This study was designed to examine whether a person's prepositioned cognitive style influenced learning achievement in a visually-oriented task for an online learning environment in higher education. Field dependence-independence was used to identify individuals' cognitive styles. A true experimental study was conducted in the fall 2005 term at the University of Central Florida. This researcher followed Dwyer and Moore's research (1991, 2002) and divided learners into three groups (field dependent [FD], field neutral [FN], and the field independent [FI] students). Eighty-three preservice teachers participated in this study; the data from 52 of the FD and the FI participants were analyzed to answer research questions. The findings in this study supported those in the literature review; students from both FD and FI cognitive styles performed equally well in online learning environments. In addition, for providing introductory-level instruction on visually-oriented tasks in an online learning environment, instructions which emphasized an FD approach benefited both FI and FD students in their knowledge-based learning achievement. In this approach, extra cues and sequence of content might have been the reasons that students had higher scores on their knowledge-based learning achievement and satisfaction levels. The findings of this study also indicated that students could demonstrate higher performance-based learning achievement if they had more experiences on the subject matter and higher knowledge-based learning achievement if they felt the instructions were easy to follow and the workload of the module was manageable. Based on the findings and conclusions, the recommendations are: (1) A larger sample size is needed to generalize the findings of the study; (2) In this study, student-to-student and teacher-to-student interactions might affect students' learning achievement. Future studies should consider those interactions as factors and examine their effect on students' learning achievement.