In virtual reality avatars are animated graphical representation of a person embedded in a virtual environment. Previous research has illustrated the benefits of having an avatar when perceiving aspects of virtual reality. We studied the effect that a non-faithful, or altered, avatar had on the perception of one's action capabilities in VR. In Experiment 1, one group of participants acted with a normal, or faithful, avatar and the other group of participants used an avatar with an extended arm, all in virtual reality. In Experiment 2, the same methodology and procedure was used as in Experiment 1, except only the calibration phase occurred in VR, while the remaining reaches were completed in the real world. All participants performed reaches to various distances. The results of these studies show that calibration to altered dimensions of avatars is possible after receiving feedback while acting with the altered avatar. Further, calibration occurred more quickly when feedback was initially used to transition from a normal avatar to an altered avatar than when later transitioning from the altered avatar arm back to the normal avatar arm without feedback. The implications of these findings for training in virtual reality simulations and transfer back to the real world are also discussed. iii DEDICATION This dissertation is dedicated to my family, Michael, Ingrid, and Kendall Day, all of whom have provided unwavering support, encouragement, and love throughout my entire life. Thank you for everything-I love you guys so much. I would like to thank my committee chair, Dr. Chris Pagano, for his assistance and guidance throughout this project, from developing a topic and writing the proposal to collecting the data and writing the defense. I am sincerely grateful for everything that you have done for me during my time at Clemson. I also would like to thank my committee members for their support. I truly appreciate all of your assistance and guidance. Specifically, I would like to thank Dr. Moore for his time, encouragement, and mentorship regarding statistics. I would also like to thank, Leah Hartman, my lab mate, for her assistance in everything I have done at Clemson-we make quite the team. In addition, I want to thank my mentor, Dr. Harry Heft. Without your help, I would not have been able to find my passion for this subject matter and your guidance in my academic career is invaluable. Finally, I would once again like to thank my family and friends for their support and encouragement throughout the years I have been working on this project. iv