<p dir="ltr">Timing and time perception is essential to humans, whose lives and biology are organized around clocks. From the simple give-and-take of conversation to understanding cause and effect, individuals rely on accurate time perception to successfully complete tasks and organize their lives. However, accurate time perception is vulnerable to all manner of influence, from both internal and external sources, including affect. A robust body of literature suggests that negative affect is positively associated with time dilation, or subjective lengthening of time, whereas positive affect is positively associated with time constriction, or subjective shortening of time. Collectively, these are known as time distortion, which has been preliminarily linked to increased impairment in anxiety, depression, and BPD. However, this literature features two key limitations. First, researchers have mostly examined time perception as an objective measure, through the use of measures such as the temporal bisection tasks, which limits our understanding of the subjective experience of time distortion and how it may contribute to psychopathology. Second, across studies, time perception is most often studied as an outcome, rather than examining the role of time perception in predicting affective change, i.e., contextualizing the role of time distortion in clinically-relevant research questions. The current project aimed to address these gaps in the literature through two studies which examined (1) the roles of brief affect and time perception manipulations on affective change and subjective time perception in an online study (Study 1) and (2) the effect of a longer time perception manipulation on affective change during an in-person experimental protocol (Study 2).</p><p dir="ltr">Across studies, participants included a community-based sample of U.S. adults over age 18 and two separate undergraduate samples recruited from introductory psychology courses at Purdue University. In Study 1, the final sample size exceeded 750 and was comprised of community-based and undergraduate participants. Online participants reported on dispositional levels of clinical measures [e.g., rumination, borderline personality disorder (BPD) features] and then completed an experimental protocol with brief mood and time perception manipulations while repeatedly reporting on their negative affect. Results suggested that the time perception manipulation was not effective, but that across the protocol, negative affect rose and positive affect decreased. Further, participants reported overall that time seemed to be passing by slower than usual during the protocol. These findings informed the design of Study 2, which lengthened the time perception manipulation and eliminated the mood induction component in order to address the more basic question of whether time perception manipulation influences mood, particularly during neutral cognitive tasks.</p><p dir="ltr">One hundred and twenty-seven undergraduate participants completed Study 2. As in Study 1, participants filled out self-report surveys about dispositional symptoms of psychopathology (e.g., rumination, emotion dysregulation, and symptoms associated with BPD, depression, and anxiety) before completing an experimental protocol which included a manipulated clock (accelerated or control clock), three runs of a modified Erkisen flanker task, and repeated measures of negative and positive affect. Primary results suggested that the time perception manipulation was successful but that the influence of time distortion was more nuanced than hypothesized. Specifically, individuals with elevated clinical symptoms exhibited lower rating of negative and positive affect levels in the accelerated clock condition, compared to individuals endorsing low symptoms, who reported higher positive affect and higher negative affect in the accelerated clock condition.</p><p dir="ltr">Altogether, the results across studies highlight the complexity of time perception in influencing affect and help provide foundational information regarding the empirical convergence between cognitive and clinical phenomena.</p>