Sexual differences in memory in shiny cowbirds

Avian brood parasites depend on other species, the hosts, to raise their offspring. During the breeding season, parasitic cowbirds (Molothrus sp.) search for potential host nests to which they return for laying a few days after first locating them. Parasitic cowbirds have a larger hippocampus/telencephalon volume than non-parasitic species; this volume is larger in the sex involved in nest searching (females) and it is also larger in the breeding than in the non-breeding season. In nature, female shiny cowbirds Molothrus bonariensis search for nests without the male’s assistance. Here we test whether, in association with these neuroanatomical and behavioural differences, shiny cowbirds display sexual differences in a memory task in the laboratory. We used a task consisting of finding food whose location was indicated either by the appearance or the location of a covering disk. Females learnt to retrieve food faster than males when food was associated with appearance cues, but we found no sexual differences when food was associated with a specific location. Our results are consistent with the view that parasitism and its neuroanatomical correlates affect performance in memory tasks, but the effects we found were not in the expected direction, emphasising that the nature of avian hippocampal function and its sexual differences are not yet understood. Received: 30 April 1998 / Accepted after revision: 5 September 1998     

Efficient nonparametric approaches for estimating the operating characteristics of discrete item responses

Rationale and the actual procedures of two nonparametric approaches, called Bivariate P.D.F. Approach and Conditional P.D.F. Approach, for estimating the operating characteristic of a discrete item response, or the conditional probability, given latent trait, that the examinee's response be that specific response, are introduced and discussed. These methods are featured by the facts that: (a) estimation is made without assuming any mathematical forms, and (b) it is based upon a relatively small sample of several hundred to a few thousand examinees.Some examples of the results obtained by the Simple Sum Procedure and the Differential Weight Procedure of the Conditional P.D.F. Approach are given, using simulated data. The usefulness of these nonparametric methods is also discussed.This research was mostly supported by the Office of Naval Research (N00014-77-C-0360, N00014-81-C-0569, N00014-87-K-0320, N00014-90-J-1456).     

成就目标对青少年成就动机和学业成就影响的研究

本研究在迈尔（Maehr）等人研究的基础上,考察了成就目标（任务目标和能力目标）与动机和学业成就之间的关系。结果表明,任务目标通过内部动机对学业成就产生积极的影响,能力目标通过外部动机对学业成就产生消极的影响。     

在内隐学习条件下任务难度对于判断准确率的影响

本研究利用自行设计的复杂规则产生出不同难度的任务系统,进而通过实验阐明了内隐学习的三个特征;（一）在任务难度极大的情况下,内隐学习并不发挥作用;（二）在任务难度降低到一定程度的时间,内隐学习开始发挥作用,这仿佛是一个“阈限”;（三）随着任务难度逐渐降低,内隐学习的效率也随着提高,但是最科停止在一个较高的水平而再继续上升,可以间接推断,内隐学习获得了样例的具体信息。     

Toward quantifying the abuse liability of ultraviolet tanning: A behavioral economic approach to tanning addiction

Many adults engage in ultraviolet indoor tanning despite evidence of its association with skin cancer. The constellation of behaviors associated with ultraviolet indoor tanning is analogous to that in other behavioral addictions. Despite a growing literature on ultraviolet indoor tanning as an addiction, there remains no consensus on how to identify ultraviolet indoor tanning addictive tendencies. The purpose of the present study was to translate a behavioral economic task more commonly used in substance abuse to quantify the "abuse liability" of ultraviolet indoor tanning, establish construct validity, and determine convergent validity with the most commonly used diagnostic tools for ultraviolet indoor tanning addiction (i.e., mCAGE and mDSM‐IV‐TR). We conducted a between‐groups study using a novel hypothetical Tanning Purchase Task to quantify intensity and elasticity of ultraviolet indoor tanning demand and permit statistical comparisons with the mCAGE and mDSM‐IV‐TR. Results suggest that behavioral economic demand is related to ultraviolet indoor tanning addiction status and adequately discriminates between potential addicted individuals from nonaddicted individuals. Moreover, we provide evidence that the Tanning Purchase Task renders behavioral economic indicators that are relevant to public health research. The present findings are limited to two ultraviolet indoor tanning addiction tools and a relatively small sample of high‐risk ultraviolet indoor tanning users; however, these pilot data demonstrate the potential for behavioral economic assessment tools as diagnostic and research aids in ultraviolet indoor tanning addiction studies.     

A two‐part mixed effects model for cigarette purchase task data

The Cigarette Purchase Task is a behavioral economic assessment tool designed to measure the relative reinforcing efficacy of cigarette smoking across different prices. An exponential demand equation has become a standard model for analyzing purchase task data, but its utility is compromised by its inability to accommodate values of zero consumption. We propose a two‐part mixed effects model that keeps the same exponential demand equation for modeling nonzero consumption values, while providing a logistic regression for the binary outcome of zero versus nonzero consumption. Therefore, the proposed model can accommodate zero consumption values and retain the features of the exponential demand equation at the same time. As a byproduct, the logistic regression component of the proposed model provides a new demand index, the “derived breakpoint”, for the price above which a subject is more likely to be abstinent than to be smoking. We apply the proposed model to data collected at baseline from college students (N = 1,217) enrolled in a randomized clinical trial utilizing financial incentives to motivate tobacco cessation. Monte Carlo simulations showed that the proposed model provides better fits than an existing model. We note that the proposed methodology is applicable to other purchase task data, for example, drugs of abuse.     

Dealing with Multiple Solutions in Structural Vector Autoregressive Models

Structural vector autoregressive models (VARs) hold great potential for psychological science, particularly for time series data analysis. They capture the magnitude, direction of influence, and temporal (lagged and contemporaneous) nature of relations among variables. Unified structural equation modeling (uSEM) is an optimal structural VAR instantiation, according to large-scale simulation studies, and it is implemented within an SEM framework. However, little is known about the uniqueness of uSEM results. Thus, the goal of this study was to investigate whether multiple solutions result from uSEM analysis and, if so, to demonstrate ways to select an optimal solution. This was accomplished with two simulated data sets, an empirical data set concerning children's dyadic play, and modifications to the group iterative multiple model estimation (GIMME) program, which implements uSEMs with group- and individual-level relations in a data-driven manner. Results revealed multiple solutions when there were large contemporaneous relations among variables. Results also verified several ways to select the correct solution when the complete solution set was generated, such as the use of cross-validation, maximum standardized residuals, and information criteria. This work has immediate and direct implications for the analysis of time series data and for the inferences drawn from those data concerning human behavior.     

Estimation of the Coefficient of Variation with Minimum Risk: A Sequential Method for Minimizing Sampling Error and Study Cost

The coefficient of variation is an effect size measure with many potential uses in psychology and related disciplines. We propose a general theory for a sequential estimation of the population coefficient of variation that considers both the sampling error and the study cost, importantly without specific distributional assumptions. Fixed sample size planning methods, commonly used in psychology and related fields, cannot simultaneously minimize both the sampling error and the study cost. The sequential procedure we develop is the first sequential sampling procedure developed for estimating the coefficient of variation. We first present a method of planning a pilot sample size after the research goals are specified by the researcher. Then, after collecting a sample size as large as the estimated pilot sample size, a check is performed to assess whether the conditions necessary to stop the data collection have been satisfied. If not an additional observation is collected and the check is performed again. This process continues, sequentially, until a stopping rule involving a risk function is satisfied. Our method ensures that the sampling error and the study costs are considered simultaneously so that the cost is not higher than necessary for the tolerable sampling error. We also demonstrate a variety of properties of the distribution of the final sample size for five different distributions under a variety of conditions with a Monte Carlo simulation study. In addition, we provide freely available functions via the MBESS package in R to implement the methods discussed.     

“You’re on ten,where can you go from there?” Tufnel problems in repeated experiential judgments

We describe a set of Tufnel problems that arise when repeated use of a fixed-point scale precipitates failures to assess a full range of subjective experiences. As empirical evidence, participants in Study 1 periodically reported their depth of mind wandering on either 5- or 7-point Likert scales during a sustained attention task. The proportion of participants providing maximum scale ratings increased quickly over time-on-task and did so more quickly for the 5-point than for the 7-point group. Participants in Study 2 completed the same task using a 10-point scale before indicating whether and where they could have used a scale extended to “11” during the task. Slightly more than 20% of participants reported needing a scale extension. This Need for 11 was associated with differences in both reports of mind wandering depth and task performance. We conclude that Tufnel problems warrant methodological consideration and reflect interesting constraints on human judgment.