發展與驗證iPad版選擇性注意力測驗於思覺失調症患者之心理計量特性

Abstract

背景與目的：選擇性注意力缺失常見於思覺失調症患者，影響其功能性表現，故評估患者之選擇性注意力有其必要性。知覺負載理論考量個體從事任務之知覺負荷量對注意力選擇機制之影響，並輔以神經生理證據，可將選擇性注意力之機制解釋地較為清楚。然而，目前缺乏以此理論及實驗典範為基礎而發展之選擇性注意力測驗，導致臨床人員無法深入評估思覺失調症患者之選擇性注意力問題。因此，本研究之目的有三：一、發展一套以知覺負載理論為理論基礎之iPad版選擇性注意力測驗 (iPad-based Selective Attention Test, iSAT)，並建立其內容效度和確定其可行性；二、驗證iSAT於思覺失調症患者之心理計量特性，以提昇iSAT於思覺失調症患者之臨床與研究應用價值；三、驗證iSAT於20至29歲年輕成人之心理計量特性，確保iSAT於建立20至29歲常模前具備適當之心理計量特性。 研究方法：本研究包含三個子研究。研究一為iSAT之發展，並建立其內容效度和確定其可行性，分成三階段進行：(一) 依據知覺負載理論及相關實驗典範和專家意見建立iSAT初版內容及行動應用程式；(二) 募集20至29歲年輕成人和20歲以上思覺失調症患者測試iSAT初版之可行性，再依測試結果及專家意見修改成iSAT二版；(三) 募集20至29歲年輕成人和20歲以上思覺失調症患者測試iSAT二版之可行性，再依測試結果和專家意見確定iSAT正式版內容，進而建立iSAT之內容效度。研究二為iSAT於思覺失調症患者之心理計量特性驗證。研究者募集20歲以上思覺失調症患者參與二次iSAT評估(間隔二週)，以檢驗iSAT應用於思覺失調症患者之再測信度、隨機測量誤差及練習效應。研究者採用配對t檢定檢驗患者初測和再測於iSAT低(高)負載和低(高)負載含干擾物情境的分數有無顯著差異，以確定iSAT之建構效度。同時，研究者以患者之蒙特利爾智能測驗 (Montreal Cognitive Assessment, MoCA)分數檢驗iSAT之收斂效度，並以患者的個人與社會功能量表分數檢驗iSAT之生態效度。此外，研究者以MoCA 26分為效標，檢驗iSAT是否可區辨思覺失調症二個年齡族群(年輕[20至39歲]及中老年[40歲以上])中整體認知功能好(MoCA≧26)及差(MoCA<26)之患者，以檢驗其區辨效度。研究三為iSAT於20至29歲年輕成人之心理計量特性驗證，作為未來常模建立之參考。研究者募集20至29歲年輕成人參與二次iSAT評估(間隔二週)，以檢驗iSAT應用於20至29歲年輕成人之再測信度、隨機測量誤差及練習效應，並檢驗二次iSAT分數平均為樣本前25%的受試者與後25%的受試者的分數是否有顯著差異，以驗證區辨效度。研究者亦採用配對t檢定檢驗患者於iSAT低(高)負載和低(高)負載含干擾物情境的分數有無顯著差異，以確定iSAT之建構效度。同時，研究者亦以平板電腦版符號數字轉換測驗檢驗iSAT之收斂效度。 結果：研究者透過5位專家對iSAT內容設計、施測方式及計分之審核，和10位20至29歲年輕成人及10位20歲以上思覺失調症患者對iSAT內容之迴饋，建立iSAT之內容效度和確定其可行性。iSAT應用於思覺失調症患者具備建構效度、適用於研究之再測信度，以及良好之收斂效度。iSAT二種低負載情境測驗具備區辨效度、可接受之隨機測量誤差和微小可忽略之練習效應，但二種高負載情境測驗不具備區辨效度，且隨機測量誤差較大，練習效應亦為低至中度。iSAT之生態效度亦不佳。另外，iSAT應用於20至29歲年輕成人具備區辨效度及中度之再測信度，二種低負載情境具備可接受之隨機測量誤差，但其練習效應為低至中度，而二種高負載情境之隨機測量誤差略大，且練習效應為中至高度。此外，iSAT於20至29歲年輕成人不具備建構效度，其收斂效度亦不佳。 結論：iSAT之心理計量特性適用於思覺失調症患者之研究，但研究者建議使用者以多次評量和平均分數降低iSAT二種高負載情境之隨機測量誤差，以提昇其區辨效度。目前iSAT之心理計量特性尚不足以建立常模。未來研究者可納入不同地區、慣用手為左手及教育年數為12至16年間之20至29歲年輕成人為樣本，再次驗證iSAT於20至29歲年輕成人之心理計量特性，便於日後建立常模。

Background and purpose: Selective attention deficit is common in patients with schizophrenia. Such deficit can affect their functional performance, so assessing selective attention in patients with schizophrenia is essential. Perceptual load theory considers the effects of the perceptual load of a task on the selectivity mechanism of attention. With the evidence of neurophysiology, perceptual load theory provides the clearest explanation of the mechanism of selective attention. However, no tests of selective attention have been developed on the basis of perceptual load theory, so clinicians are unable to provide a thorough evaluation to determine patients’ problems in selective attention. Therefore, this dissertation had three purposes: First, to develop an iPad-based Selective Attention test (iSAT) on the basis of perceptual load theory, to establish its content validity, and to evaluate its feasibility; second, to examine the psychometric properties of the iSAT in patients with schizophrenia so as to improve its utility in clinical and research settings; and third, to examine the psychometric properties of the iSAT in young adults aged 20 to 29 years so as to ensure appropriate psychometric properties for the development of future norms. Methods: This dissertation consists of 3 studies. Study 1: Development of the iSAT and determination of the content validity and feasibility of the iSAT. This study was conducted in 3 stages: (1) development of the iSAT’s first version and mobile applications on the basis of perceptual load theory and paradigm as well as expert opinion; (2) recruitment of young adults aged 20 to 29 years and schizophrenia patients aged ≧20 years to test the feasibility of the iSAT’s first version and then develop the iSAT’s second version according to the examinees’ suggestions and the experts’ opinions; (3) recruitment of young adults aged 20 to 29 years and patients with schizophrenia aged ≧20 years to test the feasibility of the iSAT’s second version so as to determine the content of the iSAT’s formal version and its content validity. Study 2: Validation of psychometric properties of the iSAT in patients with schizophrenia. The researcher recruited schizophrenia patients aged ≧20 years to be assessed twice by the iSAT (2 weeks apart) to examine the test-retest reliability, random measurement error, and practice effect of the iSAT. Paired t tests were also used to examine whether the patients’ scores of the low (high) load condition and those of the low (high) load with distractor condition were significantly different so as to determine the construct validity. Moreover, the scores of the Montreal Cognitive Assessment (MoCA) and the Personal and Social Performance scale were used to examine the convergent validity and ecological validity, respectively. A MoCA score of ≧26 was used as a criterion to evaluate whether the iSAT can discriminate two age groups in patients with schizophrenia [young (20 to 39 years) and middle aged and elderly (≧40 years)] to determine the discriminative validity. Study 3: Validation of the psychometric properties of the iSAT in young adults aged 20 to 29 years to develop future norms. The researcher recruited young adults aged 20 to 29 years to be assessed twice by the iSAT (2 weeks apart) to examine the test-retest reliability, random measurement error, and practice effect. To examine the discriminative validity, the researcher examined whether the highest 25% and lowest 25% of the iSAT average scores (mean of test and retest) were significantly different. To examine the construct validity, paired t tests were used to examine whether the scores of the low (high) load condition and those of the low (high) load with distractor condition were significantly different. Moreover, the scores of the Tablet-based Symbol Digit Modalities Test were used to examine the convergent validity. Results: The content validity and feasibility of the iSAT have been confirmed by five experts’ examinations regarding its design, administration and scoring as well as the feedback from 10 young adults aged 20 to 29 years and 10 schizophrenia patients aged ≧20 years. The iSAT had construct validity, sufficient test-retest reliability for research use, and good convergent validity in patients with schizophrenia. The two low-load conditions had discriminative validity, acceptable random measurement, and a trivial practice effect. However, the two high-load conditions did not have discriminative validity. The two high-load conditions had substantial random measurement error and a low to moderate practice effect. The ecological validity of the iSAT was insufficient. As for young adults aged 20 to 29 years, the iSAT had discriminative validity and moderate test-retest reliability. The two low-load conditions had acceptable random measurement error but a low to moderate practice effect. The two high-load conditions had slightly larger random measurement error as well as a moderate to high practice effect. Moreover, the iSAT did not have construct validity, and its convergent validity was insufficient in young adults aged 20 to 29 years. Conclusion: The psychometric properties of the iSAT are satisfactory for conducting research in patients with schizophrenia. However, the researcher suggests that prospective users use multiple administrations and average scores to lower the random measurement error found in the two high-load conditions of the iSAT and thereby to improve the discriminative validity. On the other hand, the psychometric properties of the iSAT are not sufficient to develop norms. Future studies may recruit young adults aged 20 to 29 years who are from different areas, left-handed, and have 12 to 16 years of schooling as study subjects to re-examine the psychometric properties of the iSAT in young adults aged 20 to 29 years for the development of future norms.