Emergence of reinforcer preference as a function of schedule requirements and stimulus similarity

Tustin (1994) recently observed that an individual’s preference for one of two concur-rently available reinforcers under low schedule requirements (concurrent fixed-ratio [FR] 1) switched to the other reinforcer when the schedule requirements were high (concurrent FR 10). We extended this line of research by examining preference for similar and dis-similar reinforcers (i.e., those affecting the same sensory modality and those affecting different sensory modalities). Two individuals with developmental disabilities were ex-posed to an arrangement in which pressing two different panels produced two different reinforcers according to progressively increasing, concurrent-ratio schedules. When two dissimilar stimuli were concurrently available (food and a leisure item), no clear preference for one item over the other was observed, regardless of the FR schedules in effect (FR 1, 2, 5, 10, and 20). By contrast, when two similar stimuli were concurrently available (two food items), a clear preference for one item emerged as the schedule requirements were increased from FR 1 to FR 5 or FR 10. These results are discussed in terms of impli-cations for conducting preference assessments and for selecting reinforcers to be used under training conditions in which response requirements are relatively high or effortful. DESCRIPTORS: behavioral economics, preference, reinforcer assessment Recent work in applied behavior analysis has begun to examine the variables that in-fluence choice among reinforcement op-tions. Much of this research has involved ex-tensions to human behavior of laboratory studies on the matching law, which states that the distribution of responding under concurrent schedules of reinforcement will approximate the rates of reinforcement avail-able under those schedules (Herrnstein, 1961). For example, Mace, McCurdy, and Quigley (1990) showed that when a student received reinforcement for completing either multiplication or division problems on con-current variable-ratio (VR) 2 schedules of food delivery, the student completed roughly equal numbers of the two types of problems. However, when the rate of reinforcement fo