Piaget 主張，解決認知衝突，達成內在認知與現實的均衡，是促進認知發展的主要機制，因此，其理論顯然蘊含著，認知發展是解決認知矛盾，朝向認知統合發展的基本假設。同樣的，Kohlberg的道德發展理論，從情境利我取向到普世正義原則的發展，也意味著從特定情境的局部統合到整體統合之發展趨勢。據此，本研究想要探討道德思考的統合（coherence）程度是否會隨著年齡而越來越整體統合（global coherence），以驗證Piaget 與Kohlberg 理論背後的基本假設。本研究以兩個研究測試此假設，方法是編製有關偷竊、作弊、欺騙、守信主題的四個道德情境故事，針對故事主角的行為，提供兩個彼此矛盾的道德評價，要求參與者分別評估對這兩個矛盾說法的贊成程度。研究一以小學二年級、三年級及六年級學生作為參與者，研究二則以小學六年級、高中生、大學生到大學以上的學生作為參與者。兩個研究分別發展出具有年齡合宜性的實驗材料。參與者對於兩個矛盾說法若呈正相關，代表思考越局部統合，會同時接受兩個矛盾的說法，若呈負相關，代表思考越整體統合，對矛盾說法會接受其一，拒絕其一。研究結果支持Piaget 與Kohlberg 的發展假設，在多數的情況底下，道德思考隨年齡增加而越趨整體統合，但是由於「守信行為」情境在兩個研究中均為唯一的例外，因此思考統合性的領域特定性顯然是必須更進一步加以釐清的因素。

The implicit assumption of Piaget's and Kohlberg's cognitive developmental theory is the development of cognitive coherence (equilibrium between internal cognitive structure and external environmental world) via resolution of cognitive conflict. The present study aims to investigate whether the global coherence of moral thinking develops by age. The researchers utilized four moral scenarios to evaluate the participants' responses to two contradicting arguments regarding behaviors of stealing, lying, cheating in an exam, and breaking a promise. The degree of coherence was evaluated by the correlation of the two responses. Since assessment materials should be developed differently for younger children and older subject, the researchers designed two separate studies for different age groups: Study 1 for elementary school children, and Study 2 for older subjects. Study 1 results showed that sixth graders' moral judgment was more coherent than third graders' except for the ＂Breading Promise＂ scenario. Study 2 showed that college students' moral judgment was more coherent than sixth graders' except for the ＂Breaking Promise＂ scenario, as well. Taking both Study 1 and Study 2 into account, coherence of moral thinking increases by age which supports Piaget and Kohlberg's theoretical hypothesis.