Appendix II. Studies on the Effects of Marijuana in Users

I. The Weil-Zinberg Study

In 1968 Andrew Weil, then a medical student at Harvard University, together with Norman Zinberg, a Harvard psychoanalyst, conducted a series of experiments to determine the basic physical and psychological effects of marijuana on human beings This study, which took place at Boston University, represented the first double-blind experiments with marijuana; until the study was completed, neither the subjects nor the experimenters knew who had been smoking a drug and who had been smoking a carefully disguised placebo.
Here are the conclusions, as reported in the article, "Clinical and Psychological Effects of Marihuana in Man," Science 162 (13 December 1968):1234-42.
1. It is feasible and safe to study the effects of marijuana on human volunteers who smoke it in a laboratory.
2. In a neutral setting persons who are naive to marijuana do not have strong subjective experiences after smoking low or high doses of the drug, and the effects they do report are not the same as those described by regular users of marijuana who take the drug in the same neutral setting.
3. Marijuana-naive persons do demonstrate impaired performance on simple intellectual and psychomotor tests after smoking marijuana; the impairment is dose-related in some cases.
4. Regular users of marijuana do get high after smoking marijuana in a neutral setting but do not show the same degree of impairment of performance on the tests as do naive subjects. In some cases, their performance even appears to improve slightly after smoking marijuana.
5. Marijuana increases heart rate moderately.
6. No change in respiratory rate follows administration of marijuana by inhalation.
7. No change in pupil size occurs in short-term exposure to marijuana.
8. Marijuana administration causes dilation of conjunctival blood vessels.
9. Marijuana treatment produces no change in blood sugar levels.
10. In a neutral setting the physiological and psychological effects of a single, inhaled dose of marijuana appear to reach maximum intensity within one-half hour of inhalation, to be diminished after one hour, and to be completely dissipated by three hours.

II. The Goode Study

In a study of 200 marijuana smokers conducted in 1967 and published in 1970 as The Marijuana Smokers, Erich Goode, a sociologist, reported the following results as the most common effects of smoking marijuana. The table appears in Goode's book Drugs in American Society (New York, 1972), page 48.

 

Subjective Effects of Marijuana: Goode 1970

EFFECT	PERCENTAGE OF RESPONDENTS
More relaxed, peaceful, calmer	46
Senses more "turned on," more sensitive, perceptive	36
Think deeper, have more profound thoughts	31
Laugh more; everything seems funnier	29
Exaggeration of mood; things take on greater significance	25
Time seems slowed down, stretched out	23
Become withdrawn, introverted, privatistic	22
Generally feel nice, groovy, pleasant, fun	21
Mind wanders, free-associates; stream of consciousness	21
Feel dizzy, light-headed	20
Feel lazy, lethargic, don't want to move	19
Feel light, airy, floating, elevated	18
Feel "happy"	18
Forget things, have memory gaps	18
Feel freer, more unrestrained, less inhibited	18
Stimulation of the senses is more enjoyable	18
Become hungry, want to eat more; appetite stimulated	17
Musical ear sharper, more acute, sensitive, accurate	17
Enjoy music more; greater pleasure listening to music	16
Feel paranoid	15

 

III. The Tart Study

A year after The Marijuana Smokers appeared, Charles Tart, a California psychologist, published On Being Stoned: A Psychological Study of Marijuana Intoxication. Tart distributed 750 questionnaires among California smokers, of which 150 were returned. Tart used a forced-answer checklist, so that a higher percentage of respondents reported a specific effect than was true in Goode's study, where smokers had to think up the individual effects on their own. This table appears in Drugs in American Society, page 49.

 

Subjective Effects of Marijuana: Tart 1971

EFFECT	VERY OFTEN OR USUALLY	SOMETIMES OR RARELY	NEVER
Hear subtle changes in sounds	95	4	1
Distance walking seems changed	78	21	3
Taste seems different	78	18	1
Sleep easier and better	76	14	3
Enjoy eating more; eat more	75	23	1
Time passes slowly	74	24	1
Physically relaxed, inactive	72	27	1
Can "come down" at will	70	21	5
Feel more childlike, open	68	26	5
Can understand songs better	66	30	4
Sense of touch more exciting	65	30	4
Accept things easier	64	32	2
Hard to play social games	62	28	6
Almost always feel good	61	20	5
Memory span shortened	60	36	3
Spatial separation of music	60	27	13
Mind's eye sharper	60	25	12
Difficult to read	57	29	9
See visual patterns in things	56	35	6
Sexual orgasm more pleasurable	56	31	6
Meaningful insights come to mind	55	40	3
Touch takes on new qualities	55	39	5
Deeper insights into others	55	38	7
Appreciate subtle humor in others	54	43	2
Completely present-oriented	53	44	3
Forget to finish things	53	42	4
Moving about seems smoother	53	37	7
Less boisterous at parties	52	39	5
Aware of body-emotion connection	50	36	13
Accept contradictions easier	50	32	11

 

IV. Other Studies

In 1971 a survey conducted by three physicians (James Halikas, Donald Goodwin, and Samuel Guze) was described in the Journal of the American Medical Association z17: 6gz-g4. A hundred regular marijuana smokers were asked to complete a checklist questionnaire. This table was compiled by Erich Goode, and it appears in Drugs in American Society, page 51.

 

Subjective Effects of Marijuana: Halikas, Goodwin, and Guze 1971

EFFECT	USUALLY	OCCASIONALLY	ONCE OR NEVER
Euphoria	82	17	1
Relaxation	79	21	0
Keener sound sense	76	21	3
Peaceful	74	25	1
Increased sensitivity	74	23	3
Increased hunger	72	24	4
Time slowed down	62	35	3
Increased thirst	62	32	6
Dry throat and mouth	61	38	1
Floating sensation	45	49	6
More talkative	37	51	12
Hunger for sweets	37	43	20
Laughing and giggling	36	60	4
Heightened sex feeling	34	59	7
Heightened sex arousal	33	59	8

A fifth study was conducted by Joel Hochman and Norman Brill, physicians at the University of California at Los Angeles. In 1971 a random sample of UCLA's student body was asked to respond to a forced-alternative checklist, with two categories of marijuana use by frequency (often or always, and never) and two levels of use: chronic and occasional. This table was extracted by Erich Goode from the UCLA study and appears in Drugs in American Society, page 52.

 

Subjective Effects of Marijuana: Hochman and Brill 1971

	OFTEN OR ALWAYS		NEVER
EFFECT	CHRONIC	OCCASIONAL	CHRONIC	OCCASIONAL
Hunger	85	72	3	12
Increased sex pleasure	83	50	3	20
Decreased tension	82	57	5	14
Intensified taste	80	65	6	17
Intensified hearing	79	66	6	15
Mellowness	78	59	6	12
Very happy (euphoria)	70	59	3	12
Thirst	70	57	4	17
Increased abstract thinking	70	46	6	20
Time passes slowly	66	57	6	18
Increased self-awareness	62	45	11	19
Increased sexual appetite	60	43	6	20
Desire for sweets	55	37	11	29
Sleepiness	52	50	4	11
Increased understanding of others	47	34	14	27
Increased creativity	45	25	16	35
Increased ability to communicate	42	25	16	37
Clarifies thinking	35	20	13	33
Decreased attention span	28	31	28	30
Paranoid thoughts	18	19	25	39
Able to function better	18	6	31	52
Confusion	17	15	28	32
Decreased ability to communicate	17	19	33	37
Incoordination	15	17	28	32
Irrational ideas	13	16	38	42
Dulls thinking	12	16	28	34
Rapid heartbeat	10	14	54	56
Hallucinations	6	7	44	61
Dizziness	6	5	61	59
Sadness	4	6	29	36
Shortness of breath	4	4	71	80
Increased tension	3	7	72	64
Chills	3	6	78	79
Decreased sexual appetite	2	3	75	70
Decreased sexual pleasure	1	4	85	78
Nausea	0	1	87	84