The popular construct of goal orientation has been widely researched by industrial and organizational psychologists in recent years. Unfortunately there are several issues with the goal orientation framework that have not been properly addressed in the literature. The present research introduced the three-dimensional achievement goal framework as a plausible and less problematic alternative to the three-dimensional goal orientation framework. Hypotheses regarding the interactive effects of each of the three achievement goals and task complexity on task enjoyment, mental focus and exerted effort, were derived and tested. The results indicated that the positive effects of mastery goals on the motivational variables are stronger for more complex tasks, the positive effects of performance-approach goals are stronger for simpler tasks, and the negative effects of performance-avoid goals are less severe for simpler tasks. / Ph. D.