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252 PART III: Experimental Methodsinfluence the interrogation tactics they use. Kassin and his colleagues haveconducted many studies to identify factors that lead to false confessions by innocentpeople. In the present study, Kassin et al. hypothesized that one potentialreason for false confessions is that interrogators have a confirmation biasin which their initial beliefs about a suspect’s guilt cause them to interrogatemore aggressively, ask questions in a manner that presumes guilt, and causesuspects to behave defensively (which is interpreted as guilt). In general, thisbehavioral confirmation theory has three parts: (1) the perceiver forms a beliefabout a target person; (2) the perceiver behaves toward the person in ways thatare consistent with the belief; and (3) the target person then responds in waysthat support the perceiver’s belief. Ultimately, in the criminal justice context theend result of this process can be a confession of guilt by an innocent person.Kassin and his colleagues (2003) tested the behavioral confirmation theoryin a clever experiment involving college student participants. Pairs of studentsparticipated as interrogators and suspects. “Interrogators” were asked to playthe role of a detective trying to solve a case in which $100 was stolen froma locked cabinet. Importantly, the researchers manipulated the interrogator’sexpectations regarding the suspect’s guilt. Half of the student interrogatorswere randomly assigned to the guilty expectation condition, in which the experimentersaid that 4 out of every 5 suspects in the experiment actually committedthe crime. Thus, these research participants were led to believe their chances ofinterrogating a guilty suspect were high (80% likelihood). In the innocent expectationcondition, research participants were told their chance of interrogatinga guilty suspect was low because only 1 out of 5 suspects was actually guilty(20%). This independent variable, interrogator expectation, was manipulated toinitiate a confirmation bias among interrogators.Other students played the role of suspect. Because suspects’ behavior inan actual interrogation is influenced by their true guilt or innocence, Kassinet al. manipulated students’ guilt or innocence using the independent variable,suspect status. In the guilty condition, students were asked to commit a mocktheft in which they were instructed to enter a room, find a key hidden behinda VCR, use the key to open a cabinet, take $100, return the key, and leave withthe $100. Students in the innocent condition were asked to approach the sameroom, knock on the door, wait for an answer (which did not occur), and thenmeet the experimenter. Half of the student-suspects were randomly assignedto the guilty role and half were assigned to the innocent role. All suspects wereinstructed to convince the interrogator of their innocence and to not confess.Interrogators were given the conflicting goals of trying to obtain a confessionbut also to determine whether the suspect was actually guilty or innocent. Theinterrogations were tape recorded.Factorial combination of the two independent variables created four conditionsin this 2 2 complex design:1 Actual guilt/Guilty expectation2 Actual guilt/Innocent expectation3 Actual innocence/Guilty expectation4 Actual innocence/Innocent expectation