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Interesting, I experimented a bit with this when my daughter was younger. I used to walk around the room with her in my arms singing to get her to sleep. To ensure she would be settled I would then count 300 steps before putting her in the cot. I discovered I could count and sing at the same time by visualising the number in my head, instead of using my inner monologue. But it requires more focus to maintain.

Thankfully these days she can get herself to sleep. But I miss it sometimes

I've noticed something similar. I can listen to audiobooks and follow/absorb what is going on without really paying attention, as long as I am not trying to read something. I can't follow an audiobook and read at the same time. This is probably because I subvocalize when I read. I have taken speed reading courses but I don't enjoy reading that way. I like feeling every word as I read.

Interesting, I often sing a good night lullaby to my kid and have discovered it’s trivial to read while doing so. But I just tried talking while counting in my head and it felt like a brick wall was blocking me.

This has everything to do with the fact we have two brains. The left and right brain (more specifically the left and right hemispheres of the Cerebral Cortex) hold different functions cognitively, control the motor movements of the opposite sides of the body, and communicate thru the Corpus Callosum. Your full consciousness, or thought, is almost like a 'stream' created at this meeting point of the two brains where the neural traffic is so dense (more like my own theory...). However, if you were to find a patient where this connection is severed, like an epileptic patient whos Corpus Callosum was surgically bisected to cure them of chronic seizures, you would then have someone with 2 separate brains that cant talk to one another. This is split brain theory. I wrote a paper on this in undergraduate and id have to pull up a ton of other details, but essentially go watch videos on Michael Gazzaniga and Dr. Roger Sperry's experiments with these people. They would experience the right brain reaching for one outfit to get dressed in the morning while the left brain "thought" the idea of another outfit, so they would be very confused. Its very revealing to the mapping of our brain and all the different human functions, and how we learn! Then you lead down the rabbit hole of Bicameral Mind... but anyways, i believe thats why everyone can count in their left brain, and then from there its up to each brain system to figure out how to map the second task to the right brain so they can enter the consciousness stream simultaneously. There is an internal mechanism everyone develops themselves and Feynman is showing you can test that. Its probably right around most humans cognitive limit to use the right brain to help either reading OR speaking as the left brain is the primary handler of all of these (math, reading, speech). I also think thats why Feynman saw colors with his math; his right brain was assigning a unique identifier (color) to his logical problem being worked out in his left brain (all the different symbols and letters). Fascinating.

How do we know, or would Feynman know, that they can count while reading and not just that counting and reading are simple enough tasks broken down into discrete steps that our brains can context swap in an unnoticeably short unit of time?

Just trying to read your post while counting at a consistent pace I associate with roughly 1 second per number, it didn't feel like I was reading words but instead scanning them and understanding them after the fact from memory. Usually when i read I hear the words 'in my head' but not while counting at the same time.

Honestly my takeaway from this is that simple experiments like this are very important in identifying how brains work. I am admittedly a fanboy of Feynman, but I believe these kinds of questions are worth a dozen EEGs or fMRIs asserting how the brain works.

I can also count while reading, I just tried it. But I can't write while counting.

I can have one interpretation and one generative task running at the same time.

Try counting by imagining fingers in your head and talking at the same time. (-;

I wonder how musical counts interact with this.

This is a nice example of using interference as a window into representation

> while Feynman imagined himself talking to himself

ironic )

When I was a kid, my dad (a physicist) would often read stories to me and my brother. He would sometimes fall asleep while reading, and we could tell when that was coming because suddenly our children's story would stop making sense and get filled with all these big physics terms.

The ability of the brain to do that gives me 15 min of quiet time to think about problems each evening. But you cannot follow the story in that mode, and the whole facade will collapse on a single innocent question...

> "Dad, why did he steal the biycle?!?!"

> ".... what?"

I can have an internal monologue about something completely unrelated to the story while reading it out aloud, but I won't be able to follow the story. I don't think I make mistakes, but I probably fail to put the correct intonation on sentences which require higher order thinking to infer the emotions of the characters in the story.

In school, our teachers made us take turns reading the textbook. When it was my turn, I focused entirely on how my voice sounded, trying to match my cadence and tone to the punctuation. The moment I finished the paragraph, I would have to quickly re-read it in silence just to understand what it actually said.

I think I still can't read a non-trivial text aloud while trying to make sense of it at the same time. I need the two streams just for one text.

I learned at a young age the best way for me to be a good out-loud reader was to think about something else while I'm reading aloud. If I concentrate on the words and the reading aloud I screw up but if I think about other things, even HOW I'm doing while reading or thinking about what I'm reading and going to say NEXT, then I can read aloud flawlessly.

I can do that, and i notice that i kinda stop thinking about the reading and put more "brain resources" into the independent train of thought. Then i realize i was reading all the time without putting any effort in it

Yeah it's like I suddenly realise I haven't been thinking about the reading and I'm near the bottom of the next page somehow.

Interlinked.

Well, perhaps sadly, I maintain trains of thought unrelated to my environment all the time. It's because the default state of the world is so incredibly.. bland I really, really cannot take it without something going on.

The reading task can stay largely automatic until both streams try to use the same speech-production machinery at once

I definitely cannot do that. Crazy.

or any other reading for that matter!

I've always been impressed by the controllers in centers and TRACONs. They can have multiple frequencies they're monitoring in each ear, and no matter how polite we try to be we (pilots) have no way of knowing if we're stepping on a call on another frequency. They just have to deal with it. Not to mention communication amongst themselves to some extent as they hand people off, though I haven't been in a tower for a very long time, that may be automated/digital now.

And it's not like pilot/controller conversations are about weekend BBQ plans. It's as information dense as possible without sounding like a METAR report.

That tracks. As a teacher I sometimes find myself conversing with multiple kids simultaniously as well. If it's nothing too deep that requires full focus, it works. (Though I do find it tiring and avoid it.)

Perhaps a dumb question but are they center panned (or mono, i.e. talking over each other) or is it split left ear/right ear when they come through the headset?

I believe this is why fugues are such a pleasure to listen to!

There’s a big difference between processing multiple streams, and processing multiple streams simultaneously.

You can achieve the former, without the latter, by doing time slicing. Spending a small amount of time processing stream A, then dropping that and processing stream B for a moment, then swapping back. Just like how a single core CPU can process multiple threads.

Proving the brain is continuously processing and encoding multiple streams simultaneously is an interesting finding that helps us better understand how our brains handle multitasking. That’s absolutely something worth studying and understanding, even if the headline discovery “feels” obvious. It the precise mechanism that’s interesting, not the effect the mechanism produces.

This is about multiple speech streams.

More specific from the mere ability to process multiple sensory streams in general.

There is also a different quality of processing. Textunderstanding and danger deciphering of signals.

that's fascinating. Do you have any link to this tidbit?

But the tick/tock on a real clock happens before the end of the swing anyway

I’ve actually found that I’m able to process two speech streams and one music stream independently from those. At least for me, music seems to have a dedicated sub-processor of sorts.

I can do the music part just fine. But listening to two conversations at the same time just means I understand neither of them.

Supported by the empirical evidence of cube farms, post COVID in the early “return to office” days, when office etiquette was completely forgotten and people were listening to all their meetings on speaker, but we were still having all our meetings at our desks.

I would constantly hear people around the cube farm stumbling through sentences because they could hear themselves through a neighbors computer with a slight delay.

I def process more than I want.

Its def a spectrum.

In the easiest look at people like me who complain very quick if something is wrong like to warm to cold to sweaty etc. and others not even ackknowliding it at all

Absolutely. Take a look at "unconscious perception".

I'm a native English speaking pinball freak living as an expat in a German-speaking country, and I find myself often listening to English speakers on the train, while also carrying on a conversation in German .. and I have observed that the same part of my mind that can handle multi ball-pinball events, where during a pinball session multiple balls are in play, 'feels' active.

Its a kind of context juggling mechanism in both cases, and it feels like the same mental muscle being exercised in both cases.

I wonder if there is a worthwhile experiment to be conducted wherein an EEG'ed pinball player gets to play pinball with easy multi ball targets, while also listening to German and English speakers, and then passing a test at the end of it .. because I sure have been preparing for that kind of scenario lately ..

Listening and responding are likely pretty different mental activities

You're using one of the streams for yourself. :P

When my son was about 4 or 5 he used to draw pictures with pens in both hands simultaneously which I was always amazed he could do!

And you can subvocalize (that is, think them in your mind) two different voices at once if you deliberately try to, and it's a skill that gets easier with practice. Though, no matter how much I practiced it, I was never able to get to where it would take place automatically without my forcing it.

Left ear: Mozart, right ear: The Bible in Chinese

Async-programming style single-core concurrency would still look like parallelism to an outside observer :)

That's not a good argument. First, music is not speech. It doesn't require linguistic processing. Second, you can hear chords instead of individual voices, so polyphony can be perceived as shifting harmony, and it usually is.

Not reading out loud, but I've caught myself a few times on reading and not processing that, because I was thinking about something else. Like I still did the reading, but straight to /dev/null of my brain

I experienced this too, when I started reading out loud more. At first, it was just that my eyes would scan ahead a bit from what I was saying, to help me get the right emphasis by knowing where the sentence was going. It felt like I had "handed off" saying the words out loud to a "subroutine", so my attention could be on what I was reading. Then that "readahead" extended to a whole sentence. And at that point it was like I was so far ahead of what I was saying that I had time to think about it a bit. And then at some point it was like the "reading the words" part got handed off to a "subroutine" too, so my attention could mostly stay on whatever I was thinking

This is something that has been studied and is apparently more common when reading out loud. I have this as well. I can read to my kids and at the same time plan the upcoming day. Pretty neat!

Sometimes I read a book out loud and think about something completely different.

I wonder if reading aloud might be like walking. I can be walking and speaking to a person at the same time.

Many dj mixers offer the option to split the main mix to one ear and the cue’d track to the other, i have never been able to mix like that, only with cue on headphones and main mix out in the room/monitors. Weird

Your example is needlessly bleak, but in general: yes, we're a social species and being able to process multiple speech streams seems obviously pretty important in many social contexts involving more than two people.

Also explains why we like music with two simultaneous distinct sections (bass + the rest). One without the other doesn't feel as complete

Not really (except perhaps if it's Stockhausen they're playing). A piece of music played with two hands is still one coherent information stream.