By: Philip Gerrans and Chris Letheby

In: Aeon

Date: 2018

Key Concepts:

• Psychedelics:
  • Induce an altered state of consciousness known as ‘ego dissolution’.
    • Sensations of self-transcendence.
    • A feeling in which the mind is put in touch more directly and intensely with the world.
    • Producing a profound sense of connection and boundlessness.
  • Bind to a specific type of serotonin receptor in the brain.
    • The 5-HT2A receptor.
    • Precipitates a complex cascade of electrochemical signaling.
• Complex relationship between the brain, the self and its world.
  • Where does the subjective experience of being a person come from?
  • How is it related to the brute matter that we’re made of?
• Views on consciousness / conscious experience:
  • Awareness of a ‘thinking thing’, the self.
    • Self-awareness is a form of bodily awareness.
    • Produced (at least in part) by interoception.
    • Ability to monitor and detect autonomic and visceral processes.
  • A mere stream of experiences.
    • We incorrectly infer the existence of an underlying entity from this flow of experiential moments.
    • We have perceptual, cognitive, sensory and, bodily experiences – but that is all.
    • Abnormal cognitive conditions, pathological or otherwise, serve as a crucial source of evidence.
      • They offer the chance to look at the self when it is not working ‘properly’.
• Cognitive binding.
  • The integration of representational parts into representational wholes by the brain.
  • Unclear how – the “binding problem” remains unsolved.
• Predictive processing.
  • Theory of cognition.
  • Views the brain as a prediction machine.
  • Models the causal structure of the world to anticipate future inputs.
  • Any discrepancies between an expectation and an input take = error signal.
  • Demands a response from the organism:
    • Update the internal model.
    • Or, act to reduce the unpredicted input.
  • Humans build such accurate predictive models of their world that error signals are minimised, almost to the point of being eliminated.
• Model.
  • Mental representations that organize information.
  • Allow the brain to extract signals from noise.
  • What we ultimately experience, is the model that we’ve learned is the best fit for the information to hand, that best predicts and accounts for our perceptions before they happen.
• Perception becomes little more than a kind of controlled hallucination.
  • There is some kind of world out there that our brains need to find a way to track.
  • It is by approximating the structure of this reality (even if we can’t apprehend its metaphysical truth or nature) that our predictive brains save us from getting run over.
  • We do not experience the external world directly, but via our mind’s best guess as to what is going on out there.
• Takes advantage of regularities in the environment.
  • Due to statistical regularities in the environment over time, the most predictively successful perceptual models turn out to be those that create a world and populate it with objects with particular properties, concrete and abstract, to be sensed and thought about.
  • Past experience teaches us that certain combinations of features are more likely to co-occur than others.
  • This predicted coherence is increased by attributing these features to the same persisting object.
• Your sense of self is nothing more than one of these rough-and-ready models.
  • Compressing properties of the world so that they’re easier to grasp.
  • The modeled self is a sort of meta-filter for the signals you get from the functioning of your whole organism.
• A hierarchy of models.
  • Each level deals with different aspects of organismic functioning.
    • Bodily boundaries, regulating homeostasis and sensory-motor encounters with the world.
    • Memory, inference and imagination.
    • Narrative “I”, bound across hierarchy and through time.
• Located in salience network and default mode network.
  • Salience network:
    • The significance of bodily states triggered by worldly encounters.
    • More or less: embodied self.
  • Default mode network:
    • Episodes of autobiographical thought such as memory, imagination, planning and decision-making.
    • More or less: narrative self.
• Predictions can cause stress and unhappiness.
  • Self-models can magnify the adversity of the social world.
  • Predictions can become self-fulfilling.
  • Analogy: lenses of our eyes.
• Psychedelics and ego dissolution.
  • The integrity of the self-model degrades.
  • We no longer take it for granted that our experience must be interpreted by that model.
  • Psychedelics allow you briefly to hear your personal language of subjectivity as sound, not meaning.
  • Whether you want to learn another language of selfhood is up to you.
• Self:
  • A model, not a thing.
  • Forms over a life time.
  • A fundamental cognitive strategy, one which has developed over evolutionary time.
  • [Associated with material representations, such as strengthened neural connections?]