A compactness theorem for linear equations

It is proved that a system of linear equations over an arbitrary field has a solution if every finite subsystem has a solution provided that the set of variables can be well ordered.Presented by J. Zygmunt     

Investigating Behavioral Dynamics With A Fixed-time Extinction Schedule And Linear Analysis

This paper describes the behavioral adaptation observed for 16 pigeons responding to a step transition in the reinforcement rate in a repeated-trial design. Within each trial, following exposure for a fixed period to a variable-interval schedule, there was an unsignaled change in the schedule to extinction. The step transition allowed an experimental test of the applicability of a linear analysis to steady-state dynamic behavior. The computations required for this test yielded, as an intermediate result, transfer functions for each of the 16 birds from 1 mHz to 256 mHz. The transfer functions obtained show greater responsiveness to lower frequencies (i.e., longer time-scale structures in the reinforcement schedule); hence, the pigeons have the characteristics of a low-pass filter. The outcome of the test is that some predictability of the pigeons' future behavior is possible.     

TO WAIT OR TO RESPOND?

Emitting a certain response and waiting for a specified time without making that response had the same consequence. In Experiment 1, food-deprived pigeons were as likely to wait as to respond only if waiting provided food at a much higher frequency than did pecking. In Experiment 2, the consequence for humans was a brief light flash and tone. People were not biased for responding over waiting. Instead, their choices suggested crude payoff maximization. In Experiment 3, pigeons again obtained food, but they were not food deprived and could eat freely at each opportunity. Their behavior was more like that of the humans of Experiment 2 than that of food-deprived pigeons given small quantities of food at each feeding opportunity. The three experiments together showed that biases for responding over waiting were neither inherent characteristics of species nor inevitable outcomes of particular schedules. Choice between active search and waiting depended on ecological–motivational factors even when species and schedules were held constant.     

Pigeons' wait-time responses to transitions in interfood-interval duration: Another look at cyclic schedule performance

Recent developments reveal that animals can rapidly learn about intervals of time. We studied the nature of this fast-acting process in two experiments. In Experiment 1 pigeons were exposed to a modified fixed-time schedule, in which the time between food rewards (interfood interval) changed at an unpredictable point in each session, either decreasing from 15 to 5 s (step-down) or increasing from 15 to 45 s (step-up). The birds were able to track under both conditions by producing postreinforcement wait times proportional to the preceding interfood-interval duration. However, the time course of responding differed: Tracking was apparently more gradual in the step-up condition. Experiment 2 studied the effect of having both kinds of transitions within the same session by exposing pigeons to a repeating (cyclic) sequence of the interfood-interval values used in Experiment 1. Pigeons detected changes in the input sequence of interfood intervals, but only for a few sessions—discrimination worsened with further training. The dynamic effects we observed do not support a linear waiting process of time discrimination, but instead point to a timing mechanism based on the frequency and recency of prior interfood intervals and not the preceding interfood interval alone.     

On the relationship between Fortier's simultaneous linear prediction and van den Wollenberg's redundancy analysis

The purpose of this note is to show that Van den Wollenberg's method of redundancy analysis is a special case of a simultaneous linear prediction method offered by Fortier.     

工作记忆、表达方式和同质性对线性三段论推理影响的眼动研究

采用眼动记录法,探讨了工作记忆、两个前提间的关系以及表达方式对线性三段论推理的影响。本实验采用2（表达方式：肯定、否定）×2（前提间的关系：同质、不同质）×2（工作记忆容量：高、低）的混合设计。通过分析总注视时间、第一次注视时间、第二次注视时间和回视,发现线性三段论推理过程既有语言加工的参与又有表象加工的参与。推理过程中的语言表征过程和空间关系的建立都受到工作记忆容量的影响,被试的工作记忆容量越高,就越容易建立语言表征和空间的关系。     

学龄儿童失调态度在应激与抑郁间的作用：一项多波段追踪研究

通过对3年级和7年级学龄儿童的追踪研究,探讨儿童群体中Beck抑郁理论认知易感因素在应激事件与抑郁症状间的作用。对追踪数据的多层线性模型和多层结构方程模型分析发现,作为Beck抑郁理论中认知易感因素的失调态度在3年级儿童中既没有显著的中介作用也没有显著的调节作用,而在7年级儿童中虽然失调态度仍然没有显著的调节作用,但却有显著的中介作用。研究结果可能初步揭示了失调态度在应激事件与抑郁症状关系中的发展性特征,这一发现对在儿童群体中实施抑郁的有效干预将具有较为重要的启示意义。     

多水平IRT的发展与应用述评

阶层线性模型是处理阶层结构数据的高级统计方法, 项目反应理论是精确测量被试能力的现代测量理论。多水平项目反应理论将阶层线性模型和项目反应理论相结合, 将项目反应模型嵌套在阶层线性模型内, 实现了项目参数和不同水平能力参数的估计, 对回归系数和误差项变异的估计也更加精确。作者概述了多水平项目反应理论的发展历程, 并从项目功能差异、测验等值、学校效能研究等方面评述了多水平项目反应理论在心理与教育测量中的应用, 总结了多水平项目反应理论的价值, 同时展望了今后的研究趋势。     

Algebraic Semantics for Deductive Systems

The notion of an algebraic semantics of a deductive system was proposed in [3], and a preliminary study was begun. The focus of [3] was the definition and investigation of algebraizable deductive systems, i.e., the deductive systems that possess an equivalent algebraic semantics. The present paper explores the more general property of possessing an algebraic semantics. While a deductive system can have at most one equivalent algebraic semantics, it may have numerous different algebraic semantics. All of these give rise to an algebraic completeness theorem for the deductive system, but their algebraic properties, unlike those of equivalent algebraic semantics, need not reflect the metalogical properties of the deductive system. Many deductive systems that don't have an equivalent algebraic semantics do possess an algebraic semantics; examples of these phenomena are provided. It is shown that all extensions of a deductive system that possesses an algebraic semantics themselves possess an algebraic semantics. Necessary conditions for the existence of an algebraic semantics are given, and an example of a protoalgebraic deductive system that does not have an algebraic semantics is provided. The mono-unary deductive systems possessing an algebraic semantics are characterized. Finally, weak conditions on a deductive system are formulated that guarantee the existence of an algebraic semantics. These conditions are used to show that various classes of non-algebraizable deductive systems of modal logic, relevance logic and linear logic do possess an algebraic semantics.