Carl Sagan, Cannabis and the Right Brain Hemisphere

Carl Sagan philosophised that the cannabis experience profoundly enhanced the capabilities of the right brain. Functions such as creativity, pattern recognition, insight and memory are governed by the right brain. Now, 40 years later, does modern research support Sagan’s philosophy?

What it comes down to is that modern society discriminates against the right hemisphere.

Roger Wolcott Sperry (1913-1994), neuropsychologist and neurobiologist, known for his revolutionary studies of split-brain patients

In 1971, Harvard Prof. Lester Grinspoon published his milestone book “Marijuana Reconsidered“, in which he featured an essay “Mr. X” by his best friend, the famous astronomer and scientist, Carl Sagan. In his essay, Sagan reports that for him, the cannabis high led to various cognitive enhancements, including an enhancement of cognitive abilities like enhanced episodic memory, pattern recognition, creativity, and the ability to produce insights. Sagan’s essay “Mr. X” is still one of the most illuminating accounts on the positive mind-altering potential of the cannabis high.

Sagan is not the only academic or great thinker to provide a neurophilosophical account of the cannabis experience. Philosopher Sebastian Marincolo delves into the impact of cannabis on the mind in his book, “High. Insights on -Marijuana”.

He doesn’t explore ideas strictly through the lese of cognitive sciences, but also through his philosophy of mind. His paper moves through reports given by cannabis users as well as cutting-edge research from a range of disciplines to explain his understanding of the cannabis-mind phenomenon.

Sagan’s hypothesis

Sagan was so excited about the cognitive enhancements he experienced with cannabis that he used it often to better understand his work. His biographer Keay Davidson wrote that when Grinspoon received unusual high-quality marijuana from an admirer by mail, he shared the joints with Sagan and his wife Ann Druyan. “Afterward, Sagan said, ‘Lester, I know you have only got one left, but could I have it? I’ve got serious work to do tomorrow and I could really use it.”

Sagan was famous – or, for many of his academic colleagues, infamous – for making brilliant but daring speculations – not only in his field of astronomy, but also in other scientific fields. As Keay Davidson remarks in Sagan’s biography, Sagan for instance wrongly predicted the existence of complex organic molecules on the moon. Davidson later adds, “as it turned out later, complex organic molecules pervade much of the outer solar system and beyond.”

In his Pulitzer price-winning book “The Dragons of Eden – Speculations on the Evolution of Human Intelligence” (1977), Sagan introduced a survey of what cognitive and evolutionary scientists had to say about the evolution of the human mind. He presented many of his own brilliant speculative ideas on the nature and evolution of human intelligence. Sagan also introduced a speculative thesis about the effects of cannabis on the human brain. He started from an analogy made by psychologist Robert Ornstein:

“He {Ornstein} suggests that our awareness of right hemisphere function is a little like our ability to see stars in the daytime. The sun is so bright that the stars are invisible, despite the fact that they are just as present as they are in the daytime as at night. When the sun sets, we are able to perceive the stars. In the same way, the brilliance of our most recent evolutionary accretion, the verbal abilities of the left hemisphere, obscures our awareness of the functions of the intuitive right hemisphere, which in our ancestor must have been the principal means of perceiving the world.”

In a now famous footnote to this paragraph Sagan formulates his hypothesis on how a marijuana high could affect thinking:

“Marijuana is often described as improving our appreciation of and abilities in music, dance, art, pattern and sign recognition and our sensitivity to nonverbal communication. To the best of my knowledge, it is never reported as improving our ability to read and comprehend Ludwig Wittgenstein or Immanuel Kant; to calculate the stresses of bridges; or to compute Laplace transformation. (…) I wonder if, rather than enhancing anything, the cannabinols (the active ingredient in marijuana) simply suppress the left hemisphere and permit the stars to come out. This may also be the objective of the meditative states of many Oriental regions.”

Enhancements and Suppression

Let’s distinguish two aspects of Sagan’s hypothesis: first, there is the observation that a cannabis high leads to a style of cognition which cognitive scientists consider to be predominantly based in the right hemisphere. Second, Sagan speculates that a marijuana high might suppress left hemisphere functions and, therefore, lead to what we could call “right hemisphere thinking”. “Right hemisphere thinking” is usually associated with creativity and artistry, although new brain imaging shows that creative thinking doesn’t actually prefer a hemisphere of the brain.

Sagan’s hypothesis was based on his knowledge of what current science had to say about the human brain and the different style of cognition in the left and right brain hemispheres, as well as on his own experiences with cannabis.

Sagan’s claim reconsidered

During his lifetime, Sagan did not reveal to the public that he was a user of cannabis. In isolation, Sagan’s footnote about marijuana and its possible effect on the brain hemispheres seems to be a spontaneous speculation out of nowhere. Yet, when reading Sagan’s essay “Mr.X”, it becomes clear that Sagan’s experiential basis for such a claim was actually quite vast.

In his essay, he describes in some detail not only the enhancements mentioned in his footnote, but he also mentions other cognitive enhancements, such an enhanced ability to remember past events and to obtain deep insights. Also, like some other users before him, Sagan mentions that during a high, he also experienced enhanced

”perceptions of real people, a vastly enhanced sensitivity to facial expressions, intonations, and a choice of words which sometimes yields a rapport so close it’s as if two people are reading each other’s minds.”

Sagan already knew that all of the cognitive enhancements he had described during a high would concern functions which cognitive science at the time found to be predominantly located in the right brain hemisphere. He described the research concerning split-brain patients and more on the pages preceding his hypothesis in “The Dragons of Eden”.

It’s quite obvious that Sagan draws his philosophies and theories from research and his own personal experience. But he also draws much of his philosophy from his friend, Lester Grinspoon and his research about marijuana’s mind-enhancing potential. As Lester Grinspoon told Sebastian Marincolo in private conversation, Carl Sagan had carefully read and commented on his manuscript of “Marijuana Reconsidered”. In this manuscript,  Grinspoon extensively featured reports of other users who had described similar mind enhancements.

Sadly, Sagan died in 1996, too early to witness the revolutionary discovery of the endocannabinoid system. Since then, we have learned about the amazing range of its physiological and cognitive functions. So, can we actually find evidence for or against Sagan’s hypothesis by looking at the distribution of endocannabinoid receptors (especially the CB-1 receptor, on which the exogenous THC acts)?

Sagan’s thesis and the endocannabinoid system

Since Sagan’s research, we have acquired 40 more years of exploration into cannabis, mind science and cognition. To what degree does Sagan’s hypothesis match up with modern research and philosophy?

There doesn’t seem to be extensive research that concerns lateralization and the role of endocannabinoid signalling for higher cognitive functions. One often cited study found an increased blood flow in parts of the right hemisphere during a cannabis high. However, another study states that 

“relatively high concentrations of cannabinoid receptors were consistently seen in cortical regions of the left (dominant) hemisphere, known to be associated with verbal language functions.“ “The left and the right brain hemisphere. They are anatomically similar, but different, and ongoing cognitive science is still being done to find out which cognitive functions are dominated by one side or the other.”

It seems much too early to draw conclusions from brain imaging studies to evaluate Sagan’s hypothesis. Marsicano and Kuhner remind us that „sometimes the endocannabinoid system appears to be functionally important in regions or cell types where the density of CB1 receptor is relatively low {e.g. control of pain perceptions in the brainstem}.” As far as our research takes us, we haven’t yet begun to understand how endocannabinoids are involved in affecting different higher cognitive functions based in the left or right brain hemisphere.

This could also be because the scientific community still isn’t quite sure where higher cognitive function takes place in the brain in the first place. While the cerebrum is implied in higher cognitive function, creativity apparently has no specific location in the brain, and uses a wide-spread brain network.

Recent neuroscience and reports about the cannabis high

However, some more support for Sagan’s thesis seems to come from two other sources. First, Sagan’s description of the cognitive enhancements during a marijuana high have been described in detail by other philosophers, such as Sebastian Marincolo. They are also reported by other cannabis users. The most impressive collection of recent anecdotal reports and essays about those enhancements comes from Sagan’s best friend Lester Grinspoon and can be found on his website

Second, if we look at what recent neuroscience has to say about differences in the cognitive functions and processing styles in the two brain hemispheres, Sagan still seems to have a point. From what we know now, the right hemisphere plays an important role for the cognitive processes named by Carl Sagan as enhanced during a high, as well as for many other enhancements described by other marijuana users.

In his book “The Master and his Emissary. The Divided Brain and the Making of the Modern World, (2009), psychiatrist Ian McGilchrist gives a survey of the current scientific knowledge about the different styles of cognition in the left and the right brain hemisphere. He uses stroke cases, split-brain patient cases and newer brain imaging studies to present his hypotheses.

According to McGilchrist, the right hemisphere is predominately involved in our ability to remember personal events (episodic memory), for associations between widely different concepts and ideas, complex pattern recognition, creative problem solving, insights, and the appreciation of humour (all things that Sagan alluded to in his papers).

McGilchrist also says that the right brain is responsible for the understanding of metaphors, self-awareness, the empathic understanding of others, the processing of words describing the mind, and the interpretation of emotional expression in faces, in intonation and verbal implications.

Also, the right hemisphere seems to be crucially involved in the interpretation of non-verbal communication and the perception of music. In all fairness, this list is incomplete. McGilchrist goes into great detail of the functions of the right hemisphere, many of which are reported to be enhanced during a high.

The effect of cannabis on attention

In general, then, it seems that research of the last 40 years in the neurosciences lend some more support Sagan’s thesis that marijuana leads to an enhancement of right hemisphere-based cognitive abilities. One interesting puzzle, though, is one of the fundamental effects of marijuana on attention. During a high, we seem to ‘hyperfocus’. High users often get completely absorbed by the taste of ice-cream, by an intense stream of memories or ideas, or by the sensation of a kiss.

In other words, a high seems to cause a strong selective focus on whatever we attend to.  According to McGilchrist, however, focussed attention is not a cognitive function performed primarily in the right hemisphere. Quite on the contrary, he summarizes the current research as saying that “(…) the right hemisphere is responsible for every type of attention except focused attention.”

Evaluating Sagan’s hypothesis

So, when it comes to attention, at least one of the typical cognitive changes during a high does not seem to come from an enhancement of processes in the right hemisphere. Generally, then, while Sagan seems to have been basically on the right track with his hypothesis, not all of the cognitive enhanced functions during a high seem to be predominately based in right hemisphere activities.

We will have to wait for more research to be done in this field to see how exactly cannabis affects cognitive activities in the left and right brain hemisphere.

What about Sagan’s hypothesis that a high could suppress left hemisphere function and, thus, ‘bring out the stars’ and allow for an enhanced right hemisphere activity? We are far from being able to tell whether the mind enhancements during a high observed by so many users come from a direct enhancement of certain cognitive functions, or whether they come from a suppression of some left hemisphere activities.

According to McGilchrist, the left and the right hemisphere are in a constant battle for control. In order to help us to survive, we and other animals need two conflicting systems of attention. He explains this point with the example of birds: to pick up seeds for food, a bird needs to narrowly focus on the seeds on the ground to motor control and coordinate food intake (left hemisphere function); but in order to survive, the bird has to get distracted by a predator like a fox or a falcon in the fringe of its perception.

So there must be another type of attention drawing it to unusual new sensations (right hemisphere). Only the interplay of these competing attention systems located in the two brain hemispheres allows birds and other animals like us to survive.

Clearly, then, an enhancement of cognitive processes in one hemisphere could come from the suppression or weakening of cognitive functions in the other hemisphere. We still have to wait for further research to come to a better understanding on how consumed cannabinoids affect the endocannabinoid system and, generally, its role in higher cognition.

Yet, over 40 years after Sagan’s hypothesis, it’s still safe to say that he was on an interesting track. The understanding of cannabis’ effects on attention, memory, pattern recognition, creativity and emotional insight will only come when research is specifically dedicated to this task.

As yet, there is an underwhelming amount of research regarding the connection between cannabis, the endocannabinoid system and higher cognitive function. Until this research is done, we will never know the neuroscience behind cannabis and the two brains.

  • Disclaimer:
    This article is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with your doctor or other licensed medical professional. Do not delay seeking medical advice or disregard medical advice due to something you have read on this website.


5 thoughts on “Carl Sagan, Cannabis and the Right Brain Hemisphere”

  1. Lovely. Such fond memories of Carl’s wonderful Cosmos series from childhood. I briefly discuss Carl’s use of the herb in a new book (Cannabis Regeneration) from Green Candy Press – forthcoming: Sept 2015. Carl was proof that you could explore both the inner-self and the universe with enthusiasm, vigour, passion, and an open mind.

  2. Drs. Sagan and Grinspoon were men before their times. Cannabis does, indeed, open the mind to new ideas while somewhat blocking the ability of the mind to clutter thought with mundane matters.

    Taken to its limit, perhaps the lack of Cannabis in the daily regimen of U.S. leaders is why there is such a lack of positive leadership?

  3. Men of the Earth have known the power of cannabis for centuries. Mr. Hearst made it part of the American Game and his rule was one of the more successful business/social manipulations of modern time. To bad they were never able to completely control, and in effect, set up the Legislation that is now sweeping the People of the States. The right to decide on cannabis is now a national issue. God Speed Free People of the World.

  4. Cannabis is the most useful plant on the planet; food, clothing, shelter, energy, medicine, insight, re-creation. It has been mankinds companion and helpmate since the beginning. Any law against it is a crime against humanity, creation and the Creator.

  5. Wauw that was very satisfying experience, i have just come from a private meditation session where i also vaporized some cannabis, and wanted so share my experience and express my gratitude to this article.

    First of all, im a former regularly user of cannabis, who used to have a moderate level/amount of intake, when i used/vaporized cannabis. (Meaning, i dont vape much when i do it, compared to most other users i know of).
    Now, i only use cannabis once in a while, (about 2 to 3 times a month). I have then started a practice where i sometimes vaporize some cannabis and meditate for a couple of hours thereafter.
    This night i had some insights, which led me to formulate a question which then led me to find this blog-article.
    And it was just so awesome to find out how much i resonated with the information regarding cannabis usage and the effect on our consciousness and attention-focus in (in between) the left and right hemisphere.
    Amongst other things of what i experienced, is the experience/feeling of being awake and asleep at the same time, like being conscious in the sub- or unconsciousness. Like with lucid dremaing where you “wake up” and become consciouss inside the dream.
    I also felt like being one with the now and with everything, and very aware/awake, and at total peace. It was a truly amazing experience.

    Thanks alot, Sebastián Marincolo for bringing this information to the net. It was very confirming and satisfying to me.

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    Sensi Seeds

    The Sensi Seeds Editorial team has been built throughout our more than 30 years of existence. Our writers and editors include botanists, medical and legal experts as well as renown activists the world over including Lester Grinspoon, Micha Knodt, Robert Connell Clarke, Maurice Veldman, Sebastian Maríncolo, James Burton and Seshata.
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