An operant arena for rats

Abstract

A multiunit operant arena for the study of dispersion patterns in rats is described. Lawful relationships between the spatiotemporal organization of the group and reinforcement schedules have been found. The scientific and humanistic advantages of the system are discussed. The distribution and abundance of animals is so central a feature of social organization (Krebs, 1978) that its analysis forms the core of ecological science. Ecological analysis lays considerable emphasis on the role of food supply in regulating population density pat­ terns and yet the mechanisms by which this is achieved still require clarification (Watson & Moss, 1970). It is therefore noteworthy that when animals go about the business of procuring food, they do so with respect to a schedule of reinforcement fabricated by their natural and social environment. Important features of such schedules can be simulated in an operant arena, and their effects on dispersion patterns can be analyzed. THE OPERANT ARENA A 3.7 x 3.4 x 1.2 m arena constitutes the permanent living and work area for a group of eight male hooded rats (Figure 1). Hinged Plexiglas partitions along the two opposite walls of the arena permit observation from four cubicles and access to the arena. Mirrors, 1.23 x .31 m, mounted on the walls above these partitions permit observation of the entire arena from any cubicle. Venti­ lation is achieved by a large exhaust fan situated over a drop pegboard ceiling of the arena. A suspended 1.22-cm wire-mesh floor facilitates the flow of air through the system and also permits urine and feces to fall onto a V-shaped trough. Perforated copper pipes (l.9-cm diam) along the top of the urinal discharge water periodically through the night when a solenoid control valve is pulsed by a timer. Two banks of fluorescent lights, mounted in the peg­ board ceiling, provide illumination for a 14-h/1O-h light-dark cycle. A pair of elevated wire rest shelves (55 x 35 x 36 em) fitted with an access ladder are situated on opposite sides of the arena for the animal's convenience and comfort. Eight feeding stations are arranged along two opposite ends of the arena in a bilateral symmetric pattern. A feeding station consists of an insertable response bar