二级项目题组混合IRT模型及其稳健权重估计

在心理测量和教育测量中,二级项目和题组项目是两类常见的项目类型。由这两种项目混合构成的测试在实践中有着重要的应用。被试在答题时,由于个人的潜在能力和项目难度不匹配,常常会产生异常反应,这些异常反应会影响IRT中潜在特质估计的准确性。仿真实验证明,二级项目题组混合IRT模型的稳健估计方法在出现异常值的情况下,能够比极大似然估计对被试的潜在特质做出更加准确的估计,能够满足实际测试的需求。     

Effects of Differential Item Functioning on Examinees' Test Performance and Reliability of Test

Simulations were conducted to examine the effect of differential item functioning (DIF) on measurement consequences such as total scores, item response theory (IRT) ability estimates, and test reliability in terms of the ratio of true-score variance to observed-score variance and the standard error of estimation for the IRT ability parameter. The objective was to provide bounds of the likely DIF effects on these measurement consequences. Five factors were manipulated: test length, percentage of DIF items per form, item type, sample size, and level of group ability difference. Results indicate that the greatest DIF effect was less than 2 points on the 0 to 60 total score scale and about 0.15 on the IRT ability scale. DIF had a limited effect on the ratio of true-score variance to observed-score variance, but its influence on the standard error of estimation for the IRT ability parameter was evident for certain ability values.     

PETS计算机自适应序列测试设计与模拟研究

根据PETS考试的特点,结合计算机自适应序列测试（CAST）的优势,该研究提出并设计了PETS—CAST测试。为了检验PETS—CAST测试系统的性能,该研究利用PETS试题的真实难度参数和模拟的考生能力参数生成相应的原始得分矩阵,并根据路径规则实现适应性的模块选择。研究结果表明,PETS—CAST所设计的路径能够满足不同能力水平考生的要求,且各条路径的测量精度均能够达到CAST考试的要求。曝光率方面的研究则说明,PETS—CAST应该在设计题池时充分考虑试题模块在数量方面的配置。该模拟研究为PETS—CAST的具体实施在理论和实践层面做了一些有益的尝试。     

不同形式的锚定值对时距估计决策过程的影响

采用基本锚定范式,以时间词和物理时距分别作为数字锚定值和物理锚定值,探讨了不同形式和大小的锚定值如何影响产生法（实验1）和口头估计法（实验2）中的时距估计的决策过程。55名在校大学生参加了本次实验。实验结果表明,数字锚定值被作为时距估计的调整起始点,对决策过程中的数值估计产生同化影响;物理锚定值则被作为时距估计的比较标准,同化产生法中的决策估计值,对口头估计法中的决策估计值却产生对比影响。     

回溯式时距估计的计时机制

回溯式时距估计是以记忆为主要成分, 且事后才知要对两个相继事件之间的间隔时间或某一事件持续时间的长短进行估计。可分为近时和远时的回溯式时距估计, 两者的计时机制与记忆有关, 但各有侧重：前者侧重短时或长时记忆, 直接证据来源于即时回忆单一或多个认知任务以估计时间, 间接证据则聚焦于物理、生理、心理因素的影响; 后者侧重自传体记忆, 可从问卷或访谈的测量方式以及主客体特征的影响两个方面来寻找证据。今后需以整合的观点深入探究回溯式时距估计的计时机制, 拓展回溯式时距估计行为测量的研究, 并开展对回溯式时距估计神经生物学基础的探讨。     

Robust estimation of the hierarchical model for responses and response times

Van der Linden's (2007, Psychometrika, 72, 287) hierarchical model for responses and response times in tests has numerous applications in psychological assessment. The success of these applications requires the parameters of the model to have been estimated without bias. The data used for model fitting, however, are often contaminated, for example, by rapid guesses or lapses of attention. This distorts the parameter estimates. In the present paper, a novel estimation approach is proposed that is robust against contamination. The approach consists of two steps. In the first step, the response time model is fitted on the basis of a robust estimate of the covariance matrix. In the second step, the item response model is extended to a mixture model, which allows for a proportion of irregular responses in the data. The parameters of the mixture model are then estimated with a modified marginal maximum likelihood estimator. The modified marginal maximum likelihood estimator downweights responses of test-takers with unusual response time patterns. As a result, the estimator is resistant to several forms of data contamination. The robustness of the approach is investigated in a simulation study. An application of the estimator is demonstrated with real data.     

An experimental test of stimulus estimation theory: danger and safety with snake phobic stimuli

The stimulus estimation model (Taylor & Rachman, 1994) asserts that fear overprediction stems from: (a) overprediction of the danger elements of a phobic stimulus, and (b) underprediction of existing safety resources. Using a 2x2 factorial design, with danger (high vs low) and safety (high vs low) as between-subjects variables, an experimental test of the model was conducted with 25 snake-fearful participants per condition. The four experimental conditions were matched on initial levels of snake fearfulness, as assessed by the Snake Questionnaire (SNAQ). For the 51 participants who demonstrated overprediction of fear, high danger led to reliably more fear overprediction than low danger; and low safety led to reliably more fear overprediction than high safety. The interaction between danger and safety was not statistically significant. The results offer the first convincing experimental support for the stimulus estimation model of fear overprediction.     

A timing-specific memory distortion effect in young children

It has been suggested that there are systematic distortions in children's memory for temporal durations, such that children's memory is not just less accurate than that of adults but qualitatively different. Experiment 1 replicated the memory distortion effect by demonstrating developmental change in the tendency to confuse a reference duration with one that is shorter rather than longer than it. When the long-term memory demands of the task were reduced by providing reminders of the reference duration on every trial, there were no such qualitative changes in error patterns (Experiment 2). Further evidence for developmental changes in memory distortion was found in the temporal generalization task of Experiment 3, in which stimuli were spaced logarithmically rather than linearly. In Experiment 4, a similar distortion pattern was absent in a task in which children made judgments about the pitch rather than the duration of stimuli, suggesting the effect may be specific to time estimation.     

American base‐rate neglect: It is not the math,but the context

We investigate cross‐cultural disparities in focalism bias through two studies of probability estimation. Using 60 American and 60 Chinese participants, Experiment 1 yields the standard finding that Americans manifest greater focalism bias by tending to neglect background probability base‐rates and to rely more heavily on obtained samples in estimating true probabilities, whereas Chinese participants show little tendency to ignore base‐rates. In Experiment 2, the phrasing of the probability‐estimation task is changed to bring base‐rates into the focus of the problem statement, again using a sample of 60 Americans and 60 Chinese. This allows us to test whether cross‐cultural differences result from a tendency to focus on the sample, and ignore ‘context’ (i.e., the background base‐rates), rather than simply a discrepancy in mathematical facility between the two groups. The results show far less base‐rate neglect for Americans, but essentially no change for Chinese (who always use base‐rate information, regardless of how presented). This outcome argues against the explanation that Americans are poorer Bayesians simply because they are weaker mathematicians. Implications are discussed.