Table 3. Means (M) and standard deviations (SD) of median reaction times (RT) and error rates (ER) for patients with Parkinson’s Disease (PD) and healthy controls (HC) for the two sessions (off, on) and as a function of stimulus congruency (congruent, incongruent).

		HC (N = 13)		PD (N = 13)
		M	SD	M	SD
RT (ms) (correctly completed trials)
off	congruent	406	60	414	77
	incongruent	493	82	494	89
on	congruent	412	57	466	162
	incongruent	494	62	529	146
RT (ms) (error trials)
off	congruent	491a	198a	462	163
	incongruent	392	157	369	67
on	congruent	433a	140a	467	186
	incongruent	373	133	451	220
ER (%)
off	congruent	1.5	1.4	8.8	7.0
	incongruent	10.4	5.5	21.8	19.2
on	congruent	1.5	1.5	7.5	5.9
	incongruent	10.4	5.6	20.8	14.4

Note. For PD patients, the conditions “off” and “on” indicate the actual medication state (i.e., whether the patients had taken their usual dose of medication [on] or were tested after withdrawal from dopaminergic medication [off]). The HC group was not administered with dopaminergic medication at any time, and the conditions “off” and “on” were merely used to assign control participants to one of two possible orders of medication conditions (see Methods for detailed explanation).

^aBased on n = 11.