Table 5.

Correlations between dispersion index and education and performance in different tasks.

	Young		Middle-Old		Old-Old
	iSD	Education	iSD	Education	iSD	Education
DS forward (score)	0.403	−0.045	−0.020	0.429	−0.279	0.196
DS backward (score)	0.657∗∗	0.132	−0.143	0.325	−0.343	0.041
TMT A† (sec)	−0.296	0.169	0.101	0.545∗	0.061	0.598∗∗
TMT B/A† (sec)	0.211	0.232	−0.172	0.401	−0.755∗∗∗	0.129
VF phonemic (score)	0.083	0.394	0.083	0.652∗∗	−0.161	0.310
VF semantic (score)	0.092	0.248	0.010	0.409	−0.208	0.110
WS 4 (score)	−0.098	0.114	0.104	0.418	−0.101	0.098
WS 5 (score)	−0.078	−0.084	−0.298	0.463∗	−0.350	0.153
WS 7 (score)	0.580∗∗	0.211	−0.002	0.480∗	−0.063	0.132
Overall performance	0.403	0.278	−0.120	0.661∗∗	−0.499∗	0.373

Significant results are in bold. ^∗p ≤ 0.05; ^∗∗p ≤ 0.01, ^∗∗∗p ≤ 0.001. ^†Sign has been sign-reversed here for consistency with the other tests, so that all correlations are presented in the same direction. iSD (intra-individual SD, an index of dispersion across all the tasks: the higher the iSD, the higher the dispersion); DS, digit span; TMT, trail making test; VF, verbal fluency; WS, word span.