This research was conducted in order to uncover the characteristics of, and factors related to, the emergence of the three phenomenologically distinct modes of rational, intuitional and insightful decision making. The theoretical foundation for these three distinct modes was crafted from the theoretical domains of Social Psychology, Gestalt, Creativity, Insightful, and Biofunctional theory. The study involved the use of two sampling groups. Sample 1 consisted of 68 undergraduate students, and Sample 2 consisted of 98 undergraduate students. Participants' problem solving performance was examined with a series of time-limited novel and non-novel word puzzles, in which a set of three clue words was presented. There were two phases of problem solving, with an incubation period between phases. These problem outcomes were examined against problem difficulty, current affect, personality preferences for rationality and intuition, solution cues in the environment during incubation, problem novelty status, and intelligence. The data revealed a strong bias for insight for solved novel problems, while a strong bias for rationality was found for novel problems that participants failed to solve. As problem difficulty increased, participants used rationality proportionally more often to solve problems. When current affect was higher, participants were more likely to use insight for solved novel problems, and when current affect was lower, rational solutions were more likely. Intelligence was found to increase the number of problems solved and problem solving speed. The findings provided evidence for three distinct problem-solving modes. Rational problem solving was slowest and least frequently used to solve novel or non-novel problems. Insightful novel solutions took half the time of rational solutions. Insight is affectively informed sudden knowing, and was the predominant novel problem solution mode. Intuition is also affectively informed sudden knowing. Intuition was found to be the fastest and most successful solution mode for non-novel problems. This research provided empirical evidence to counteract the common conflation of intuition and insight. It illustrated the distinctiveness of the rational, insightful and intuitional modes of decision making and produced evidence of the relationship between each mode and the factors commonly considered to influence decision making.