Table 1.

Sample Description

	ADHD	TD	difference
N	75	29	-
Age in years M (SD)	9.28 (1.34)	8.83 (1.23)	p = .106
Female	29%	34%	p = .785
Non-White	39%	31%	p = .619
Task Accuracy M (SD)	80% (9%)	85% (7%)	p = .003
Full-Scale IQ M (SD)	109 (10)	118 (11)	p = .001
Average ADHD Symptom Severity M (SD)	1.42 (0.62)	−0.66 (0.59)	p < .001
Individual P3 Trials M (SD)	25.72 (3.52)	27.31 (1.87)	p = .004
Trial-Centered P3 Trials M (SD)	20.49 (3.21)	21.66 (2.72)	p = .068

Note: ADHD = attention deficit hyperactivity disorder; TD = typically developing. M = mean; SD = standard deviation. Average ADHD symptom severity was calculated as the mean severity of parent ratings of 18 ADHD symptoms on the SWAN, with a range of −3 to 3; higher scores indicate greater ADHD symptom severity. Individual P3 and Trial-Centered P3 Trials = the number of trials included in the individual P3 amplitude or trial-centered P3 variables, respectively. Difference tests were independent samples t-tests for continuous variables (age, accuracy, novel trials, IQ); and chi-square tests for categorical variables (female, non-white). Bolded p values indicate statistically significant group differences at p < .05.