(Sam) Chung Xiann Lim, PhD

All Publications

• Inflexible responses to uncertainty: The mediating role of psychological inflexibility in the link between intolerance of uncertainty, traumatic stress, and somatic symptoms. Psychological trauma : theory, research, practice and policy Lim, C. X., Mueller, E. A., Short, L. B., Xia, R., Suvanbenjakule, P., O'Brien, W. H. 2026; 18 (7): 1391-1400

  Abstract

  Intolerance of uncertainty (IU) and psychological inflexibility (PI) were shown to be risk factors of traumatic stress (TS) and somatic symptoms (SS) during COVID-19. The present study tested a structural equation model where PI mediated the relationships between IU, TS, and SS based on their theoretical and experimental overlaps. The contribution of all six PI facets including experiential avoidance (EA) and cognitive fusion (CF) were investigated.The sample was made up of 656 participants who reported elevated scores for TS and SS. Mediation analysis was conducted via structural equation modeling to test the proposed model. A sensitivity analysis followed the mediation analysis. Follow-up hierarchical regressions were conducted to examine the individual contribution of each PI facet.The overall model demonstrated a good fit (comparative fit index = .98; root-mean-square error of approximation = .07; total effects on TS and SS: β = .78, β = .60). IU was positively associated with TS and SS, and the relations were mediated by PI, with PI accounting for most of the effect. Hierarchical analyses revealed the less studied PI facets explained additional variance over and beyond EA and CF. EA and CF were no longer significant predictors of TS and SS after all PI facets were entered while controlling for IU and demographic variables.The findings were consistent with previous researchers positing PI as an overarching construct encompassing IU and other related psychological vulnerabilities. PI facets beyond EA and CF warrant more investigations. Clinically, PI and PI facets could be important intervention targets for high IU individuals in times of uncertainty. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

  View details for DOI 10.1037/tra0001860

  View details for PubMedID 40029269

• Perseverative cognition and vagally mediated heart rate variability in laboratory studies: A series of meta-analyses. International journal of psychophysiology : official journal of the International Organization of Psychophysiology Lim, C. X., Mueller, E., O'Brien, W. H. 2026; 224: 113368

  Abstract

  Perseverative cognition (PC), including worry and rumination, is linked to adverse health outcomes and reduced vagally-mediated heart rate variability (vmHRV) among healthy subjects. While PC-vmHRV associations across resting, reactivity, and recovery conditions represent distinct regulatory mechanisms, they have not been meta-analyzed separately. This study conducted six meta-analyses to examine within- and between-subjects effect sizes across resting, reactivity, and recovery conditions. Web of Science, PubMed, and PsycINFO were searched for laboratory studies of healthy samples including PC inductions/measurements alongside vmHRV. Risk of bias was. Effect sizes (Hedges' g) were computed using random-effects models. Moderators included age, sex, PC subtype, recording duration, and study quality. 60 effect sizes were extracted from 28 eligible studies. PC was significantly associated with lower resting vmHRV (k = 14, g = 0.46, 95% CI [0.26, 0.66]), within-subjects reactivity vmHRV (k = 18, g = 0.22, 95% CI [0.11, 0.33]), and within-subjects recovery vmHRV (k = 9, g = 0.19, 95% CI [0.03, 0.36]). Between-subjects effect sizes were non-significant. Significant heterogeneity was detected across meta-analyses but not accounted for by the examined moderators. Sensitivity analyses supported the stability of these findings. PC is significantly associated with reduced vmHRV across resting, reactivity, and recovery conditions. Effect magnitudes vary by measurement period and study design. The findings aligned with leading theories on PC and health vulnerability, supporting PC as a promising modifiable target in improving well-being. Within-subjects designs appear most sensitive for detecting the PC-vmHRV relationships. Implications for mechanistic and intervention research were discussed.

  View details for DOI 10.1016/j.ijpsycho.2026.113368

  View details for PubMedID 41865891

• Psychological flexibility prospectively predicts COVID-19 PPE use across a two-month interval. Psychology, health & medicine H O'Brien, W., Wang, S., Varga, A. V., Lim, C. X., Xu, H., Jarukasemthawee, S., Pisitsungkagarn, K., Suvanbenjakule, P., Braden, A. 2024; 29 (3): 484-491

  Abstract

  Perceived susceptibility, psychological flexibility and health behaviors (PPE use, social distancing) were measured at two time points spaced 2 months apart during the height of the COVID-19 pandemic and lockdown in the U.S.A (Time 1 April 2020; Time 2 June 2020). Demographic variables were also collected. Data from 151 Mturk workers indicated that Time 1 psychological flexibility significantly predicted PPE use and social distancing. The effect sizes were substantial. Perceived susceptibility was not a significant predictor. Psychological flexibility messaging and interventions could be an important way to increase the likelihood of people performing health protective behaviors to better constrain the continuing COVID-19 outbreak.

  View details for DOI 10.1080/13548506.2022.2162936

  View details for PubMedID 36593532

• An Examination of the Orienting and Defensive Responses Using HR and HF-HRV JOURNAL OF PSYCHOPHYSIOLOGY O'Brien, W. H., Watford, T., Lim, C., Sims, T., Jarukasemthawee, S., Pisitsungkagarn, K., Suvanbenjakule, P., Settawacharawanich, S. 2023; 37 (4): 181-190

  View details for DOI 10.1027/0269-8803/a000320

  View details for Web of Science ID 001004633300001

• Lesser degree of HR and HF-HRV recovery from an evaluative stressor is associated with higher levels of perfectionism and self-compassion. Behaviour research and therapy O'Brien, W. H., Peijsel, C., Koerten, H. R., Boonyarit, I., Lim, C. X., Chavanovanich, J. 2023; 164: 104305

  View details for DOI 10.1016/j.brat.2023.104305

  View details for PubMedID 37028227

• Acculturative stress and eating disorder psychopathology: A meta-analysis. Eating behaviors Kalantzis, M. A., Chung Xiann Lim, S., Dauber, A. K., Studer-Perez, E. I., Silverman, Z. J., O'Brien, W. H. 2023; 48: 101694

  Abstract

  The present meta-analysis aims to extend Doris and colleagues' (2015) systematic review and address the comprehensive, quantitative gap in the relation between acculturative stress and eating disorder psychopathology reported by studies in the past 20 years. A total of 14 eligible studies were included in our meta-analysis. Across all study samples, there were 2681 participants. The overall relation between eating disorder psychopathology and acculturative stress measurements was examined. Moderation analyses were run to investigate the substantial heterogeneity detected between studies. Results indicated a small effect size for the relationship between eating pathology behaviors and acculturative stress. These results provide insight for clinicians working with individuals who are experiencing acculturative stress, as well as highlight future research directions.

  View details for DOI 10.1016/j.eatbeh.2022.101694

  View details for PubMedID 36621037

• Psychological Inflexibility and HF-HRV reactivity to laboratory stressors JOURNAL OF CONTEXTUAL BEHAVIORAL SCIENCE Lim, C., Brien, W. H., Watford, T. S., Suvanbenjakule, P. 2022; 26: 134-138

  View details for DOI 10.1016/j.jcbs.2022.09.004

  View details for Web of Science ID 000878213300004

• Coping with COVID-19: Survey data assessing psychological distress to COVID-19 and vaccine hesitancy with measures of theory of planned behavior, mindfulness, compassion, cultural orientation, and pandemic fatigue DATA IN BRIEF Mueller, E. A., Suvanbenjakule, P., Lim, C., O'Brien, W. H., Chavanovanich, J., Jarukasemthawee, S., Pisitsungkagarn, K., Suavansri, P. 2022; 43

  View details for DOI 10.1016/j.dib.2022.108390

  View details for Web of Science ID 000822547300004

• Predicting personal protective equipment use, trauma symptoms, and physical symptoms in the USA during the early weeks of the COVID-19 lockdown (April 9-18, 2020) JOURNAL OF CONTEXTUAL BEHAVIORAL SCIENCE O'Brien, W. H., Wang, S., Varga, A., Xu, H., Sims, T., Horan, K., Lim, C. 2021; 21: 37-47

  View details for DOI 10.1016/j.jcbs.2021.05.003

  View details for Web of Science ID 000687831300005

• Psychological reactions to COVID-19: Survey data assessing perceived susceptibility, distress, mindfulness, and preventive health behaviors DATA IN BRIEF O'Brien, W. H., Wang, S., Xu, H., Wang, S., Yang, Z., Yang, J., Liu, Q., Zhang, X., Tang, L., Varga, A. V., Sims, T., Lim, C., Jarukasemthawee, S., Pisitsungkagarn, K. 2021; 34

  View details for DOI 10.1016/j.dib.2020.106687

  View details for Web of Science ID 000617525400073