Figures are available here .
82 of the participants were undergraduates between the ages of 18 and 40 enrolled in an introductory psychology course at the University of Washington. These people participated in the experiment in return for extra credit in their class. For the four weeks of the study during which the Psychology Department s human subject pool was unavailable, the remaining 43 participants were recruited through an advertisement in the campus paper. These recruited participants were between the ages of 18 and 50 and were paid an hourly rate for their participation. Materials and apparatus.