The initial objective was to determine whether an increase in cooperative responses (minimal cooperation) was also accompanied by an increase in the degree of correspondence in the number of reinforcers of the two subjects (maximal cooperation). Correct matching-tosample responses of seven pairs of male adolescents were reinforced with money. On each trial, a subject could (1) give the matching-to-sample problem to his coactor (give or cooperative responses), or (2) take the problem for himself (take responses). The first member of the pair to respond made the choice. Correspondence did increase under this procedure as compared to a baseline where problems were distributed randomly. However, the increased cotrespondence usually resulted from take responses rather than cooperative give responses. This equitable method of problem distribution, designated as sharing, was characterized by the subjects alternately taking problems. The spacing of daily sessions may have been partly responsible for the high degree of correspondence, because correspondence did not increase within the usual number of sessions when the sessions were massed, i.e., all in one day. Daily sessions require cooperative responses, i.e., each subject has to show up each day for the other to earn money, and this dependency upon the coactor's behavior may facilitate some sharing or cooperation to ensure the coactor's attendance.A cooperation procedure may be defined as one in which the reinforcers of each member of a pair are at least partly dependent upon the responses of the other member (Hake and Vukelich, 1972). The cooperation effect is then defined by increases in these responses by both members of the pair. Hake and Vukelich (1972) suggested a second cooperation effect. While increases in cooperative responses are indicative of control by the reinforcer resulting from the cooperation procedure, control by the reciprocal nature of the cooperation procedure also requires equality or at least an increase in the degree of correspondence between the numbers of reinforcers or cooperative responses of the members of the pair. If cooperation is to be considered a social behav-

Pairs of high-school students matched-to-sample for money. On each trial, the first pair member to complete a fixed ratio of knob-pulling responses could work the matching problem on that trial. Competition occurred when both pair members responded for the problem. Sharing occurred when only one pair member responded on each trial, and the subjects alternated trials. Hence, sharing requires less responding and still allows a moderate number of reinforcers for each subject. Recent research has shown that increasing the response requirement to the point that it may have aversive properties will produce a change from competition to sharing. A related variable is an adjusting schedule that adjusts the subjects' response requirements so that their abilities to take reinforcers are equal. In this way, subjects might learn that competition requires more responding but produces no more reinforcers. However, recent research also suggests that competition decreases over sessions without experimental manipulations. Because of this possibility of a time-related variable, ratio size and an adjusting schedule were studied in a group design. Competition did decrease for all groups over sessions, but the large-ratio groups switched from competition to sharing sooner than the low-ratio groups. The adjusting schedule had a similar but smaller effect.

Two pairs of high-school students matched-to-sample for money. On each trial, a subject could either respond on one lever to take the matching-to-sample problem himself (taking response) or respond on a second lever to give the problem to his coactor (giving response). The first subject to complete the response requirement determined the distribution of the problem. Competition maximizes the amount of responding over trials, i.e., both subjects make taking responses on each trial. Sharing and cooperation minimize responding: only one subject makes a taking response (sharing) or a giving response (cooperation) on each trial, and the subjects alternate responding such that there is an equitable distribution of responses and reinforcers over trials. Large increases in the fixed-ratio response requirement to distribute problems produced: (l) a switch from competition to sharing or cooperation, (2) the expected concomitant change from inequitable to equitable distributions of reinforcers, and (3) a reduction in the amount of responding for three of the four subjects. Previous animal research has shown that large response requirements may have aversive properties. Switching from competition to sharing or cooperation at large response requirements allows a reduction in responding and, at the same time, a moderate number of reinforcers for each subject.

Several states and the United States have laws that exempt persons who have mental retardation from the death penalty and other severe sentences. Two recent murder cases in Indiana, which has such a law, illustrate some of the problems in applying it. The characteristics of the two defendants were quite similar, but one defendant was found to have mental retardation and was exempted from the death penalty and the other was not. The disparity was attributed to differences in the assessment of adaptive behavior and to general stereotypes of people who have mental retardation. Equal application of sentencing limitation laws requires greater involvement of professionals with specialized training and experience in mental retardation.