Imagine sitting in a quiet house and hearing a faint sound. On its own, you might barely notice it. Now imagine that same sound paired with a small movement in your peripheral vision. Neither signal is strong. *But together, they demand attention. *Your brain snaps into alert; the world doesn’t just suddenly get loud. Instead, uncertainty skyrockets. Something is happening, and your brain wants to know what.
This is a normal feature of perception. It’s also a clue to why sensory overload isn’t always about “too much” stimulation.** **Often, it’s about how much interpretive work the brain is being asked to do. The brain isn’t a passive receiver of the world. It constantly combines…
Imagine sitting in a quiet house and hearing a faint sound. On its own, you might barely notice it. Now imagine that same sound paired with a small movement in your peripheral vision. Neither signal is strong. *But together, they demand attention. *Your brain snaps into alert; the world doesn’t just suddenly get loud. Instead, uncertainty skyrockets. Something is happening, and your brain wants to know what.
This is a normal feature of perception. It’s also a clue to why sensory overload isn’t always about “too much” stimulation.** *Often, it’s about how much interpretive work the brain is being asked to do. The brain isn’t a passive receiver of the world. It constantly combines information from sight, sound, touch, movement, and timing to figure out what’s happening and whether it matters. In neuroscience, in the process of *multisensory integration, distinct sensory signals are processed and integrated into a unified perceptual experience. Most of the time, this works smoothly. We naturally pair a voice with a face. Footsteps line up with movement. The world feels coherent without any effort on our part.
But coherence isn’t guaranteed
When sensory information is inconsistent, poorly aligned, or hard to interpret, the brain works harder to reduce uncertainty. That extra work is often what people describe as “overload.” One idea from neuroscience helps make this clearer. The brain doesn’t always combine sensory information in the same way. Strong integration with signals depends on how clear or reliable those signals seem.
When information is weak or ambiguous, the brain tends to amplify combinations of signals. Neuroscientists have coined this as superadditive integration, and this is the example we started with. A faint sound paired with a flicker of movement draws attention far more than either would alone. When information is already clear, the brain does something totally different. Adding more input doesn’t help much and can even get in the way. Neuroscientists call this *subadditive integration. *If someone is speaking clearly right in front of you, background noise or visual clutter doesn’t improve understanding; it makes the situation more effortful.
The point is simpler than it sounds The brain works harder when information is unclear, and it eases off when things are easy to interpret. This is why some environments feel draining even when they aren’t especially loud or bright. Many everyday spaces are not intense so much as messy. Conversations overlap. Visual information flickers or moves unpredictably. Sounds don’t quite line up with what you see. Any one of these might be manageable on its own. But, together, they keep the brain in a constant problem-solving mode, turning signals up, checking for meaning, and sustaining that effort over time.
From the outside, this appears to be oversensitivity. From the inside, it often feels like *work that never quite lets up. *This is especially noticeable in autism and ADHD. It’s something I’ve experienced and heard repeatedly, in how autistics and ADHDers describe their days—not as being bombarded by sensation, but as feeling worn down by the effort of constantly staying oriented.
In many cases, the issue isn’t that sensations are stronger. It’s that the** effort required to interpret them stays high for longer. **When sensory systems place greater weight on incoming information, they may remain in this high-effort mode even in ordinary settings. Over time, that sustained effort adds up. Fatigue sets in. Tolerance narrows. Small changes that would usually be manageable feel too much. From this angle, sensory overload starts to look less like fragility and more like endurance.
Neuroscience offers another strategy known as gain control. I like to describe it as the brain’s volume knob. When information is unclear, the brain turns the signal up to extract meaning. That helps, but it also means that everything feels louder, including variability and noise. High gain makes sense in uncertain situations. It becomes costly when it stays turned up for too long. This is why sensory tolerance often collapses with fatigue or stress. The system isn’t failing. It’s running out of room to compensate.
None of this means that sensory challenges are purely environmental, or that they can be solved by removing all stimulation. Sensory experience depends on how well a person’s brain matches the demands of their surroundings—and how long that effort has to be maintained. Some spaces feel easier because they reduce uncertainty. Others are harder because they require constant interpretation. That difference matters more than we often acknowledge.
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When sensory overload is treated only as a personal limitation, the solution is always the same: cope more, adapt faster, tolerate longer. Using a multisensory lens doesn’t replace one explanation with another, but it does add nuance. It shifts attention to effort—how much is required, how long it lasts, and when it finally becomes unsustainable.
As you move through your day, it may be worth noticing what feels loud or bright, and what feels hard to interpret. Where does your brain get to relax—and where does it have to keep working?
References
Stein, B. E., & Stanford, T. R. (2008). Multisensory integration: Current issues from the perspective of the single neuron. Nature Reviews Neuroscience, 9(4), 255–266.