Usually tunnel vision has a bad connotation. In fact, I claim there is a good version of it. This is happening when you are part of a really deep, meaningful, and thus genuine dialog with another person, or a group of people.
Have you ever caught yourself having a conversation with someone at e.g. a restaurant and at the end you finally notice that the patrons have long gone, but you had not noticed that? In fact, you may not have noticed what your waiter looked like, and that literally hours had passed you by. That is what I call positive tunnel vision.
Part of it is that your mind is deeply in thought about what is said and you keenly focus on your dialog with your partner(s). It is fun to partake in the discussion and you mutually benefit from what you talk about.
A key area of this is not only fun, but very fulfilling: Dates. Have you ever noticed how fast times flies right on by you and you do not notice anything but your date? How can this get any better than this? Make good use of times like these ones.
Another good sign that you have had such a genuine discussion is that you may feel exhausted. It takes a lot of energy out of you when you are totally present and in the moment. That is even more so a good reason to be really picky about with whom you have a chat like this.
It is always a great idea to think about how much of a time limit you want to give yourself. Also, think about what you want to get out of a conversation at a minimum; you do not want to come out of a meeting with no tangible outcome. For example, a list of topics you wanted to cover at a minimum. So much energy and time should not go in vain.
Tunnel vision is a loss of peripheral vision – you focus on the middle and notice nothing around it. Sometimes this can be really bad, but at the same time it can be good because you can focus all of your attention on your conversation partners. The latter can be very rewarding and provide you and your discussion partner with long term mutual benefits.