1990, 53, 5-19

JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR

NUMBER 1

(JANUARY)

MOTIVATIONAL EFFECTS OF SMOKED MARIJUANA: BEHAVIORAL CONTINGENCIES AND LOW-PROBABILITY ACTIVITIES RICHARD W. FOLTIN, MARIAN W. FISCHMAN, JOSEPH V. BRADY, DANIEL J. BERNSTEIN, RICHARD M. CAPRIOTTI, MARGARET J. NELLIS, AND THOMAS H. KELLY' THE JOHNS HOPKINS UNIVERSITY SCHOOL OF MEDICINE AND THE UNIVERSITY OF NEBRASKA Six adult male research volunteers, in two groups of 3 subjects each, lived in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system, and subjects' behavior was monitored continuously and recorded. During the first part of each day, subjects remained in private rooms doing planned work activities, and during the remainder of each day, they were allowed to socialize. Two cigarettes containing active marijuana (2.7% A9-THC) or placebo were smoked during the private work period and the period of access to social activities. Three-day contingency conditions requiring subjects to engage in a low-probability work activity (instrumental activity) in order to earn time that could be spent engaging in a high-probability work activity (contingent activity) were programmed during periods of placebo and active-marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low-probability instrumental activity and decreased the time spent engaged in the high-probability contingent activity. During active-marijuana administration, however, the increases in instrumental activity were consistently larger than observed under placebo conditions. The decreases in contingent activity were similar to those seen under placebo conditions. Smoking active marijuana was thus observed to produce increments in instrumental activity under motivational conditions involving contingencies for "work activities." Key words: marijuana, performance, motivation, behavioral regulation, amotivational syndrome, work activity, humans

for the paucity of laboratory research on this issue. First, motivational processes are operationally indistinguishable from the multiple historical and contemporary factors that influence the behavioral interactions by which they are identified and defined (Mendelson, Kuehnle, Greenberg, & Mello, 1976). Second, what constitutes "heavy" marijuana use has been difficult to determine in the experimental analysis of marijuana's motivational effects. Studies assessing the behavioral effects of smoked marijuana have, for the most part, relied on monetary contingencies for the mainI D. J. Bernstein and M. J. Nellis are at the University tenance of performance. Under such condiof Nebraska; the other authors are at the Johns Hopkins tions, drug-induced motivational changes have University School of Medicine. This research was supported by Grant No. DA-03476 not been readily determined despite the refrom the National Institute on Drug Abuse. Joseph V. ported intoxicating effects of the drug (Mello Brady is the recipient of Research Scientist Award KO5 & Mendelson, 1985; Mendelson et al., 1976; DA-00018 from the National Institute on Drug Abuse. the use of money The assistance of Cleeve Emurian, Jerry Locklee, Jeffrey Miles et al., 1974). Although in these studies approximates workplace setJ. Rachlinski, Andrea J. Rose, and Michelle Woodland is gratefully acknowledged. A preliminary report of some tings, other behavioral contingencies may proof these findings was made at the 1985 meeting of the vide a more sensitive baseline from which to Committee on the Problems of Drug Dependence. Address measure marijuana's purported motivational correspondence and reprint requests to Richard W. Foltin, Department of Psychiatry and Behavioral Sciences, The effects. A previously reported study (Foltin et Johns Hopkins University School of Medicine, 600 North al., in press) demonstrated the effects of smoked Wolfe St., Houck E-2, Baltimore, Maryland 21205. marijuana on a performance baseline mainIn a report published almost a century ago, the Indian Hemp Drugs Commission (1893) first described the amotivational effects of "heavy" marijuana use as "lethargy," "apathy," "inactivity," and "loss of goal-directed behavior." Despite recurrent references to this cluster of signs and symptoms, however, as well as the formal designation of an "amotivational syndrome" (McGlothin & West, 1968; Smith, 1968), the experimental literature on marijuana provides sparse documentation of these effects. At least two factors may account

5

RICHARD W. FOLTIN et al. tained without reliance upon explicit monetary located on the desk, and a similar computer contingencies. Individuals were instructed to was located in the main room of the social area. engage in empirically determined low-proba- A detailed description of the laboratory has bility recreational activities in order to gain been published elsewhere (Brady, Bigelow, access to high-probability recreational activi- Emurian, & Williams, 1974). ties. Smoked marijuana attenuated increases Output from a video and audio monitoring in instrumental performances maintained by system terminated in an adjacent control room. contingent access to preferred recreational ac- Subjects were observed continuously except in tivities. The present report extended the anal- private dressing areas and toilet facilities. A ysis of the motivational effects of smoked mar- computerized observation program (Bernstein ijuana to behavioral hierarchies involving & Livingston, 1982) provided the structure for structured work rather than recreational ac- continuous recording of each subject's behavior tivities. Specifically, drug-behavior interac- in categorical form. Communication between tions were examined under conditions in which subjects and experimenters was kept to a minaccess to preferred "work" activities was con- imum and was accomplished using a nettingent upon participation in less preferred worked computer system consisting of the comwork activities. puters in each room of the laboratory and in the main control room. This communication system permitted continuous on-line interacMETHOD tion between subjects and experimenters. To Subjects minimize day-to-day variability as a function Six healthy adult male research volunteers of external events, access to television, radio, ranging in age from 19 to 30 years participated mail, or newspapers was not permitted during in continuous residential experiments lasting the course of the experiments. 15 days. All subjects, recruited via newspaper advertisements, were experienced marijuana Standard Day users who reported smoking from one to 20 The day consisted of two periods: a private marijuana cigarettes per week. Participants, work period and a period of access to social who were paid for participation, passed med- and other recreational activities. Subjects were ical and psychiatric examinations and signed awakened at 9:00 a.m. by presenting a tone a consent form detailing all aspects of the re- until the subject signaled that he was awake. search. Subjects engaged in morning activities (e.g., eating, dressing) until the start of a private Laboratory work period at 10:00 a.m. The private work Subjects, in groups of 3, lived in a residential period lasted until 4:45 p.m. and was followed laboratory designed for continuous observation by a social access period that lasted from 5:00 of human behavior over extended periods. The to 11:45 p.m. Subjects remained in their prifacility consisted of six rooms connected by a vate rooms until 5:00 p.m. The day ended with common corridor and was housed in a wing lights out at midnight. Clocks or watches were of The Johns Hopkins Hospital. Three iden- not permitted, but subjects were told the time tical private rooms were similar to small ef- via computer at each activity transition. ficiency apartments with kitchen, bathroom, During the private period subjects were indesks, and sleeping areas. The common social structed to remain in their private rooms and area had a recreation room, an exercise room, engage in one of four structured tasks. There and a bathroom. The recreation room con- were no constraints on which task was pertained kitchen facilities, lounge furniture, a formed nor on the pattern of switching among variety of games, puzzles, a videogame system, tasks. Subjects could use the toilet facilities or and a video cassette recorder with monitor. eat at any time. If a subject did not perform a The exercise room contained exercise equip- task for 5 consecutive minutes, he was inment and laundry facilities. Two-way cabinets structed via the communication system to rein each room of the laboratory allowed the turn to work with a standard message ("Please transfer of items between subjects and exper- select a work task."). Finally, a single optional imenters without physical contact. Each pri- 30-min "lunch" break during which the subvate room had an Apple IIe® microcomputer ject could stop engaging in work activities was

MOTIVATIONAL EFFECTS OF MARIJUANA

available at the subject's request during the work period. A computer-controlled vigilance task, a computer-controlled digit-symbol-substitution task (DSST; McLeod, Griffiths, Bigelow, & Yingling, 1982), a manual nonsense-word-alphabetizing task, and a manual bingo-chip-sorting task served as the work options. These activities were called work activities; unpublished observations indicate that in the absence of instructions, subjects will not voluntarily engage in these activities. Subjects initiated a computerized task by pressing the appropriate key on the computer, whereas the manual tasks were initiated by opening the appropriately labeled drawer storing the items for that activity. At the start of the vigilance task, the number 1 " was displayed in the middle of the subject's computer screen, and this number incremented every 1.25 s. On 90% of the occasions the number increased by one, and on the other occasions, the number increased by two. The subjects were instructed to signal whenever the number on the screen increased by two by pressing the space bar. Correct responses resulted in a "HIT" message appearing on the lower left portion of the screen, incorrect responses resulted in a tone and a "FALSE ALARM" message appearing on the lower left portion of the screen, and when a subject did not signal an increment by two within 1.25 s of the signal presentation, a tone sounded and a "MISS" message appeared on the lower left portion of the screen. The digit-symbol-substitution task (McLeod et al., 1982) consisted of nine 3 x 3 arrays of asterisks and dashes along the top of the screen. Each row of each array contained two dashes and one asterisk. Above each array was a number (1 through 9) that identified that array of symbols. Each array was laid out to correspond with the ninenumber keys on a numeric key pad connected to the computer. A number appeared in the middle of the screen, and subjects were required to look at the corresponding array and press the three keys on the numeric key pad corresponding to each of the three asterisks (one per row). When button presses matched the correct asterisk pattern, a new number appeared in the middle of the screen, and when button presses did not match the asterisk pattern, the computer sounded a tone three times in rapid succession before presenting the number of the next array to be entered. The rate

at which new numbers appeared, signaling a new trial, was dependent on each subject's rate of responding. Each time the subjects initiated this activity nine new arrays of dashes and stars appeared at the top of the screen. The word-sorting task consisted of alphabetizing a list of 300 seven-character nonsense words. The words were presented on one continuous sheet of printer paper, and subjects were required to cut them out before alphabetizing them. The bingo-chip-sorting task consisted of sorting, by type and color, a box of approximately 7,360 bingo chips. There were no restrictions on how much time was to be spent on each task, on how much of each task a subject had to perform when engaging in that task, or on the number of times a subject could start and stop each activity. No programmed contingencies were associated with task performance. The following written instructions regarding the work period were included in the protocol provided to the subjects prior to the start of the study: There will be one 63/4 hour work period each day beinning at 10:00. One half hour of the work period may be used as a break. You may take the break whenever you wish, and you are not required to take the break at all if you do not wish to do so. During break you may eat and relax, but you may not engage in work tasks (e.g., VIGI) or recreation activities (e.g., reading). You may begin the optional break anytime after the work period has started. The 30-minute break begins when you call the control room and indicate that you are starting your break. The control room will signal the end of the break with a message on the computer. Please return immediately to one of the four work tasks. During the work period you must engage in one of the four designated work tasks. You may do only one task at a time, but you may spend as much time as you wish on a particular task and switch back and forth between tasks as often as you like. When you are working on a task, keep all other task materials in their appropriate drawers. When you stop doing a task, return materials appropriate to that task to its drawer.

Experimental Procedures The experimental design included both baseline and contingency conditions, with placebo and active-marijuana cigarette smoking

RICHARD W. FOLTIN et al.

superimposed on these conditions. The order of exposure to placebo and active marijuana was reversed between groups. Baseline activity levels following placebo and active-marijuana administration were determined on Days 2 through 7. Three-day contingency conditions were tested under placebo conditions on Days 8 through 10 in Group 1 and on Days 11 through 13 in Group 2. Three-day contingency conditions were tested under active-marijuana conditions on Days 11 through 13 in Group 1 and on Days 8 through 10 in Group 2. Finally, baseline activity levels following placebo were determined on Days 14 and 15 in both groups. During baseline conditions, subjects engaged in work tasks in the absence of restrictions. Each subject's behavior was monitored continuously using the computerized observation system, and time spent on each work task was recorded for each subject. Time-based behavioral hierarchies measured during the 3 baseline days were determined separately under placebo and active-marijuana conditions. Although the use of separate placebo and activedrug baselines provided different activities between placebo and active marijuana for some subjects, it controlled for active-drug-induced changes in distribution of activities. The resultant behavioral hierarchies determined the contingency conditions under which subjects had to spend time doing the most consistent low (nonzero) probability work task in their hierarchy in order to earn time to engage in their most consistent high-probability work task. A contingency relationship was determined for each subject using the responseprobability procedure of Premack (1965). The contingency specified that subjects engage in four times the amount of time spent in their lowest probability work task during baseline conditions (the instrumental activity) in order to maintain access to baseline levels of their highest probability work task (the contingent activity). For example, if during baseline conditions a subject spent 40 min performing the vigilance task and 240 min sorting disks, the subject would be required to spend 160 min performing the vigilance task to maintain the opportunity to spend 240 min sorting disks during contingency conditions (i.e., every 1 min of vigilance performance earned 1.5 min of disk-sorting time). During contingency periods, lack of avail-

ability of the contingent activity was indicated by illumination of a red light in the subject's room. If a subject started to engage in the contingent activity while the restriction light was illuminated, he received on his computer a standard "Restriction is on. Credit time is used up." message. Time earned for the contingent activity accumulated continuously as time was spent performing the instrumental activity. As long as there was time accumulated for the contingent activity, each subject could use it as he chose. Subjects could also choose to engage in intermediate hierarchical activities that had no effect on the time earned for the contingent activity. Time earned was carried over each day for the entire contingency period. Thus, subjects could accrue substantial amounts of time for the contingent activity in 1 day that could be used on subsequent days. Each morning subjects were given written instructions describing the contingency in effect during the private period. No information was provided regarding the number of days that a contingency period was in effect or the amount of time accumulated for the contingent activity. The following written instructions regarding contingency restrictions were included in the protocol: On some days during the experiment a work activity will be restricted. The presence of the restriction will be indicated by the red signal light. When the restriction is on, i.e., the light is on, the restricted activity is not available. The restriction itself will not be constant. You can make the restriction go off if you wish to by devoting time to another designated activity. The more time you devote to the designated activity, the longer the restriction will stay off and the restricted activity will remain available. You need not do the restricted activity as soon as the restriction goes off; the time you obtain as a result of doing the other designated activity will not disappear. It will only be used when you actually engage in the restricted activity. You need not use up your accumulated time in order to accumulate additional time for the restricted activity. The system works much like a bank account, except that you will not know the exact balance. Each morning of the experiment you will be notified via a card in your mailbox if a restriction is in effect. If a restriction is in effect that day, you will be told which activity is restricted and which designated activity earns time to engage in the restricted activity. Time earned one day can be

MOTIVATIONAL EFFECTS OF MARIJUANA used the next day, and the bank account will last until the restriction period ends. Please note that you are not required to engage in either the restricted activity or the designated activity but if you want to do so, you know how they will be related to each other.

Subjects received the following instructions each day of a contingency period on an index card passed through the mail slot of their private rooms: A work restriction is in effect today. Your restricted activity is C-. Time spent on I earns time for C-. The more time you spend on I_, the more time you'll have available for C-. You need not engage in either A_ or C-, but if you wish to do so, you know how to make C_ available.

(I was the instrumental activity and C was the contingent activity.) After the first 3-day contingency condition was completed, subjects received the following message in their mail slot along with the daily contingency instructions: "This is a new restriction. Credit has been re-set to zero." Drug Administration One-gram marijuana cigarettes with 0% (placebo) or 2.7% (1.3% for 1 subject) A9-THC (w/w) concentrations (provided by the National Institute on Drug Abuse) were smoked using a uniform puff procedure cued by stimulus lights located in each room. Onset of the first light signaled the subjects to light the cigarette with minimal inhalation and then wait 30 s. A series of lights signaled a 5-s inhalation followed by a 10-s hold, exhalation, and a 45-s rest. This procedure was repeated for five inhalations, which usually resulted in pyrolysis of the entire cigarette. This paced smoking procedure has been previously described in studies of marijuana effects on heart rate (Foltin, Fischman, Pedroso, & Pearlson, 1987), social behavior (Foltin, Brady, Fischman, Emurian, & Dominitz, 1987; Foltin & Fischman, 1988), and food intake (Foltin, Brady, & Fischman, 1986; Foltin, Fischman, & Byrne, 1988). Cigarettes containing placebo or active marijuana were smoked by the subjects alone in their private rooms prior to the start of the private activity period and at 1:15 p.m. Subject 3 reported unpleasant effects following the first active-marijuana cigarette, and he smoked cig-

9

arettes containing only 1.3% A9-THC (w/w) for the remainder of the study. Previous studies using multiple daily dosing under similar conditions (Foltin et al., 1986, 1988) have indicated that, although THC may accumulate within days, there were no carryover effects from day to day. The written instructions for marijuana smoking were: When it is time to smoke, in your private room you will find a cigarette in a box in your G.C. Drawer. Please sit with your side to the desk while you smoke in your private room. However, you must be sure to watch the lights closely. No tone accompanies their illumination, so you must be attentive. Do not light the cigarette until you are signaled to do so. You will be paced through the cigarette by the illumination of the yellow and white signal lights. That is, you will be signaled when to inhale, when to stop inhaling, and when to exhale. Initially only

the white light will be illuminated, indicating that you have thirty seconds to light up your cigarette with as small an inhalation as possible. The puff cycle takes 60 seconds and is signaled as follows:

Light illuminated white/yellow

Duration 5s

white yellow

5s 10 s

none

40 s

Activity prepare to inhale, put cigarette in mouth inhale stop inhaling and hold smoke in lungs exhale, relax

This procedure will continue for as long as five consecutive minutes resulting in as many as five inhalations. After the last inhalation, both white and yellow lights will be flashed as a signal to put the cigarette out. It is imperative that you take each and every puff this way. If you feel that you are getting too stoned, you may stop puffing and raise your left hand to indicate that you are ending this marijuana administration. You are not required to complete the entire sequence of puffs. If your cigarette burns down to the plastic holder, put the

cigarette out in the ashtray and leave it in the ashtray until both white and yellow signal lights are flashed. When the white and yellow signal lights are flashed return the holder and the remaining end of the cigarette to the box and place it in the G.C. Drawer.

RICHARD W. FOLTIN et al. General Instructions to the Subjects The following instructions, which specified the consequences for violating the protocol, were included at the end of the instruction manual: Please adopt a deliberate approach to solving errors or encountering unforeseen circumstances. If events go awry, don't panic or become overly disturbed. Consult your protocol. Simply make the best decision you can, and continue with the program. Of course, you are expected to follow the instructions as carefully as you can, and the experiment will be terminated if any subject conspicuously and flagrantly violates the procedure. Further, you are free to terminate your participation in the experiment at any time, and the emergency exit doors are always available for this purpose.

RESULTS All subjects rapidly adapted to the laboratory, and, although all four of the work tasks were repetitious activities, subjects spent unequal amounts of time working on them. Subjects were engaged continuously in work activities, and it was rarely necessary to instruct subjects to continue working during the work period (i.e., less than once per subject). Figures 1 and 2 present the daily amount of time each subject spent engaging in the instrumental and contingent activities under baseline and contingency conditions. The Appendix presents these data for all of the activities. The instrumental activity for Subjects 2, 3, and 4 varied between placebo and active marijuana conditions, whereas for the other 3 subjects the same instrumental activity was used under both drug conditions. The contingent activity in 5 subjects was the same under both drug conditions, whereas for Subject 2 the contingent activity varied between active and placebo marijuana conditions. In those cases in which instrumental or contingent activities differed across drug conditions, only data for the activity functioning as the instrumental or contingent activity are presented. Although variable from day to day, under baseline conditions all 6 subjects spent between 0 and 150 min of the available time engaging in the work task that served as the instrumental activity during contingency periods, while spending 100 to 350 min of the available time engaging in the work task that

served as the contingent activity during the contingency periods. The instrumental activity was a computer task (DSST or vigilance), and the contingent activity was a manual task (work or disk sorting) for 4 of the 6 subjects (Subjects 2, 3, 4, and 5). For Subject 6 both instrumental and contingent activities were manual tasks, and for Subject 1 the instrumental activity was a manual task and the contingent activity was a computer task. During contingency periods (when the data are combined across all 3 days) all 6 subjects showed greater increases above the 3-day baseline in instrumental activity under active-marijuana conditions than under placebo conditions. For Subjects 1, 3, 4, and 5, these differences between placebo and active marijuana are clearly seen by the greater absolute amount of time spent in the instrumental activity under active marijuana conditions, even though relative baseline levels were similar between drug conditions. For Subjects 2 and 6, the greater increase in instrumental activity is evidenced by similar amounts of instrumental activity under both placebo and active-marijuana contingency conditions but relatively lower amounts of baseline instrumental activity under active marijuana compared to placebo. In contrast to the difference between drug conditions in increases in instrumental activity, there was no consistent difference between placebo and active marijuana with respect to changes in contingent activity. Subjects 2 and 3 had consistently greater decreases in contingent activity under placebo conditions, whereas the remaining subjects had similar decreases in contingent activity under both drug conditions. Table 1 presents the total frequency and mean duration of bouts of instrumental and contingent activity during the 3-day baseline and contingency periods as a function of drug administration. Implementation of the behavioral contingency reliably increased the frequency of instrumental activity bouts (with the exception of Subject 1 under placebo conditions). The increase in instrumental activity frequency was greater under active-marijuana conditions for Subjects 1, 3, 4, and 6. The behavioral contingency also reliably decreased the frequency of contingent activity bouts. This decrease in contingent activity frequency was

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Fig. 1. The amount of time that each subject in Group 1 spent engaging in the instrumental and contingent activities as a function of experimental day. Smoking placebo and active marijuana was superimposed on baseline and contingency periods. During baseline periods all activities were available in the absence of restraints, whereas during contingency periods subjects were required to engage in the instrumental activity to gain access to the contingent

Fig. 2. The amount of time that each subject in Group 2 spent engaging in the instrumental and contingent activities as a function of experimental day. Smoking placebo and active marijuana was superimposed on baseline and contingency periods. During baseline periods all activities were available in the absence of restraints, whereas during contingency periods subjects were required to engage in the instrumental activity to gain access to the contingent

activity.

activity.

greater under placebo conditions for Subjects 1, 2, and 3. In contrast to the consistent changes

3-day baseline and contingency periods as a function of drug administration. Switching from the instrumental activity to the instrumental activity occurred when subjects paused (off task for a minimum of 5 s) in their performance and resumed that activity, and switching from the instrumental activity to the contingent activity occurred when subjects terminated the instrumental activity and then initiated the contingent activity. The probability

in frequency during contingency conditions, there was no consistent pattern of changes in mean duration of each activity bout as a function of either contingency or drug conditions (bottom portion of Table 1). Table 2 presents the probability of continuing the instrumental activity after a pause or switching to the contingent activity during the

RICHARD W. FOLTIN et al. Table 1 Frequency and mean duration of instrumental and contingent activities during baseline (Base) and contingency (Cntgy) conditions as a function of drug administration.

Placebo Subject

Instrumental Base Cntgy

1 2 3 4 5 6 M SEM

15 8 13 7 7 59 18.2 9.1

9 78 25 13 28 168 53.5 27.4

1 2 3 4 5 6 M SEM

9.6 11.2 7.1 12.1 13.9 5.9 10.0 1.4

11.4 3.8 6.4 14.8 9.2 4.6 8.4 1.9

Marijuana

Contingent Base Cntgy Frequency 26 4 91 0 33 0 47 15 55 26 112 44 60.7 14.8 15.2 7.8 Mean duration (min) 14.5 15.4 5.7 0.0 17.1 0.0 11.1 11.9 8.7 11.3 5.6 5.1 10.4 7.3 2.1 2.9

of returning to instrumental activity after pausing increased in 4 subjects during placebo contingency periods and increased in 5 subjects during active-marijuana contingency periods. This follows from the increase in frequency of the instrumental activity compared to other activities under contingency conditions. The probability of initiating the contingent activity after a bout of instrumental activity decreased during contingency conditions for 4 subjects during placebo and active-marijuana administration. Table 3 presents performance data for the instrumental and contingent activities during the 3-day baseline and contingency periods as a function of drug administration. No rate measure was available for the vigilance task, and no accuracy measures were available for the disk- or word-sorting tasks. There were no consistent patterns of changes in either rate or accuracy of performance as a function of either contingency condition or drug administration. In summary, when contingencies were in effect, subjects increased the amount of time spent engaging in the low-probability instrumental activity to a greater extent under activedrug conditions than under placebo conditions.

Instrumental Base Cntgy

Contingent Base Cntgy

17 4 15 19 10 54 19.8 7.9

20 30 170 97 25 227 94.8 38.9

18 85 39 58 47 150 66.2 20.9

12 56 31 24 39 26 31.3

10.0 9.3 9.4 5.7 11.1 4.6 8.3 1.2

10.4 11.1 3.7 7.5 13.5 3.4 8.3 1.8

23.9 7.1 12.0 10.5 8.9 4.4 11.1 3.0

10.4 5.9 12.1 13.6 7.0 4.8 9.0 1.6

6.7

The increase in instrumental activity was due to an increased frequency of instrumental activity bouts without consistent changes in mean bout duration. Under both placebo and activemarijuana conditions, however, similar decreases in the amount of time spent engaging in the contingent work tasks were observed.

DISCUSSION The results of this experiment demonstrate that increases in performance of low-probability work behavior during contingency periods were greater when subjects smoked active marijuana compared to placebo. This change in performance was either maintained by the accumulation of time to engage in high-probability work behavior or was the result of instructions describing the contingency. Despite the greater amount of time spent engaging in instrumental activity under active-marijuana conditions, however, the decrease in the amount of time spent engaging in contingent work activity was similar to, or in some instances greater than, that observed under placebo conditions. The greater increments in instrumental activity under active-marijuana conditions were in contrast to the previously reported ef-

MOTIVATIONAL EFFECTS OF MARIJUANA

13

Table 2 Probability of continuing the instrumental activity (I) or switching to the contingent activity (C) during baseline (Base) and contingency (Cntgy) conditions as a function of drug administration.

Placebo

Marijuana I to C

I to I

I to I

I to C

Subject

Base

Cntgy

Base

Cntgy

Base

Cntgy

Base

Cntgy

1 2 3 4 5 6 M SEM

.714 .375 .461 .571 .000 .810 .489 .117

.667 .910 .600 .538 .346 .915 .663 .090

.214 .000 .153 .142 .833 .051 .232 .124

.222 .000 .000 .076 .230 .012 .090 .045

.500 .330 .600 .789 .300 .846 .561 .093

.850 .689 .941 .905 .217 .911 .752 .113

.250 .330 .000 .000 .500 .076 .193 .083

.050 .069 .005 .031 .304

fect of smoked marijuana on contingencies involving high-probability recreational activities (Foltin et al., in press). In that report, subjects showed attenuated increases above baseline in instrumental recreational performances maintained by contingent access to preferred recreational activities following active-marijuana smoking compared to placebo cigarettes. In both studies, however, the decrements in contingent activity were similar under placebo and active-marijuana conditions. Thus, the motivational effects of smoked marijuana were critically dependent on the environmental contingencies under examination. The present findings concerning work contingencies also differ from previous investigations of the effects of smoked marijuana on contingency-controlled behavior in residential settings using monetary reinforcement (see review by Miles, 1975). In studies with male (Mendelson et al., 1976) and female (Mello & Mendelson, 1985) research volunteers residing continuously in a hospital ward, for example, responses on a portable manipulandum earned points exchangeable for goods (including marijuana cigarettes) or money. There was no evidence of performance changes during periods of access to marijuana cigarettes. A similar procedure was used by Miles et al. (1974), who required male research volunteers to assemble wooden stools for money, which could be saved or exchanged for goods, including marijuana and alcohol. Work hours decreased, but efficiency increased, during marijuana administration, and there was little performance decrement during periods of ac-

.013 .079 .046

cess to marijuana cigarettes, suggesting that contingencies involving monetary gains produced behavioral effects that were insensitive to active marijuana. Pihl and Sigal (1978) also reported that performance decrements following marijuana administration decreased as monetary gain increased. Similar interactions between ethanol effects and behavioral consequences have been reported by Haubenreisser and Vogel-Sprott (1987). These studies highlight the importance of the motivational conditions maintaining performance baselines. The finding of greater increases in instrumental work activity following active-marijuana smoking in the present study is not easily reconciled with the results from previously reported experiments that drug-induced decrements in performance are determined by the interactions between environmental contingencies and behavioral consequences (e.g., Foltin et al., in press; Haubenreisser & VogelSprott, 1987). Clearly, appeal to sources of control other than the contingent consequences of the instrumental work activity is necessary in providing an account of the observed performance-augmenting effects of smoked marijuana. A key element in these work-activity studies appears to be the degree to which maintenance of task participation was dependent on instructional control (Baron & Galizio, 1983; Catania, Matthews, & Shimoff, 1982; Hayes, Brownstein, Haas, & Greenway, 1986). Although subjects would not engage in such work activity in the absence of instructions (unpublished observations), the allocation of required time among the different work tasks

RICHARD W. FOLTIN et al. Table 3 Mean rate and accuracy of performance of the instrumental and contingent activities during baseline and contingency conditions as a function of drug administration (SEMs in parentheses). Rate

Subject Placebo

Marijuana

1 2 3 4 5 6 1 2 3 4 5 6

Instrumental activity Baseline Contingency 6.4 (0.45)a 15.98 (1.06)c NA NA 25.12 (1.14)c 6.8 (0.45)a 7.3 (0.45)a NA 18.95 (4.11)c 14.10 (2.89)c 23.15 (2.56)c 5.4 (0.45)a

7.3 (0.45)a 17.18 (1.89)c NA NA 27.72 (0.90)c 5.4 (0.45)7.7 (0.23)NA 10.82 (1.27)c 14.96 (1.66)c 28.53 (1.02)c 5.9 (0.23)-

Contingent activity Baseline Contingency NAb 3.65 (0.47)d 5.9 (0.23)a 4.5 (1.82)a 8.6 (0.90)a 3.10 (0.21)d NA 7.7 (0.23)a 6.9 (0.45)a 5.0 (0.45)a 8.2 (0.45)a 2.16 (0.09)d

NA 5.0 (0.45)a 10.0 (0.23)a 3.03 (0.26)d NA 8.6 (0.45)a 6.4 (0.45)a 1.8 (2.25)a 10.4 (0.90)a 3.79 (0.65)d

Disk sorting (grams per minute). task (no rate available). c Digit symbol substitution task (responses per minute). d Word sorting (words per minute). e Digit symbol substitution task (errors per minute). I Vigilance task (proportion of missed signals). Note: NA, data not available. a

b Vigilance

was not under explicit instructional control. Therefore, any explanation of the observed differences between the effects of smoked marijuana on work and recreational activities must take into account multiple determinants including, but not limited to, instructional control. In addition to differences in instructional control between work tasks and the free-choice recreational performances (Foltin et al., in press), consideration must be given to differences in response probabilities between recreational as opposed to work activities. In the absence of instructional constraints, the probability of subjects engaging in recreational activities would be greater than the probability of subjects engaging in the work tasks. These differences in basic response probabilities (i.e., allocation of time among activities in the absence of explicit behavioral contingencies) may have contributed to the differential drug effects. An additional feature of this responseprobability hypothesis calls attention to the relation between the instrumental and contingent performances in the two activity conditions showing differential drug effects. There is reason to question whether the differences in response probability between instrumental

and contingent performances were equivalent across the recreational-activity and work-task conditions. It seems likely that the differences in basic response probabilities between the several work tasks in which subjects engaged only under instructional control were small compared to the observed differences in specific recreational activity probabilities. Under worktask conditions, for example, subjects generally engaged in three or all four of the performance choices each day. In contrast, time allocation under recreational conditions was generally restricted to the two activities represented by the instrumental and contingent performances, a fact that may account at least in part for the greater correspondence in drug effects on these two activities in the study of recreational activities (Foltin et al., in press) than in the current work study. In any event, the extent to which such potential differences between the instrumental and contingent activities during recreational and work periods may have contributed to the differential effects of smoked marijuana remains to be elucidated by further research. The procedures used in the present experiment, involving a time-based model of value (i.e., the Premack Principle; Premack, 1965),

MOTIVATIONAL EFFECTS OF MARIJUANA

15

Table 3 (Extended) Accuracy Instrumental activity Baseline

Contingency

NA 0.37 (0.12)' 0.285 (0.078)f 0.421 (NA)f 0.443 (0.079)' NA

NA

NA 0.035 0.616 0.264 0.470 NA

NA 0.104 0.399 0.596 0.548 NA

(0.022)f (0.132)' (0.050)' (0.064)'

NA 0.73 (0.18)' 0.268 (0.033)f 0.342 (0.023)f 0.583 (0.059)'

(0.029)f (0.043)e (0.120)' (0.047)'

differed from previous studies in several ways other than the absence of monetary contingencies in the maintenance of performance baselines. There was no requirement that subjects engage in the contingent activity, and increases in instrumental performances did not necessarily produce increases in contingent activity, as is the case with the more common reciprocal contingency schedule (Allison, 1983). In addition, feedback regarding the status of contingency "bank accounts" was limited to information regarding the availability or nonavailability of access without time specification. Both of these procedures should have enhanced the independent evaluation of drug effects on instrumental and contingent activities. Subjects characteristically accumulated more time for access to the contingent activity than they used; this was observed whether work or recreational activities were involved. In the latter case, for example, Foltin et al. (in press) found that the effects of smoked marijuana in decreasing instrumental recreational performances were not accompanied by similar decreases in contingent recreational activities. In contrast to the conditions under which previously reported studies using monetary contingencies failed to find instrumental performance decrements following marijuana smoking (Mello & Mendelson, 1985; Mendelson et al., 1976; Miles et al., 1974), the Foltin et al. (in press) procedure permitted

Contingent activity Contingency 0.065 (0.01 1)f 0.004 (NA)f Baseline

NA NA NA NA NA

NA NA NA NA NA

0.018 (0.006)f NA NA NA NA NA

0.016 (0.014)f NA NA NA NA NA

decreases in the instrumental activity to occur without decreasing the time subjects spent engaging in the contingent activity. The difference in reinforcement contingencies may be a major factor accounting for the differences in outcomes. Clearly, the present results indicate that much is needed in the way of an experimental analysis of the motivational effects of drugs. For example, the findings may have been influenced by the fact that different instrumental and contingent activities were used between placebo and active-drug conditions in 3 subjects. This indicates one difficulty with research on motivation, in that if the same instrumental and contingent activities had been used under both placebo and active-drug conditions, then for these 3 subjects changes in baseline behavior probabilities would have been ignored. In addition, the absence of baseline recovery under both drug conditions complicates the interpretation of these findings. Although the generality of the findings may be limited, they highlight, in any case, the important interaction between environmental variables and drug effects. The motivational effects of smoked marijuana have provided a focus for a range of clinical and experimental research observations over the past several decades with widely varying results. Those clinical reports that emphasize the amotivational effects of marijuana

16

RICHARD W. FOLTIN et al.

(Lantner, 1982; McGlothin & West, 1968; Mellinger, Semers, Davidson, & Manheimer, 1976; Schwartz, 1987; Smith, 1968; Voth, 1982) are contradicted by equally prestigious clinical pronouncements to the contrary (e.g., Brill & Christie, 1974; Brill, Crumpton, & Grayson, 1971). Moreover, well-controlled clinical-epidemiological studies of cannabis used in Jamaica (Comitas, 1976; Rubin & Comitas, 1976), Greece (Boulougouris, Liakos, & Stefanis, 1976; Stefanis, Dornbush, & Fink, 1977) and Costa Rica (Carter, 1980; Carter & Doughty, 1976; Page, 1983) have failed to confirm the amotivational syndrome even in chronic smokers. Experimental studies in residential settings have also yielded disparate results. The conditions under which motivational changes are and are not observed, however, can be more precisely specified in such controlled research. In evaluating performances maintained by monetary rewards, for example, several investigators (Mello & Mendelson, 1985; Mendelson et al., 1976; Miles et al., 1974) have failed to find evidence for an amotivational syndrome even in long-term marijuana smokers. In studies within the framework of a timebased model of value in which performance involving low-probability behavior is maintained by access to high-probability behavior, however, Foltin et al. (in press) and the results of the present study have shown that there are conditions under which performance changes associated with marijuana smoking can be readily demonstrated. Clearly, the complex interactions between behavioral activities and environmental contingencies (including instructional control) must be analyzed in great detail under a range of clinical, epidemiological, and experimental conditions in order to appreciate the complicated effects of smoked marijuana on the motivational aspects of human performance.

REFERENCES Allison, J. (1983). Behavioral economics. New York: Praeger. Baron, A., & Galizio, M. (1983). Instructional control of human operant behavior. Psychological Record, 33, 495-520. Bernstein, D., & Livingston, C. (1982). An interactive program for observation and analysis of human behavior in a long-term continuous laboratory. Behavior Research Methods & Instrumentation, 14, 231-235.

Boulougouris, J. C., Liakos, A., & Stefanis, C. (1976). Social traits of heavy hashish users and matched controls. Annals of the New York Academy of Sciences, 282, 17-23. Brady, J. V., Bigelow, G., Emurian, H., & Williams, D. M. (1974). Design of a programmed environment for the experimental analysis of social behavior. In D. H. Carlson (Ed.), Man-environment interactions: Evaluations and applications: Vol. 7. Social ecology (pp. 187208). Strousburg, PA: Dowden, Hutchinson & Ross. Brill, N. Q., & Christie, R. L. (1974). Marihuana use and psychosocial adaptation: Follow-up study of a collegiate population. Archives of General Psychiatry, 31, 713-719. Brill, N. Q., Crumpton, E., & Grayson, H. M. (1971). Personality factors in marijuana use: A preliminary report. Archives of General Psychiatry, 24, 163-165. Carter, W. E. (1980). Cannabis in Costa Rica. Philadelphia: Institute for the Study of Human Issues. Carter, W. E., & Doughty, P. L. (1976). Social and cultural aspects of cannabis use in Costa Rica. Annals of the New York Academy of Sciences, 282, 2-16. Catania, A. C., Matthews, B. A., & Shimoff, E. (1982). Instructed versus shaped human verbal behavior: Interactions with nonverbal responding. Journal of the Experimental Analysis of Behavior, 38, 233-248. Comitas, L. (1976). Cannabis and work in Jamaica: A refutation of the amotivational syndrome. Annals of the New York Academy of Sciences, 282, 24-32. Foltin, R. W., Brady, J. V., & Fischman, M. W. (1986). Behavioral analysis of marijuana effects on food intake in humans. Pharmacology Biochemistry and Behavior, 25, 577-582. Foltin, R. W., Brady, J. V., Fischman, M. W., Emurian, C. S., & Dominitz, J. (1987). Effects of smoked marijuana on social interaction in small groups. Drug and Alcohol Dependence, 20, 87-93. Foltin, R. W., & Fischman, M. W. (1988). Effects of smoked marijuana on human social behavior in small groups. Pharmacology Biochemistry and Behavior, 30, 539-541. Foltin, R. W., Fischman, M. W., Brady, J. V., Kelly, T. H., Bernstein, D. J., & Nellis, M. N. (in press). Motivational effects of smoked marijuana: Behavioral contingencies and recreational activities. Pharmacology Biochemistry and Behavior. Foltin, R. W., Fischman, M. W., & Byrne, M. F. (1988). Effects of smoked marijuana on food intake and body weight of humans living in a residential laboratory. Appetite, 11, 1-14. Foltin, R. W., Fischman, M. W., Pedroso, J. J., & Pearlson, G. D. (1987). Marijuana and cocaine interactions in humans: Cardiovascular consequences. Pharmacology Biochemistry and Behavior, 28, 459-464. Haubenreisser, T., & Vogel-Sprott, M. (1987). Reinforcement reduces behavioural impairment under an acute dose of alcohol. Pharmacology Biochemistry and Behavior, 26, 29-33. Hayes, S. C., Brownstein, A. J., Haas, J. R., & Greenway, D. E. (1986). Instructions, multiple schedules, and extinction: Distinguishing rule-governed from schedule-controlled behavior. Journal of the Experimental Analysis of Behavior, 46, 137-147. Indian Hemp Drugs Commission. (1893). Marijuana report. Silver Springs, MD: T. Jefferson. Lantner, I. L. (1982). Marijuana abuse by children and

17

MOTIVATIONAL EFFECTS OF MARIJUANA teenagers: A pediatrician's view. In Marijuana and youth: Clinical observations on motivation and learning (pp. 8492). (DHHS Publication No. ADM 82-1186.) Washington, DC: U.S. Government Printing Office. McGlothin, W. H., & West, L. J. (1968). The marijuana problem: An overview. American Journal of Psychiatry, 125, 370-378. McLeod, D. R., Griffiths, R. R., Bigelow, G. E., & Yingling, J. (1982). An automated version of the digit symbol substitution test (DSST). Behavior Research Methods & Instrumentation, 14, 463-466. Mellinger, G. D., Semers, R. H., Davidson, S. T., & Manheimer, D. I. (1976). The amotivational syndrome and the college student. Annals of the New York Academy of Sciences, 282, 37-55. Mello, N. K., & Mendelson, J. H. (1985). Operant acquisition of marijuana by women. Journal of Pharmacology and Experimental Therapeutics, 235, 162-17 1. Mendelson, J. H., Kuehnle, J. C., Greenberg, I., & Mello, N. K. (1976). Operant acquisition of marijuana in man. Journal of Pharamacology and Experimental Therapeutics, 198, 42-53. Miles, C. G. (1975). A selective review of studies of long-term use of cannabis on behaviour, personality and cognitive functioning. In P. H. Connell & N. Dorn (Eds.), Cannabis and man (pp. 66-86). Edinburgh: Churchill Livingstone. Miles, C. G., Congreve, G. R. S., Gibbins, R. J., Marshman, J., Devenyi, P., & Hicks, R. C. (1974). An

experimental study of the effects of daily cannabis smoking on behaviour patterns. Acta Pharmacologica et Toxicologia, 34 (Suppl. 7), 1-43. Page, J. B. (1983). The amotivational syndrome hypothesis and the Costa Rica study: Relationships between methods and results. Journal of Psychoactive Drugs, 15, 261-267. Pihl, R. O., & Sigal, H. (1978). Motivational levels and the marijuana high. Journal of Abnormal Psychology, 87, 280-285. Premack, C. (1965). Reinforcement theory. In D. Levine (Ed.), Nebraska symposium on motivation (Vol. 13, pp. 123-180). Lincoln: University of Nebraska Press. Rubin, F., & Comitas, L. (1976). Ganja in Jamaica. Garden City, NY: Doubleday. Schwartz, R. H. (1987). Marijuana: An overview. Pediatric Clinics of North America, 34, 305-317. Smith, D. E. (1968). Acute and chronic toxicity of marijuana. Journal of Psychedelic Drugs, 2, 37-47. Stefanis, C., Dornbush, R., & Fink, M. (1977). Hashish: Studies of long-term use. New York: Raven Press. Voth, H. M. (1982). The effects of marijuana on the young. In Marijuana and youth: Clinical observations on motivation and learning (pp. 51-60, includes commentary). (DHHS Publication No. ADM 82-1186.) Washington, DC: U.S. Government Printing Office.

Received February 1, 1989 Final acceptance September 2, 1989

APPENDIX Distribution of time (in minutes) among activities during private period. Subject

Day

Drug

Condition

Misa

Disks

Words

DSSTb

VIGIC

Otherd

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11

none Pbo Pbo Pbo MJ MJ MJ Pbo Pbo Pbo MJ MJ MJ Pbo Pbo none Pbo Pbo Pbo MJ MJ MJ Pbo Pbo Pbo MJ

Base Base Base Base Base Base Base Contingency Contingency Contingency Contingency Contingency Contingency Base Base Base Base Base Base Base Base Base Contingency

53 32 20 20 28 28 16 12 24 41 32 28 32 20 28 24 53 73 57 41 73 45 36 28 57 53

122 32 45 69 57 53 61 0 36 69 122 85 0 32 16 247 53 61 4 308 0 288 150 279 4 198

65 105 101 97 77 166 0 0 275 174 85 207 296 0 81 20 146 130 247 0 292 0 0 0 0 0

65 81 61 57 65 81 36 356 12 45 53 0 32 0 36 57 73 20 0 0 0 0 113 0 178 45

69 117 138 122 142 36 251 0 20 41 73 49 4 300 186 24 45 73 57 12 0

32 36 41 41 36 41 41 36 36 36 41 36 41 53 57 32 36 49 41 45 41 49 41 41 41 45

2

Contingency Contingency Contingency

24 65 57 126 65

RICHARD W. FOLTIN et al. APPENDIX (Continued) Subject

3

4

5

6

Day

Drug

Condition

Misa

Disks

Words

DSSTb

VIGIC

Otherd

12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10

MJ MJ

Contingency Contingency Base Base Base Base Base Base Base Base Base Contingency Contingency Contingency Contingency Contingency Contingency Base Base Base Base Base Base Base Base Base Contingency Contingency Contingency Contingency Contingency Contingency Base Base Base Base Base Base Base Base Base Contingency Contingency Contingency Contingency Contingency Contingency Base Base Base Base Base Base Base Base Base Contingency Contingency Contingency

53 41 28 53 24 28 24 24 101 20 20 32 53 49 32 28 28 36 12 65 32 36 20 12 41 16 28 28 20 32 24 24 36 24 45 61 49 45 49 36 32 49 45 53 45 57 45 53 53 61 53

0 134 109 0 166 117 203 243 93 194 178 0 0 0 89 101 182 235 352 154 186 77 344 170 0 352 0 0 324 93 85 0 0 158 134 122 150 150 150 170 162 93 93 85 89 105 97 113 113 45 134 61 53 105 89 150 227 251 304

223 0 77 0 53 36 57 61 32 41 41 113 247 271 0 4 0 45 0 49 138 109 0 0 101 0 0 0 0 0 0 65 0 0 73 97 93 113 101 97 93 81 81 97 117 109 122 113 109 203 174 235 251 227 235 170 77 49 0

4 0 0 207 81 162 69 8 65 41 36 85 36 36 243 231 150 49 0 81 0 109 0 178 138 0 336 336 49 182 198 207 328 186 65 49 36 28 32 28 41 117 105 117 81 85 89 61 57 28 0 0 0 0 0 0 0 0 0

85 182 138 53 49 53 8 32 73 69 89 130 28 4 0 0 0 0 0 28 0 28 0 0 85 0 0 0 0 61 57 73 0 0 57 41 41 24 24 24 32 28 32 12 16

41 49 53 93 32 8 45 36 41 41 41 45 41 45 41 41 45 41 41 28 49 45 41 45 41 36 41 41 12 36 41 36 41 36 32 36 36 45 49 49 45 36 49 41 57 45 49 49 49 36 45 24 49 12 36 36 41 49 45

Pbo Pbo none Pbo Pbo Pbo MJ MJ MJ Pbo Pbo Pbo MJ MJ MJ Pbo Pbo none MJ MJ MJ Pbo Pbo Pbo MJ MJ MJ Pbo Pbo Pbo Pbo Pbo none MJ MJ MJ

Pbo Pbo Pbo MJ MJ MJ Pbo Pbo Pbo Pbo Pbo none MJ MJ MJ

Pbo Pbo Pbo MJ MJ MJ

85 53 61 45 49 61 57 57

4 4

16 24 32 0 0 0 0 0 0 0 0 0

MOTIVATIONAL EFFECTS OF MARIJUANA

19

APPENDIX (Continued) Subject

Day

Drug

Condition

Misa

Disks

45 320 Contingency 11 Pbo 49 211 Contingency 12 Pbo 36 235 Pbo Contingency 13 49 126 14 Pbo Base 53 215 Base Pbo 15 a Mis = miscellaneous-not engaging in any activities. b DSST = digit symbol substitution task. c VIGI = vigilance task. d Other = time spent using toilet facilities and optional 30-min break.

Words

0 101 122 182 93

DSSTb 0 0 0 0 0

VIGIC 0 0 0 0 0

Otherd 41 45 12 49 45