The effects of fixed‐interval schedules on variability of pigeons' pecking location

Many studies that have investigated performance under reinforcement schedules have measured response rate or interresponse time, which reflect the temporal dimension of responding; however, relatively few studies have examined other dimensions. The present study investigated the effects of fixed‐interval schedules on the location of pigeons' pecking response. A circular response area 22.4 cm in diameter was used so that the pecking responses were effective over a wide range. Pigeons were exposed to a fixed‐interval schedule whose requirement was systematically varied between conditions. Response location moved closer to the location of the last reinforced response as time elapsed in each trial. Additionally, as the fixed‐interval duration requirement increased, response locations shifted to the border of the response area and the variability of response locations increased. These results suggest that fixed‐interval schedules systematically control response location.     

社会网络分析在心理研究中的应用

个体不是孤立存在的, 其心理与行为的变化常依赖于与他人存在的关系。社会网络分析正是考虑到了这种依赖性, 发展出相应的处理关系变量的方法。在介绍社会网络理论的中心思想、社会网络分析的基本概念、数据表示方法和研究方法以及在个体水平和关系水平上的静态统计模型后, 使用UCINET软件展现了处理关系数据的基本步骤, 并简述社会网络分析在人格心理学、发展与教育心理学和管理心理学中的应用。     

Additive summation following intradimensional discrimination training

Rats were exposed to intradimensional composite stimuli presented on the response lever that varied in both light intensity and flicker rate. For all subjects, pressing the lever was reinforced when it was illuminated at a high intensity and flickered at a low rate (I + f) or when it was illuminated at a low intensity and flickered at a high rate (i + F). For half the subjects, lever responding was not reinforced when it was illuminated at a low intensity and flickering at a low rate (i + f). For the remaining subjects, lever presses were not reinforced when the lever was illuminated at a high intensity and flickered at a high rate (I + F). When the composite stimulus composed of the light intensity and flicker rates that had been associated only with reinforced responding was displayed (I + F for half the subjects and i + f for the remaining subjects), it controlled the highest response rate of all stimuli (additive summation). The results demonstrated that similar attentional processes control intra- and interdimensional composite-stimulus discriminations in a manner consistent with Weiss' (1972) analysis of summation.     

任职者任务绩效水平对其工作分析结果的影响

在控制了个体人口统计学变量和排除组织水平变量的影响下,探讨了电厂设计和编辑两个职位任职者的任务绩效水平对于他们Occupational Information Network (以下缩写为O*NET)工作分析问卷评价结果的影响。层次回归结果发现,控制了相关因素后,发电厂设计人员的任务绩效水平能显著影响其对技术性技能的水平评价,编辑的任务绩效水平能显著影响信息处理的重要性评价和水平评价,在一定程度上证实了“工作分析结果差异来源于真实差异”的理论     

CD_4~+ CD_(25)~+调节性T细胞在妊娠与分娩中的作用

近代生殖免疫学研究认为,正常妊娠维持有赖于母胎免疫耐受的形成,耐受一旦失调,就可能妊娠失败,发生如流产,妊娠期高血压疾病,胎膜早破,分娩发动等。近几年来,国内外学者逐渐认识到CD4+CD25+调节性T细胞在妊娠中的重要作用并进行系列研究。本文就目前CD4+CD25+调节性T细胞在妊娠与分娩中的作用作一综述。     

Effects of d-amphetamine and pentobarbital under concurrent fixed-ratio schedules.

Pigeons were studied under a two-key concurrent fixed-ratio schedule of food presentation. During the first five sessions, the fixed-ratio requirements were 30 responses on one key (major key) and 120 responses on the other key (minor key): responding occurred almost exclusively on the major key. When the fixed-ratio requirements were then made equal at 30 responses on both keys, responding continued to predominate on the major key. The asymmetric distribution of responses persisted when the concurrent fixed-ratio fixed-ratio schedule was interrupted with periods during which the major key was associated with extinction while the other key remained associated with a fixed-ratio schedule. Additionally, in some subjects the fixed-ratio requirements were increased. These schedule modifications decreased the asymmetry in responding but did not eliminate it. d-Amphetamine decreased rates on both keys and slightly increased the asymmetric distribution of responses, while pentobarbital reversed the distribution of responses by increasing low rates and decreasing high rates. The pigeons maintained their original asymmetric distribution of responses during the 1 1/2-year-long study, despite schedule alterations and drug administrations.     

Human Sensitivity To Concurrent Schedules Of Reinforcement: Effects Of Observing Schedule-correlated Stimuli

The determinants of human sensitivity to concurrent variable-interval variable-interval schedules of reinforcement have been difficult to identify, in part because of procedural differences separating published experiments. This experiment investigated vigilance to stimuli correlated with concurrent schedules. Across phases, 3 college students were provided with either no schedule-correlated stimuli, an observing response that provided brief access to the stimuli, or a contingency that required the subject to identify the stimulus correlated with the source of each obtained reinforcer. Sensitivity, as quantified by the generalized matching equation, was low when no stimuli were available. When the stimuli were response contingent, 1 subject observed them, and her behavior became more sensitive to the distribution of reinforcers across the concurrent schedules. When the procedure required discrimination of the stimulus correlated with each reinforcer, the other 2 subjects also observed the stimuli, and their schedule sensitivity was increased as well. These results implicate procedural differences, rather than inherent behavioral differences, as the source of differences in sensitivity to schedules of reinforcement between humans and nonhumans.     

Earning and obtaining reinforcers under concurrent interval scheduling

Contingencies of reinforcement specify how reinforcers are earned and how they are obtained. Ratio contingencies specify the number of responses that earn a reinforcer, and the response satisfying the ratio requirement obtains the earned reinforcer. Simple interval schedules specify that a certain time earns a reinforcer, which is obtained by the first response after the interval. The earning of reinforcers has been overlooked, perhaps because simple schedules confound the rates of earning reinforcers with the rates of obtaining reinforcers. In concurrent variable-interval schedules, however, spending time at one alternative earns reinforcers not only at that alternative, but at the other alternative as well. Reinforcers earned for delivery at the other alternative are obtained after changing over. Thus the rates of earning reinforcers are not confounded with the rate of obtaining reinforcers, but the rates of earning reinforcers are the same at both alternatives, which masks their possibly differing effects on preference. Two experiments examined the separate effects of earning reinforcers and of obtaining reinforcers on preference by using concurrent interval schedules composed of two pairs of stay and switch schedules (MacDonall, 2000). In both experiments, the generalized matching law, which is based on rates of obtaining reinforcers, described responding only when rates of earning reinforcers were the same at each alternative. An equation that included both the ratio of the rates of obtaining reinforcers and the ratio of the rates of earning reinforcers described the results from all conditions from each experiment.     

Drug discrimination using a conditioned taste-aversion paradigm in rhesus monkeys.

The development of drug discrimination was assessed in rhesus monkeys using the conditioned taste-aversion paradigm. Monkeys were initially trained to respond under a fixed-ratio 30-response schedule of food-pellet delivery to assess the rate-decreasing effects of alprazolam (0.03 to 3 mg/kg, i.m., 60 min presession). Alprazolam decreased responding at doses greater than 0.1 mg/kg. Discriminative stimulus effects of alprazolam were then assessed by giving 0.03 mg/kg before sessions in which 1.8 mEq/kg lithium chloride was given immediately after the session (alprazolam/lithium session). On intervening days, saline was given before and after the session (saline/saline session). Rates of responding decreased over successive alprazolam/lithium sessions and also during the saline/saline session that immediately followed an alprazolam/lithium session. During subsequent saline/saline sessions, rates of responding returned to levels near baseline rates within two to four sessions. The discriminative stimulus effects of alprazolam were then assessed by giving 0.1 mg/kg before sessions in which 1 mg/kg d-amphetamine was given immediately after the session (alprazolam/d-amphetamine session). Rates of responding decreased during subsequent alprazolam/d-amphetamine sessions in drug-experienced monkeys, but did not decrease during intervening saline/saline sessions. These findings demonstrate that drug stimuli associated with postsession drug injections can rapidly develop control over behavior and suggest that similar methods be explored in the assessment of drug discrimination.     

Ralph Burhoe's Evolutionary Theory of Religion

Ralph Wendell Burhoe's legacy rests on a series of interrelated theories that deal with (1) the emergence of life within physical nature; (2) the symbiosis of genes and cultures in human evolution; (3) the central importance of the brain in this symbiosis; and (4) the function of religion within this evolutionary process to carry the traditions of trans-kin altruism that make human civilization possible. These theories give rise to a number of issues that are of current importance. Burhoe's stature is enhanced when one considers that these theories were first articulated by him in the 1970s, in reliance upon the work of J. Bronowski, Alfred E. Emerson, and Donald T. Campbell.