Grouping by proximity and grouping by good continuation in the perceptual organization of random dot patterns

The spontaneous perception of structure in random dot patterns and the role of the Gestalt grouping principles of proximity, collinearity, and good-continuation were investigated. In three experiments observers reported the perceived organization in random dot patterns by either circling the groups they perceived or by clicking on the dots that appeared to belong to the same groups. These reported organizations were analyzed to determine within-subject and between-subject consistency, and they were used as an empirical foundation for a quantitative model of perceptual organization. The quantitative model that is presented uses graph-theoretic techniques to determine the neighborhoods of dots in the random dot patterns. Within these neighborhoods strengths of grouping by proximity, collinearity and good-continuation are computed. Additionally, in a computer simulation the model performed multiple trials with the experimental stimuli and, in a stochastic process, predicted grouping frequencies. It was found that the empirical data could be accurately accounted for by a model based on grouping by proximity and by good-continuation and that computed neighborhoods in a global fashion. In a fourth experiment this model was tested in a new context and the time-course of perceptual organization in random dot patterns was investigated. The results of this experiment showed that the predictions of the model captured human performance and that display duration did not affect the responses. The results of the four experiments and the model-fitting are interpreted as evidence that the perceptual organization of random dot patterns is an early, automatic, and global process.