159
Forensic Science International, 14 (1979) 159 - 164 0 Elsevier Sequoia S.A., Lausanne - Printed in the Netherlands
THE EFFECTS WRITING*
ROBERT North
OF MARIJUANA
AND ALCOHOL
USAGE ON HAND-
G. FOLEY
Delta
Crime
Laboratory,
Monroe,
Louisiana
(U.S.A.)
A. LAMAR MILLER Alabama
Department
of Toxicology
(Received September 24,197S;
and Criminal
Investigation,
Auburn,
Alabama
(U.S.A.)
in revised form April 9, 1979; accepted May 1, 1979)
Summary In this study the handwriting of twelve individuals under the influence of marijuana, alcohol, and a combination of the two was compared with control samples. It was found that marijuana smoking in moderate amounts had less effect on the handwriting of the individuals than did alcohol. It was also found that when the two were combined the gross changes observed were probably due to the effect of the alcohol alone.
Marijuana usage in our society today is increasing in popularity. In many circles the use of cannabis is as acceptable as the social drink. In fact, many marijuana users report that the two are often mixed. The effects of alcohol on handwriting have been documented; however, the effects of marijuana intoxication on handwriting have not been studied. As laws regulating the use of marijuana are relaxed, it is apparent that handwriting prepared while under the influence of marijuana will become an increasing problem in the future. The purpose of this study was to examine and comment on the effects of marijuana and alcohol on handwriting from the questioned document examiner’s point of view. As far back as 1961 Gesell [l] commented on the need for research on the effects of drugs on handwriting and proposed a research protocol. Purtell [ 21 noted that the handwriting of narcotic addicts shows little deterioration during periods of drug intoxication. Hirsch et al. [3] found that subjects under the influence of five hallucinogenic drugs - including LSD - demonstrated considerable individual variation in their handwritings. More errors, irregularities and carelessness were observed in their writings. Vollmer [4] observed that the use of orphenadrine led to restoration of writing ability in patients with Parkinson’s disease. An improvement in handwriting [ 51 and motor performance with the use of dopamine in these patients has also been noted [6]. Legge et al. [ 71 discovered that administration of nitrous oxide *Presented at the joint meetings of The International Association of Forensic Sciences and the American Society of Questioned Document Examiners, Wichita, Kansas, U.S.A., May 23,1978.
160
produced a systematic increase in the overall size of handwriting. Zirkle et al. [ 81 have determined that meprobamate (a tranquilizer) combined with small amounts of alcohol seriously affected human performance and judgment. The combination of meprobamate and alcohol was found to be synergistic. On this premise, Purtell [2] has suggested a possible deterioration of a person’s handwriting under the influence of a mixture of these two substances. The effect of alcohol on handwriting has been studied by many workers. Baker [9] pointed out the well-known fact that persons under the influence of alcohol show uncontrolled muscular movements and tremor in their writing. Rabin and Blair [lo] concluded that subjects wrote larger and were less accurate in copying a test paragraph after consuming alcohol. Their research also revealed that those under the influence of alcohol had a tendency to write more slowly than their sober counterparts. Reporting on a study in 1972, Osborn [ 111 concluded that gross base misalignment, increased variation and poorly executed letter forms were evidence of questioned signatures having been written under the influence of alcohol. Todd [12] described handwriting as the product of many finely conditioned motor and psychic activities which as such are more rapidly affected by alcohol intoxication than some of the more overt movements or activities of the individual. Hilton [ 131 extensively documented the influence of alcohol intoxication on handwriting. Such changes as larger letter forms, increased lateral spacing, decreased legibility, and poor alignment were seen. These changes were correlated with specific blood levels. Anderson’s [14] study also determined the effects of various blood alcohol concentrations on handwriting and generally corroborated Hilton’s earlier work. The effect of marijuana smoking on motor skills, and sensory and perceptual functions has been examined. Peter et al. [ 151 extensively studied the effects of A9-tetrahydrocannabinol (A9-THC) (an active ingredient of marijuana) on volunteer subjects. Their findings revealed that the drug produced a small but consistently detrimental effect on both proficiency and variability of performance. But, in contrast, A9-THC exerted a profound effect on the subjective experiences of the volunteers. These results suggest that the principle effects of marijuana are centered in the autonomic nervous system rather than in higher cortical functions. Salvendy and McCabe [16] found consistent patterns of inferior performance on manipulative and coordination skills in subjects under the influence of marijuana. In exploring the effects of marijuana smoking on sensitivity to pain, touch, and visual stimuli, Hill et al. [17] found increased sensitivity to the stimuli utilized in their experiment. These findings suggest that marijuana has a stimulating effect on the central nervous system. Roth et al. [18] reported the results of a study in which subjects taking A 9-THC committed more errors tracking a moving object than those receiving a placebo. Todd [12] commented that handwriting executed under the influence of marijuana could possibly be seriously impaired. Tinklenberg et al. [19] in an experiment comparing the effects of marijuana and alcohol
161
reported that perception of time intervals by subjects under the influence of marijuana was significantly altered. Manno et al. [20] found that volunteers smoking cigarettes calculated to deliver a high dose of A 9-THC had significant impairment of both mental and motor tests and that alcohol induced an additional effect. In studying the effect of marijuana and alcohol on simulated driving performance, Crancer et al. [21] found that more total errors occurred in those intoxicated with alcohol than those under the influence of marijuana. Beth et al. [22] also utilized a driving simulator to measure the effect of alcohol and marijuana on the ability to estimate time and distance. In this study, marijuana was found to have a stronger effect than alcohol. Rafaelsen et al. [23] found that both alcohol and marijuana increased the time required to start to brake in simulated driving tests.
Experiment The effects of marijuana used alone and the combined effects of marijuana and alcohol on handwriting have not been documented. In order to explore such possible effects this study was undertaken. Twelve individuals between the ages of 18 and 29 were surveyed. Five were females, seven were males, and none were first time users of marijuana. Eight were considered to be habitual users, smoking marijuana at least twice a week. Three were considered to be infrequent users, smoking at least once a month. One subject seldom used marijuana. Three individuals reported that they frequently mixed alcohol and marijuana. Signatures and handwriting control samples were taken prior to the smoking of marijuana and the consumption of alcohol. Comparison samples were taken between thirty minutes and one hour after use of the drugs. Samples were obtained from subjects using alcohol and marijuana separately and in combination. Between one and five marijuana cigarettes were smoked prior to the final sampling. The A9-THC content of the marijuana cigarettes was not determined. The amount of alcohol ingested was recorded; however, the blood level of alcohol was not quantitated.
Results To determine if any changes occurred, the test and control handwriting samples were compared for speed, letter forms, proportions, height ratios, size, slant, and alignment. Comparison of the control samples with those taken after the smoking of one marijuana cigarette revealed little or no change in the handwriting. This was generally found to be true in all subjects. After smoking three marijuana cigarettes, some handwriting changes were observed in the subjects tested. These changes were most evident in the individuals with little previous experience with marijuana. The handwriting produced after smoking this quantity of marijuana was generally found to be
162 (A)
Fig. 1. Sample A is a portion of extended writing executed prior to the smoking of marijuana. Sample B is a portion of extended writing executed after smoking three marijuana cigarettes, Some increase in size is noted in the samples taken after smoking marijuana. Both of these samples were copied from prepared text by the test subjects. Note that the word “counter” was written as “county” in the sample prepared after smoking marijuana. Also note modification in letter form in the “m” of “made” or the “n” in “counter”, ‘Qzounty”, as well as the “OS” connection in “purposely”.
slightly larger with some alterations in the letter forms (see Fig. 1). Comparison of the controls with the writing produced after smoking five marijuana cigarettes generally revealed increased letter size, baseline deviation, and careless execution. The comparison of control samples with samples taken after the consumption of three 12 ounce cans of beer revealed increased writing speed, larger letter size, and expanded lateral spacing. Changes in height ratios and in the slant of the writing was also observed. Examination of the writing produced by subjects drinking three 12 ounce cans of beer and smoking three marijuana cigarettes revealed changes and variations similar to those observed in writing produced after the ingestion of alcohol alone (see Fig. 2).
163
Fig. 2. The effect of marijuana and ethanol on signatures. Sample A is a control written before the experiment began. Sample B was written after smoking marijuana. Sample C was written after smoking marijuana and drinking alcoholic beverages. Sample D was written after consuming a large quantity of alcohol. The most pronounced effect appears in the samples taken after consumption of a large quantity of alcohol.
Discussion The neuromuscular activity necessary to produce normal handwriting is directed by the central nervous system (CNS). The CNS depressant activity of alcohol is responsible for the marked effect of this substance on normal handwriting. The literature suggests that while marijuana does affect the CNS, it does not greatly depress the CNS activity used to direct manipulative functions such as handwriting. This may explain the reason the individuals in this study experienced a subjective change in mood, such as a “high” from smoking marijuana cigarettes, and yet were able to write without the gross departure from normal handwriting seen when the “high” was the result of alcohol ingestion.
References 1 H. J. E. Gessel, Drugs and questioned document problems. J. Forensic Sci., 8 (1961) 76 - 82. 2 D. J. Purtell, Effects of drugs on handwriting. J. Forensic Sci., 10 (1965) 335 - 346.
164 3 M. W. Hirsch, M. E. Jarvic and H. A. Abramson, Lysergic acid diethylamide (LSD-25): VII. Effects of LSD-25 and six related drugs upon handwriting. J. Psychol. 41 (1956) 11 -22. 4 H. Vollmer, Bulgarian treatment of Parkinson disease. Arch. Neurot. Psychiat., 43 (1940) 1075 - 1080. 5 J. M. English, Georgetown University Institute of Criminal Law and Procedure, Forensic Sciences Laboratory, Washington, D.C., Personal communication, September, 1973. 6 L. S. Goodman and A. Gilman, The Pharmacological Basis of Therapeutics, 4th Edition, Macmillan, London, 1970, pp. 233. 7 D. Legge, H. Steinberg and A. Summerfield, Simple measures of handwriting as indices of drug effects. Percept. Mot. Skills, 18 (1964) 549 - 558. 8 G. A. Zirkle, 0. B. McAtee and P. D. King, Meprobamate and small amounts of alcohol. J. Amer. Med. Ass., 173 (1960). 9 J. N. Baker, Law of Disputed and Forged Documents, Michie Co., Charlottesville, Va., 1955, p. 347. 10 A. Rabin and H. Blair, The effects of alcohol on handwriting. J. Clin. Psychol. 9 (1953)
284
- 287.
11 A. D. Osborn, Document
Writing done while intoxicated.
Examiners, Intercommunicating Abnormal Handwriting Inservice
American Society of Questioned Correspondence, August 7,1972. Training, U.S. Secret Service, Washing-
12 I. Todd, ton, D.C. 13 0. Hilton, A study of the influence of alcohol on handwriting. J. Forensic Sci., 14 (1969) 309 - 316. 14 G. J. Anderson, Varying effects of alcohol on handwriting. American Academy of Forensic Sciences, Dallas, Texas, 1974. 15 B. A. Peter, E. G. Lewis, R. E. Dustman, R. C. Straight and E. C. Beck, Sensory, perceptual, motor and cognitive functioning, and subjective reports following oral administration of 9-tetrahydrocannabinol. Psychopharmacology, 47 (1976) 141 - 148. 16 G. Salvendy, G. P. McCabe, Jr., Marijuana and human performance. Human Factors, 17 (1975) 229 - 235. 17 S. Y. Hill, D. W. Goodwin, R. Schwin and B. Powell, Marijuana: CNS depressant or 131 (1974) 313 - 315. excitant? Amer. J. Psychiot., 18 W. T. Roth, J. R. Tinklenberg, C. A. Whitaker, C. F. Darley, B. S. Kopell and L. E. Hollister, The effect of marijuana on tracking task performance. Psychopharmacotogia, 33 (1973). 19 J. R. Tinklenberg, B. S. Kopell, F. T. Melges and L. E. Hollister, Marijuana and alcohol. Arch. Gen. Psych&., 27 (1972) 812 - 815. 20 J. E. Manno, G. F. Kiplinger, N. Schloz and R. B. Forney, The influence of alcohol Ther., 12 (1971) and marijuana on motor and mental performance, Chn. Pharmacol. 202
- 211.
A. J. Crancer, J. E. Dille, J. C. Delay, J. E. Wallace and M. D. Haykin, Comparison of the effects of marijuana and alcohol on simulated driving performance. Science, 164 (1969) 851 - 854. 22 P. Beck, L. Rafaelsen and 0. J. Rafaelsen, Cannabis and alcohol: effects on estimation of time and distance. Psychopharmacologia, 32 (1973) 373 - 381. 23 0. J. Rafaelsen, P. Beth, J. Christiansen, H. Christrop, J. Nyboe and L. Rafaelsen, Cannabis and alcohol: effects on simulated car driving. Science, 179 (1973) 920 - 923. 21
Forensic Science International, 14 (1979) 159 - 164 0 Elsevier Sequoia S.A., Lausanne - Printed in the Netherlands
THE EFFECTS WRITING*
ROBERT North
OF MARIJUANA
AND ALCOHOL
USAGE ON HAND-
G. FOLEY
Delta
Crime
Laboratory,
Monroe,
Louisiana
(U.S.A.)
A. LAMAR MILLER Alabama
Department
of Toxicology
(Received September 24,197S;
and Criminal
Investigation,
Auburn,
Alabama
(U.S.A.)
in revised form April 9, 1979; accepted May 1, 1979)
Summary In this study the handwriting of twelve individuals under the influence of marijuana, alcohol, and a combination of the two was compared with control samples. It was found that marijuana smoking in moderate amounts had less effect on the handwriting of the individuals than did alcohol. It was also found that when the two were combined the gross changes observed were probably due to the effect of the alcohol alone.
Marijuana usage in our society today is increasing in popularity. In many circles the use of cannabis is as acceptable as the social drink. In fact, many marijuana users report that the two are often mixed. The effects of alcohol on handwriting have been documented; however, the effects of marijuana intoxication on handwriting have not been studied. As laws regulating the use of marijuana are relaxed, it is apparent that handwriting prepared while under the influence of marijuana will become an increasing problem in the future. The purpose of this study was to examine and comment on the effects of marijuana and alcohol on handwriting from the questioned document examiner’s point of view. As far back as 1961 Gesell [l] commented on the need for research on the effects of drugs on handwriting and proposed a research protocol. Purtell [ 21 noted that the handwriting of narcotic addicts shows little deterioration during periods of drug intoxication. Hirsch et al. [3] found that subjects under the influence of five hallucinogenic drugs - including LSD - demonstrated considerable individual variation in their handwritings. More errors, irregularities and carelessness were observed in their writings. Vollmer [4] observed that the use of orphenadrine led to restoration of writing ability in patients with Parkinson’s disease. An improvement in handwriting [ 51 and motor performance with the use of dopamine in these patients has also been noted [6]. Legge et al. [ 71 discovered that administration of nitrous oxide *Presented at the joint meetings of The International Association of Forensic Sciences and the American Society of Questioned Document Examiners, Wichita, Kansas, U.S.A., May 23,1978.
160
produced a systematic increase in the overall size of handwriting. Zirkle et al. [ 81 have determined that meprobamate (a tranquilizer) combined with small amounts of alcohol seriously affected human performance and judgment. The combination of meprobamate and alcohol was found to be synergistic. On this premise, Purtell [2] has suggested a possible deterioration of a person’s handwriting under the influence of a mixture of these two substances. The effect of alcohol on handwriting has been studied by many workers. Baker [9] pointed out the well-known fact that persons under the influence of alcohol show uncontrolled muscular movements and tremor in their writing. Rabin and Blair [lo] concluded that subjects wrote larger and were less accurate in copying a test paragraph after consuming alcohol. Their research also revealed that those under the influence of alcohol had a tendency to write more slowly than their sober counterparts. Reporting on a study in 1972, Osborn [ 111 concluded that gross base misalignment, increased variation and poorly executed letter forms were evidence of questioned signatures having been written under the influence of alcohol. Todd [12] described handwriting as the product of many finely conditioned motor and psychic activities which as such are more rapidly affected by alcohol intoxication than some of the more overt movements or activities of the individual. Hilton [ 131 extensively documented the influence of alcohol intoxication on handwriting. Such changes as larger letter forms, increased lateral spacing, decreased legibility, and poor alignment were seen. These changes were correlated with specific blood levels. Anderson’s [14] study also determined the effects of various blood alcohol concentrations on handwriting and generally corroborated Hilton’s earlier work. The effect of marijuana smoking on motor skills, and sensory and perceptual functions has been examined. Peter et al. [ 151 extensively studied the effects of A9-tetrahydrocannabinol (A9-THC) (an active ingredient of marijuana) on volunteer subjects. Their findings revealed that the drug produced a small but consistently detrimental effect on both proficiency and variability of performance. But, in contrast, A9-THC exerted a profound effect on the subjective experiences of the volunteers. These results suggest that the principle effects of marijuana are centered in the autonomic nervous system rather than in higher cortical functions. Salvendy and McCabe [16] found consistent patterns of inferior performance on manipulative and coordination skills in subjects under the influence of marijuana. In exploring the effects of marijuana smoking on sensitivity to pain, touch, and visual stimuli, Hill et al. [17] found increased sensitivity to the stimuli utilized in their experiment. These findings suggest that marijuana has a stimulating effect on the central nervous system. Roth et al. [18] reported the results of a study in which subjects taking A 9-THC committed more errors tracking a moving object than those receiving a placebo. Todd [12] commented that handwriting executed under the influence of marijuana could possibly be seriously impaired. Tinklenberg et al. [19] in an experiment comparing the effects of marijuana and alcohol
161
reported that perception of time intervals by subjects under the influence of marijuana was significantly altered. Manno et al. [20] found that volunteers smoking cigarettes calculated to deliver a high dose of A 9-THC had significant impairment of both mental and motor tests and that alcohol induced an additional effect. In studying the effect of marijuana and alcohol on simulated driving performance, Crancer et al. [21] found that more total errors occurred in those intoxicated with alcohol than those under the influence of marijuana. Beth et al. [22] also utilized a driving simulator to measure the effect of alcohol and marijuana on the ability to estimate time and distance. In this study, marijuana was found to have a stronger effect than alcohol. Rafaelsen et al. [23] found that both alcohol and marijuana increased the time required to start to brake in simulated driving tests.
Experiment The effects of marijuana used alone and the combined effects of marijuana and alcohol on handwriting have not been documented. In order to explore such possible effects this study was undertaken. Twelve individuals between the ages of 18 and 29 were surveyed. Five were females, seven were males, and none were first time users of marijuana. Eight were considered to be habitual users, smoking marijuana at least twice a week. Three were considered to be infrequent users, smoking at least once a month. One subject seldom used marijuana. Three individuals reported that they frequently mixed alcohol and marijuana. Signatures and handwriting control samples were taken prior to the smoking of marijuana and the consumption of alcohol. Comparison samples were taken between thirty minutes and one hour after use of the drugs. Samples were obtained from subjects using alcohol and marijuana separately and in combination. Between one and five marijuana cigarettes were smoked prior to the final sampling. The A9-THC content of the marijuana cigarettes was not determined. The amount of alcohol ingested was recorded; however, the blood level of alcohol was not quantitated.
Results To determine if any changes occurred, the test and control handwriting samples were compared for speed, letter forms, proportions, height ratios, size, slant, and alignment. Comparison of the control samples with those taken after the smoking of one marijuana cigarette revealed little or no change in the handwriting. This was generally found to be true in all subjects. After smoking three marijuana cigarettes, some handwriting changes were observed in the subjects tested. These changes were most evident in the individuals with little previous experience with marijuana. The handwriting produced after smoking this quantity of marijuana was generally found to be
162 (A)
Fig. 1. Sample A is a portion of extended writing executed prior to the smoking of marijuana. Sample B is a portion of extended writing executed after smoking three marijuana cigarettes, Some increase in size is noted in the samples taken after smoking marijuana. Both of these samples were copied from prepared text by the test subjects. Note that the word “counter” was written as “county” in the sample prepared after smoking marijuana. Also note modification in letter form in the “m” of “made” or the “n” in “counter”, ‘Qzounty”, as well as the “OS” connection in “purposely”.
slightly larger with some alterations in the letter forms (see Fig. 1). Comparison of the controls with the writing produced after smoking five marijuana cigarettes generally revealed increased letter size, baseline deviation, and careless execution. The comparison of control samples with samples taken after the consumption of three 12 ounce cans of beer revealed increased writing speed, larger letter size, and expanded lateral spacing. Changes in height ratios and in the slant of the writing was also observed. Examination of the writing produced by subjects drinking three 12 ounce cans of beer and smoking three marijuana cigarettes revealed changes and variations similar to those observed in writing produced after the ingestion of alcohol alone (see Fig. 2).
163
Fig. 2. The effect of marijuana and ethanol on signatures. Sample A is a control written before the experiment began. Sample B was written after smoking marijuana. Sample C was written after smoking marijuana and drinking alcoholic beverages. Sample D was written after consuming a large quantity of alcohol. The most pronounced effect appears in the samples taken after consumption of a large quantity of alcohol.
Discussion The neuromuscular activity necessary to produce normal handwriting is directed by the central nervous system (CNS). The CNS depressant activity of alcohol is responsible for the marked effect of this substance on normal handwriting. The literature suggests that while marijuana does affect the CNS, it does not greatly depress the CNS activity used to direct manipulative functions such as handwriting. This may explain the reason the individuals in this study experienced a subjective change in mood, such as a “high” from smoking marijuana cigarettes, and yet were able to write without the gross departure from normal handwriting seen when the “high” was the result of alcohol ingestion.
References 1 H. J. E. Gessel, Drugs and questioned document problems. J. Forensic Sci., 8 (1961) 76 - 82. 2 D. J. Purtell, Effects of drugs on handwriting. J. Forensic Sci., 10 (1965) 335 - 346.
164 3 M. W. Hirsch, M. E. Jarvic and H. A. Abramson, Lysergic acid diethylamide (LSD-25): VII. Effects of LSD-25 and six related drugs upon handwriting. J. Psychol. 41 (1956) 11 -22. 4 H. Vollmer, Bulgarian treatment of Parkinson disease. Arch. Neurot. Psychiat., 43 (1940) 1075 - 1080. 5 J. M. English, Georgetown University Institute of Criminal Law and Procedure, Forensic Sciences Laboratory, Washington, D.C., Personal communication, September, 1973. 6 L. S. Goodman and A. Gilman, The Pharmacological Basis of Therapeutics, 4th Edition, Macmillan, London, 1970, pp. 233. 7 D. Legge, H. Steinberg and A. Summerfield, Simple measures of handwriting as indices of drug effects. Percept. Mot. Skills, 18 (1964) 549 - 558. 8 G. A. Zirkle, 0. B. McAtee and P. D. King, Meprobamate and small amounts of alcohol. J. Amer. Med. Ass., 173 (1960). 9 J. N. Baker, Law of Disputed and Forged Documents, Michie Co., Charlottesville, Va., 1955, p. 347. 10 A. Rabin and H. Blair, The effects of alcohol on handwriting. J. Clin. Psychol. 9 (1953)
284
- 287.
11 A. D. Osborn, Document
Writing done while intoxicated.
Examiners, Intercommunicating Abnormal Handwriting Inservice
American Society of Questioned Correspondence, August 7,1972. Training, U.S. Secret Service, Washing-
12 I. Todd, ton, D.C. 13 0. Hilton, A study of the influence of alcohol on handwriting. J. Forensic Sci., 14 (1969) 309 - 316. 14 G. J. Anderson, Varying effects of alcohol on handwriting. American Academy of Forensic Sciences, Dallas, Texas, 1974. 15 B. A. Peter, E. G. Lewis, R. E. Dustman, R. C. Straight and E. C. Beck, Sensory, perceptual, motor and cognitive functioning, and subjective reports following oral administration of 9-tetrahydrocannabinol. Psychopharmacology, 47 (1976) 141 - 148. 16 G. Salvendy, G. P. McCabe, Jr., Marijuana and human performance. Human Factors, 17 (1975) 229 - 235. 17 S. Y. Hill, D. W. Goodwin, R. Schwin and B. Powell, Marijuana: CNS depressant or 131 (1974) 313 - 315. excitant? Amer. J. Psychiot., 18 W. T. Roth, J. R. Tinklenberg, C. A. Whitaker, C. F. Darley, B. S. Kopell and L. E. Hollister, The effect of marijuana on tracking task performance. Psychopharmacotogia, 33 (1973). 19 J. R. Tinklenberg, B. S. Kopell, F. T. Melges and L. E. Hollister, Marijuana and alcohol. Arch. Gen. Psych&., 27 (1972) 812 - 815. 20 J. E. Manno, G. F. Kiplinger, N. Schloz and R. B. Forney, The influence of alcohol Ther., 12 (1971) and marijuana on motor and mental performance, Chn. Pharmacol. 202
- 211.
A. J. Crancer, J. E. Dille, J. C. Delay, J. E. Wallace and M. D. Haykin, Comparison of the effects of marijuana and alcohol on simulated driving performance. Science, 164 (1969) 851 - 854. 22 P. Beck, L. Rafaelsen and 0. J. Rafaelsen, Cannabis and alcohol: effects on estimation of time and distance. Psychopharmacologia, 32 (1973) 373 - 381. 23 0. J. Rafaelsen, P. Beth, J. Christiansen, H. Christrop, J. Nyboe and L. Rafaelsen, Cannabis and alcohol: effects on simulated car driving. Science, 179 (1973) 920 - 923. 21
