Daniels Carter W, Sanabria Federico
Department of Psychology, Arizona State University.
J Exp Psychol Anim Learn Cogn. 2017 Jul;43(3):280-294. doi: 10.1037/xan0000144.
According to the biexponential refractory model (BERM) of variable-interval (VI) performance, operant behavior is organized in bouts, described by 3 dissociable components: between-bout interresponse times (IRTs), within-bout IRTs, and bout lengths. Research has shown that between-bout IRTs are sensitive to changes in rate of reinforcement and reinforcer efficacy, the length of some bouts is selectively sensitive to changes in response-reinforcer contingencies, and within-bout IRTs are relatively insensitive to both manipulations. BERM assumes that within- and between-bout IRTs are exponentially distributed, and bout lengths are described by a mixture of negative binomial and geometric distributions. To assess BERM assumptions and the interpretation of associated findings, Fischer 344/DuCrl rats were trained on a heterogeneous tandem VI fixed-ratio (FR) schedule of reinforcement intended to dissociate the components of operant behavior. Initial (VI) and terminal (FR) links were programmed on separate levers; no stimulus signaled the completion of the initial link. FR requirement, VI requirement, and deprivation level were varied. Typical performance consisted of single responses on the VI lever separated by response runs on the FR lever. It was hypothesized that (a) the interval between the end of each FR run and the first subsequent VI response (FR-VI IRTs) would constitute between-bout IRTs, and would be sensitive to changes in VI requirement and deprivation level, (b) FR runs would constitute response bouts, so the length of a fraction of them would be selectively sensitive to changes in FR requirement, and (c) intervals between consecutive FR responses (FR-FR IRTs) would constitute within-bout IRTs, and would be relatively robust to all manipulations. Findings were consistent with these expectations. The underlying distributions of FR-FR IRTs, FR-VI IRTs, and FR run lengths, however, were inconsistent with BERM assumptions. These data support the distinct components of operant performance, but challenge the simple processes assumed to underlie their generation. (PsycINFO Database Record
根据可变间隔（VI）行为表现的双指数不应期模型（BERM），操作性行为是以发作形式组织起来的，由三个可分离的成分描述：发作间反应时（IRT）、发作内IRT和发作长度。研究表明，发作间IRT对强化速率和强化物效力的变化敏感，一些发作的长度对反应-强化物偶联的变化有选择性地敏感，而发作内IRT对这两种操作相对不敏感。BERM假设发作内和发作间IRT呈指数分布，发作长度由负二项分布和几何分布的混合来描述。为了评估BERM假设及相关研究结果的解释，对Fischer 344/DuCrl大鼠进行了异质串联VI固定比率（FR）强化程序训练，旨在分离操作性行为的成分。初始（VI）和终端（FR）环节设置在不同的杠杆上；没有刺激信号表明初始环节的完成。改变FR要求、VI要求和剥夺水平。典型的行为表现为在VI杠杆上的单次反应，中间穿插在FR杠杆上的反应序列。研究假设如下：（a）每次FR反应序列结束与随后第一个VI反应之间的间隔（FR-VI IRT）将构成发作间IRT，并且对VI要求和剥夺水平的变化敏感；（b）FR反应序列将构成反应发作，因此其中一部分的长度将对FR要求的变化有选择性地敏感；（c）连续FR反应之间的间隔（FR-FR IRT）将构成发作内IRT，并且对所有操作相对稳健。研究结果与这些预期一致。然而，FR-FR IRT、FR-VI IRT和FR反应序列长度的潜在分布与BERM假设不一致。这些数据支持了操作性行为表现的不同成分，但对假定为其产生基础的简单过程提出了挑战。（PsycINFO数据库记录）
