# on this day... ```dataview LIST file.link WHERE file.cday = date(this.file.name) AND file.name != this.file.name SORT file.cday ASC ``` # Chat about Bayesian Inference - https://chatgpt.com/c/67c9989c-5af0-8005-8cae-b066654ddee2 - Bayesian inference and perceptual phenomenology The text addresses the concern that Bayesian inference might seem overly abstract or detached from the rich phenomenology of perception—seeing isn't just labelling but involves rich experiential content. This problem is addressed through a hierarchical structure: Hierarchical perceptual inference: Bayesian inference is applied across multiple levels of a sensory hierarchy, ranging from basic sensory details (variant aspects, e.g., lighting or shadows) to stable recognitions (invariant aspects, e.g., seeing a face). The hierarchical arrangement allows perception to represent [[not just]] labels or categories but rich phenomenological details from a first-person perspective. This hierarchy is crucial in creating the difference between conceptual categorisation and true [[perceptual experience]]: “Perception captures our immediate and constantly varying first-person perspective” while simultaneously allowing for invariant recognition of stable, enduring objects (p. 29). - 7. What this means philosophically (why it's exciting) This "meta-inferential" view of introspection has major [[philosophical implications]]: Epistemology of introspection: It reframes introspection not as direct, privileged access, but as probabilistic inference about inference—thus fallible but systematically reliable. Phenomenology of uncertainty: Explains vividly why certain perceptual and cognitive uncertainties feel the way they do. Theory of mind and self-consciousness: Suggests introspection and consciousness exist because [[the predictive mind]] needs a model of its own predictions, for reasons of predictive reliability, adaptive flexibility, and social communication. - In [[predictive coding]] terms, attentional introspection involves voluntarily increasing the precision-weighting of certain internal [[mental states]] to enhance their salience in consciousness, without [[the need]] to correct prediction error. Here, attention increases the "gain" on particular [[internal representations]] to amplify subjective experience. - Meditative introspection could be understood as deliberately reducing precision-weighting on high-level predictive models. This allows lower-level sensory and internal experiences (typically treated as noise) to become phenomenologically vivid. The mind becomes aware of prediction-error signals without immediately resolving them, creating a sense of open presence and acceptance. # [[predictive processing]] and psychedelics --- ## Step 1: Understanding the Baseline—Phenomenal Transparency Under normal circumstances, according to **[[predictive processing]] (PP)** (Hohwy 2013, Clark 2016, Letheby 2021): - The brain constructs hierarchical models to predict sensory inputs. - [[Conscious experience]] results from these predictions. We do **not** perceive these experiences as representations or simulations. Instead, we feel as if we're directly encountering an external, objective reality. - This "direct realism" is a result of **phenomenal transparency**. ### Phenomenal transparency defined explicitly: > “‘Transparency’ refers to a property of conscious representations, namely, that **they are not experienced as representations**. Therefore, the subject feels as if [they are] in direct and immediate contact with [the] content [of the representations]” (Metzinger, quoted by Letheby, p.115). In simple terms: - When you look at a tree under normal conditions, you **do not experience your mental representation of the tree as a representation**. You experience the tree itself as directly and straightforwardly present in your consciousness. - Thus, the models constructed by your brain are "transparent"—they feel like reality, not internal constructions. --- ## Step 2: What Do Psychedelics Do According to PP? According to Carhart-Harris and Friston’s **REBUS model** (Relaxed Beliefs Under Psychedelics, 2019), psychedelics act primarily by: - Binding to serotonin (5-HT2A) receptors densely expressed in **high-level cortical areas** ([[Default Mode Network]] [DMN], Salience Network [SN]). - Weakening (reducing precision weighting on) the **high-level priors**—deep, fundamental assumptions about: - Self-identity - Causality - Space and time - Stability and permanence of external objects - Boundaries between self and external world Letheby explicitly notes that, under psychedelics, these “high-level priors” become relaxed, destabilised, or lose their "confidence-weighting." --- ## Step 3: From Relaxed Priors to Phenomenological Opacity Letheby makes the following crucial claim explicitly: > "According to PP, psychedelics expand the phenomenological possibility space [...] by diminishing the brain’s confidence in its foundational axioms." (Letheby, p.121) However, Letheby does **not explicitly** spell out exactly how and why relaxing these priors makes consciousness phenomenologically opaque. **My elaboration** ([[what you]]'re specifically interested in) is precisely here: explicitly detailing this transition from transparency to opacity. Let’s elaborate this systematically: --- ## Step 3: Detailed Elaboration of Phenomenological Opacity under Psychedelics (My Explicit Elaboration) When psychedelics relax high-level priors, the phenomenological transparency of consciousness breaks down. [[How does]] this happen step-by-step? **A. Reduced High-Level Precision** - Normally, high-level priors (beliefs about reality’s structure, stability, coherence, etc.) have very high precision or certainty. They act as powerful “filters” or constraints on incoming sensory evidence. - Under psychedelics, these priors lose precision: their power to shape incoming sensory data decreases. **Example:** - Normally, when looking at a tree, your brain’s strong prior belief "trees are stable, solid objects with fixed boundaries and stable identity" easily overwhelms minor anomalies (wind-induced motion, changing shadows). Under psychedelics, this prior is weakened, and sensory evidence that trees might move or flow (subtle motion from wind, shifting shadows) now exerts more influence on the [[resulting model]]. Thus, the tree might appear to subtly breathe or shimmer. --- ## B. Increased Phenomenological Awareness of Constructed Nature (Opacity) Because high-level priors are weakened, the brain’s internal inference mechanisms are suddenly more "exposed": - The sensory input previously explained away as irrelevant prediction error now rises vividly into consciousness. - The predictive "model-building" process, typically automatic and invisible, becomes more apparent, revealing conscious experience explicitly as an internal construction or simulation. **Example elaboration (mine):** Imagine looking at a friend's face. Normally, you perceive it as directly present—just your friend, immediately and simply "there." Under psychedelics, weakening of high-level assumptions about object permanence or stability may lead to the face appearing surreal, plastic, or mutable. Your experience explicitly becomes that of seeing an internally generated representation, rather than straightforwardly seeing your friend as objectively present. Thus, your phenomenology becomes opaque—you explicitly experience your visual representation as constructed. --- ## C. Experiential Analogies to Explain this Phenomenal Opacity To deepen your understanding, consider this analogy: - **Dream analogy (explicitly referenced by Metzinger and Letheby)**: Normally, dreams are internally generated and phenomenologically opaque: we’re often aware on waking or lucidly that dreams were internal creations, mere representations. However, waking reality is typically transparent—we take the world simply as given, forgetting it’s also internally represented. - Under psychedelics, waking consciousness becomes dream-like or opaque. Your experiential "dream-maker" (predictive brain) no longer hides its workings: you can perceive directly that your conscious reality is a product of your internal predictive models. --- ## Step 4: Concrete Example—The Tree Again (my elaboration): Imagine you’re staring at a tree under psychedelics: - **Initially (Transparent):** - Normally, the tree appears unquestionably real, objectively external. You don’t experience your representation of the tree, you experience “just the tree.” - **Under Psychedelics (Opaque):** - High-level priors weaken: your brain suddenly has less confidence in its "tree"-representation. - Lower-level sensory evidence (e.g., changing shadows, shifting leaves) is now weighted more heavily, making the perceptual model unstable or uncertain. - The representation itself becomes explicit as a model—you might experience the tree as “artificial,” “animated,” or “not entirely real,” explicitly noticing its representational nature. --- ## C. Conscious Meta-awareness of Representational Nature Critically, this opacity also involves introspection: predicitve processing + psychedelics - psychedelic aesthetics - llm text - Thus, psychedelics simultaneously trigger introspection and opacity: they weaken high-level predictions and at the same time encourage introspection to determine what caused this violation of experiential expectation. --- ## Step 4: Bringing It All Together (Elaboration Summary) - **Normal cognition:** - Strong priors → phenomenal transparency (experience not recognised as representational). - **Psychedelics:** - Priors weakened → phenomenological opacity (explicit representational nature consciously perceived). - Phenomenological transparency breaks down, exposing the brain’s internal construction processes explicitly. - **Introspection’s role:** - Psychedelics prompt introspective inference ("meta-inference"), leading you explicitly to perceive your perceptual experiences as internal constructions. --- ## Why Does This Matter? - This phenomenological opacity can lead to radical shifts in consciousness, awareness of subjective construction, and transformative insights into the workings of your own mind. - It profoundly illustrates the PP framework by concretely showing what happens when hierarchical Bayesian inference is weakened. --- This gives you a full, detailed, explicitly elaborated account of precisely how psychedelic phenomenology can shift consciousness from transparency (ordinary direct realism) into opacity (explicitly representational phenomenology). This elaboration connects directly to your interests in introspection as meta-inference.