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Effects of smoked marijuana on social interaction in small groups
Drug
and Alcohol
Dependence,
87
20 (1987) 87-93
Elsevier Scientific Publishers Ireland Ltd.
EFFECTS OF SMOKED SMALL GROUPS
R.W. FOLTIN*, Division Hopkins IUS. A.)
J.V. BRADY,
MARIJUANA
M.W. FISCHMAN,
ON SOCIAL
C.S. EMURIAN
INTERACTION
IN
and J. DOMINITZ
of Behavioral Biology, Department of Psychiatry and Behavioral Sciences, University School of Medicine, 600 N. Wolfe Street, Houck E-2, Baltimore.
The Johns MD 21205
(Received January lst, 1987)
SUMMARY
Twelve adult male research volunteers, in four groups of three subjects each, resided continuously in a residential laboratory for up to 18 days. Subject’s behaviors, including social interaction, were continuously recorded. During the first part of the day (lOOO-1600), subjects remained in their private rooms doing work activities, and during the remainder of the day (1600-2345), they had the option to socialize with the other subjects. Four cigarettes containing active marijuana (1.84%, A9-tetrahydrocannabinol (A9 (THC)), w/w) or placebo were smoked daily: one each prior to the work and social access period, and two during the social access period. When the results were averaged across all groups and individuals, active marijuana significantly increased total daily social interaction time. However, drug effects were a function of the baseline amount of social interaction. The results of these experiments also showed that the pattern of increases in social interaction following smoked active marijuana varied within different groups of individuals. Key words: Marijuana -
Social interaction -
Humans
INTRODUCTION
The effects of smoked marijuana on social interaction have been pre viously described in both survey [e.g. l] and experimental studies [e.g. 2,3]. While survey studies report an increase in self-orientation [4] and a decrease in interpersonal skills [5], residential experiments have described both transient increases in social interaction [6,7], as well as decreases in interaction
*To whom correspondence should be addressed. 0376-87161871$03.50 0 Elsetier Scientific Pub&hers Ireland Ltd. Printed and Published in Ireland.
accompanied by increases in coaction, i.e. independent participation in identical activities without verbal exchanges [3,8]. Although marijuana smoking frequently occurs in a group [9], effects on social interaction have been shown to vary as a function of drug state [lo], gender [ll] and amount of prior drug use [2,3]. The present report describes an experimental analysis of the effects of smoked marijuana on social interaction compared to the levels of social interaction that occurred in the absence of drug. METHOD
Subjects Groups of three healthy adult male research volunteers ranging in age from 22 to 38 years participated in four separate experiments. All 12 subjects had histories of marijuana use ranging from 2-3 cigarettes/week to 2 -3 cigarettes/day. Subjects received complete medical and psychiatric examinations, signed consent forms detailing all aspects of the research, and were paid for participation. Laboratory Experiments were conducted in a residential laboratory designed for continuous observation of human behavior over extended periods of time. The facility consisted of six rooms connected by a common corridor. Three identical private rooms were similar to small efficiency apartments with kitchen, bathroom, desks, and sleeping areas. A common social area had a recreation room, an exercise room and a bathroom. The recreation room contained kitchen facilities, lounge furniture, games, puzzles and a videogame system. The exercise room contained exercise equipment and laundry facilities. A detailed description of the laboratory has been published elsewhere [12]. Video and audio equipment throughout the residential facility were interfaced with a monitoring system in an adjacent control room. Subjects were continuously observed except in private dressing and toileting rooms. A computerized observation program [13] provided for continuous recording of each subject’s behavior in categorical form. Subjects were instructed that communication between them and the experimenters via a networked computer system was to be kept to a minimum. No other outside communication was permitted. Standard day The day was divided into three periods: a private work period, a task performance period, and a period of social access. Subjects were awakened at 0900, given an opportunity for breakfast, and had a work period from approximately 1000 to 1500. A one-hour performance assessment’was then completed and followed by a social access period which lasted from approximately 1600 to 2400. During the social access period, each subject
89
was permitted to remain in his own private room engaging in private recreational activities (e.g. reading) or to enter the social area and participate in social activities (e.g. games). Subjects were not allowed in each other’s rooms and social activities were available only in the social area during periods of social access. Drug
administration
Cigarettes containing 0% (w/w; placebo) or 1.84% (w/w) Ag-tetra-hydrocannabinol (THC), supplied by The National Institute on Drug Abuse, were smoked using a uniform puff procedure cued by stimulus lights located in each private room and in the main social room. This procedure, which has been used in previous research in this laboratory, produces reliable drug effects [14,15]. Onset of the first light signalled that subjects should light the cigarette with minimum inhalation, and then wait for 30 s. A series of four lights signalled a 5-s inhalation followed by a 10-s breath hold, an exhalation, and a 45-s rest. This procedure was repeated for five inhalat.ions, and in most cases resulted in pyrolysis of the entire cigarette. Subjects smoked placebo or active marijuana cigarettes in their individual rooms at 1000 and 1525, and together in the social area at 1925 and 2200. The social interaction data included in the present analyses were collected according to the following schedule. In Experiments 1 and 2 (15 days duration), subjects smoked active marijuana cigarettes on days 7 through 9 and placebo cigarettes on days 4-6 and 13-15. In experiments 3 and 4 (18 days duration), subjects smoked active marijuana cigarettes on days 14 and 15 and placebo cigarettes on days 16 through 18. During the intervening days a contingency requirement on private activities was in effect. Descriptive
statistics
A social interaction was scored whenever two or more subjects in the social area engaged in a vocal exchange. A coaction was scored whenever two or more subjects were in the social area in the absence of verbal exchanges. Daily total social interaction times and daily total coaction times were recorded for each subject individually in each experiment. In addition, daily total social interaction times and daily total coaction times were recorded for all possible pairs of subjects (i.e. dyads) across all experiments (e.g. Sl with S2, Sl with S3, S2 with S3 for each of the 4 separate experiments) and for each group of 3 subjects (i.e. triads) in the 4 experiments. RESULTS
All subjects readily adapted to living in the residential laboratory. Duration and frequency of social interactions and coactions stabilized rapidly during the initial non-smoking and placebo conditions (less than 10% variation from day to day). The mean total daily social interaction time averaged across all 12 subjects was 146.1 f 31.0 min ( + S.E.M.) under placebo
90
conditions. This mean daily social interaction time increased significantly by nearly 60 min to 203.5 + 36.4 min during smoked active marijuana periods [paired t(l1) = 3.54, P < 0.0051. Dyadic and triadic interaction times, averaged across groups, showed consistent increases under conditions of active marijuana smoking as compared to placebo baselines, but these increases were not statistically significant. Coactions occurred infrequently, with no subject having a total coaction time greater than 10 min during placebo administration or greater than 17 min during active marijuana administration. Figure 1 compares the mean total daily social interaction times under placebo and active marijuana conditions for all subjects individually and for all dyads and triads across the 4 experiments. In the three experiments (i.e. 1, 3 and 4) in which moderate to high social interaction levels were observed, 8 of 9 individual subjects showed an increase in mean total daily social interaction time during active marijuana smoking periods as compared to pla-
EXPERIMENT 2
EXPERIMENT 1 ml 350
1
2
3
1-2
1 3
2-3
1
I-2-3
GROUP
SUBJECT
2
3
1-2
SUBJECT
EXPERIMENT 3
1-3
2-3
I-2-3
GROUP
, EXPERIMENT 4
“. 1
2 SUBJECT
3
1-2
1-3
2-3
GROUP
1-2
3
1
2 SUBJECT
2
12
1-3
2 3
1-2-3
GROUP
Fig. 1. Upper Left Panel: the left portion of the panel contains the mean total daily social interaction time for each subject following placebo (open bars) and active marijuana (hatched bars) administration in Experiment 1. The right portion of the panel contains the mean daily social interaction time for each dyad and the triad following placebo (open bars) and active marijuana (hatched bars) administration for Experiment 1. Errors bars indicate S.E.M. Upper Right Panel: results presented similarly for Experiment 2. Lower left Panel: results presented similarly for Experiment 3. Lower Right Panel: results presented similarly for Experiment 4.
91
cebo social interaction time levels. In contrast, the subjects in Experiment 2, characterized by extremely low levels of social interaction, showed negligible effects of drug administration on social interaction time. The significant mean increase in total interaction time did not predict changes in dyadic or triadic interaction times. These changes were more variable and not statistically significant. In Experiment 1, for example, the observed increases in social interaction time under active marijuana conditions were accounted for completely by increases in dyadic social interaction times, with triadic social interaction time decreasing under drug conditions. In contrast, the observed increases in social interaction time under active marijuana conditions during Experiment 3 were accounted for almost completely by increases in triadic social interaction time. In Experiment 4, the observed increases in social interaction time under active marijuana conditions were accounted for by increases in both dyadic and triadic social interaction times, although one dyad (2-3, Expt. 4) showed a decrease in social interaction time under active marijuana conditions. Finally, in Experiment 2, which was characterized by minimal social interaction under placebo conditions, smoking active marijuana had no effect on social interaction time for any subject. DISCUSSION
The results of this experiment show clearly that the effects of smoked marijuana on social interaction were dependent upon the levels of social interaction that occurred under placebo conditions. Although total daily social interaction time averaged across all groups and individuals in four experiments increased significantly under smoked marijuana conditions compared to placebo, such drug effects were a function of the levels of social interaction observed under placebo conditions. Smoking active marijuana had no effect on social interaction in any of the 3 subjects in Experiment 2 who had extremely low baseline levels of social interaction. In contrast, eight of the nine subjects in Experiments 1, 3 and 4 with moderate to high baseline levels of social interaction showed an increase in social interaction time during active marijuana smoking periods compared to placebo periods. These increases in social interaction are consistent with the results of previously reported marijuana studies [1,6,7,9] and as well, suggest that baseline amounts of social interaction modulate drug effects on social interaction [2,3,10,11]. The results of these experiments also show that smoked marijuana can affect social interaction in varying ways within different groups of individuals. In one group (i.e. Expt. l), an increase in dyadic interaction times across all pairs of subjects accompanied by a marked decrease in triadic interaction time occurred after smoked active marijuana. In a second group (i.e. Expt. 3), triadic interaction time increased markedly under drug conditions with little or no change in dyadic interaction time. In a third group
92
(i.e. Expt. 4), both dyadic and triadic interaction times increased under marijuana with the exception that one of the dyads showed a decrease in social interaction time during drug periods. Previous reports [3,8] have indicated that smoked marijuana increases the amount of time individuals spend in social settings participating in identical activities without verbal interaction. The reported increases in such coaction (as compared to verbally mediated social interaction effects) under conditions of active marijuana smoking were not confirmed in the present study. There were, of course, important differences between the previously reported studies and the present experiment in the range of activities available to the participants during periods of social access. The absence of television or group music options in the social area of the residential environment could well account for the low coaction time under both placebo and active marijuana conditions. The absence of significant increases in coaction during periods of active marijuana smoking supports the generality of the finding that marijuana has no effect on social interactions in those participants with low social activity levels under placebo conditions. The findings of the present study provide another confirmation of the fact that the effects of a drug are influenced by the baseline rate of the dependent measure [e.g. 161. Methodologically, however, these results extend such data to human social interaction and demonstrate the utility of an analysis based upon continuous monitoring and recording of behavior in long-term residential experiments. ACKNOWLEDGMENTS
This research was supported by Grant DA-3476 from The National Institute on Drug Abuse (M.W. Fischman, P.I.). J.V. Brady is a recipient of Research Scientist Award DA-00018 from The National Institute on Drug Abuse and R.W. Foltin was supported by 5T32MH15330 from The National Institute on Mental Health. REFERENCES 1 2 3 4 5 6 7 8 9 10 11 12
MI. Soueif, Bull. Narc., 19 (1967) 1. T.F. Babor et al., Int. J. Addict., 13 (1978a) 89. T.F. Babor et al., Int. J. Addict., 13 (1978b) 947. C.S. Adamec and R.O. Pihl, Psychiatry Women Q., 2 (1978) 334. D. Janowsky et al., Arch. Gen. Psychiatry, 36 (1979) 781. A. Georgotas and P. Zeidenberg, Comp. Psychiatry, 20 (1979) 427. C.G. Miles et al., Acta Pharmacol. et Toxicol., 34 (1974) 1. Mayor’s Report, The Marihuana Problem in the City of New York, 1944. E. Goode, Sot. Probl., 17 (1969) 48. L. Haines and W. Green, Br. J. Addict., 65 (1970) 347. J. Orcutt and D. Biggs, Int. J. Addict., 10 (1975) 229. J.V. Brady et al., Man-Environment Interactions: Evaluations and applications. Ecology, 1974, p. 187.
7: Social
93 13 14 15 16
D. Bernstein and C. Livingston, Behav. Res. Meth. Instr., 14 (1982) 231. R.W. Foltin et al., Problems of Drug Dependence, 1985 (1986a) 355. R.W. Foltin et al., Pharmacol. Biochem. Behav., 25 (1986b) 577. R.T. Kelleher and W.H. Morse, Ergeb. Physiol. Biol. Chem. Exp. Pharmacol.,
60 (1968)
1
and Alcohol
Dependence,
87
20 (1987) 87-93
Elsevier Scientific Publishers Ireland Ltd.
EFFECTS OF SMOKED SMALL GROUPS
R.W. FOLTIN*, Division Hopkins IUS. A.)
J.V. BRADY,
MARIJUANA
M.W. FISCHMAN,
ON SOCIAL
C.S. EMURIAN
INTERACTION
IN
and J. DOMINITZ
of Behavioral Biology, Department of Psychiatry and Behavioral Sciences, University School of Medicine, 600 N. Wolfe Street, Houck E-2, Baltimore.
The Johns MD 21205
(Received January lst, 1987)
SUMMARY
Twelve adult male research volunteers, in four groups of three subjects each, resided continuously in a residential laboratory for up to 18 days. Subject’s behaviors, including social interaction, were continuously recorded. During the first part of the day (lOOO-1600), subjects remained in their private rooms doing work activities, and during the remainder of the day (1600-2345), they had the option to socialize with the other subjects. Four cigarettes containing active marijuana (1.84%, A9-tetrahydrocannabinol (A9 (THC)), w/w) or placebo were smoked daily: one each prior to the work and social access period, and two during the social access period. When the results were averaged across all groups and individuals, active marijuana significantly increased total daily social interaction time. However, drug effects were a function of the baseline amount of social interaction. The results of these experiments also showed that the pattern of increases in social interaction following smoked active marijuana varied within different groups of individuals. Key words: Marijuana -
Social interaction -
Humans
INTRODUCTION
The effects of smoked marijuana on social interaction have been pre viously described in both survey [e.g. l] and experimental studies [e.g. 2,3]. While survey studies report an increase in self-orientation [4] and a decrease in interpersonal skills [5], residential experiments have described both transient increases in social interaction [6,7], as well as decreases in interaction
*To whom correspondence should be addressed. 0376-87161871$03.50 0 Elsetier Scientific Pub&hers Ireland Ltd. Printed and Published in Ireland.
accompanied by increases in coaction, i.e. independent participation in identical activities without verbal exchanges [3,8]. Although marijuana smoking frequently occurs in a group [9], effects on social interaction have been shown to vary as a function of drug state [lo], gender [ll] and amount of prior drug use [2,3]. The present report describes an experimental analysis of the effects of smoked marijuana on social interaction compared to the levels of social interaction that occurred in the absence of drug. METHOD
Subjects Groups of three healthy adult male research volunteers ranging in age from 22 to 38 years participated in four separate experiments. All 12 subjects had histories of marijuana use ranging from 2-3 cigarettes/week to 2 -3 cigarettes/day. Subjects received complete medical and psychiatric examinations, signed consent forms detailing all aspects of the research, and were paid for participation. Laboratory Experiments were conducted in a residential laboratory designed for continuous observation of human behavior over extended periods of time. The facility consisted of six rooms connected by a common corridor. Three identical private rooms were similar to small efficiency apartments with kitchen, bathroom, desks, and sleeping areas. A common social area had a recreation room, an exercise room and a bathroom. The recreation room contained kitchen facilities, lounge furniture, games, puzzles and a videogame system. The exercise room contained exercise equipment and laundry facilities. A detailed description of the laboratory has been published elsewhere [12]. Video and audio equipment throughout the residential facility were interfaced with a monitoring system in an adjacent control room. Subjects were continuously observed except in private dressing and toileting rooms. A computerized observation program [13] provided for continuous recording of each subject’s behavior in categorical form. Subjects were instructed that communication between them and the experimenters via a networked computer system was to be kept to a minimum. No other outside communication was permitted. Standard day The day was divided into three periods: a private work period, a task performance period, and a period of social access. Subjects were awakened at 0900, given an opportunity for breakfast, and had a work period from approximately 1000 to 1500. A one-hour performance assessment’was then completed and followed by a social access period which lasted from approximately 1600 to 2400. During the social access period, each subject
89
was permitted to remain in his own private room engaging in private recreational activities (e.g. reading) or to enter the social area and participate in social activities (e.g. games). Subjects were not allowed in each other’s rooms and social activities were available only in the social area during periods of social access. Drug
administration
Cigarettes containing 0% (w/w; placebo) or 1.84% (w/w) Ag-tetra-hydrocannabinol (THC), supplied by The National Institute on Drug Abuse, were smoked using a uniform puff procedure cued by stimulus lights located in each private room and in the main social room. This procedure, which has been used in previous research in this laboratory, produces reliable drug effects [14,15]. Onset of the first light signalled that subjects should light the cigarette with minimum inhalation, and then wait for 30 s. A series of four lights signalled a 5-s inhalation followed by a 10-s breath hold, an exhalation, and a 45-s rest. This procedure was repeated for five inhalat.ions, and in most cases resulted in pyrolysis of the entire cigarette. Subjects smoked placebo or active marijuana cigarettes in their individual rooms at 1000 and 1525, and together in the social area at 1925 and 2200. The social interaction data included in the present analyses were collected according to the following schedule. In Experiments 1 and 2 (15 days duration), subjects smoked active marijuana cigarettes on days 7 through 9 and placebo cigarettes on days 4-6 and 13-15. In experiments 3 and 4 (18 days duration), subjects smoked active marijuana cigarettes on days 14 and 15 and placebo cigarettes on days 16 through 18. During the intervening days a contingency requirement on private activities was in effect. Descriptive
statistics
A social interaction was scored whenever two or more subjects in the social area engaged in a vocal exchange. A coaction was scored whenever two or more subjects were in the social area in the absence of verbal exchanges. Daily total social interaction times and daily total coaction times were recorded for each subject individually in each experiment. In addition, daily total social interaction times and daily total coaction times were recorded for all possible pairs of subjects (i.e. dyads) across all experiments (e.g. Sl with S2, Sl with S3, S2 with S3 for each of the 4 separate experiments) and for each group of 3 subjects (i.e. triads) in the 4 experiments. RESULTS
All subjects readily adapted to living in the residential laboratory. Duration and frequency of social interactions and coactions stabilized rapidly during the initial non-smoking and placebo conditions (less than 10% variation from day to day). The mean total daily social interaction time averaged across all 12 subjects was 146.1 f 31.0 min ( + S.E.M.) under placebo
90
conditions. This mean daily social interaction time increased significantly by nearly 60 min to 203.5 + 36.4 min during smoked active marijuana periods [paired t(l1) = 3.54, P < 0.0051. Dyadic and triadic interaction times, averaged across groups, showed consistent increases under conditions of active marijuana smoking as compared to placebo baselines, but these increases were not statistically significant. Coactions occurred infrequently, with no subject having a total coaction time greater than 10 min during placebo administration or greater than 17 min during active marijuana administration. Figure 1 compares the mean total daily social interaction times under placebo and active marijuana conditions for all subjects individually and for all dyads and triads across the 4 experiments. In the three experiments (i.e. 1, 3 and 4) in which moderate to high social interaction levels were observed, 8 of 9 individual subjects showed an increase in mean total daily social interaction time during active marijuana smoking periods as compared to pla-
EXPERIMENT 2
EXPERIMENT 1 ml 350
1
2
3
1-2
1 3
2-3
1
I-2-3
GROUP
SUBJECT
2
3
1-2
SUBJECT
EXPERIMENT 3
1-3
2-3
I-2-3
GROUP
, EXPERIMENT 4
“. 1
2 SUBJECT
3
1-2
1-3
2-3
GROUP
1-2
3
1
2 SUBJECT
2
12
1-3
2 3
1-2-3
GROUP
Fig. 1. Upper Left Panel: the left portion of the panel contains the mean total daily social interaction time for each subject following placebo (open bars) and active marijuana (hatched bars) administration in Experiment 1. The right portion of the panel contains the mean daily social interaction time for each dyad and the triad following placebo (open bars) and active marijuana (hatched bars) administration for Experiment 1. Errors bars indicate S.E.M. Upper Right Panel: results presented similarly for Experiment 2. Lower left Panel: results presented similarly for Experiment 3. Lower Right Panel: results presented similarly for Experiment 4.
91
cebo social interaction time levels. In contrast, the subjects in Experiment 2, characterized by extremely low levels of social interaction, showed negligible effects of drug administration on social interaction time. The significant mean increase in total interaction time did not predict changes in dyadic or triadic interaction times. These changes were more variable and not statistically significant. In Experiment 1, for example, the observed increases in social interaction time under active marijuana conditions were accounted for completely by increases in dyadic social interaction times, with triadic social interaction time decreasing under drug conditions. In contrast, the observed increases in social interaction time under active marijuana conditions during Experiment 3 were accounted for almost completely by increases in triadic social interaction time. In Experiment 4, the observed increases in social interaction time under active marijuana conditions were accounted for by increases in both dyadic and triadic social interaction times, although one dyad (2-3, Expt. 4) showed a decrease in social interaction time under active marijuana conditions. Finally, in Experiment 2, which was characterized by minimal social interaction under placebo conditions, smoking active marijuana had no effect on social interaction time for any subject. DISCUSSION
The results of this experiment show clearly that the effects of smoked marijuana on social interaction were dependent upon the levels of social interaction that occurred under placebo conditions. Although total daily social interaction time averaged across all groups and individuals in four experiments increased significantly under smoked marijuana conditions compared to placebo, such drug effects were a function of the levels of social interaction observed under placebo conditions. Smoking active marijuana had no effect on social interaction in any of the 3 subjects in Experiment 2 who had extremely low baseline levels of social interaction. In contrast, eight of the nine subjects in Experiments 1, 3 and 4 with moderate to high baseline levels of social interaction showed an increase in social interaction time during active marijuana smoking periods compared to placebo periods. These increases in social interaction are consistent with the results of previously reported marijuana studies [1,6,7,9] and as well, suggest that baseline amounts of social interaction modulate drug effects on social interaction [2,3,10,11]. The results of these experiments also show that smoked marijuana can affect social interaction in varying ways within different groups of individuals. In one group (i.e. Expt. l), an increase in dyadic interaction times across all pairs of subjects accompanied by a marked decrease in triadic interaction time occurred after smoked active marijuana. In a second group (i.e. Expt. 3), triadic interaction time increased markedly under drug conditions with little or no change in dyadic interaction time. In a third group
92
(i.e. Expt. 4), both dyadic and triadic interaction times increased under marijuana with the exception that one of the dyads showed a decrease in social interaction time during drug periods. Previous reports [3,8] have indicated that smoked marijuana increases the amount of time individuals spend in social settings participating in identical activities without verbal interaction. The reported increases in such coaction (as compared to verbally mediated social interaction effects) under conditions of active marijuana smoking were not confirmed in the present study. There were, of course, important differences between the previously reported studies and the present experiment in the range of activities available to the participants during periods of social access. The absence of television or group music options in the social area of the residential environment could well account for the low coaction time under both placebo and active marijuana conditions. The absence of significant increases in coaction during periods of active marijuana smoking supports the generality of the finding that marijuana has no effect on social interactions in those participants with low social activity levels under placebo conditions. The findings of the present study provide another confirmation of the fact that the effects of a drug are influenced by the baseline rate of the dependent measure [e.g. 161. Methodologically, however, these results extend such data to human social interaction and demonstrate the utility of an analysis based upon continuous monitoring and recording of behavior in long-term residential experiments. ACKNOWLEDGMENTS
This research was supported by Grant DA-3476 from The National Institute on Drug Abuse (M.W. Fischman, P.I.). J.V. Brady is a recipient of Research Scientist Award DA-00018 from The National Institute on Drug Abuse and R.W. Foltin was supported by 5T32MH15330 from The National Institute on Mental Health. REFERENCES 1 2 3 4 5 6 7 8 9 10 11 12
MI. Soueif, Bull. Narc., 19 (1967) 1. T.F. Babor et al., Int. J. Addict., 13 (1978a) 89. T.F. Babor et al., Int. J. Addict., 13 (1978b) 947. C.S. Adamec and R.O. Pihl, Psychiatry Women Q., 2 (1978) 334. D. Janowsky et al., Arch. Gen. Psychiatry, 36 (1979) 781. A. Georgotas and P. Zeidenberg, Comp. Psychiatry, 20 (1979) 427. C.G. Miles et al., Acta Pharmacol. et Toxicol., 34 (1974) 1. Mayor’s Report, The Marihuana Problem in the City of New York, 1944. E. Goode, Sot. Probl., 17 (1969) 48. L. Haines and W. Green, Br. J. Addict., 65 (1970) 347. J. Orcutt and D. Biggs, Int. J. Addict., 10 (1975) 229. J.V. Brady et al., Man-Environment Interactions: Evaluations and applications. Ecology, 1974, p. 187.
7: Social
93 13 14 15 16
D. Bernstein and C. Livingston, Behav. Res. Meth. Instr., 14 (1982) 231. R.W. Foltin et al., Problems of Drug Dependence, 1985 (1986a) 355. R.W. Foltin et al., Pharmacol. Biochem. Behav., 25 (1986b) 577. R.T. Kelleher and W.H. Morse, Ergeb. Physiol. Biol. Chem. Exp. Pharmacol.,
60 (1968)
1