Gallo and McClintock (1955)
' in reviewing the variables affecting performance in mixed-motive games, noted that the amount and type of communication between the participants appeared to be an important factor. Most experiments using games of the Prisoner's Dilemma (PD) type involve limited communication.
Little is known about the effects of nonverbal cues on bargaining performance. Vocal expression is frequentIy used to convey emotion. Soskin and Kauffman (1961), among others, have demonstrated that emotions can be recognized by judges even when the content has been eliminated from the speech. In the present experiment the emotions 'angry' and 'pleased' were selected for study. The author (Steer, 1971) has previously shown that judges agreed in their recognition of the two emotions expressed by subjects who were counting aloud. She also found that 'angry' and 'pleased' were assessed as bipolar when judges rated them on the sematic differential. Deutsch (1960) had found evidence for an instruction effect when subjects were told to adopt a competitive, cooperative or individualistic orientation. How exactly competitive and cooperative approaches are executed in bargaining games is not known. Each may be associated with appropriate emotional expressions. 'Angry' and 'pleased' vocal expression may be associated, respectively, with competitive and cooperative orientations. This experiment examines the effects of vocal expression and instructions on performance in a modified PD game, to test the hypothesis that each would affect the number of cooperative choices, fewer being found for the 'angry' and 'competitive' conditions. The payoff matrix used is given in Figure 1. * This study is based on part of a Ph. D. R. Shaw for technical assistance. thesis submitted to the University of Lon-** Requests for reprints should be sent to don. The author would like to express Angela B. Summerfield, Department of Psythanks for their advice to Arthur Summer-chology, Birkbeck College, Malet Street, field an the late Thelma Veness. She