Attentive fields are related to focal and contextual features: a study of Müller-Lyer distortions

The mathematical model associated with integrative field theory was used to infer the size of attentive fields in a task involving judgments of size. A compounded Müller-Lyer task was employed in which fins between or outside the standard shafts were systematically removed. Performance on this task was simulated by a computer that generated families of theoretical functions varying in the parameter of attentive field size. Individual theoretical functions were then correlated with an empirical function obtained from real observers. The value of attentive field size that provided the best fit between functions was then selected. The results showed that, in almost all cases, the optimum size of the attentive field was smaller for the shrinkage form than for the expansion form of the Müller-Lyer pattern, that the attentive field changed more dramatically with changes in stimulus variables in the expansion form than in the shrinkage form, and that changes in viewing distance had little effect on the optimum size of the attentive field. It was concluded that the attention was involved both in figure-ground segregation and in maintaining object constancy. The similarity of these results to data obtained in recognition and detection tasks was noted.