ABSTRACT
Match-to-sample (MTS) is a sequential “if … then” or conditional discrimination. There are several characteristics of the MTS procedure that make it suitable for studying such aspects of animal cognition as short-term memory, perceptual categorization or concept formation, counting, abstraction and some aspects of language, especially semantic comprehension. (For reviews of MTS paradigms as they relate to concept formation, abstraction, and semanticity, see Schusterman & Gisiner, 1989; Sidman & Tailby, 1982; Carter & Werner, 1978.) When visual cues are used in MTS, a sample stimulus is displayed, usually in a central position, equidistant from subsequent choice stimuli. The sample stimulus is followed by comparison or choice stimuli. The comparison stimuli are presented simultaneously on two or more side panels. If the physical characteristics of sample and comparison configurations are different, the relations between these types of stimuli are considered “arbitrary” (Cumming & Berryman, 1965). In animal language research, sample stimuli as well as comparison stimuli may be presented in a variety of ways (Schusterman & Krieger, 1984). In the original and simplest case, there are two sample stimuli and two comparison stimuli. In this chapter, the two sample stimuli are designated as A1 and A2 and two comparison stimuli are designated as B1 and B2. Reinforcement contingencies are arranged by the experimenter so that an animal’s choice of B1 is correct and reinforced in the presence of A1, but not in the presence of A2, while its selection of B2 is correct and reinforced in the presence of A2 but not in the presence of A1. For example, a monkey may be trained to match a set of geometric figures as samples (A1 = circle; A2 = triangle) to pictures of animals as comparisons (B1 = hawk; B2 = leopard).
