A number of years back, I had noticed that almost all experiences while "on vacation" seemed to be more enjoyable than similar experiences while at home. The most puzzling to me was that even something as mundane as filling the gas tank of the car seemed to do this, and that seemed impossible! How could such an action, which normally has no "enjoyment" whatever, seem to become pleasant?
On one specific trip, as I got out of the car at a gas station, I realized that the AIR smelled nicer and that there seemed to be more birds chirping! That seemed to be an unlikely reality, so I thought about it further, and through following months. I eventually came to realize that I unconsciously would take deeper breaths of air in those gas stations while on vacation, than I did at home. The air was not actually any more "interesting" but I was taking in around 20% more air in those deeper breaths. The smell sensors inside my nose were therefore having 20% more air go by them, and therefore, there was 20% more stimulus of them!
As a scientist, I eventually figured out a way to check this out. At home, when I would get out of the car in a gas station, I would INTENTIONALLY inhale more deeply. Amazingly, the sensation was VERY much like the enhanced vacation experience!
Have you ever realized that ALL the exhilarating experiences of your life, whether enjoyable or fear-ridden, whether positive or negative, whether involving Graduation or a new job or Marriage or sex or dozens of other things, all seem to be associated with increased heartbeat and increased respiration? Whatever the stimuli that caused the more rapid activity of the body, it results in the body receiving substantially more stimuli than normal. At a rock concert or attending a football game, the sounds are loud and everywhere, and it is exhilarating. In scary movies, the visual information supplies your nervous system with far more unusual visual stimuli than it is used to. During almost any experience where a lot of things are happening quickly, like in a car accident, or being present during a robbery, or being in a fistfight, there is a LOT of mostly visual stimuli that is unusual and unexpected. In my earlier examples of smells from deeper breathing, or tactile stimuli from a massage, the result is similar.
The brain winds up having to deal with substantially more stimulus information than it normally has to, and there is a sensation of exhilaration as a result of this increase in activity.
For the vast majority of us, our day-to-day lives are pretty repetitive. Eating, dressing, commuting, working, watching TV, reading; these all have aspects of variations but there are great amounts of repetitive behavior where the brain doesn't really have to do much.
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C Johnson, Physicist, Physics Degree from Univ of Chicago