Table 2

t test for difference between CS+ and CS− in valence and arousal ratings

Valence	Session	t	df	p-value	Mean CS− (±SD)	Mean CS+ (±SD)
Placebo	Acquisition	7.81	47	<0.001*	72.56 ± 21.59	31.88 ± 20.80
	Recall	4.33	47	<0.001*	61.59 ± 22.49	43.29 ± 21.33
Doxycycline	Acquisition	6.34	48	<0.001*	74.11 ± 21.36	36.51 ± 23.85
	Recall	3.47	48	0.001*	56.56 ± 21.21	43.62 ± 20.91

Arousal	Session	t	df	p-value	Mean CS− (±SD)	Mean CS+ (±SD)

Placebo	Acquisition	−8.11	47	<0.001*	21.16 ± 21.75	69.25 ± 26.99
	Recall	−3.93	47	<0.001*	35.73 ± 27.18	53.33 ± 26.53
Doxycycline	Acquisition	−5.41	48	<0.001*	36.22 ± 30.44	67.97 ± 24.83
	Recall	−3.46	48	0.001*	34.48 ± 29.60	48.20 ± 30.30

Valence ratings: “How do you feel when seeing this triangle? (0 = very negative, 100 = very positive)” Arousal ratings: “How aroused do you feel when seeing this triangle? (0 = very calm, 100 = very excited).” p-value: paired t-test significant differences (p < 0.05) are marked with ‘*’; SD: standard deviation.