效率市場假說認為只要資訊的實質一樣，表達方式並不會影響投資人的判斷；然而，許多心理學研究卻發現人類的判斷會受到表達格式的影響，因此，本研究以國內三十四號公報「金融商品之會計處理準則」為例，探討此問題。實驗ㄧ採2*2受試者間測試之設計，以國內會計研究所之學生為受試者，將個案設計成兩種，一個是按照成本與市價孰低法評價，證券投資相關損益呈現持續上升，而以公平價值法評價則呈現不規則波動，另一個是按照成本與市價孰低法評價，證券投資相關損益呈現不規則波動，而以公平價值法評價則呈現持續上升。實驗二改採受試者內設計，目的在檢驗投資人對相同的經濟實質若有不同的判斷，係屬於自覺的或不自覺的行為。實驗ㄧ發現，投資人都會僵固在報表的數字而不管資訊的實質。因此，實驗ㄧ結果支持不同的會計處理，確實會影響投資人的判斷。實驗二發現當受試者同時填答成本與市價孰低法與公平價值法之情況時，會計處理方法並不會影響他們的投資判斷。因此，投資人對相同的經濟實質有不同的判斷係屬於不自覺的偏誤行為。 According to Efficient Market Hypothesis, holding constant the available information and underlying economics, different presentations of financial information would not have an impact on investors’ judgments. However, many psychological researches result in adverse conclusions. Therefore, the objective of this research is to determine whether the presentations of financial information would have an impact on nonprofessional investors’ judgment, using Taiwan’s SFAC No.34 “Accounting for Financial Instruments.” First experiment uses a 2*2 between-subjects experiment to test on a pre-selected focus group, which consists of graduate accounting students, by giving them two different scenarios: (1) gain or loss on investments in securities rise as using Lower of Cost or Market Method whereas it fluctuates irregularly as using Fair Value Method; (2) gain or loss on investments in securities fluctuates irregularly as using Lower of Cost or Market Method whereas it rise as using Fair Value Method. Alternatively, the second experiment is a within-subjects design to investigate that it is conscious or unconscious bias behavior, if investors have different judgments on the same economic substance. The result of first experiment shows that the focus group simply fixated on reported income rather than the substance of the information. Thus, the first experiment concludes that alternative presentations of financial information do affect investors’ judgments. The second experiment shows that different presentations of financial information do not affect its readers in their investment judgments, when giving them the financial statement using Lower of Cost or Market Method and it using Fair Value Method meanwhile. Consequently, it is unconscious bias behavior that investors generally have different judgments on the same economic substance.