Table 2

Summary of significant results for all 76 participants and for each of the four experiments

Measure^2-a	All Participants^2-b (n = 76)	Expt. 1^2-c	Expt. 2,^2-d Dose Effects		Expt. 3,^2-e Suppression of Withdrawal		Expt. 4,^2-f Duration of Exposure (No. Days)
Measure^2-a	All Participants^2-b (n = 76)	Expt. 1^2-c	100	300	600	300	200	100	50	25	0	1	3	7	14
	300 versus 0	300 versus 0	versus 0		versus 300		300 versus 0
Headache	0.001	0.001	0.005	0.001	0.001	^2-g					0.001			0.007	0.007
Cluster scales
Headache/poor mood	0.001	0.017			0.006						0.031		0.018	0.007	0.046
Activity/alertness (↓)	0.01	0.018		0.014	0.016					0.028	0.034		0.019	0.003
Physical symptoms			0.029
Tiredness	0.001	0.003	0.011	0.019	0.001			0.043	0.02	0.031	0.04		0.002	0.001	0.003
Flu-like symptoms		0.001			0.041								0.030
POMS^2-h
Fatigue	0.001	0.036	0.015	0.023	0.012			0.017		0.04	0.007		0.001	0.002	0.014
Confusion-Bewilderment	0.03		0.028	0.027	0.007
Vigor (↓)	0.001	0.025		0.013	0.005						0.006
Friendly (↓)	0.009	0.043			0.006
Total mood disturbance	0.04				0.011						0.012		0.013	0.027

↵2-a For all significant effects shown, substitution of placebo or lower caffeine doses (expt. 3) increased all measures relative to caffeine except for Activity/Alertness, Vigor (POMS), and Friendly (POMS), which were decreased significantly, as indicated by down arrow.
↵2-b Comparison between last 2 days of caffeine (300 mg/day) and first 2-day placebo substitution (0 mg/day) across all four experiments.
↵2-c Comparison between last 2 days of caffeine (300 mg/day) and 2-day placebo substitutions for data collapsed across two dosing intervals and three replications.
↵2-d Comparison between last 2 days of each caffeine maintenance dose and corresponding 2-day placebo substitution.
↵2-e Comparison between last 2 days of caffeine (300 mg/day) and corresponding 2-day dose substitution.
↵2-f Comparison between last 2 days of 14-day caffeine condition (300 mg/day) and first 2 days of placebo substitution after each of the caffeine exposures (i.e., 1, 3, 7, or 14 days of 300 mg/day caffeine).
↵2-g No value indicates comparison was not statistically significant at p ≥ .05.
↵2-h Three POMS scales (Anger-Hostility, Depression-Dejection, Tension-Anxiety) are not shown in this table because they did not show significant caffeine withdrawal effects in any experiment.