Conditional discrimination and equivalence relations: A theoretical analysis of control by negative stimuli

A detailed analysis is presented of the ways in which control by the negative stimulus in two-comparison conditional discriminations may be expected to affect the outcome of tests for the properties of equivalence relations. Control by the negative stimulus should produce the following results: (a) no observable effect on symmetry tests; (b) reflexivity test results should look like “oddity” rather than “identity”; and (c) transitivity tests that involve an odd number of nodes should yield results that are 100% opposite to tests that involve an even number of nodes. The analysis also considers the effects of variation in the type of comparison-stimulus control between and within baseline conditional discriminations. Methods are suggested for experimentally regulating the type of control, and for verifying the predictions that the analysis generates. If suggested experiments continue to support the analysis, investigators who use two-comparison conditional discriminations to study equivalence relations will either have to control explicitly whether the positive or the negative comparison governs their subjects' choices, or they will have to abandon two comparisons and use three or more comparisons instead.     

Intertrial-interval effects on sensitivity (A') and response bias (B") in a temporal discrimination by rats.

Killeen and Fetterman's (1988) behavioral theory of animal timing predicts that decreases in the rate of reinforcement should produce decreases in the sensitivity (A') of temporal discriminations and a decrease in miss and correct rejection rates (decrease in bias toward "long" responses). Eight rats were trained on a 10- versus 0.1-s temporal discrimination with an intertrial interval of 5 s and were subsequently tested on probe days on the same discrimination with intertrial intervals of 1, 2.5, 5, 10, or 20 s. The rate of reinforcement declined for all animals as intertrial interval increased. Although sensitivity (A') decreased with increasing intertrial interval, all rats showed an increase in bias to make long responses.     

区分度和难度分布在测验效度上的效应比较的模拟试验研究

运用计算机模拟试验方法,研究了４种不同的区分度分布和４种不同的难度分布在测验效度上的效应变化规律。结果表明：（１）在难度分布一定的条件下,测验效度随测验中较高区分度的项目数的递增而单调地提高;（２）在区分度分布一定的条件下,测验中的项目难度分布与考生的能力分布相一致时测验放度较高;（３）区分度分布对效度的影响比难度分布的影响更直接。     

Burden of Proof Rules in Social Criticism

The article discusses burden of proof rules in social criticism. By social criticism I mean an argumentative situation in which an opponent publicly argues against certain social practices; the examples I consider are discrimination on the basis of species and discrimination on the basis of one's nationality. I argue that burden of proof rules assumed by those who defend discrimination are somewhat dubious. In social criticism, there are no shared values which would uncontroversially determine what is the reasonable presumption and who has the burden of proof, nor are there formal rules which would end the debate and determine the winner at a specific point.     

Item information and discrimination functions for trinary pcm items

For trinary partial credit items the shape of the item information and the item discrimination function is examined in relation to the item parameters. In particular, it is shown that these functions are unimodal if ₂ – ₁ < 4 ln 2 and bimodal otherwi The locations and values of the maxima are derived. Furthermore, it is demonstrated that the value of the maximum is decreasing in ₂ – ₁. Consequently, the maximum of a unimodal item information function is always larger than the maximum of a bimodal one, and similarly for the item discrimination function.The work reported herein was partially supported under the National Assessment of Educational Progress (Grant No. R999G30002; CFDA No. 84.999G) as administered by the Office of Educational Research and Improvement, US Department of Education.     

Individual,family, and societal dimensions of genetic discrimination: A case study analysis

Background. As the development and use of genetic tests have increased, so have concerns regarding the uses of genetic information. Genetic discrimination, the differential treatment of individuals based on real or perceived differences in their genomes, is a recently described form of discrimination. The range and significance of experiences associated with this form of discrimination are not yet well known and are investigated in this study. Methods. Individuals at-risk to develop a genetic condition and parents of children with specific genetic conditions were surveyed by questionnaire for reports of genetic discrimination. A total of 27,790 questionnaires were sent out by mail. Of 917 responses received, 206 were followed up with telephone interviews. The responses were analyzed regarding circumstances of the alleged discrimination, the institutions involved, issues relating to the redress of grievances, and strategies to avoid discrimination. Results. A number of institutions were reported to have engaged in genetic discrimination including health and life insurance companies, health care providers, blood banks, adoption agencies, the military, and schools. The alleged instances of discrimination were against individuals who were asymptomatic and sometimes impacted on other asymptomatic relatives. Few surveyed respondents knew of the existence of institutions such as state insurance commissions or the Medical Information Bureau, Inc., which may play roles in redress of grievances or correction of misinformation. Conclusions. Genetic discrimination is variable in form and cause and can have marked consequences for individuals experiencing discrimination and their relatives. The presence of abnormal genes in all individuals makes each person a potential victim of this type of discrimination. The increasing development and utilization of genetic tests will likely result in increased genetic discrimination in the absence of contravening measures. All authors contributed equally to this work. This work was supported by a grant from the U.S. Department of Energy and funding from the Department of Mental Retardation of the Commonwealth of Massachusetts.     

拼读困难儿童某些认知特征的实验研究

通过两级筛选以验证中国儿童在学习汉语拼音时是否也存在拼读困难,并通过认知心理学方法对拼读困难儿童与同年龄正常儿童进行比较研究,以期深入了解他们的认知整合能力和精细分辨能力。研究结果提示：１．经对１０６０名小学一、二年级学童进行卷面和口试筛选,共发现１２名儿童有汉语拼音拼读困难,约占总样本的１２％。２．拼读困难儿童的某些认知整合能力和精细分辨能力均比正常儿童差,这可能是他们拼读困难的认知心理学基础。     

The effects of varying the distribution of generalization stimuli within a constant range upon the bisection of a sound-intensity interval by rats

Two male, albino rats were trained on a two-valued, self-paced, discrete-trials auditory discrimination. In the presence of a high-intensity stimulus (90 decibels SPL, 4 kiloHertz), response A was reinforced; in the presence of a low-intensity stimulus (50 decibels SPL, 4 kiloHertz), response B was reinforced. When discrimination performance was asymptotic, stimuli intermediate in intensity were presented with the training stimuli in a maintained generalization paradigm. Generalization gradients were derived from the relative frequencies of response A in the presence of each stimulus. A relative frequency of 0.50 was then determined and used as the bisection point of the intensity interval defined by the 90- and 50-decibel stimuli. The bisection point varied with the distribution of the stimuli presented in generalization. This effect was similar to context effects seen in human psychophysics.     

Procedural antecedents of behavioral contrast: a re-examination of errorless learning

Behavioral contrast reliably occurred in pigeons following errorless discrimination training, contrary to Terrace's (1963) observations. In the main experiment, a 60-sec green keylight, associated with a variable-interval 30-sec schedule of reinforcement alternated with a 60-sec period of extinction when the key was dark. Such aspects of the discrimination training procedure as: (1) the amount of prior nondifferential exposure to the positive stimulus before the discrimination was instituted, and (2) the rapidity with which the negative stimulus was introduced (whether progressively or abruptly) directly influenced the amount of behavioral contrast produced. This occurred independently of the number of errors made by a pigeon during acquisition of the discrimination. In a series of control experiments, substitution of a red keylight for the dark key during extinction resulted in greater behavioral contrast, while an increase to 3 min in the duration of the green keylight associated with reinforcement attenuated the behavioral contrast effect.     

Successive discrimination training with equated reinforcement frequencies: failure to obtain behavioral contrast

In two experiments, pigeons were trained on two-component multiple schedules in which responding in one component (S₁) was always maintained by a variable-interval schedule. In Experiment I, low response rates were reinforced in the second (S₂) component for six master subjects. This schedule was adjusted to equate reinforcement frequencies in the two components. These subjects were compared to yoked partners, for which reinforcement in the S₂ component was made available on a variable-interval schedule whose value was determined by the master subjects. A similar procedure was used in Experiment II, where the S₂ schedule for master subjects made reinforcers contingent on the absence of responding. No evidence was found in either experiment for a behavioral contrast effect in the S₁ component attributable to response reduction in the S₂ component. A reliable contrast effect was obtained from a group of pigeons given extinction conditions in the S₂ component, which was compared to a group maintained throughout on a multiple variable-interval schedule. The results suggest that previous indications of behavioral contrast in similar situations were probably caused by uneven reinforcement distributions or reflect uncontrolled fluctuations in response rates.