Abstract
We have shown in previous work that the perception of order in point patterns is consistent with an interval scale structure (Protonotarios, Baum, Johnston, Hunter, & Griffin, 2014). The psychophysical scaling method used relies on the confusion between stimuli with similar levels of order, and the resulting discrimination scale is expressed in just-noticeable differences (jnds). As with other perceptual dimensions, an interesting question is whether suprathreshold (perceptual) differences are consistent with distances between stimuli on the discrimination scale. To test that, we collected discrimination data, and data based on comparison of perceptual differences. The stimuli were jittered square lattices of dots, covering the range from total disorder (Poisson) to perfect order (square lattice), roughly equally spaced on the discrimination scale. Observers picked the most ordered pattern from a pair, and the pair of patterns with the greatest difference in order from two pairs. Although the judgments of perceptual difference were found to be consistent with an interval scale, like the discrimination judgments, no common interval scale that could predict both sets of data was possible. In particular, the midpattern of the perceptual scale is 11 jnds away from the ordered end, and 5 jnds from the disordered end of the discrimination scale.
Highlights
The notion of order appears in Gestalt psychology (Koffka, 1935), and is related to arrangements of objects where their relative placement has significance
In previous work (Protonotarios, Baum, Johnston, Hunter, & Griffin, 2014) we have shown, using pairwise comparisons of point patterns from a diverse set, that observers are highly consistent in their judgments of order, and that these are compatible with an interval scale structure
We investigate whether a common interval scale can account for the data of both experiments, and whether appearance and discrimination form a consistent basis for quantification of order
Summary
The notion of order appears in Gestalt psychology (Koffka, 1935), and is related to arrangements of objects where their relative placement has significance. Order may consist of specific regularities (laws), and these may interact synergistically (Wagemans, Wichmann, & de Beeck, 2005). It was suggested that the visual system seeks order (e.g., symmetry) so as to make sense of sensory signals. The ability of the visual system to detect regularities has been proposed as a method of compressing information to reduce redundancy (Attneave, 1954). Gestalt principles considered under this view are functions of the perceptual machinery that group information together and provide an economical description of visual reality. Subjective assessments of the degree of order are common in everyday life and in scientific research when visual patterns are examined (Cohen, Baum, & Miodownik, 2011; Cook, 2004; Marinari et al, 2012).
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