TABLE 4.

Means and standard deviations of the mean amplitudes (μV) of the Frontal Negativities for all groups and conditions.

	All participants			Excluding participants with shorter than
				12 h abstinence since last cannabis use
	Control group	Cannabis users	Polydrug users	Cannabis users	Polydrug users
Old image	-3.92 (3.60)	-4.80 (4.38)	-4.54 (3.26)	-4.61 (4.62)	-4.65 (3.31)
New image	-4.45 (3.26)	-5.28 (3.69)	-4.98 (2.95)	-5.23 (3.90)	-5.12 (2.95)
Mean	-4.16 (3.35)	-5.04 (3.97)	-4.74 (3.00)	-4.90 (4.20)	-4.88 (3.01)