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Vsauce, in this video, You Live In The Past, viewed over 5 million times, claims that when you tap your nose and your toes at the same time, they feel as if they happened at the exact same time (which they did, but it takes longer for the signal to reach your brain from your feet than from your face) because the brain waits a short period of time before processing the two sensory inputs to mitigate the difference in time due to distance traveled.

Since it's waiting on signals that haven't arrived yet, I'd assume that means the brain has to always assume a signal might be coming from further away, and as Vsauce says, if you're taller, that means you're always living further in the past than someone who's shorter than you.

If this is accurate, that would be incredible. Maybe it is, but I'm skeptical. Does the brain really delay processing of sensory data based on how tall you are in order to improve comprehension accuracy of the senses?

And if so, how does the brain figure out how long to delay (or in other words, how tall you are)?

  • Of course it does not delay processing of all sensory data, only in the situations that he describes where it is advantageous for us to experience 'same moment'. – Jan Doggen Jul 21 '16 at 9:16
  • To indicate what delays we are talking about: Muscle and touch neurons have a nerve conduction velocity of 4-120 m/s. That translates to a time difference of 4-125 msec for a length difference of 0.5m – Jan Doggen Jul 21 '16 at 9:21
  • @JanDoggen I removed "all" but it seems to me like if the processing of any sensory data (such as touch) is delayed, all (or at least most) of the rest of the sensory data would have to wait to be processed in sync too. I mean, if I touch my ankles and whistle at the same time, and the feeling of my mouth making a whistle motion is being delayed to match the time the impulse from my ankle arrives, do I hear the whistle before feeling the air leave my lips? No.. So it seems like if this synchronization is happening, it would have to happen to nearly all sensory data. – Viziionary Jul 21 '16 at 10:14
  • @Viziionary To the integrated conscious experience, maybe, but it is possible that there is a different reaction time for reflexes. – called2voyage Jul 21 '16 at 12:46
  • I think this is really a communication issue on vsauce part, or an over-simplification. Its more apt to say the brain will 'catch-up' new signals with other temporally matching signals. We have a chemically oscillating clock reinforcing our perception of time; your brain naturally adapts your body signals to make sense but it doesnt wait to start processing signals. – Garet Claborn Jul 22 '16 at 19:24

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