According to the MBTI model, the ISTPs are mainly oriented towards introverted thinking (Ti). This orientation reveals a more analytical perspective for problem-solving, based on the understanding of structures and how to use it in their favor. Secondarily, the extraverted sensing (Se) helps compose this type’s need for independence, concrete decision making according to the situation and adaptable thinking, always in a logical way. These are the main ‘cognitive functions’ that characterize the ISTP type. The model extends to other functions considered inferior or/and unconscious, summing up to 8 cognitive functions.
ISTPs are described by Dario Nardi as vigorous problem-solvers who like to observe and understand how things work. For Nardi, they love having new ideas and sharing them, are moved by exciting experiences, and by emotional impulse, while Kelly, Barbara, and Paul D. Tieger focused more on their unceremonious, detached, and self-oriented aspects. For the Tieger family, ISTP’s Extraverted Intuiting side contributes to their awareness about the environment, and Extraverted Feeling regulates their intensity of communication. It results in a decisive, strict, reflective, and questioning character. Despite their tendency to be less talkative (except for especially interesting conversations), this MBTI type has a better perspective about themselves in social environments than what others tend to have about them since their engagement in conversation oscillates significantly depending on the subject. Moments of stress can cause them either to remain silent or to reveal their most critical and argumentative side during a discussion. Their logical, methodic, and strategic thinking might affect their relations negatively, for they don’t mind taking a decision that upsets others if they judge it’s the best choice. ISTPs can be viewed as snobby, unapproachable, unsympathetic, and good-natured at the same time, and they learn by experimentation and testing of strategies and ideas, Tieger family added.
According to David Keirsey, ISTP’s are inclined to arts and crafts, are pleasure-seeking, optimistic, pursue honor, and value generosity. Keirsey emphasizes their impulsiveness and fierce struggle for freedom and independence, considering this type as the most capable of mastering the use of tools between all MBTI types. They are also described as tactical, eager for activities that give them adrenaline and tendency to get bored when not entertained, unless in case of enjoyable activities that require patience. They can be wrongly diagnosed as dyslexic or as having a learning disability because of a simple lack of focus in communication, and as “brain-damaged,” hyperactive, or as having attention deficit disorder because of lack of will to do what they are told to. ISTPs are egalitarian, loyal, and helpful to comrades, but at the same time, they are loners, who’re not always willing to cooperate when feeling pressured by schedules or procedures. For Keirsey, they are also likely to neglect their children’s safety, while more likely to spoil them, although they can be harsh parents sometimes.
Other characteristics of ISTPs reported by Isabel and Peter B. Myers are their interest in science (especially mechanics), being good with manual activities, a talent for organizing, classifying and interpreting data and facts, along with statistics. As a weak point, they are also described as tending towards shyness and having low interest in socialization.
By: Regina Burde- “Someone who likes to explore human behavior, be it through the perspective of arts or science.”
 Keirsey, D. (1998). Please Understand Me II: Temperament Character Intelligence. Prometheus Nemesis Book Company. 1 edition.