Some child researchers have found that both nonreward and interruption invigorate subsequent instrumental performance; others have found that interruption decreases vigor of subsequent performance (Ryan & Watson, 1968). Ford (see Ryan & Watson, 1968) offered a self-other blame hypothesis to explain this discrepancy suggesting that subjects who responded less vigorously following interruption had been led to believe that they were to blame for the interruption. This self-blame set was assumed to be inhibiting.Efforts thus far to test the self-other blame hypothesis have yielded inconsistent results (Pederson & McEwan, 1970;Ryan & Strawbridge, 1969). A further and more rigorous test of the self-blame hypothesis was devised to (a) use other blame conditions which would vary the social power of the interrupting agent and (b) employ an experimental task that allowed believable manipulation of the source of blame.The Haner-Brown marble game was presented to third-grade, white, middle-class males ages 8-10. On each of 24 trials, the subject attempted to fill a marble board. Following either interruption or noninterruption on the marble game (Task 1), the subject pulled a lever (Task 2).In Study 1, 84 subjects received one of four sets of instructions. One set focused the blame for the interruption on the subject, while the other sets focused blame on an external agent:1 This article is based on a doctoral dissertation submitted to the Department of Psychology at the University of Georgia.