Behavioural Processes 44 (1998) 11–17
Behavioral contrast using different reinforcers: effect of baseline
rate of reinforcement
Jeffrey N. Weatherly
a,b,
*, Cam L. Melville
a
, Samantha Swindell
b
a
Department of Psychology, McNeese State Uni6ersity, Lake Charles, LA
70609
-
1895
, USA
b
Washington State Uni6ersity, Pullman, WA, USA
Received 8 January 1998; received in revised form 20 April 1998; accepted 6 May 1998
Abstract
The present study determined whether behavioral contrast would occur when different reinforcers were delivered in
the different components and whether its size would vary at different baseline rates of reinforcement. Pigeons pecked
keys on a multiple variable-interval schedule. Mixed grain was the reinforcer in one component and wheat was the
reinforcer in the other component. In contrast conditions, the rate of wheat reinforcement was increased or decreased,
from the baseline delivery rate, by a factor of four. Contrast was studied at four different baseline rates of
reinforcement. Contrast was usually observed and its size almost always varied directly with the programmed baseline
rate of reinforcement. The present results indicate that changes in the condition of reinforcement of a different
reinforcer can produce contrast. They also broaden the potential implications of behavioral contrast. © 1998 Elsevier
Science B.V. All rights reserved.
Keywords
:
Baseline rate of reinforcement; Behavioral contrast; Key peck; Mixed grain; Pigeon; Wheat
1. Introduction
Behavioral contrast can be defined as an inverse
relationship between rate of responding in one
(constant) component of a multiple schedule and
the conditions of reinforcement in another
(changing) component (McSweeney, 1978; Mc-
Sweeney and Norman, 1979; Ettinger et al., 1981;
Weatherly et al., 1997). Negative contrast is a
decrease in response in the constant component
when the conditions of reinforcement in the
changing component are enriched. Positive con-
trast is an increase in response in the constant
component when the conditions of reinforcement
in the changing component are worsened.
The present study attempted to produce con-
trast when different reinforcers were delivered in
the constant and changing components. Previous
studies have investigated contrast using different
* Corresponding author. Tel.: + 1 318 4755435; fax: + 1
318 4755467; e-mail: jnweath@mail.mcneese.edu
0376-6357/98/$ - see front matter © 1998 Elsevier Science B.V. All rights reserved.
PII
S0376-6357(98)00027-8