Stimulus exposure and discrimination in rats: A test of a theory for the role of contextual factors

In two experiments rats were trained on a simultaneous discrimination in a jumping stand. On each trial choice always lay between one stimulus (an obliquely striped object in Experiment I, and a plain grey object in Experiment II) and a second that varied from trial to trial. On half the trials this variable stimulus bore horizontal stripes (H) and on the remaining trials it bore vertical stripes (V). It was argued that the solution of this discrimination would be hindered if the animals tended to classify H and V apart (Bateson and Chantrey, 1972). It was found, however, that prior exposure to H and V in the home cage (which has been supposed to promote classifying apart) facilitated learning and that prior exposure to H and V in the apparatus itself (which might be thought to promote classifying together) hindered later learning. Possible alternative accounts for these exposure learning effects are discussed.     

A test of the melioration theory of matching

Melioration theory entails that matching in concurrent schedules occurs because the subjects equalize the local reinforcement rates (reinforcers received for each alternative divided by the time allocated to each alternative). The role of local reinforcement rates was tested by using multiple schedules in which one component involved an alternative with a high absolute rate of reinforcement and a low local reinforcement rate while the second component involved an alternative with a low absolute rate and a high local rate. These alternatives were then presented simultaneously in probe trials to determine preference between them. Contrary to melioration, the absolute rate of reinforcement, not the local rate, was the controlling variable.     

A test of the neo-behaviouristic theory of extinction

A test between Moltz's and Deutsch's theory of extinction was devised. Animals were trained to go to the same goal-box via two different paths. Then they were divided into two groups. The first found the goal-box empty, the second found the entrance into the goal-box blocked. The choices of the animals on the next trial were observed. The results are those predicted by Deutsch.     

A test of the gravity lens theory.

Naito and Cole [1994, in Contributions to Mathematical Psychology: Psychometrics and Methodology Eds G H Fischer and D Laming (New York: Springer)] provide a configuration which they describe as the Gravity Lens illusion. In this configuration, four small dots are presented in proximity to four large disks, and one is asked to compare the slope of an imaginary line which connects one pair of dots with the slope of a line which connects the other pair. In fact the slopes are the same, i.e. their axes are parallel, but because of the positioning of the large disks they appear to be at different orientations. Naito and Cole propose that the perceptual bias is analogous to the effects of gravity on the metrics of physical space, such that mental projections in the vicinity of a disk (or an open circle) are distorted just as the path of light is bent as it passes a massive body such as a star. Here we provide a simple test of this concept by having subjects judge alignments of dots which lie near tangents to a circle. Subjects were asked to project straight lines through pairs of stimulus dots, selecting and marking points in open space which were collinear with each pair. As would be predicted by the Gravity Lens theory, the locations selected by subjects were displaced from straight lines. However, the error magnitudes were substantially larger for judgments of dot pairs which had an oblique alignment, as compared with dot pairs which were aligned with a cardinal axis. This differential of effect as a function of stimulus orientation is not predicted by the gravity concept.     

Binocular fusion: A test of the suppression theory

Binocular fusion may be due to interocular inhibitory suppression, an hypothesis difficult to evaluate by phenomenal inspection. A test probe method (reaction time to a light pulse) was used to measure visual sensitivity during binocular rivalry and fusion. The absence of inhibitory effects during fusion fai Is to support the suppression theory of fusion.     

Binocular fusion: A test of the suppression theory

Binocular fusion may be due to interocular inhibitory suppression, an hypothesis difficult to evaluate by phenomenal inspection. A test probe method (reaction time to a light pulse) was used to measure visual sensitivity during binocular rivalry and fusion. The absence of inhibitory effects during fusion fails to support the suppression theory of fusion.     

Chemical aversion conditioning as a treatment for alcoholism: A re-analysis

The literature on chemical aversion conditioning is characterized by the lack of controlled clinical research. The existing data derive primarily from methodologically inadequate studies. Although short-term conditioned aversion reactions to alcohol have been demonstrated, the independent efficacy of this technique in clinical treatment remains to be shown. Beyond the failure to demonstrate the value of adding chemical aversion conditioning to more standard treatments for alcoholism, evaluation in terms of broader outcome criteria (e.g. safety, intrusiveness, acceptability, the availability of alternative methods, and cost-effectiveness) indicates that chemical aversion conditioning cannot be recommended as a standard form of treatment for alcoholism.     

A test of constancy scaling theory in a modified Mueller-Lyer illusion

The center line of each of the two Mueller-Lyer figures was replaced by a rectangle whose length and width were both judged. The rectangle, bounded by wings positioned outward, was judged both longer and narrower than a standard rectangle of equal size, while the rectangle bounded by wings oriented inward was judged to be both shorter and wider than the standard rectangle. These results were considered to provide evidence against a constancy scaling explanation of geometric illusions. Other theories to account for the results were considered and found inadequate.     

A meta-analytic test of intergroup contact theory

The present article presents a meta-analytic test of intergroup contact theory. With 713 independent samples from 515 studies, the meta-analysis finds that intergroup contact typically reduces intergroup prejudice. Multiple tests indicate that this finding appears not to result from either participant selection or publication biases, and the more rigorous studies yield larger mean effects. These contact effects typically generalize to the entire outgroup, and they emerge across a broad range of outgroup targets and contact settings. Similar patterns also emerge for samples with racial or ethnic targets and samples with other targets. This result suggests that contact theory, devised originally for racial and ethnic encounters, can be extended to other groups. A global indicator of Allport's optimal contact conditions demonstrates that contact under these conditions typically leads to even greater reduction in prejudice. Closer examination demonstrates that these conditions are best conceptualized as an interrelated bundle rather than as independent factors. Further, the meta-analytic findings indicate that these conditions are not essential for prejudice reduction. Hence, future work should focus on negative factors that prevent intergroup contact from diminishing prejudice as well as the development of a more comprehensive theory of intergroup contact.     

A statistical test of a prediction from information theory in a card-sorting situation

Previous work with cards left the joint effects of varying entropy and discriminability on choice-reaction times somewhat in doubt. A card-sorting situation is here constructed in which entropy and discriminability can be varied independently. Two experiments are described with naive subjects and two different treatments of the practice effect. The effect of varying entropy with discriminability held constant is. shown to be significantly non-linear, contrary to the prediction from information theory. Finally a statistical model is proposed which shows at least, qualitative agreement with the results of these experiments.     

A critical test of the failure-to-engage theory of task switching

When people switch between two tasks, their performance on each is worse than when they perform that task in isolation. One theory of this “switch cost” is the failure-to-engage (FTE) theory, which posits that observed responses are a simple mixture of prepared and unprepared response strategies. The probability that participants use prepared processes can be manipulated experimentally (e.g., by changing preparation time). The FTE theory is a binary mixture model and therefore makes a strong prediction about the existence of fixed points in response time distributions. We found evidence contradicting this prediction, using data from 20 participants in a standard task-switching paradigm. In this article, we examine reasons for the failure of the FTE theory, and we demonstrate that a generalized version of FTE theory accommodates our data.     

A direct test of the original version of regret theory

This paper reports on a direct experimental test of the original version of Regret Theory using a total of 64 subjects in three groups. The experiment, which was run on PCs, was designed to elicit from subjects' responses the two key elements in this theory: namely the basic utility function, and the regret/rejoicing function. It was also designed to provide a quick direct test of the implications of the theory. We found that the evidence refuted this original version of Regret Theory.     

the relationship between elements and manifestations of low self-control in a general theory of crime: two comments and a test

I discuss two issues about the empirical assessment of Gottfredson and Hirschi's (1990) general theory of crime. First, regarding the internal validity of corresponding causal models, I argue that more attention must be paid to the distinction between independent and dependent variables (elements versus manifestations of low self-control). Second, regarding the interpretation of statistical results, I argue that researchers should not lose sight of the distinction between statistical and substantive significance. I also report a test of the theory based on data from a representative sample of high school seniors in the United States. The results of the test show that low self-control is a correct and certain, yet weak, predictor of certain deviant behaviors (skipping class, traffic violations, cigarette smoking, and the use of alcohol and marijuana).     

The transmission of support: a Bayesian re-analysis

Crispin Wright’s discussion of the notion of ‘transmission-failure’ promises to have important philosophical ramifications, both in epistemology and beyond. This paper offers a precise, formal characterisation of the concept within a Bayesian framework. The interpretation given avoids the serious shortcomings of a recent alternative proposal due to Samir Okasha.