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Q: human nervous system ( Answered 2 out of 5 stars,   5 Comments )
Subject: human nervous system
Category: Science
Asked by: morganhd-ga
List Price: $15.00
Posted: 24 Apr 2005 09:02 PDT
Expires: 24 May 2005 09:02 PDT
Question ID: 513495
How many thoughts and sensations cross the mind in one second?

Request for Question Clarification by pafalafa-ga on 01 May 2005 17:26 PDT
George Miller, in his book "The Psychology of Communication" estimated
that humans have thoughts at a rate of 7 +/- 2 per second.

I don't have access to his book right now to explore how he arrived at
this figure.  You can see a brief reference to his study in these
Google search results:


but the actual articles they link to cannot be accessed unless you
have a subscription to Science magazine.

Is that sort of statistic the type of thing you're after?  If not,
what else do are you seeking?


Clarification of Question by morganhd-ga on 01 May 2005 21:35 PDT
The comments provided are satisfactory, thanks.
Subject: Re: human nervous system
Answered By: pafalafa-ga on 07 May 2005 05:32 PDT
Rated:2 out of 5 stars

I'm glad to hear that the information I provided meets your needs. 
Before you rate this answer, please let me know if there's anything
else I can do for you.

All the best,


search strategy -- Google search on [ "thoughts per second" ]
morganhd-ga rated this answer:2 out of 5 stars

Subject: Re: human nervous system
From: supamike318-ga on 24 Apr 2005 09:08 PDT
There are other ways to estimate the brain's computational power. We
might count the number of synapses, guess their speed of operation,
and determine synapse operations per second. There are roughly 1015
synapses operating at about 10 impulses/second [2], giving roughly
1016 synapse operations per second.
Subject: Re: human nervous system
From: andrewxmp-ga on 01 May 2005 16:15 PDT
supamike is right to offera different, more practicl approach.  We
really don't understand much of how cellular activity gives rise to
complex and quite abstract phenomena like "thoughts" and if different
thoughts take more power than others, questions like that.
Subject: Re: human nervous system
From: drhakan-ga on 07 May 2005 05:02 PDT
i dont agree that humans have thoughts at a rate of 7 +/- 2 per
second.That ias only a piece we senced.For example in our dreams we
can do an action that we could do for 2-3 hours in a 10 seconds
Subject: Re: human nervous system
From: theoracleofdelphi-ga on 19 May 2005 18:24 PDT
Alas, Morganhd, I think you do not yet have your answer.  The
statistic of '7 +/- 2' thoughts in the original answer comes from a
study of stuttering; the number is derived from the average number of
syllables pronounceable per second.  The assumption, of course, is
that a syllable = a thought.  The link given in the original answer
actually leads to a letter to the editor of Science, by Rosenfield and
Viswanath at Baylor College of Medicine, which CRITIQUES the 7 +/- 2
assertion, pointing out that obviously people can think faster than
they can talk.  (Although, to be honest, I have met plenty of people
who seem to talk much faster than they think).  Rosenfield and
Viswanath say, for example, that:

"Certainly, Broca's area and Wernicke's area can process data more
rapidly than 7  2 items per second. Miller's review related to issues
of absolute judgement and immediate memory when humans are in a
stimulus- response setting or functioning in a communication system.
He discussed how brains overcome the apparent 7  2 limit, for
instance, by making stimuli multidimensional, and he emphasized that
such recoding powerfully increases the amount of information that can
be processed."

So good sense and an actual READING of the cited article (you
shouldn't cite stuff without reading it carefully, Pafalafa!) argue
that humans have more the 7 +/-2 thoughts per second -- assuming, of
course, that equating a thought with a language component is even

So what's the true number?  Supamike has an interesting approach,
except for the fact that he is way off on his estimate of the number
of synapses in the human brain, or even the number of synapses in the
cortex, which is arguably the part of the brain most likely to
generate 'thoughts' (The 10 impulses/second is fairly reasonable,
though).  Each brain cell can make THOUSANDS of functional connections
(synapses) with other cells.  I just whipped up a pubmed search and
the first paper I pulled up, a rather boring but apparently well done
piece of work by DeFelipe et al, 1999 (Cerebral Cortex 9(7):722-732)
says that there are about one and a half BILLION synapses per cubic
millimeter of cortex.  Depending on the size of your brain, you
clearly have trillions and trillions of synapses in your cortex alone.
 Supamike's method argues for a heck of a lot of thoughts per second. 
A rather unbelieveable number, if you want my opinion.  Which I think
is easy to argue, since one impulse is highly unlikely to encode a
thought.  A single impulse doesn't even encode a sensation.  A
momentary light touch triggers hundreds to thousands of impulses.

So what's the answer?  Heck if I know.  And I am saying this as a
neuroscience professor (really!).  Andrew hits the nail on the head
when he said that "we really don't understand much of how cellular
activity gives rise to complex and quite abstract phenomena like

So there's the heart of the problem:  No one really knows what the
biological basis for a 'thought' is, so we can't compute how fast a
brain can produce them.  Once you figure out the biological basis for
a thought (and return from the Nobel ceremony) you can ask the
question again and expect a reasonable scientific answer.

In the mean time, you could probably get a bunch of psychologists to
argue about the definition of a thought for a while, and get a varying
set of answers that depend highly on the definitions.

But now that I re-read the original question, I see that you are
asking about 'sensations' too.  This is easier to answer, since the
timing of sensation is much better understood.  Nothing mysterious
about it.  A sensation takes basically just as long as sensation is. 
We can do a back-of-the-envelope calculation here for sensations/sec. 
The problem is that I'm not sure exactly what sort of sensation you're
talking about.  A photon stimulating a retinal cone cell?  A sound
pulse?  A flash of pain from a hot piece of metal?  An itch?  The need
to take a dump triggered by expansion of the colon?  The slow rise of
hormonally-triggered sexual excitement you get on a hot date?  The
gradual feeling of sleepiness that grows as the night wears on and you
read long Google answers from bored university professors surfing the
web?  Anyway, let's say that the duration of the average sensation is
about a second (though obviously this can vary widely).  How many
sensations do you think you can handle at the same time?  One?  Ten? 
Do we only count sensations for which we're consciously aware?  If so,
let's go with 5 sensations at the same time (I just pulled that number
out of thin air, but is sounds reasonable to me and hey -- I *AM* an
expert, right?)  So 5 simultaneous sensations x 1 sensation per second
= 5 sensations per second.

There's your answer.  Complete B.S., but I guarantee it's as good as
any you'll get anywhere.  It was a good question.  Now, of course, we
need to figure out why caffeine and nicotine and stuff like that seems
to speed up the 'thought rate'.  Given that we have a pretty decent
idea how many stimulants work at the cellular level, maybe that gives
a clue about what a the biological basis of a 'thought' is.  Hey,
maybe we're finally getting somewhere...

(By the way, if you think my answer is best you can keep the money. 
Spend it on beer or something and argue about what a thought is with
some friends.  If you ever figure it out, let me know.)
Subject: Re: human nervous system
From: morganhd-ga on 19 May 2005 20:29 PDT
The comment by theoracleofdelphi-ga made the most sense to me, but I
appreciated all of them. I am a seventy-two yr old grandmother; the
question occured to me while 'watching' my mind in meditation. Thanks
to all

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