Kindle Notes & Highlights
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May 13 - July 14, 2019
Intoxication consistently impairs time perception, reading difficult material aloud, mental arithmetic, complex reaction time, and certain aspects of memory and perception.
Proving that a drug has no effect is difficult.
Intoxicated individuals recall the appropriate words as often as people who smoked placebo pot, suggesting that the drug does not impair simple learning (e.g., Chait & Pierri, 1992; Hooker & Jones, 1987).
Remote memory, which concerns the ability to retrieve material already learned, does not suffer during intoxication.
Thus, it is unclear if cannabis intoxication prevents people from responding quickly, inhibiting automatic reactions, and persisting on long, tedious assignments.
PERCEPTION Marijuana intoxication alters the senses. People report changes in taste, touch, smell, sight, and hearing.
Cannabis intoxication also appears to alter vision. After smoking marijuana, people do not distinguish colors well.
READING ABILITY In a series of studies, participants read unfamiliar passages of difficult text forward or backward while hearing their own voices though earphones.
ARITHMETIC Marijuana impairs mathematical performance.
Although simple reaction times do not always appear impaired during marijuana intoxication, as tasks grow more complicated, performance declines.
MEMORY Although memory for material learned prior to intoxication often remains intact after smoking marijuana, other aspects of memory decline dramatically.
Another type of memory, free recall, shows definite impairment during intoxication.
Although much of this work reveals no gross impairment in chronic users, some studies report lower test scores or deviant brain waves in those who smoke daily for extended periods.
In general, despite the many critiques of the research so far, chronic marijuana consumption does not appear to create gross neuropsychological impairments.
Regular use for many users does, however, lead to deficits on
highly sensitiv...
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In summary, quite a bit of research reveals no gross cognitive impairments related to chronic consumption of marijuana. Nevertheless, these studies may have biased, small samples, users with less-extensive drug histories, users who claim to be nonusers in the control group, or tests that require less skill for sufficient performance.
POLYDRUG CONSUMPTION Differences between chronic users of cannabis and nonusers may not arise from marijuana itself. Instead, the users may have consumed other drugs that created impairments.
Other tests of chronic exposure in rats found learning deficits that did not improve, even after months of abstinence (e.g., Stiglick & Kalant, 1982a, b). These animal studies offer compelling evidence that marijuana, and not some other drug, creates problems in learning and memory.
These data suggest that long-term use creates specific memory and attention problems, but differences prior to ever using the drug cannot be completely ruled out.
A study of 25 nonusing undergraduates and 25 who smoked at least twice a week suggested that marijuana interferes with transferring information into long-term memory.
A couple of other studies revealed the unexpected superior performance of users over nonusers.
This study offers potential support for marijuana-induced impairment and also may imply that intermediate and light use does not create cognitive deficits.
The potential impact of cannabis in adolescence has not received appropriate attention.
A body of evidence reveals that chronic, heavy marijuana smokers may not perform as well as nonsmokers on complex cognitive tasks.
Thus, chronic users appeared to have more trouble distinguishing between these different stimuli.
These results suggest that the ability to separate relevant from irrelevant stimuli may take longer to recover. In contrast, the slowing of the P300 was no longer present in the ex-users. Apparently, this aspect of processing recovers more quickly.
Perceptions change during marijuana intoxication. Time and space appear distorted. The senses seem more sensitive.
This huge variation in responses suggests that no one person’s intoxication experience is typical.
Zinberg (1984) refers to the relevant environment as the setting and the individual’s expectations as the set. He asserts that both set and setting can contribute to the impact of any psychoactive drug. Many studies support his ideas.
One of the first formal investigations of the phenomenology of marijuana intoxication asked more than 200 questions of 150 people who had used the drug at least a dozen times (Tart, 1971).
The research identified over 30 experiences that were characteristic of the marijuana high. Tart (1971) defined a characteristic effect as one that at least half of the people indicated that they experienced very often or usually.
Common effects were those that half of the participants (or more) reported experiencing at least sometimes.
Time Literary accounts of intoxication frequently mention a distorted flow of time (Gautier, 1846; Ginsberg, 1966). Early case studies of cannabis’s effects also emphasized the feeling that time slowed.
Space Moreau’s (1845) early studies of hashish intoxication revealed a deviant sense of spatial relationships.
Vision Changes in vision often accompany marijuana intoxication. Intoxicated individuals report enhanced visual acuity and depth perception, but laboratory studies suggest impairment in these same abilities.
Nevertheless, 9% of Tart’s (1971) sample considered hallucinations a usual effect that began at very high levels of intoxication.
Thus, research confirms that people think that cannabis improves their imaginations, but has yet to confirm any actual positive changes.
Cannabis intoxication may also alter perceptions of depth.
Nevertheless, data reveal that people think marijuana can enhance some visual processes, and laboratory research suggests it actually impairs some of them.
Hearing Marijuana intoxication may alter the perception of sounds.
A common, related auditory effect concerns sound taking on visual, colorful qualities. Researchers call this confusion of one sense for another “synaesthesia.”
Touch Altered perceptions of tactile stimuli serve as a hallmark sign of marijuana intoxication. Literary accounts of intoxication consistently emphasize an altered sense of touch.
These tactile sensations may contribute to marijuana’s legendary enrichment of sexual experiences, which appears in more detail in the discussion of higher functions.
Despite self-reports and literary examples of enhanced tactile senses, experiments suggest that related abilities may actually suffer during intoxication.
Taste Gautier (1846) claimed that the simplest water tasted like exquisite wine after eating hashish.
Tart’s (1971) sample revealed a related, characteristic effect: intoxicated individuals enjoyed eating and reported consuming large quantities of food. They also commonly craved sweets during intoxication.
This result suggests that marijuana may slow metabolism as well as increase food consumption (Foltin, Fischman, & Byrne, 1988). Results like these have inspired the medical use of cannabinoids to improve appetite for people with problematic weight loss, as discussed in chapter 8
Emotion Any drug’s impact on human feelings determines its potential for repeated use. Literary works devoted to cannabis frequently mention its pleasant influence on emotion.
This effect appeared at moderate levels of intoxication or more. Users also grew more relaxed at this level of intoxication.
