Table 1.

General performance in the stop signal task

Session	Median go RT, ms	% go	% stop	SSRT, ms	FP effect (effect size)	PES (effect size)
M	605 ± 92	96.6 ± 1.5	52.6 ± 2.1	182 ± 38	1.2 ± 1.5	1.4 ± 1.7
P	631 ± 122	96.0 ± 1.7	52.4 ± 3.8	238 ± 41	1.3 ± 1.6	2.0 ± 1.2
P value	0.4108	0.3146	0.8387	0.0024	0.8493	0.3338

Note: %go and %stop: percentage of successful go and stop trials; SSRT: stop signal reaction time; FP: foreperiod; PES: posterror slowing; M: methylphenidate; P: saline placebo. All numbers are mean ± SD. P value based on two-tailed paired sample t test.