Table 5.

Hierarchical regression analysis predicting total distance traveled in response to the challenge day of treatment. Interactions were entered independently, such that interactions were tested then removed from the model. See Table 1’s description for the interpretation of R², β, and t.

	Step and predictor variable	R2	β	t
Step 1		.10
	IEN		−.08	0.44
	NPP		−.29	1.52
	H-USV FM		.05	0.27
Step 2		.49**
	Repeated Low 0.3 mg/kg		.32	1.50
	Acute High 1.0 mg/kg		.62	3.17**
	Repeated High 1.0 mg/kg		.83	3.56**
Step 3
	Repeated Low 0.3 mg/kg × IEN	.51	−.11	0.29
	Acute High 1.0 mg/kg × IEN		−.12	0.42
	Repeated High 1.0 mg/kg × IEN		.10	0.36
	Repeated Low 0.3 mg/kg × NPP	.50	−.18	0.59
	Acute High 1.0 mg/kg × NPP		−.08	0.24
	Repeated High 1.0 mg/kg × NPP		−.11	0.13
	Repeated Low 0.3 mg/kg × H-USVFM .57		−.20	0.69
	Acute High 1.0 mg/kg × H-USV FM		−.14	0.66
	Repeated High 1.0 mg/kg × H-USV FM		.20	0.71
	IEN × NPP	.50	−.19	0.92
	IEN × H-USV FM	.48	.01	0.07
	NPP × H-USV FM	.48	−.05	0.24

^*p < .05;

^**p < .01;

^***p < .001