Goal maintenance: examining capacity, competition, and duration, and their relation to intelligence and processing speed

Abstract

Goal maintenance is the ability to keep task rules active in-mind so that they can guide behaviour. When this process fails, individuals are unable to use task rules appropriately, and consequently perform poorly on the given task. The rate of goal neglect has been shown to increase with the complexity of the information to be maintained, especially for those with low levels of fluid intelligence. The main aim of this thesis was to examine whether this effect arises from the limited capacity for task rules, the limited ability to cope with competition between task rules, or the limited ability to sustain maintenance of a rule over time both in younger and older adults. A second aim was to investigate whether fluid intelligence and processing speed contribute to performance when goal maintenance is taxed. In particular, the number of instructions presented at the start of the task (Experiments 1-4), the speed at which rules had to be used (Experiment 5), the infrequency with which a task-relevant goal was used relative to a task-irrelevant goal (Experiment 6), and the duration for which rules had to be maintained (Experiment 7) were manipulated. Finally, the importance of goal maintenance in a more real-world setting was examined by testing the relationship between goal neglect and academic performance in children (Experiments 8 and 9). Goal maintenance was not limited by the number of rules to be held in mind, but goal neglect did increase as the degree of competition between rules and the duration with which they were maintained increased. Fluid intelligence accounted for little of the variation in goal maintenance abilities, but processing speed played a moderating role in older adults. In terms of academic performance, goal maintenance in school-aged children significantly predicted mathematics abilities, but not language.