Variable-interval reinforcement schedule value influences responding following REM sleep deprivation

The effects of rapid-eye movement sleep deprivation (REMSD) in rats were studied in relation to variable-interval (VI) reinforcement schedule value. Initially, lever pressing was maintained on a VI 30-s schedule of food pellet delivery. After a baseline was established, rats were repeatedly exposed to 96 hr of REMSD and control conditions of an equivalent duration. Responding decreased following REMSD but not after exposure to control conditions. Lever pressing was then maintained on a VI 15-s schedule of food pellet delivery and exposure to the REMSD and control conditions was repeated. Under this condition following repeated REMSD exposures, rates of lever pressing became similar to baseline responding. A VI 30-s schedule of food pellet delivery was then reinstated and REMSD and control conditions were repeated. Lever pressing following exposure to the REMSD condition decreased for 3 of 4 rats. Results suggest that VI schedule value influences the effects of REMSD on responding.     

中文阅读中的语音类似效果

两个实验中的音韵和同声母没有启动效果这个事实,表明中文词视觉认知是经过正字法路线直接通达语义的。然而实验二同音词的启动效果可得出与以上相反的结论,即语音在中文阅读中有一定作用。两种不同的结果表明,语音在中文阅读中是否有作用,对书写词本身包含的语音类似信息具有依赖性。可能的结论是,在词汇通达中语音激活是自动的,但在中文似乎要比拼音文字弱;中文阅读也许更具有直通语义的特点。此研究支持双通道理论。     

Human self-control and the density of reinforcement

Choice responding in adult humans on a discrete-trial button-pressing task was examined as a function of amount, delay, and overall density (points per unit time) of reinforcement. Reinforcement consisted of points that were exchangeable for money. In T 0 conditions, an impulsive response produced 4 points immediately and a self-control response produced 10 points after a delay of 15 s. In T 15 conditions, a constant delay of 15 s was added to both prereinforcer delays. Postreinforcer delays, which consisted of 15 s added to the end of each impulsive trial, equated trial durations regardless of choice, and was manipulated in both T 0 and T 15 conditions. In all conditions, choice was predicted directly from the relative reinforcement densities of the alternatives. Self-control was observed in all conditions except T 0 without postreinforcer delays, where the impulsive choices produced the higher reinforcement density. These results support previous studies showing that choice is a direct function of the relative reinforcement densities when conditioned (point) reinforcers are used. In contrast, where responding produces intrinsic (immediately consumable) reinforcers, immediacy of reinforcement appears to account for preference when density does not.     

‘Attentional Bias’ in correlation judgments? Smedslund (1963) revisited

Smedslund (1963) reports one of the first studies that investigated human judgments of correlation. Smedslund's conclusion, that people reason about correlation mostly from a consideration of the number of times two variables co-occur, has become textbook wisdom (e.g. Baron's "attentional bias", 1994). Yet the data reported in Smedslund's paper fall short of endorsing such a conclusion. After reviewing the original paper, we present the method with which we replicated Smedslund's main experiment. In Experiment 1 subjects were presented with symptom-disease correlation data through a simulated medical diagnosis task. Subjects clearly discriminated between data sets which shared an equal number of symptom-disease co-occurrences but which otherwise showed different levels of correlation. Subjects' diagnoses showed a propensity to predict the disease in the presence of the symptom, and symptom-disease co-occurrences were overestimated in two of the five data sets presented to the subjects. Experiment 2 used a novel abstract scenario with a symmetric predictor variable. Judgments again indicated good discrimination, and biases in prediction responses and case recall were eliminated. In both experiments, judgments of zero correlation were a function of the outcome base rate. We evaluate and contrast the extent to which Cheng's (1997) model of causal induction and two associative models, Rescorla and Wagner (1972) and Pearce (1987) can anticipate the observed pattern in the mean judgments.     

海洛因成瘾者的脑灰质密度下降

本研究对海洛因成瘾者（n=34）和无毒品依赖的正常被试（n=34）进行磁共振脑结构扫描,用基于体素的形态学测量（VBM）方法分析被试间灰质密度的差异,并考察了海洛因成瘾者用药时间与灰质密度之间的关系。结果表明,同正常对照组相比,海洛因成瘾者其额叶和颞叶下部的灰质密度显著下降。进一步分析显示,用药时间短于5年的成瘾者其灰质密度下降不明显,而用药时间5年以上的患者其灰质密度下降非常显著。本文讨论了上述结果的潜在临床价值和理论意义。     

USING FIXED‐TIME SCHEDULES TO MAINTAIN BEHAVIOR: A PRELIMINARY INVESTIGATION

The purpose of this study was to evaluate the potential of fixed‐time (FT) schedules to maintain behavior. Two children who had been diagnosed with autism were taught a functional task. Subsequently, three different FT schedules (i.e., yoked, thin, dense) were compared to determine their capacity to maintain task responding. Results suggested that FT schedules may be used to maintain previously acquired behavior.     

语素意识与听写的双向预测关系:来自追踪研究的证据

听写是个体书面语言发展的重要任务之一,语素意识作为阅读认知技能,与听写关系密切。为探究语素意识和听写的双向预测关系,对小学一、五年级共294名儿童的语素意识（同音语素意识、同形语素意识）和听写进行了为期一年的追踪研究。在控制了智力、年龄、语音意识和自回归效应后,结果发现：（1）一年级儿童的同音语素意识和同形语素意识对听写具有跨时间点的正向预测作用（解释率分别为7%、8%）,而五年级儿童的语素意识对听写的跨时间点预测作用不显著;（2）五年级儿童的听写对同音语素意识和同形语素意识具有跨时间点的正向预测作用（解释率分别为5%、6%）,而一年级儿童的听写对语素意识跨时间点的预测作用不显著。研究结果表明汉语儿童的语素意识和听写是单向的预测关系,二者关系随年级的变化而变化。     

Aggressive behavior in a confined troop of Japanese macaques: Effects of density,season, and gender

A troop of Japanese macaques (Macaca fuscata) confined in a 2-acre outdoor corral increased from 107 to 192 individuals during the 5-year tenure of a project that assessed the effects of density, season, and gender on the expression of adult aggressive behavior. Two statistical subgroups of 16 males and 28 females that were adults at the start of the project and that survived until its completion were studied intensively. There were significant season and sex differences in all groups: males were much more aggressive than females, and males were most aggressive during the fall and and winter mating season; females were most aggressive during the spring and summer birth season. Only the 16 adult males increased their frequency of aggressive behavior as the population density increased. This increase was due to the greater number of potential antagonists available each year.     

Item Response Theory with Estimation of the Latent Population Distribution Using Spline-Based Densities

The purpose of this paper is to introduce a new method for fitting item response theory models with the latent population distribution estimated from the data using splines. A spline-based density estimation system provides a flexible alternative to existing procedures that use a normal distribution, or a different functional form, for the population distribution. A simulation study shows that the new procedure is feasible in practice, and that when the latent distribution is not well approximated as normal, two-parameter logistic (2PL) item parameter estimates and expected a posteriori scores (EAPs) can be improved over what they would be with the normal model. An example with real data compares the new method and the extant empirical histogram approach.     

A similarity-based smoothing approach to nondimensional item analysis

The probability that an examinee chooses a particular option within an item is estimated by averaging over the responses to that item of examinees with similar response patterns for the whole test. The approach does not presume any latent variable structure or any dimensionality. But simulated and actual data analyses are presented to show that when the responses are determined by a latent ability variable, this similarity-based smoothing procedure can reveal the dimensionality of ability very satisfactorily.The author wishes to acknowledge the support of the Natural Sciences and Engineering Research Council of Canada through grant A320, and to thank Educational Testing Service for making the data on the Advanced Placement Chemistry Exam available.