Memory

Memory occurs where the present and the past collide. Experts and smokers alike agree that marijuana temporarily impairs short-term memory. But although it has been less studied, marijuana has another effect on memory: in Charles Tart's survey of smokers, nearly 40 percent of those asked said that their memory for otherwise forgotten events was improved by smoking and that it was even better than when, without marijuana, they consciously tried to recall these events. Over half of the sample reported that, high, they spontaneously remembered things they hadn't thought of in years.[3]
    Not surprisingly, most studies have concentrated on the negative aspects of marijuana's effects on memory. About a decade ago, a group of Stanford University researchers headed by Frederick Melges conducted several experiments to determine exactly which aspects of memory were affected by marijuana.[4] Using graduate student volunteers, the research team administered several well-known memory tests. In one, known as "serial sevens," subjects were asked to begin counting with a number around 100, and then to subtract seven serially until they reached zero, as in: 99, 92, 85, and so on. This test measured long-term arithmetical memory as well as the ability to concentrate, and even very high doses of THC did not affect the scores.
    To assess the impact of THC on short-term memory, the experimenters asked the students to repeat a series of random digits forward and backward. This test indicated that the performance of subjects declined under the influence of THC (which had been extracted from marijuana), although increasingly higher doses did not cause a progressive deterioration of memory.
    Finally, the volunteers were given a more complicated test, which involved both immediate memory and a mental manipulation of remembered facts. Each volunteer was assigned a number between 106 and 114 and was asked to subtract 7, and then to add 1, 2 or 3, repeating the alternate subtractions and additions until he arrived at a predetermined number between 46 and 54. The students who had ingested THC had considerable difficulty with this test. Apparently, their problems were due not only to impaired memory but also to a lessened ability to coordinate the processes of memory and thought.
    In Erich Goode's survey, one-fifth of the respondents reported that they tended to forget simple things when they were high. Goode points out that smokers may indeed discover that their recent memory is affected by marijuana, but, strictly speaking, immediate memory is not. The smoker experiences no present-tense loss: he does not forget who he is, or who his friends are, or where he is, although he may indeed forget what he was saying just a few moments earlier.[5]
    Smokers are more amused than disturbed by their lapses of memory. The problem occurs most frequently in a user's inability to remember how he began a particular sentence whose first part sometimes seems to have been spoken twenty minutes earlier. Along similar lines, some smokers find that they have little difficulty in playing chess while they are stoned, but that they are continually forgetting whose move it is. "It's a little embarrassing to be deep in a game," says one serious chess player, "and then suddenly to blurt out, 'Excuse me, but am I playing white or black?'"
    One man refers to his lapses of memory while he is stoned as "black holes"; he says that they usually become filled in again within a few days. Mark, not surprisingly, has a more academic explanation:

Psychologists speak of short-term memory in terms of a theory developed by George Miller known as seven-plus-or-minus-two. Essentially, the idea is that you can keep seven discrete things in your mind. If you want to hold onto more than that, you somehow have to chunk things together in a new grouping, so that you still hold seven chunks of information. Marijuana cuts this ability roughly in half.
    Think of it as a line of seven things. You put new things at the start of the line, and old things fall off the end. If you want to retain what fell off you have to pick it up and put it at the beginning again. If you keep it around long enough, you'll eventually remember it. Of course, all of this goes on at an unconscious level.

    Karl and Martha have never heard of this theory, but their explanation of the effects of marijuana on their own ability to remember is strikingly similar to Mark's theoretical outline. They call it "the train thing":

When you're stoned, your mind is like a train, and it runs on tracks. New cars are always coming on one end, and old cars are falling off the other. Normally, your mind can retain all of these thought-cars, or at least some of them, and there's usually a strong connection between each car and its neighbor.
    But when you're stoned, each new car that comes along knocks off one of the others. We visualize this train going down the track, and the track gets increasingly shorter as you get stoned, and you can't hold onto as many cars. Whenever this happens, and one of us forgets something, we'll say, "Oops, a car just fell off!"
    Sometimes we can actually feel that car falling off. The thing is that you can feel yourself in the act of forgetting; you can physically feel that car falling off.

    The idea that short-term memory is impaired by marijuana may be a negative way of looking at an essentially positive process. "I used to think it was simply a matter of marijuana impairing short-term memory," notes Andrew Weil. "But now I see that a common feature of many altered states of consciousness is increased concentration on the present. When you are high on marijuana, you pay more attention to the present and less to the immediate past, and this shift may be beneficial."
    Some smokers agree, and they believe that the effects of marijuana on their memory may be precisely what makes so much that happens while smoking feel new and fresh. For these people, each episode of lovemaking, eating or even watching television stoned may contain at least a suggestion of what the experience was like the first time.
    This process may take place most dramatically in terms of language. An astonishing 88 percent of Tart's sample found that, at least occasionally, "commonplace sayings or conversations seem to have new meanings, more significance" when they are stoned. Jenny provides an example:

We were on vacation at a ski lodge, and people were playing cards. I was stoned, and walked up to the table and took a seat. "Deal me in," I said without thinking. Then, when I thought about what I had said, I felt great pleasure that I was using the phrase in its original context rather than as a metaphor for something else.[6]

    The ability of some smokers to recall past events spontaneously has clear implications for psychiatry.[7] This is also one of the causes of "bad trips," wherein a person may be flooded with the details of a feeling or event he has no wish to remember. A parallel and more pleasant experience is a trick often played by the stoned memory: the occasional tendency to "recognize" faces in a crowd that remind the smoker of people he has known. An American traveling in India describes this phenomenon:

Often I see people I know in people I don't. It's especially true traveling. Even with people of different races here in India, and wearing different clothes, it still happens at least once a day. A person at one moment in India is a person I know in Miami, and I have to stop myself from going over to say hello. I find that smoking breaks down restricted ideas of the self and others; in a crucial way, people are other people.

    A similar process was noted by Walter Benjamin, the German-Jewish literary critic, in an essay written in 1932 entitled "Hashish in Marseilles":

It was above all men's faces that had begun to interest me. Now began the game, to be long maintained, of recognizing someone I knew in every face; often I knew the name, often not; the deception vanished as deceptions vanish in dreams: not in shame and compromised, but peacefully and amiably, like a being who has performed his services.[8]

    Scientists are still undecided as to exactly how marijuana affects the human memory. Does the disruption of short-term memory occur during the acquisition of information into the memory, during the storage of that information, or during the demand for its retrieval? In Aldous Huxley's famous book on mescaline, The Doors of Perception, he wonders whether the brain and nervous system might function in a way that is mostly eliminative. He suggests that at any given moment, each person is theoretically capable of remembering everything that has ever happened to him, which would mean that the function of the brain and nervous system is to protect us from being overwhelmed and confused by so much information. If Huxley's idea is correct, then marijuana may simply shut out peripheral information as it opens the windows of the mind and memory a little wider.