Dr Lachlan Kent and Dr Brennan Spiegel are joined by Elisa R. Ferrè, professor of cognitive neuroscience at Birkbeck, University of London, and one of the world’s leading experts on graviception and the vestibular system.

Together, they explore how the brain senses gravity without a single “gravity receptor,” why the vestibular system has no primary cortex, and how gravity is computed as a distributed, multisensory model integrating vestibular, visual, proprioceptive, and visceral signals. The conversation spans neuroscience, emotion, aesthetics, culture, spaceflight, and mental health—revealing gravity as the hidden scaffolding of perception, meaning, and wellbeing.

1. What Is Graviception?

The brain’s ability to sense and model gravityNot driven by a single receptor or cortical areaConstructed through multisensory integrationFundamental to embodiment, orientation, and survival

Why the Vestibular System Is Unique

No unimodal “vestibular cortex”
Projects broadly across the brain
Does not produce a clear conscious sensation
Becomes noticeable mainly when something goes wrong (dizziness, vertigo, nausea)

The vestibular system acts as the glue binding mind and body, anchoring us in a single embodied perspective.

How the Brain Computes Gravity

Gravity is not perceived directlyThe brain integrates:

• Vestibular otolith signals (head tilt, linearacceleration)
• Visual cues (verticality, alignment)
• Proprioception (joints, muscles, posture)
• Visceral signals (internal organs)

Each signal is weighted by reliability to form an internal model of terrestrial gravity.

Gravity, Meaning, and Culture

Preferences for verticality (upright lines, tall buildings)
Vertical = power, stability, positivity
Downward tilt = unease, disorder
Gravity shapes art, architecture, language, and metaphor

Up = good, free, elevated
Down = heavy, negative, constrained

Emotion, Fear, and the Vestibular System

Vestibular pathways connect directly to:

• Amygdala
• Insula
• Hypothalamus

This explains why vestibular disturbances are emotionally chargedDizziness and vertigo trigger fear, nausea, and autonomic responses
Gravity sensing is deeply tied to survival systems

Weightlessness and Freedom

Parabolic flight (“vomit comet”) as a unique graviceptive state
Weightlessness described as profound freedom
Also physiologically challenging
Post-flight “down” feelings mirror return to gravity

Freedom comes with a cost: sensory conflict and adaptation demands.

Space Adaptation & Neuroplasticity

Astronauts experience space motion sickness
Symptoms: nausea, disorientation, brain fog
The brain can adapt through neuroplasticity
Adaptation takes time, energy, and training

Implicationsfor long-term space travel and Mars exploration.

Gravity, Mental Health, and Everyday Life

Anxiety as mis-tuned gravity anticipation
Depression as altered temporal and bodily grounding
Mental fitness as trainable gravity resilience

Tools discussed:

• Yoga and posture
• Breath awareness
• Grounding through the feet
• Weighted blankets
• Music, rest, and multisensory regulation

Practical Graviceptive Tip

Stand still and feel the pressure through the soles of your feet
Notice the security of 1G
Use grounding as a way to reduce anxiety and reset expectations

Timecodes

00:00 — Introduction & guest welcome
02:00 — What makes the vestibular system unique
05:00 — Why gravity is mostly unconscious
06:30 — How the brain computes gravity
09:30 — Homunculus vs gravity computation
11:30 — Gravity as a prior for perception
14:00 — Semantics, aesthetics & verticality
17:00 — Architecture, art & meaning
20:00 — Vestibular system & emotion
22:00 — Parabolic flight & weightlessness
24:00 — Freedom, addiction & the cost of zero-G
28:30 — Space adaptation syndrome
31:00 — Can humans adapt to Mars?
35:30 — Everyday graviception & grounding
38:00 — Closing reflections

Resources

The Gravity Doctors: https://thegravitydoctors.com
Dr Brennan Spiegel: https://brennanspiegelmd.com
Dr Lachlan Kent: https://lachlankent.au