Modes of Apprehension, and Indicators thereof, in Visual Discrimination of Relative Mass

Sammanfattning: Perception is a fundamental function because it allows organisms to be in contact with the environment and adjust to environmental conditions. Humans also possess higher intellectual functions, which allow for elaborate handling of perceptually obtained information. The thesis concerns a distinction between an inferential ("cognitive") mode and a (direct-)perceptual mode of apprehension, and a notion of perceptual skill acquisition as a transition from the inferential to the perceptual mode. The mode distinction and the mode-transition model was formulated by Runeson, Juslin, and Olsson (2000) within the ecological direct-perception framework (Gibson, 1966, 1979).The modes of apprehension were investigated in an experimental paradigm that concerned visual perception of the relative mass of two colliding objects. The relative mass is specified by an optical variable in the collision movement pattern, which observers may pick up while functioning in the perceptual mode. However, novices often rely on other, nonspecifying, optical variables that may constitute cues that are used in the inferential mode (Runeson et al., 2000).Four tentative mode indicators were employed: participants' realism of confidence, introspective mode reports, amplitudes of brain event-related potentials, and response times. Generally, the results did not support the mode-transition model of skill acquisition. Furthermore, results suggested that reliance both on the specifying and nonspecifying variables might have occurred either in the inferential or in the perceptual mode. However, the mode indicators may not have captured mode as intended. For instance, the discriminability of used optical variables, and not the mode of apprehension, may have affected both amplitudes of event-related potentials and mode reports.It is argued that the mode-transition model and the distinction between two modes of apprehension should be further investigated employing other methodologies, and, furthermore, that the mode distinction has a place within an ecological framework.