Wikisocion.org is a great site for finding out information on the various functions. I haven't ever seen anyone on this forum mention it before so I thought it would be an interesting read for all of you. I looked at each function's page and only took the information relevant to ISFJs. Perhaps this will help everyone better understand why ISFJ's are the way they are. Enjoy!
Introverted Sensing Base (1)
A strong ability to recognize internal physical states in themselves and others, to understand how these states are reached, and to recreate and avoid these physical states.
Individuals who possess Si as a base function are drawn to situations that satisfy their inner physical experience. Whenever Si base function individuals are taking part in something that involves recognizing, recreating, or analyzing physical states, they feel a great deal of personal power and enthusiasm.
The avoidance of discomfort is one of the primary motivations of these types. Feelings of internal discomfort can arise from a tense psychological atmosphere, working too hard and sapping the body's resources, being pressured by other people or by numerous "things to do," and from unsatiated or oversatiated physical needs. These types tend to quickly recognize and be quite vocal about discomfort that arises and either take clever measures to dissipate it or simply get out of whatever is bothering them. They are very receptive to other people sharing feelings of discomfort with them and can help alleviate the tension and offer good solutions.
Si leading types are constantly adjusting themselves to their environment (which includes the people around them), and rarely have any fixed ideas about what is "appropriate" to desire in a given situation. Thus they are willing to accommodate other people's needs in an ad hoc manner. It is enough for something to "feel right" for them to justify doing it. This behavior may seem random to outside observers, since it is concomitant with weak Ni.
Extraverted Feeling Creative (2)
The person is sensitive to the emotional atmosphere around him, either from an individual, or a group, or even from inanimate objects such as the landscape, the state of the physical environment he happens to be in, or his own emotional associations with the place or people around him. A positive emotional atmophere is essential for his sense of well being and inner peace, and he either tries to promote it himself by directly influencing it around him, or by simply moving away from the environment or the people causing a negative emotional environment in his view.
For the SEI, this takes an on-the-spot aspect and is reflected in cracking jokes, trying to make people laugh, or simply moving away from people he perceives as affecting him negatively. For the IEI, this takes a longer-term perspective; so the focus, rather than being on the immediate emotional environment, is on the perceived longer-term emotional state of others towards the individual, and is reflected in trying to be on good terms with those he interacts with or seeking distance or protection from, or "preventively" attacking, those he sees as irremediably hostile emotionally.
Introverted Thinking Role (3)
The individual is able to talk about things from a dispassionate academic or theoretical point of view for brief periods of time, but seems overly bookish when doing so and tends to grows tense. When feeling obliged to justify logically a personal decision taken for reasons determined by Fi, the individual attempts to do so but grows quickly annoyed especially if the inconsistency in the logical argument is pointed out. He then either explains the ethical motivation or avoids the issue altogether.
Extraverted Intuition Vulnerable (4)
The individual is highly skeptical about ideas and opportunities that appear not to lead anywhere specific, and seeks assurance that new innovations will definitely bring material benefits. He prefers the kind of ideas and innovations that offer solutions to existing problems rather than the kind that have uncertain consequences and are likely to bring upheaval and unnecessary change.
The individual may tend to forcefully restrict other people's activities in areas he thinks they have no natural talent in. At the same time, he or she is prone to make errors when judging whether or not a person is capable of doing something.
The individual generally does not try hard to understand multiple viewpoints, but concentrates on developing only his own. He is not very good at intriguing others with his ideas, even when they have significant merit.
The individual dislikes it when people evaluate others' potential to engage in activities or develop skills in which they haven't had experience yet; above all he is uncomfortable with such discussions by other people regarding himself. He is inclined to be either over-skeptical of his own potential or going to the other extreme and overestimate his possibilities in specific areas on occasion.
Extraverted Sensing Suggestive (5)
The individual is often characterized by his inertia. If left to his own devices, he may choose to do relatively little to interact with the outside world. When he does interact with the outside world, he often finds his activities to be empty and unfulfilling. To this individual, life is often characterized by periods of stimulation. For him, however, true stimulation is often spontaneous, and interludes between periods of stimulation are often characterized by tedium, inertia, and apathy. He is often not very adept at finding new areas of interest, and may seek to continue to reproduce past experiences instead of moving on to new things. In order to break out of this cycle, he requires an outside stimulus of spontaneity and activity. With such a degree of spontaneity introduced into his life, the tedium and perceived meaninglessness is replaced by a constant state of activity in which he can experience new things and escape from the confines of his own mind.
He is additionally very indecisive. He may lack the ability to make important decisions, especially with regards to his own future. He may know what he wants to achieve out of life in a broad or long term sense, but will find it very difficult to set and finish the short term projects leading to it. In order to be able to act, he needs a tangible and definite stimulus from somebody well grounded in external reality and who has a clear picture of what must be done in a certain situation.
Introverted Feeling Mobilizing (6)
The individual longs for establishing stable personal relationships with other individuals based on mutual trust and understanding where deeper and private feelings and experiences can be easily shared. However, the individual lacks the initiative to establish such relationships and usually expects others to make gestures in that area, admiring those who do so. In the context of extroverted ethics (Fe) as a vulnerable function, it should be emphasized that these types especially value emotional bonds where feelings go unsaid between partners, and are simply "understood."
Extraverted Thinking Ignoring (7)
The individual is adept at finding external sources of factual information and confident in his ability to evaluate their value, but regards collecting data as secondary to making them fit into a consistent logical system. To him, listing facts without analyzing their relationships is a trivial and boring exercise. He values efficiency and productivity but is skeptical that they will be achieved if one's actions and process do not follow a clear procedure.
Introverted Intution Demonstative (8)
The individual is quite adept at following discussions on the developments of present trends into the future and at contributing to them on occasion if he feels so inclined, but he does not take that as seriously compared to investigating possibilities in the areas he is interested in at present. He usually dismisses supernatural claims as being silly, wishful thinking, unless they happen to be related to the very specific religion he feels inclined to believe in and which he may be inclined to make part of his leisure activities.