In this paper we investigate the relationship between bimanual (two-handed) manipulation and the cognitive aspects of task integration, divided attention and epistemic action. We explore these relationships by means of an empirical study comparing a bimanual technique versus a unimanual (one-handed) technique for a curve matching task. The bimanual technique was designed on the principle of integrating the visual, conceptual and input device space domain of both hands. We provide evidence that the bimanual technique has better performance than the unimanual technique and, as the task becomes more cognitively demanding, the bimanual technique exhibits even greater performance benefits. We argue that the design principles and performance improvements are applicable to other task domains.