This paper reports the development and initial validation of the Persian language Irrational Performance Beliefs Inventory (iPBI-Persian). The original iPBI was developed to provide a validated measure of the four core irrational beliefs of rational emotive behavior therapy (REBT) within performance-based samples, such as athletes. Data retrieved from 334 athletes (169 men, 165 women, Mage = 21.52 ± 4.00 years) were analyses using SPSS and LISREL software packages. After the linguistic and cross-cultural adaptation processes, confirmatory factor analysis (CFA) results showed that six items did not have acceptable factor loadings. After removal of problem items, a 22-item version was developed (CFI = 0.96). The iPBI-Persian demonstrated excellent levels of reliability, with internal consistency and test–retest reliability, as well as construct validity. This paper indicates that the 22-item iPBI-Persian can be used as a self-assessment instrument to evaluate irrational performance beliefs in Iranian athlete samples.

Although several studies have reported the effects of rational emotive behaviour therapy (REBT) with athletes, significant methodological limitations have been observed in the extant research. These include a lack of randomised control trials (RCT), a lack of objective performance measurement, and often poor internal and external validity. Accordingly, these limitations are addressed in the present study, and the effects of REBT on performance under pressure in adolescent soccer players are assessed using an RCT design. In this study, 24 adolescent soccer players were recruited. After completing pre-intervention measures of irrational beliefs, social anxiety, and performance under pressure, players were divided into two groups, an experimental (n = 12) and placebo control group (n = 12). The experimental group underwent ten REBT sessions and the placebo control group underwent ten sessions of video clips related to new soccer technologies. Indicators of irrational beliefs, social anxiety, and performance under pressure were collected at a post-intervention and at a four-month follow-up. Results demonstrated a significant decrease in irrational beliefs and social anxiety and an improvement in performance under pressure in the experimental group, compared to the placebo control group. These significant changes were maintained in the experimental group at follow-up. Results are discussed in relation to advancements to the extant research, and recommendations for future applied work are proffered.

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