Your mental age is determined by what you observe first. By mental age, we do not mean age in terms of being smart or slow. Mental age, in this regard, is how you see the world, through the eyes of a kid or through the lens of someone elder.
The concept of mental age was introduced by Alfred Binnet and assumed that mental development need not correspond to chronological age. To measure the mental age, Binnet devised a test that included items specified for different age group levels.
In simple terms, mental age is a measure of the intellectual level at which an individual functions. For example, someone described as having a mental age of 6 years would be functioning at the level of an average 6-year-old child.
If you saw old man
If you saw the old man first, it implies that you are mature in your thoughts and have seen the world, and have experienced several ups and downs. You have had all the experiences and knowledge which have helped you grow as a person. And as time passed by, you have grown as a wise soul. It might also be interesting for you to note that if this was the picture you first observed, you are calm and humble as well.
If you saw a young girl
If you saw the young girl in this illusion, it means that you are still a kid at heart and still see the world with the curiosity of a child. Despite your experiences and troubles, you decided to not say goodbye to your innocence and managed to keep it alive in this cruel world. It is a rare quality to have as most of us tend to ignore our inner child as we grow up. Keep in mind that it is difficult to hold onto childhood and innocence. Yet, you have managed to preserve this beautiful side of your personality and still find joy and happiness in the simplest things in life.
