was observed, this reduction was not statistically significant. Similarly, participants reported slight reductions in emotional discomfort and believability, and minimal increases in willingness to engage with the self-referential thoughts, however these changes were not statistically significant. An alternative control task to the one employed in the Experiment 1 was utilized in Experiment 2, whereby participants were requested to employ the typical strategies that would normally use to manage unwanted psychological content. Similar to the effects observed in the intervention condition, control group participants (n=16) reported a significant reduction in state anxiety post the control task. A slight pre-to-post reduction in psychological inflexibility/avoidance was observed, however the reduction was not statically significant. Slightly reduced levels of emotional discomfort and believability, and slightly increased levels of willingness to engage with self-statements were reported, however these changes were not statistically significant. Findings pertaining to both experiments are discussed in relation to those reported in previous analog component process studies. A discussion of the basic behavioural processes that may have moderated these outcomes is also provided. To the author’s knowledge, no previous empirical research has examined the Hands as Thoughts defusion exercise (Harris, 2009) in isolation from other defusion exercises, thus, a discussion of the basic processes in that may mediate the outcomes of this research may not necessarily apply to other ACT-based defusion exercises, due to the variation of procedural elements involved across different defusion techniques. Behaviour-analytic research surrounding the concept of defusion is not mature, and there remains a deficit of knowledge, and indeed discussion, as to the basic behavioural processes that underlie the concept. The term defusion is somewhat problematic as it is appears to refer to a set of outcomes, which are moderated by an unknown set of behavioural processes, as well as to a number of different therapeutic methodologies. Thus, despite their clinical utility, defusion-based therapeutic methods/techniques are currently being applied with limited precision (Assaz, Roche, Kanter & Oshiro, in press). In addition to extending the current program of empirical research in the area, the present research hopes to contribute to discussions surrounding the behavioural processes that may moderate defusion outcomes from a behaviour-analytic perspective, whilst also considering the procedural limitations of this research, and offering suggestions for future examinations in this area.