Table 9.

Performance on Executive Functioning Tasks by Threshold of Exposure Grouping

	Heavier exposure			Light or no exposure
Variable	n	Mean	SD	n	Mean	SD	Kruskal-Wallis test statistic
Alcohol
Tapping inhibition	36	7.4	5.5	142	8.7	5.7	1.7
Category fluency	46	4.8	3.4	213	5.3	3.3	1.0
Motor planning	50	3.3	1.8	230	3.4	2.0	0.4
Cocaine
Tapping inhibition	50	7.8	5.9	128	8.7	5.6	1.7
Category fluency	74	5.0	3.5	185	5.3	3.3	0.8
Motor planning	69	3.6	2.0	211	3.4	2.0	0.5
Marijuana
Tapping inhibition	9	5.8	3.8	169	8.6	5.7	2.6*
Category fluency	11	5.5	3.8	248	5.2	3.4	0.03
Motor planning	7	3.4	1.8	253	3.4	2	0.1

^*p < 0.10.