Table 3.

Hierarchical regressions of fluid processing ability (composite measure) and crystallized knowledge in older adults

Model	Response	Step	Predictor(s)	R2	df	F	p
A	Fluid processing ability	1	Age	0.0003	1,17	0.005	0.946
		2	+ Visual (SVM)	0.308	2,16	3.560	0.052
			R2 increment	=0.308	1,17	7.114	0.017
B	Crystallized knowledge	1	Age	0.020	1,17	0.339	0.568
		2	+ Visual (SVM)	0.020	2,16	0.166	0.849
			R2 increment	=0.0007	1,17	0.012	0.914
C	Fluid processing ability	1	Age	0.0003	1,17	0.005	0.946
		2	+ Visual (Corr)	0.268	2,16	2.924	0.083
			R2 increment	=0.267	1,17	5.843	0.028
D	Crystallized knowledge	1	Age	0.020	1,17	0.339	0.568
		2	+ Visual (Corr)	0.024	2,16	0.195	0.825
			R2 increment	=0.004	1,17	0.070	0.796

In model A, fluid processing ability was explained by age (first step) and the neural specificity measure from the SVM approach (second step). In model B, crystallized knowledge was explained by age (first step) and the neural specificity measure from the SVM approach (second step). R² increment represents the variance explained by the neural specificity measures beyond age. Models C and D are identical to A and B, respectively, except that the neural specificity measure from the correlation approach was used instead.