The behavior of focus samples central to the multiple-look model of Trabasso and Bower is examined by three methods. First, exact probabilities of success conditional upon a certain brief history of stimulation are determined. Second, possible states of the organism during the experiment are defined and a transition matrix for those states determined, permitting prediction over all possible numbers of trials. Third, Fisher's generalizations and corrections of the Trabasso and Bower focus sample theory are examined. A general solution for the conditional probability of success is derived from Fisher's equation for the probability of n successes between any two errors. One very strong implication of the theory is given in Section 5. (Author)