The visual implications of inspection time

The quest to define human intelligence has led researchers down a large range of paths. One such path has been to search for a single psychometric measure that can be used to account for a large portion of the variance in human mental ability. Inspection Time (IT) has emerged at the forefront of these efforts and is often referred to as the amount of time required to make a single observation of sensory input. IT can be shown to account for approximately 20% of the variance in human mental ability. In this study, we attempt to gain an insight into the nature of IT as a psychometric measure by contrasting individuals that are adept. at performing the IT task (those with low ITs) with individuals that are not (those with high ITs) using oculomotor and task-performance measures recorded during two visual tasks. These tasks were designed to test participants' visual-attentional control and visual working memory under varying degrees of difficulty. The data show that a sensory-level theory of IT is incapable of accounting for the results found during the visual tasks, which leads us to introduce a novel theory of IT that places IT as a measure of information propagation. A discussion is presented on the implications and need for future validation of the theory.