Table 2.

Mean proportion AB (dimensional identity) and BC (overall similarity) classifications

Reference	Description	Age	BC	AB
Smith & Kemler, 1977, exp 1	Triad; size-shade
		5–6 yrs	0.56	0.34
		7–8 yrs	0.40	0.50
		10–11 yrs	0.22	0.68
Smith & Kemler, 1977, exp 2	Tetrad: Size-shade
		5–6 yrs	.58	.34
		10–11 yrs	.18	.80
Ward, 1980, exp 1	Triad: length-density
(columnar condition)		4–6 yrs	.56	.28
		Adults	.34	.61
Shepp, Burns & McDonough, 1980, exp 1	Triad: size-shade
		4 yrs	0.80	.13
		6–7 yrs	0.45	.48
		11–12 yrs	0.21	.79
Shepp et al., 1980, exp 1	Triad: size-angle
		4 yrs	0.78	.15
		6–7 yrs	0.43	.50
		11–12 yrs	0.26	.67
Kemler, 1982, exp 1	Triad: size-shade
		4–5 yrs	.70	.20
Smith, 1983, exp 1	Tetrad: size-shade
		4–5 yrs	.66	.29
		5–6 yrs	.66	.30
Smith, 1989, exp 1a	Triad: size-shade
		2 yrs	.48	.20
		3 yrs	.55	.24
		4 yrs	.52	.28
		5 yrs	.62	.28
		8yrs	.30	.70
		Adult	.03	.97
Ruskin & Kaye, 1990	Triad: size-shade
		5–6 yrs	.33	.60
		11–12 yrs	.16	.82

Note. Overall similarity proportions for some experiments are calculated from dimensional identity and haphazard grouping.

^aIn Smith’s (1989) experiment, items could be grouped freely, so there were more than 2 possibilities. (Numbers were estimated from Smith, 1989, Figure 11).