Ni - implications
Ne - parallels
Se - instincts (or realities)
Si - experiences
Ni - If this quality is true, then these qualities are implied.
Ne - This quality is just like this other, different quality.
Se - This quality naturally leads to this other quality (instinctual, pursuing qualities to find other qualities).
Si - This quality reminds me of this other quality I remember.
Ni is also subjective with its implications, meaning that its perceptions are based on the qualities of the subject (you) rather than the object.
Ne is also objective with its parallels, meaning that its perceptions are based on the qualities of the objects rather than the subject.
Se is also objective with its instincts and realities, meaning that its perceptions are based on the qualities of the objects rather than the subject.
Si is also subjective with its experiences, meaning that its perceptions are based on the qualities of the subject rather than the object.
Thus, Pe is the detachment of the self and the self's contents (understandings, experiences, knowledge, etc.) from the objects which are being studied. The perception is independent of the attitudes of the subject.
Pi is the attachment of the self and the self's contents to the information received that is being studied. The perception is dependent on the attitudes of the subject.