本研究以連續性負向對比（successive negative contrast, SNC）動物行為模式進行比較行為所涉及的心理歷程及神經生理系統之探究。實驗首先建立以大白鼠在舔舐不同濃度蔗糖液所引發的連續性負向對比效果之模式，繼而探討飢餓動機在此模式中所扮演的角色，並且以benzodiazepines受體促進劑diazepam進行週邊及中樞注射，期望對此模式之神經行為機制有進一步的發現，並釐清benzodiazepines在當中所扮演的角色。實驗一是為了建立本實驗室大白鼠在舔舐蔗糖液由較高濃度（32﹪）降為較低濃度（4﹪）時產生的連續性負向對比行為的表現，從結果發現剝奪吃食的大白鼠或自由吃食的大白鼠皆有連續性負向對比行為的效果產生，剝奪吃食的大白鼠在減抑負向對比的行為效果比自由吃食的大白鼠還快，而自由吃食的大白鼠在連續性負向對比的行為保持上會持續較久。實驗二是操弄吃食狀態的調換，以檢視大白鼠在負向對比效果表現是否隨飢餓驅力的高低而變化，就結果而言，剝奪吃食改為自由吃食組大白鼠之連續性負向對比行為的產生只發生在蔗糖液濃度變化後的第一、二天，而自由吃食改為剝奪吃食組大白鼠會發生在蔗糖液濃度變化後的四天。實驗三大白鼠進行diazepam腹腔注射，結果發現能有效減抑負向對比效果，但只發生在蔗糖液濃度改變後的第二天。實驗四進行大白鼠腹腔注射diazepam 5 mg/kg以檢視其是否因增加對蔗糖液的喜好因素而減抑了連續性負向對比的效果，結果顯示大白鼠在第一、二天負向對比的效果就不明顯，不過受藥物作用的影響，可以發現舔水次數或舔水量等指標都有增加趨勢，此可解釋為diazepam增加對蔗糖液的喜好得影響。實驗五進行了內側杏仁體及背側海馬體的diazepam微量注射，結果發現蔗糖液濃度改變後第一天，上述兩部位的藥物注射後皆產生負向對比效果，但第二天只有注射內側杏仁體大白鼠減抑了負向對比效果，而背側海馬體大白鼠則繼續保持負向對比效果。綜觀上述結果顯示以舔舐蔗糖液濃度差異所引發連續性負向對比效果所涉及的心理歷程及神經生理系統有其複雜性，benzodiazepines受體促進劑diazepam的藥物測試結果發現會影響此行為模式。 / The present study successive negative contrast (SNC) investigated what psychological processes and neural systems were involved in the comparison behavior. The SNC effect induced by rat’s licking different concentrations of sucrose solution was established and the effect in diazepam (a benzodiazepine agonist) as well as experimental manipulation of food deprivation were observed. In Experiment 1, the SNC effect was induced when the sucrose solution shifted from 32% down to 4%.This effect was observed across the consecutive 4 post-shift days in the free-feeding subjects; however, such effect was gradually diminished in the food-deprived subjects. Experiment 2 manipulated the food deprivation states to study how the hunger drive would affect the SNC. The results revealed that the food-deprived subjects in the pre-shift session show the SNC effect only on the second day of post-shift session with food supplied freely. However, the SNC effects were observed in the consecutive four post-shift days in the subject with free-feeding in the pre-shift session but was then altered into the state of food-deprivation. In Experiment 3, the SNC effect was attenuated by systemic injection of diazepam with the observation of the reduced licking suppression on the second post-shift day. In Experiment 4, with similar manipulation of food supply, diazepam was found to enhance the sucrose licking in addition to its reduction of the SNC effect. The central loci for diazepam to attenuate the SNC effect were investigated in Experiment 5. Although the SNC effect was attenuated by diazepam infused into the medial amygdala or the dorsal hippocampus, the time courses to observe such reduction were different for drug infused into both sites. The study indicates that（a）the SNC effect on licking can be reliably induced by decreasing the sucrose concentration,（b）such effect is attenuated by diazepam via central neural mechanisms. However, further research is needed to determine whether the attenuation of SNC by diazepam is based on the anxiety suppression or appetite enhancement process.