Role of Symmetry and Simplicity in Shape Disruption Perception Tasks

Purpose of the present research was further examination of roles of symmetry and complexity in visual perception tasks. We tested hypothesis from perceptual economy theory, and since we used shape disruptions as one of the stimulus characteristics we could also address Luccio’s two step theory concerning perception of shape disruptions on good forms. Four experiments were conducted, visual search and simultaneous and delayed matching. Symmetry and complexity were varied, as well as set size in visual search experiment. Dependent variables were reaction time and error number. In all four experiments, symmetry had dominant effect, while significant effect of complexity was registered only in Experiment 1. However, in first three experiments interaction of symmetry and complexity was also significant. Analysis of reaction times and performance suggested that our results follow the pattern suggested by perceptual economy, i.e. that symmetry is dominant in easier tasks, while complexity was significant in most difficult task. Our results couldn’t completely support Luccio’s assumption that shape disruption is better perceived on good forms, although it can’t be completely discarded. Key words: symmetry, complexity, perceptual economy, visual search, matching task Gestalt psychology states that the visual field is organized according to some global structural qualities (Köhler, 1947; Koffka, 1935). These qualities (also called Prägnant qualities – Prägnanzqualität) are present in every perceptual unit, but in different quantities. According to Wetheimer, the more these qualities are present, the more that unit will be integrated, or Prägnant (Koffka, 1935). Although Gestaltists defined Prägnant form (or good form) as subjective category, stimulus characteristics determine the level of possible goodness. In other words, the form will be as good as stimulus constraint allow (Koffka, 1935). Some of the stimulus qualities that make Prägnant structure ar