The free classification of analyzable and unanalyzable stimuli

A psychophysical approach to dimensional separability

“…Whereas stimuli varying on integral dimensions are grouped according to overall similarity relations (maximizing withingroup similarity and minimizing between-group similarity), stimuli varying on separable dimensions are grouped according to a shared value on one dimension, ignoring overall similarity relations and values on the second dimension (Handel & Imai, 1972). Such free classification results can also be explained by psychophysical corresponder!ce.…”

One or two dimensions in spontaneous classification: A simplicity approach

“…Most empirical results argue in favor of a unidimensional preference (Ashby et al, 1999;Medin et al, 1987;Regehr & Brooks, 1995). A preference for multidimensional classification has been observed, by manipulating the stimulus format and experimental procedure (e.g., Handel & Imai, 1972;Milton, 2006), or by providing a causal scenario to relate the dimensions of a set of objects (Medin et al, 1987). To our knowledge, ours is the first empirical demonstration showing a two-dimensional bias in spontaneous classification, on the basis of the abstract stimulus structure.…”

“…For example, a stimulus could be composed of a bottle, a cup, a trumpet, and a cake, enclosed within a rectangle. Milton and Wills (2004;Milton, 2006;Handel & Imai, 1972) observed that stimulus format does affect unidimensional vs. multidimensional classification, but it was difficult to formulate general principles.…”

Measuring category intuitiveness in unconstrained categorization tasks

“…That such a process is unsupervised is evident in that there are no external constraints to guide categorization; a participant can create any kind of groups he/she wants. Several researchers have employed free sorting tasks, mostly to examine the impact of various methodological variations on participant performance (Ashby et al, 1999;Handel & Preusser, 1969;Handel & Imai, 1972;Handel & Rhodes, 1980;Medin et al, 1987;Milton & Wills, 2004;Regehr & Brooks, 1995). For example, does it make a difference whether participants see all the stimuli at once instead of sequentially?…”