The Effects of Brief‐stimulus Presentations in Fixed‐ratio Second‐order Schedules

Abstract

Pigeons' responses were reinforced according to a three-component multiple schedule. In Component 1, key pecks produced food according to a fixed-ratio second-order schedule with fixed-ratio units. Here, a fixed number of fixed-ratio units produced food, and the brief stimulus terminating each unit also accompanied food. Responses in Component 2 produced food on an identical schedule except that the brief stimulus was not paired with food. Component 3 contained a simple fixed-ratio schedule whose response requirement equaled that of Components 1 and 2. Across conditions the size of the fixed-ratio unit (five, ten, twenty, forty, and eighty responses) and the total number of responses per reinforcement were parametrically manipulated. The highest response rates and shortest preratio pauses were observed in Component 3 (no brief stimulus). The lowest rates and longest pauses were found in the component with paired brief-stimulus presentations, indicating that the food-paired brief stimulus suppressed responding. The suppressive effects were greatest when the fixed-ratio units were small (e.g., fixed-ratio 5) and the total fixedratio requirement was large (e.g., fixed-ratio 160). Under no conditions did the paired brief stimulus facilitate responding. The nonpaired brief stimulus also suppressed responding but to a lesser extent. The suppressive effects of nonpaired brief stimuli were greatest when the fixed-ratio units were small and the total response requirement was large. These data suggest that the suppressive effects of the brief stimuli may have masked the conditioned-reinforcing effects reported in other studies, and that conditions that maximize suppression in second-order schedules involve the use of fixed-ratio schedule units and the presentation of many brief stimuli per reinforcer.Key words: second-order schedules, brief-stimulus presentations, multiple schedules, conditioned reinforcement, key peck, pigeonsIn a second-order schedule of reinforcement, responses maintained by one schedule of reinforcement (the unit schedule) are treated as single responses and reinforced according to another schedule of reinforcement (e.g., Kelleher, 1966b 1977; Kelleher, 1966a;Marr, 1969) this schedule may be designated FR 15 .Many experiments have examined secondorder schedules, primarily as a means of studying the conditioned reinforcing functions of brief-stimulus presentations (see Gollub, 1977, for a review). Unfortunately, even though considerable research has been conducted, there have been few parametric examinations of second-order schedules (see Gollub, 1977;Lee & Gollub, 1971). A thorough understanding of the behavior controlled by these schedules and the effects of brief-stimulus presentations requires systematic manipulation of many variables including unit schedules, overall reinforcement schedules, and brief-stimulus presentations. Consequently, the present study was a parametric examination of fixed ratio (FR)

The influence of brief stimuli uncorrelated with reinforcement on choice between variable-ratio schedules

“…In the Reed and Hall study, presentation of the tone midway through the ratio produced much the same behavior as would be expected from presenting primary reinforcement in this position. Similar effects have been reported for second-order fixed-ratio (FR) schedules (e.g., Cohen & Calisto, 1981) and for second-order interval schedules (e.g., Squires, Norborg, & Fantino, 1975).…”

EFFECTS OF d‐AMPHETAMINE ON RESPONDING UNDER SECOND‐ORDER SCHEDULES OF REINFORCEMENT WITH PAIRED AND NONPAIRED BRIEF STIMULI

“…Actually, many variables affect rates and patterns of responding within components of second-order schedules, including duration (Cohen, Hughes, & Stubbs, 1973) and type of brief stimulus (Stubbs & Cohen, 1972). These variables may interact to determine whether or not paired and nonpaired brief stimuli differentially affect behavior (Cohen & Calisto, 1981;Stubbs, Vautin, Reid, & Delehanty, 1978). For example, under a second-order schedule with fixed-interval components, Stubbs et al (1978) found no differences between paired and nonpaired briefstimulus presentations with a 2.5-s brief stimulus but did obtain differential effects with a 0.5-s stimulus change (i.e., greater FI cur-vature with a shorter paired brief stimulus than a shorter nonpaired stimulus).…”