Looking at animals shows great insight into our more subconscious brain patterns. The most basic of human instincts.

If we look at snails we can see how they react to contact with objects and the recoil of their proboscis. Our senses are directly wired into our subconsciousness. Touch, Sight, Taste, Hear & to Smell. Just perhaps we have missed a Meta sense, and that is to "Know".

The more highly evolved the animal the more it uses the relay of information from the differing senses to consciously prioritise actions and store for future occasions, therefore affecting the subconscious sense of "Knowing".

Humans, use these two levels of consciousness in varying degrees according to their relative strengths. They appear to be the most basic building blocks of all psychological types.

With reference to Jung’s work, in an evolved subject the subconscious appears to have Intuition (Knowing), and conscious Thinking. To Not think is to allow the subconsciousness to rule and thus mostly rely on the basic stored senses (Instincts, such as "feeling"). To not utilise Intuition "Knowing" efficiently is to rely on more current sensory input (Such as evidenced in short term memory).

The most intelligent of humans will be those that use the consciousness and subconsciouness in an integrated fashion. Consciousness can endlessly refine the subconsciousness creating a feedback loop, which can be positive or negative.

Looking further at animals, the more evolved they are it would seem, the more risk adverse they are. "Knowing" danger requires greater use of the senses in a coordinated way and the storing for future action (Intuition), it also requires extensive analysis of the permutations and contingency planning, which all increase the future ability of the subconscious. However, the more risk adverse, the greater the propensity for introversion.

The pack mentality limits the use of conscious thought unless it is aligned to the subconsciousness of the group. Those that conform to the group and are safest in that group will be the most extroverted.