The study of cognition as it relates to expert performance in sport is an area that has received increased attention over the last 25 years. This has been made possible by the fact that the domain of sport offers a rich and diverse setting in which to study cognition and its links to human performance, coupled with the abundant supply of highly practiced athletes providing unique opportunities to study these factors in a natural environment. The quality of on-field decision-making of expert athletes has received attention in a number of open-skill sporting codes, including basketball, field hockey and soccer. Decision-making quality of expert athletes in rugby union, as an invasive, open-skill sporting code, has not received the same amount of attention. Past studies on the decision-making of expert athletes in sport have tended to be carried through the isolation of specific cognitive functions and describing the role of each isolated function in the decision-making process. Given the speed at which decisions have to be made, as a result of time pressure, the isolation of cognitive functions yields valuable insights into the decision-making processes of expert athletes in competitive, on-field situations. While these cognitive functions can be studied in isolation, they do however form part of a bigger process that enables the expert athlete to make high quality on-field decisions. It is for this reason that it was decided to study these different functions in combination, as set out by the Information Processing Approach to cognitive functioning. According to this approach, the decision-making process consists on three main phases, namely that of Visual Search Strategies, Anticipation and Response Selection. This study was aimed at examining the quality of on-field decision-making of expert rugby players, as well as the influence of the competitive level at which rugby is played on decision-making quality. In order to achieve this goal it was necessary to develop a measurement instrument that can be used by expert rugby players to assess the quality of decisions made on the field of play. As it is difficult for outside observers to establish what players are thinking or focusing their attention on when making decisions on the field, it was necessary to design the instrument as a self-report measure of decision-making. By being made aware of one’s strong and weak points in on-field decision-making, expert rugby players can focus their attention on improving the underdeveloped facets of their game. The measurement of decision-making according to three distinct phases allows for increased accuracy in the identification of those cognitive areas that need improvement in order to improve overall playing ability. By changing the way the expert rugby player thinks about certain aspects of the game, most notably those aspects that the player has difficulty with, it becomes possible for the player to address these difficulties and make improvements wherever necessary. Copyright / Dissertation (MA)--University of Pretoria, 2008. / Psychology / unrestricted