Table 1.

Behavioral and demographic findings

	VV	SD	VM	SD	MM	SD	F	p
	(n = 8)		(n = 8)		(n = 6)
Age	28.17	7.11	33.38	7.09	27.00	9.62	1.78	0.19
Gender (number of males)	4		5		4		χ² = 0.45	0.80
Education	16.17	2.71	16.75	2.60	16.80	3.27	0.09	0.91
WAIS IQ	101.0	13.6	109.4	14.1	103.8	7.2	0.81	0.46
Accuracy
Numerical size judgement (J)	0.908	0.074	0.900	0.104	0.930	0.027	0.37	0.69
Numerical computation and J (CJ)	0.867	0.113	0.756	0.247	0.850	0.141	1.05	0.37
Retrieval and J (E_RJ)	0.933	0.061	0.969	0.053	0.920	0.076	0.12	0.89
Numerical computation in working memory and J (E_CJ)	0.733	0.061	0.700	0.235	0.770	0.110	0.35	0.71
Motor task (M)	0.992	0.020	0.969	0.059	0.980	0.045	0.28	0.76
Reaction time (s)
Numerical size judgement (J)	1.388	0.289	1.407	0.263	1.318	0.148	0.65	0.53
Numerical computation and J (CJ)	1.983	0.256	1.795	0.376	1.908	0.113	0.73	0.49
Retrieval and J (E_RJ)	1.152	0.191	1.091	0.204	1.130	0.156	0.29	0.75
Numerical computation in working memory and J (E_CJ)	1.804	0.256	1.849	0.204	2.041	0.229	0.24	0.79
Motor task (M)	0.918	0.206	0.918	0.110	0.911	0.117	0.17	0.85

There were no significant demographic or performance differences across COMT genotype groups. VV, Val-homozygote; VM, Val-Met hetrozygote; MM, Met-homozygote.