Negativity bias in defeasible reasoning

In defeasible reasoning, initially drawn conclusions can be withdrawn in light of new information. In this paper, we examine how the conclusions drawn from conditionals describing positive or negative situations can be defeated by subsequent negative or positive information, respectively. Participants were confronted with conditionals of the form “If [situation], then I am happy/sad” which were either followed by no additional information or by additional information describing situations of the same or the opposite valence. The participant's task was to decide on a question asking for a possible conclusion (“Am I happy?” vs. “Am I sad?”). We found a negativity bias in defeasible reasoning: negative information defeated positively charged conclusions more strongly than positive information defeated negatively charged conclusions. We discuss our results in relation to the new psychology of reasoning.     

Home environment and cognitive development of black infants in impoverished South African families

This study examined the interrelationships between home environment, mental and psychomotor development, growth, and educational and occupational indices of socioeconomic status among an urban sample of 305 African infants aged 2 to 30 months. The infants were assessed on the Bayley Scales of Infant Development and the Home Screening Questionnaire, and their heights and weights were recorded. Information regarding the family's socioeconomic status was obtained during interviews with caretakers. No significant relationships were found between parental education and occupation and infant cognitive development, but quality of the home environment was positively correlated with these indices of parental socioeconomic status. On the other hand, home environment scores were found to be significantly related to mental development, independent of parental education and occupation. There was considerable variation in home environments in the sample, which was drawn from generally impoverished urban communities. These findings from an African cultural group support the generalizability of the importance of the quality of the home environment for infant development.     

Wittgensteinian Foundationalism

The idea that there is such a thing as Wittgensteinian foundationalism is a provocative one for two reasons. For one thing, Wittgenstein is widely regarded as an anti-foundationalist. For another, the very word `foundationalism' sounds like the name of a theory, and Wittgenstein famously opposed the advancing of theories and theses in philosophy. Nonetheless, in his book Moore and Wittgenstein on Certainty, Avrum Stroll has argued that Wittgenstein does indeed develop a foundationalist view in his final work, On Certainty. On this basis, Stroll goes on to argue against a number of contemporary views, including forms of relativism and scientism. In what follows I will examine what Stroll calls Wittgenstein's foundationalism (in Section 1) and argue that Stroll's reading of Wittgenstein, though original and interesting, is misguided in important ways and so cannot be used against the views he opposes (in Section 2). Finally, in Section 3, I offer a brief summary of the reading of Wittgenstein that I recommend.     

Quantal Nature of Generalization and Acquisition Responding by Rats in a Drug Discrimination Task

The Psychological Record -     

IMPROVING CLASSROOM BEHAVIOR IN MENTALLY RETARDED CHILDREN THROUGH CORRESPONDENCE TRAINING

Except for a few studies, most research investigating correspondence training procedures has been more analogue in nature. The purpose of the present set of studies was to examine whether a “say-do” correspondence training technique could be used with children in special education classes to improve classroom behavior. The specific behaviors targeted for change included: out-of-seat behavior (Experiment 1), sitting posture (Experiment 2), and on-task behavior (Experiment 3). The say-do procedure used in Experiment 1 resembled that of previous studies, whereas that in Experiment 2 was more elaborate in the specificity of verbal statements required from the children and the feedback given them. The training procedure in Experiment 3 used a format similar to the say-do approach, but stressed visual rather than verbal cuing because it was used with nonverbal children. All three studies used single-subject designs and examined maintenance and/or generalization questions. Experiments 2 and 3 also evaluated whether concomitant changes in performance on academic tasks occurred. The results of the three studies provide strong evidence that correspondence training can be effectively used with educationally handicapped children. Moreover, the successful modification of the “say-do” to a “show-do” procedure in Experiment 3 points out the flexibility of the correspondence training approach.     

Drinking in a patchy environment: the effect of the price of water.

Rats in a laboratory foraging paradigm searched for sequential opportunities to drink in two water patches that differed in the bar-press price of each "sip" (20 licks) of water within a bout of drinking (Experiment 1) or the price and size (10, 20, or 40 licks) of each sip (Experiment 2). Total daily water intake was not affected by these variables. The rats responded faster at the patch where water was more costly. However, they accepted fewer opportunities to drink, and thus had fewer drinking bouts, and drinking bouts were smaller at the more costly patch than at the other patch. This resulted in the rats consuming a smaller proportion of their daily water from the more costly patch. The size of the differences in bout frequency and size between the patches appears to be based on the relative cost of water at the patches. The profitability of each patch was calculated in terms of the return (in milliliters) on either effort (bar presses) or time spent there. Although both measures were correlated with the relative total intake, bout size, and acceptance of opportunities at each patch, the time-based profitability was the better predictor of these intake measures. The rats did not minimize bar-press output; however, their choice between the patches and their bout sizes within patches varied in a way that reduced costs compared to what would have been expended drinking randomly. These data accord well with similar findings for choices among patches of food, suggesting that foraging for water and food occurs on the basis of comparable benefit-cost functions: In each case, the amount consumed is related to the time spent consuming.