How Your Thoughts Are Built & How You Can Shape Them | Dr. Jennifer Groh

The Brain's Multisensory Integration

Right from the start, Dr. Groh invites us to rethink how we experience the world by explaining how our senses—especially vision and hearing—merge seamlessly in the brain. She recounts her initial fascination with the superior colliculus, a midbrain structure where visual and auditory information first truly collide. This blending is dynamic: as our eyes move, neurons adjust their receptive fields, recalibrating where sounds appear in our spatial world. Have you ever noticed how effortlessly you match the voice to the person's moving lips, even if sounds come from speakers placed elsewhere?

Though this task seems straightforward with pencil and paper, the brain's ability to relocate sound in relation to shifting eye positions is a marvel. Beyond the superior colliculus, multisensory integration permeates several brain areas, showing that our brain continually remaps sensory inputs for a coherent perception. This commission of senses is essential to orienting quickly to our environment and inserting us fluidly into the sensory landscape.

Precision Localization

Dr. Groh delves into the intricate physics of auditory localization, highlighting astounding biological acuity. Our brains detect minuscule differences—on the order of half a millisecond—in the time sound takes to reach each ear, enabling us to pinpoint a sound's origin. What's striking is this temporal resolution is even shorter than the duration of a single neuronal action potential, challenging our assumptions about neural processing speed.

This ultra-fine timing is complemented by level differences in sound—how loud it is at each ear—and by unique frequency filtering caused by the folds of our ears. These biological structures act as signature filters that help us identify not just direction but also subtle spatial cues. Remarkably, people with differently shaped ears essentially have customized auditory 'fingerprints' to distinguish sound sources, allowing us to adapt even with hearing loss or physical changes to our ears.

Consciousness and Sensory Integration

Though sensory integration begins in subcortical structures like the superior colliculus, Dr. Groh notes that much of this process happens outside conscious awareness. Our brains perform elaborate computations beneath the surface, stabilizing a visual and auditory scene that would otherwise be incoherent—such as the massive jitter of the retina during rapid eye movements.

This subconscious synthesis prompts a fundamental question: where is consciousness localized in this sensory symphony? While the exact neural seat of conscious awareness remains an open frontier, it's clear that many sensory integration processes proceed automatically to create seamless experience. We often take for granted the effortless merging of multisensory signals that guide our focus and actions without requiring deliberate thought. Isn't it fascinating that your brain's backstage calculations sculpt what you ultimately become aware of?

Physical Environments Shapes Perception

Dr. Groh enriches our understanding by discussing how physical spaces modulate sound perception. For instance, the whispering gallery in New York's Grand Central station allows people to hear soft voices over remarkable distances, thanks to the architecture directing sound waves along curved surfaces. Such environmental peculiarities beautifully illustrate how our surroundings enhance or alter sensory experience.

Conversely, expansive spaces such as cathedrals create delayed sound reflections, producing reverberations or echoes that linger and enrich musical performances. These acoustic properties influence the tempo and style of music historically composed for those spaces, like Gregorian chants, where slower, sustained notes blend harmoniously with natural echoes. How often do you think about the room you are in when you listen to music or speak to someone?

The Role of Frequency and Resonance

Music and sound are not merely environmental phenomena—they profoundly influence our emotions. Dr. Groh invites us to consider the physics of sound frequency and resonant vibrations and their links to emotional states. Bass tones tend to carry farther and can evoke feelings tied to vigor or menace, while high-frequency flutters are associated with lightness or excitement, concepts often employed by composers and filmmakers alike.

This connection extends beyond aesthetics to evolutionary theories, such as music's role in synchronizing group behaviors or signaling readiness for collective action, like the Māori haka before rugby games. Music might act as a primal social glue, tapping into ancient neural systems that link sound, emotion, and movement. What feelings does your favorite song evoke, and could these be tied to the underlying frequencies more than the lyrics?

Thought as a Simulation

One of the most compelling insights from Dr. Groh's work is the idea that thinking itself is the brain running internal sensory-motor simulations. When you think of a 'cat,' for example, your brain may activate patterns in the visual cortex reminiscent of seeing a cat, in the auditory cortex the cat's meows, and perhaps even olfactory areas involved with scent. This view frames thoughts not as abstract, symbolic constructs but as internally generated experiential replays.

This explains why thoughts can feel multi-sensory and vivid and why distractions or demands on sensory processing can impair complex tasks—like why talking impairs driving in difficult traffic. If thinking depends on a sensory-motor substrate, it requires cognitive resources similar to real perception and action. Have you ever felt mentally fatigued simply from a complex internal "conversation" or extended visualization? Perhaps that's why.

Attention, Flow, and Brain States

Building on the nature of thought, the discussion draws attention to how brain states govern our ability to focus or enter flow. Dr. Groh introduces attractor states—stable patterns of neural activity akin to a ball settling into a valley on a landscape—which shape how attention narrows and sustains. Flow states represent the deep trenches where cognitive resources are efficiently engaged, often accompanied by a temporary loss of self-awareness.

Yet, sustaining attention is costly, and cognitive fatigue spreads the landscape, making focus harder to achieve. Apparent distractions and fragmented thoughts partly arise when one's attentiveness is spread thin. This dynamic is compounded by modern sensory overload, such as constant phone notifications. What strategies might help flatten those distractions so your mental "ball" can settle deeper into the flow valley?

The Challenge of Controlling Thought

Dr. Groh remarks on the protean nature of thought—how often our ideas zipping through our minds are incomplete, jumpy, or fragmented, rather than neat, continuous sentences. This scattered pattern challenges common beliefs that focused, linear thinking is the default. Instead, cognitive processes naturally shift rapidly among topics or sensory modalities.

Interestingly, attempts to produce completely unrelated thoughts are almost impossible because cognitive networks link ideas strongly, making truly arbitrary thinking a rarity. This has implications for creativity, problem-solving, and emotional health. How often have you caught yourself jumping from one idea to another and wondered why your mind won't "stay on track"?

Sensory-Motor Integration

When it comes to performing complex tasks like music, Dr. Groh explains how attention and motor control interplay tightly. She shares her own experience juggling the demands of singing and banjo playing—singing benefiting from adrenaline while fine motor control can falter under pressure. This balance underscores the nuanced relationship between brain arousal states and skill execution, consistent with the Yerkes-Dodson law.

In high-pressure situations, "choking" can occur because of too much motor unit recruitment leading to impaired precision. Understanding this helps us see flow not just as mental focus but as finely tuned sensorimotor coordination. Could this insight transform how athletes, musicians, and even public speakers prepare for performance?

Vision's Influence on Brain State

Vision is uniquely powerful in shaping attention and brain states. Dr. Groh highlights examples ranging from the hypnotic fixation seen in chickens held in a state of "tonic immobility," to human classroom techniques in China where students train their eyes on a single point to boost attention. Such practices demonstrate vision's ability to narrow cognitive focus—a hyperfocused state akin to hypnosis.

Natural vision of broad landscapes, like distant horizons, conversely induces relaxation, engaging parasympathetic modes linked to panoramic vision. These opposing effects reveal how eye movement and gaze patterns modulate arousal and cognitive readiness. How might consciously shifting your gaze bring you instantly into focus or calm?

Modern Technology's Impact on Cognitive Focus

Dr. Groh acknowledges the complex role of smartphones and digital devices in cognitive life today. While these tools offer immense convenience and access, they also flood our sensory space with endless, contextless stimuli, fragmenting attention and increasing cognitive load. The seamless on-ramp to new information with no clear stopping point creates "attention traps" similar to slot machines compelling users to stay engaged.

Her pragmatic approach includes deliberate boundaries: separating devices, limiting social media to less accessible platforms, and creating physical spaces conducive to undistracted work. Can we redesign our environments and habits to reclaim focus in the digital age?

Trusting the Flow and Rest Cycles

Finally, Dr. Groh and Andrew Huberman discuss the natural oscillations in brain states—periods of intense focus punctuated by breaks and downtime. Just as athletes train with intervals, mental work similarly thrives by respecting these rhythms. Creative insights often emerge through marination during rest or distraction, not just during active effort.

Rather than forcing continuous output, embracing these cyclical states enables productivity and mental health. The key lies in tuning into your own natural attention cadence and creating systems that support them. Could the secret to better thinking be less about pushing harder and more about flowing with your brain's own tempo?