核心假定量表：心理計量特性檢驗及其與創傷和創傷後壓力症狀之關連

The Core Assumptions Scale (CAS): Psychometric Evaluation and Its Associations with Trauma and Posttraumatic Stress Symptoms

Janoff-Bulman（1992）的假定撼動理論主張個體擁有三類基本假定：世界是良善的、世界具有意義及自我具有價值。當個體遭逢創傷後，上述假定可能遭受撼動而導致創傷調適困難。世界假定量表（Janoff-Bulman, 1989）乃現今最常用的假定評估工具，但研究指出其心理計量特性不佳，而晚近發展的類似工具亦存在部分限制。據此，本研究以假定撼動理論與創傷認知論述為基礎，編製適用於評估基本假定的工具，命名為核心假定量表（Core Assumptions Scale, CAS），並以兩個子研究檢驗其適用性。研究一聚焦於建構CAS，樣本為156名大學生（69.9%女性）。透過對CAS原始題庫的項目分析與探索性因素分析衍生15題的CAS版本，包括安全世界、正義世界、掌控世界及自我價值分量表。研究二為前瞻性設計，聚焦於檢驗CAS的心理計量特性，樣本為809名大學生（60.2%女性），於兩個月後進行追蹤再測。驗證性因素分析指出以四項分量表為基礎的四因素模型，適配水準較優且可接受，故以此架構進行心理計量檢驗。分析指出CAS的內部一致性信度佳，八至十週再測信度適當，同時效度大致適切。CAS可顯著預測後續憂鬱症狀嚴重度。各類創傷組在CAS總分上呈顯著差異，以遭暴力侵害組得分最低，PTSD組的CAS總分顯著低於非PTSD創傷組與從未經歷創傷組。本研究證實CAS為信效度良好的假定評估工具，可區分與檢驗不同類型創傷組與PTSD個體的認知內涵。

Janoff-Bulman's (1992) shattered assumptions theory proposes that people possess three kinds of fundamental assumptions, specifically that the world is benevolent, the world is meaningful, and the self is worthy. According to the theory severe trauma shatters and challenges these assumptions, resulting in posttraumatic adaptation difficulties. Janoff-Bulman's World Assumption Scale (WAS) is by far the most widely used measure for assessing these fundamental assumptions (Janoff-Bulman, 1989). However, its psychometric properties have been challenged by recent studies. Recently several measures assessing similar constructs have been developed, but their limitations also have been noted. Accordingly, based on the shattered assumptions theory and the literature on trauma-related cognition, the present study, using two sub-studies, aimed to develop a new, theory-reflective, and more applicable measure, the Core Assumptions Scale (CAS), to assess hypothesized fundamental assumptions. In Study 1, we developed the item pool of the CAS and administered it to 156 college students (69.9% female). Through item analysis and exploratory factor analysis, we arrived at our 15-item CAS, comprised of four subscales: safe world, just world, controllable world, and selfworth. In Study 2, a prospective study, the psychometric properties of the CAS were evaluated in 809 college students (60.2% female), who were followed up 2 months later. Confirmatory factor analyses showed that the overall fit of our four-factor model was superior to that of other proposed factor-models, with related indices reaching acceptable levels. Therefore, we used this model for further psychometric examination. In these investigations the CAS showed good internal consistency and adequate 8 ~ 10 weeks test-retest reliability. Moderate inter-subscale correlations suggested that the fundamental assumptions assessed by the CAS were significantly associated with each other. Concurrent and predictive validity were adequate. The CAS total was able to significantly predict subsequent depressive severity, and its explained variance was superior to that of the WAS total. Significant differences were noted among different trauma groups on the CAS total and its subscale scores, with the assaultive violence group scoring the lowest. Moreover, the PTSD group scored lower on the CAS total and subscales than the no-PTSD trauma group and the no-trauma group. Taken together, these findings suggest that the CAS is a psychometrically sound measure of fundamental assumptions, making it suitable for investigating trauma survivors and peopl e with PTSD.