One of the fun things about The Accidental Mind and Blog, has been the opportunity to hear from folks with really interesting questions about brain function. A few days ago, I received this clever query from Jim:
Is there a connection between the brain processes that keep us from tickling ourselves and whatever it is that makes our personal odors more noticeable to others than to ourselves?
Here’s my answer….
In the more general sense, all of our sensory systems are designed to pay less attention to sensory stimuli that are always there and more attention to those that are new. You know this from your own experience:
When you first sit down at your computer, you may notice the faint whine of the hard drive, but this will rapidly fade from your consciousness. Likewise, if you visit a friend's house after they've had fish for dinner, you'll notice the odor when you first walk in the door but you'll adapt to it in a minute or so and it will not remain a strong sensation. In this way, we are all rather well-adapted to our own personal odors, simply because they are always around. If you wear a cologne every day, you'll adapt to that too.
In the more limited sense, however, the answer is more complicated. Do our noses and brains "know" that our personal odors derive from ourselves?
To my knowledge, there is no compelling evidence that this is true. My understanding is that our brains treat self-odors the same way that they would treat the cologne: just another constant stimulus to largely ignore. This is different than the brain processes that keep us from tickling ourselves. In that case, the brain "knows" that the tickling motion is self-generated because it has the signals that were used to drive the hand's tickling motion and it subtracts those self-generated signals from the tickling sensations to blunt them.
Do you have a question about brain function? Feel free to send it along using the email link on the “About the Author” page.