A theoretical analysis is presented in which the four major attachment patt
erns (A, B, C, and D) are viewed as adaptations to particular forms of earl
y contingency experience. The author proposes that human infants analyze co
ntingency experience on the basis of two computations of conditional probab
ility, one prospective and one retrospective. Ideally, when these computati
ons do not agree, the direction of disagreement Provides information as to
how the infant should adjust effective behavior and/or how potential contin
gent consequences should be redefined. The author also proposes that the sp
ecific patterns of insecure attachment (A, C, and D) are a result of parent
al responsiveness that is by nature inconsistent or out of balance and that
the infant interprets this imbalance as his or her misperception of a bala
nced contingency. The observed symptoms of attachment insecurity are seen a
s consistent with specific attempts by infants to adjust behavior and/or di
scrimination according to the direction of imbalance in conditional probabi
lities they have experienced in interactions with their caretakers.