Year

1993

Degree Name

Master of Arts (Hons.)

Department

Department of Psychology

Abstract

Many studies have found that the global elements of hierarchically organized stimuli are processed more quickly than the local elements. This is known as the global precedence effect (GPE). It has been suggested that this reflects the activities of two visual sub-systems: a fast-transmitting sub-system sensitive to low spatial frequencies, and a slow-transmitting sub-system sensitive to high spatial frequencies. The present series of experiments investigates the role of these spatial frequency channels in the GPE by manipulating factors that are known to affect these channels to see if they also have a predictable effect on the GPE. These factors include controlling the size, presentation position and visibility of stimuli, varying the colour of stimuli, and adapting the subject to a coloured grating prior to stimulus presentation. It is concluded that the GPE is a reflection of lower-order visual processes. However, it is argued that the inconsistency effect, in which the identification of the local element is interfered with by an inconsistent global element, is produced by a separate higher-order cognitive process.

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