In the past decade, a number of personalized learning systems have been developed. Prior knowledge has widely been considered in the development of personalized learning systems. On the other hand, previous research suggested that cognitive styles have great effects on student learning. To this end, this study examine how cognitive styles, affect learners' reactions to a personalized and non-personalized learning systems based on learners' priop knowledeg. Forty-four undergraduate and postgraduate students participated in this study. The results show that Serialists show positive reactions to the personalized learning system while Holists demonstrate equal reactions to the personalized learning system and the non-personalized learning system. The implications of these results for the design of personalized learning systems are discussed.