Honestly it is possible but hardly. When people say that they usually mean that if you think of all the traits of animal you will slmehw change for that cause you thought about it enough and you now believe it. You can't really and your human for a reason, there are some however who are born with gifts that almost seem animal like. Via this change.
Mental shifting is when your mind changes into something else. Like an animal for example. I have had one expierience with mental shifting. I was a dog in mental shift.
In Norse Paganism, there is a technique that is just as you described, called Berserkergang, in which the person mentally takes on animalistic characteristics through various methods including trance. The purpose of this originally was for fighting, but has other uses as well.
In other shaman practices, the shaman 'transform' into an animal, although this is often taken as shape-shifting, which is not possible , it is really the shaman embodying the spiritual aspects of the animal.
I haven't much experience with this, but there are plenty of practitioners on this site who practice Berserkergang, if you want more information you need to look no further than the 'Norse Paganism' section of the site, there Personified has written a couple great articles about the subject.
In my old age it still amuses me that people still distinguish Humans and Animals. There are still people who think we are different. Strip off your clothes, and look at yourself in a full-length mirror. You are an ape! We are not "descended" from apes; we are apes! Just as different from a Chimpanzee, as a Gorilla is different from a Baboon. But,nevertheless,we are apes.
And just as any other animal, we have an affinity with all animals. As animals, we may not be able to actually "talk" with other animals; but we can certainly "communicate", just as they can.
There are many instances of one species raising the young of other species. They "know", just as we do!
We may have a larger brain, are maybe more intelligent (though I doubt that!), but we are animals.
If I have not made myself clear; I am talking about Mental Shift. For instance; if you place a week old orphan kitten with a litter of pups,perhaps the mother dog will kill the kitten. But very often she will raise the kitten as a dog! The kitten will always be a cat! But it will "think", and very often will "act", like a dog. That, is a Mental Shift!
I had also embraced the animal classification of human beings, too. That, and I've noticed that many animals have individual personalities, so to say that I become so-and-so animal means that I remain myself or else I'd be horrible speciesist (specieist? Prejudiced and discriminating based on species, anyway.)
This actually got in the way of my fully getting into the spirit of a therianthropic spiritual paradigm (Norse paganism and fylgja, for one example; Native American influenced New Ageism with spirit animals, for another example.)
At the same time, I sort of get it now I think. Everything outside of us has characteristics and values associated with them (that we project onto the thing). It's like a magical correspondent, except instead of building a system of symbols to express something to the world or the universe... it's sort of how we do magic on ourselves on a conceptual level.
There are many cases of human babies raised by wild animals. Quite a few from India.At least one found as late as 1975! They have been the inspiration of many novels; such as The Jungle Book, and Tarzan Of The Apes. One in particular, from the late 19th century, was found wondering in the wilderness of northern India (what is now Pakistan) at the age of ten. He was "rescued"; but even when he grew to be an adult, he still considered himself to be a wolf!
You couldn't have a better example of a Mental Shift than that!
