Barnes, D., & Keenan, M. (1989). Instructed human fixed-interval performance: The effects of the experimental setting. The Psychological Record, 39, 351-364.
The authors (researchers at the Behavioral Analysis and Behaviroal Reasearch Ctr, Ireland) conducted an experiment in which four adults (aged 20-24 yrs) were exposed to 600-sec, 300-sec, and 60-sec FI schedules of reinforcement and were given instructions specifying the FI-based nature of the schedules and the behavior required to obtain points exchangeable for money. The experimental setting was 3 rooms: Room A, with reading material, food snacks, and drinks; Room B, with a computer keyboard (KB); and Room C, with a monitor connected to the KB in Room B. Ss were instructed to type "FEED" on the KB in Room B and then immediately check the monitor in Room C for delivery of points. Findings demonstrate a potentially powerful interaction between the experimental setting, the nature of the operant, and the FI value in determining overall schedule performance.