How Do We See Simultaneous Events?

This piece, by Onno Berkan, was published on 10/01/25. The original text, was published by Nature Neuroscience on 07/22/25.

This Nature Research Briefing summarizes new research on how we perceive simultaneous visual inputs – multiple things happening at once – and perceive them as happening at once, even though the visual information associated with them takes vastly different paths to the brain.

Temporal coherence is fundamental to the brain; it's essential for interpreting the world the way we do, yet the mechanisms underlying it remain unclear. In sensory systems, such as the auditory system, minute differences in signals have significant meanings (delays in signals used for sound localization). So, how does the brain achieve temporal coherence in the visual system?

Your vision begins with light striking your eyes. This light is then processed by a part of the nervous system located in your eyes, which converts it into neural signals and sends them all the way to the brain. What they won't tell you is that these signals don't all travel through neurons of equal length. With millisecond-level accuracy being vital, the time it takes for one signal to travel down a shorter and longer axon could mean a difference in when you perceive it.

The researchers employed a variety of methods to study this phenomenon, ultimately finding that longer axons compensated for their increased length by being thicker, thereby allowing for faster signal transmission. There you go – Ohm's law applied.

This increase in thickness, while explaining a significant portion of the difference, did not fully compensate for the remaining length discrepancy. Researchers are unsure what else is at play here or how this increase in thickness occurs.

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