Reserve, the fourth and most subtle form of privacy, is the creation of a psychological barrier against unwanted intrusions; this occurs when the individual's need to limit communication about himself is protected by the
willing discretion of those surrounding him. Most of our lives are spent not in solitude or anonymity but in situations of intimacy and in group settings where we are known to others. Even in the most intimate relations, communication of the self to others is always incomplete and is based on the need to hold back some part or parts of one's self as either too personal and sacred or too shameful and profane to express. (Westin, 1967) This circumstance gives rise to what Simmel called "reciprocal reserve and indifference" the relation that creates a mental distance to protect the personality. (Wolff, 1950) Interviews, questionnaires, and the like, which collect not only highly personal but highly identifiable information, constitute an intrusion of a person's right to reserve when administered to unwilling persons.