[Caleb (OP)]

I have had this notion for the past 35 years or so, that gum-chew is a physically arousing response, leading on to another chew.
if I was going to design an organism that could derive nutrition out of materials that were not immediately nutritious, I would want one chew to lead onto another chew, such as a cow having to ingest much grass before giving up the chewing response.
In humans, the chewing response seems to me to me physiologically very similar to suckling milk--that is, the jaw moves up and down in a fashion similar to chewing food. One could think of it as a mild type of energizing behavior which is present in infants as well as adults.
Certainly the prototypic salesperson, as well as basketball players and baseball players, etc., regularly chew gum as they engage in their behaviors which are helped by increased arousal and attention..
We see that people will chew one all kinds of things, including pencils, gone once the sugary taste has left, etc.
Any thoughts?
Yours, Caleb

[alancalverd]

Fascinating question!

It's noticeable that people make "chewing faces" when concentrating on a task, even if they aren't chewing anything: pursed lips, rotating jaw motion, sucking in lips and cheeks.... We even speak of "ruminating" ove a problem.

My guess is that it is connected with the mouth having the greatest socially acceptable concentration of sensors, and being capable of self-stimulation whilst leaving the hands free to investigate/write the answer/fly the plane or whatever, chewing does indeed make the brain more alert to other sensations and possibly stimulates conscious memory recall ("where did I taste that before?" is an important survival check).   

It's also possible that chewing, particularly gum,  acts a bit like the one-legged stool that people used to use when monitoring critical chemical reactions: it stops you falling asleep because you have to consciously move the wad around and swallow every so often. I always chew gum when flying: not sure whether it improves my aviation but it certainly prevents a dry mouth and thus maintains radio intelligibility in an environment where liquid intake (or falling asleep!) can make life uncomfortable.   

[Caleb (OP)]

Very neat observation -- about showing chewing motions when thinking. Never thought about that, but people chew on pencils, and maybe isn't only to create a kind of "white noise." Very good insight! Your noting our "ruminating" over a problem seems very insightful and maybe related to "chewing/mullilng over" an idea, etc. That is, not only thinking of an idea over time, but actually having facial expressions to indicate actual focus, involvement and arousal in the process.
In terms of flying, chewing helps clear the eustachian canals to let the ears "pop" and accommodate to changes in air pressure.
But from my personal experience (and that is worth less than zip), when I chew gum repeatedly, my upper cheek muscles tighten below my eyes, and this also happens when try to concentrate and really focus on something. That is, in a variety of games/sports, I tighten the muscles around my eyes and this seems to help greatly with my performance.
Yours,
Caleb -- again, very good observation! I have thought of this general topic a long time but have not come up with your great insights!

[RD]

... we see that people will chew one all kinds of things, including pencils, gone once the sugary taste has left, etc.
Any thoughts?

Maybe have a look at the hypotheses attempting to explain onychophagia & pica

[CliffordK]

There are some actions that are essentially reflexes.  They can be modified by the brain, or can exist independent of the brain activities. 

For example, a cat with a severed spinal cord can produce walking movements with its legs.

It is likely that chewing is essentially hard-wired, with repeated opening and closing of one's mouth.  Flexors and extensors are "wired" so that generally they are activated at opposite times.

Most people are aware of their patellar reflex, but there are many different reflexes with different muscle groups around the body.  Chewing may involve some reflex actions.

[CliffordK]

Hmmm...  thinking of chewing.
I wonder if there would be a burst of insulin with chewing.
And, then, of course, also glucose to compensate if necessary.

[evan_au]

I find that chewing helps with alertness - even when it is low sugar gum.

My dentist recommends against chewing continuously - he says it wears out the teeth too quickly. I guess if you increase chewing from 3 meals of 20 minutes each up to 8 hours per day with chewing gum, that will reduce the lifetime of your teeth by many years. But if you are careful to ensure that the teeth only run into soft chewing gum and not other teeth, that shouldn't wear them out too much.

[Caleb (OP)]

About your thoughts: "

To RD -- You wrote: "Maybe have a look at the hypotheses attempting to explain onychophagia & pica.

Relatedly, I have thought for a long time that this would also explain bruxism (teeth-grinding). Many disabled people show this behavior and it seems to be self-stimulating for them, perhaps physiologically and also perhaps in part because of the internal sounds produced. Bruxism, as well as continuing to chew gum once the flavor has left, are interesting responses.

I just found the following http://www.nhs.uk/news/2013/02February/Pages/Chewing-gum-aid-concentration.aspx

"Conclusion:

"This study has suggested that chewing gum may improve reaction times in healthy adults in a specific computerised cognitive task. The study only assessed 17 healthy relatively young adults, and the results may not apply to other groups of people.

"Most importantly, this specially designed cognitive experiment was performed in a laboratory environment, and may not represent what would happen in a real-world setting. For example, we can't say for certain whether people's reaction speeds when driving a car would be improved by chewing gum.

"The study may be of interest to some researchers, but at the moment it does not have any obvious practical implications for people's health or day-to-day lives."

Interesting results, but the fMRI findings were somewhat inconclusive.

Part of my "waking up for contests" behaviors used to include gum-chewing as well as opening my eyes quite wide (widening the palpebral fissure, the distance between eyelids). Probably some of that is expectancy events, but those methods did appear to help with focus. Seems to me that very wide-open eyes are also arousal-inducing.

Caleb

[cheryl j]

This is an interesting topic.
In addition to chewing facilitating thinking, it also seems that mouth movements help inhibit behavior or sensation - clenching the teeth when in pain, for example. My dentist once asked me if I was under a lot of stress and I said "why?" He put the mirror up to my face and said "stick out your tongue" and showed me the serrated indentations on the edges of my tongue from pressing it against the sides of my teeth.

Nail biting is sometimes said to be a stress reaction, and is possibly genetic. And I don't know if it's related, but some people have to walk around or pace the room when when they are trying very hard to figure something out. In a way, that doesn't seem to make sense, because you would think walking around would give the brain one more task and be distracting, but for some odd reason it seems to help. Unfortunately, it looks crazy and is highly annoying to others.