Table 1. Demographic and Behavioral Performance Data.

For % Correct and RT data, values in first line reflect sample included in ERP analyses and values in second line reflect full sample. Patient - co-twin pairs and control pairs did not differ in age (patient - co-twins: mean of 48.0 years, control twins: mean of 48.7 years; F(1, 35) = 0.07, P = 0.80), gender distribution, handedness, or race/ethnicity (all White, non-Hispanic).

	Schizophrenia Patients (n=9) Mean (S.E.M.)	Patients’ Co-twins (n=9) Mean (S.E.M.)	Control Twins (n=18) Mean (S.E.M.)
Descriptive Variable
Age (years)	47.97 (1.85)	47.97 (1.85)	48.67 (1.02)
Gender	4 female	4 female	8 female
Handedness	9 right-handed	9 right-handed	18 right-handed
SAPS score	2.8 (0.4)
SANS score	4.4 (1.2)
Task Condition
% Correct - 1 location	92.8 (2.3) 94.6	96.1 (1.3) 95.9	96.6 (1.1) 97.3
% Correct - 3 locations *	78.7 (3.5) 78.8	91.3 (1.9) 91.2	83.6 (2.8) 83.7
% Correct - 5 locations	72.3 (3.9) 72.2	76.4 (3.1) 77.7	76.4 (3.4) 76.4
% Correct - 7 locations	69.5 (4.6) 65.0	79.8 (3.8) 78.0	73.6 (3.7) 65.5
RT (ms) - 1 location §*	1001 (64) 999	733 (36) 737	767 (30) 793
RT (ms) - 3 locations *	1405 (134) 1401	1070 (90) 1066	1116 (43) 1157
RT (ms) - 5 locations	1473 (134) 1479	1253 (100) 1243	1243 (40) 1237
RT (ms) - 7 locations	1374 (141) 1430	1310 (113) 1314	1313 (41) 1375

^§Patients different from controls, P < 0.05

^*Patients different from their cotwins, P < 0.05