Social reality can be created through self-fulfilling prophecies and perceptual biases. A self-fulfilling prophecy is a false belief that leads to its own fulfillment. A perceptual bias occurs when an individual believes that her or his inaccurate expectation about another has been confirmed to a greater extent than it has in reality. Although research findings bearing on these processes are robust, these effects are typically small. Nonetheless, this does not mean that self-fulfilling prophecy and perceptual bias effects are always small. There are conditions under which such effects have the potential to be powerful. The current experiment tested this possibility by addressing two main goals: 1) to examine if expectancy effects accumulate across perceivers and 2) to examine whether unfavorable or favorable expectancies produce more powerful cumulative expectancy effects. Sessions were run with groups of two perceivers and one target (N=145 groups). Whereas some perceivers were induced with either an unfavorable (i.e., hostile) or a favorable (i.e., friendly) expectancy, other perceivers were not induced with any expectancy. All perceivers then interacted with a target in a reaction time task, during which they used a noise weapon on an alternating basis. After the reaction time task, participants' impressions of each other were measured. The average noise level that targets administered to perceivers was the dependent variable used to test for self-fulfilling prophecy effects. Perceivers' impressions of targets was the dependent variable used to test for perceptual bias effects. Results failed to support the occurrence of a self-fulfilling prophecy. However, perceptual bias effects were observed - perceivers induced with an unfavorable expectancy judged targets' as significantly more hostile than perceivers who were not induced with an unfavorable expectancy. However, further analyses indicated that perceptual bias effects did not accumulate across perceivers. Possible implications and some limitations of the experiment are discussed.