Aging and rule learning: the case of the multiplicative law

This work examined the effect of age on the ability to learn multiplicative combination rules. Participants learned the multiplicative relationship between daily tobacco intake, daily alcohol intake, and risk of esophageal cancer. The hypothesis was that younger adults would learn to implement a multiplicative combination rule and older adults would not, despite feedback. Among the younger adults, complete rule learning took place. Before receiving feedback, they used an underadditive rule, a result consistent with previous studies. After only a limited amount of feedback, they learned to use a multiplicative rule. Even after receiving feedback, however, the older adults still showed difficulties in using the multiplicative rule. These results strengthen the proposition by Chasseigne, Mullet, and Stewart (1997) that the differences between younger and older adults in function learning are related mainly to flexibility of functioning.     

Context and the interpretation of likelihood information: the role of intergroup comparisons on perceived vulnerability

Four experiments investigated how people's perceptions about a group's (e.g., women's) vulnerability to a disease are influenced by information about the prevalence of the disease in a comparable group (e.g., men). Participants read symptom and prevalence infomation about fictitious diseases before answering questions regarding target group vulnerability. Participants used the prevalence rate for a nontarget group as an immediate comparison standard for intuitively interpreting the degree of vulnerability of a target group, resulting in robust contrast effects. Experiments 3 and 4 illustrated that these contrast effects can cause a person's intuitive perceptions about a group's vulnerability to selected diseases to conflict with his or her knowledge of the prevalence rates for the diseases. The results support a distinction between 2 components of psychological uncertainty-beliefs in objective probability and more intuitive perceptions of certainty.     

Ability evaluation by proxy: role of maximal performance and related attributes in social comparison

Four experiments tested the effects of information about a proxy's related attributes and maximal effort in social comparisons of ability. In Study 1, a proxy's prior performance at maximal effort exerted systematic effects on participants' personal performance predictions for a novel task. When information about the proxy's effort was ambiguous (Study 2). information about related attribute similarity was used in the formulation of performance predictions. In Studies 3 and 4, 2-way interaction terms revealed that participants used related attribute information in generating performance predictions when the proxy's maximum effort was unknown. However, related attribute information was disregarded when proxy's maximum effort was unambiguous. Results were consistent with the proxy comparison model of ability self-evaluation (L. Wheeler, R. Martin, & J. Suls, 1997).     

Visual habituation at five months: short-term reliability of measures obtained with a new polynomial regression criterion

Using a new polynomial regression criterion, the authors investigated empirically the short-term reliability of infants' visual habituation measures. Twenty-one 5-month-old infants were tested twice with a 1-day interval. Results revealed many reliable habituation measures, a reliable reaction to novelty measure, and a new reliable measure of interest. The 2nd-order polynomial regression criterion probably produced this improvement because it uses all of the available looking time data.     

Developmental and content effects in reasoning with causal conditionals

Two predictions derived from Markovits and Barrouillet's (2001) developmental model of conditional reasoning were tested in a study in which 72 twelve-year-olds, 80 fifteen-year-olds, and 104 adults received a paper-and-pencil test of conditional reasoning with causal premises ("if cause P then effect Q"). First, we predicted that conditional premises would induce more correct uncertainty responses to the Affirmation of the consequent and Denial of the antecedent forms when the antecedent term is weakly associated to the consequent than when the two are strongly associated and that this effect would decrease with age. Second, uncertainty responding to the Denial of the antecedent form ("P is not true") should be easier when the formulation of the minor premise invites retrieval of alternate antecedents ("if something other than P is true"). The results were consistent with the hypotheses and indicate the importance of retrieval processes in understanding developmental patterns in conditional reasoning with familiar premises.     

Physical activity,motor ability,and school readiness of 6-yr.-old children

The aim of this investigation was to study the relationships between physical activity, motor ability, and school readiness in 6-yr.-old children. In total, 294 healthy children from Tartu were studied (161 boys and 133 girls). The physical activity of children was reported by parents and teachers using the questionnaire of Harro. The motor ability of children was evaluated using various tests from the Eurofit test battery as well as the 3-min. endurance shuttle run test. The Controlled Drawing Observation rest was used as a predictor of school readiness and development of mental abilities. Indoor physical activities predicted 19-25% of total variance in motor scores for these preschool children. Motor ability tests, which demand children's total attention and concentration, appear related to the chosen measures of school readiness.     

Lack of association of computer use and ability with spontaneous mental visualization

Relationships between frequency of computer use or ability to use the computer effectively with the tendency to construct and process visual mental images were investigated by administering a computer-use questionnaire and a visualization questionnaire to a sample of 185 Italian and Spanish undergraduates. Analysis did not support associations between either (a) frequent computer use of any kind or (b) high competence in using the computer for various purposes and spontaneous use of imagery.     

Causal conditional reasoning and semantic memory retrieval: a test of the semantic memory framework

This study tested and refined a framework that proposes a mechanism for retrieving alternative causes and disabling conditions (Cummins, 1995) during reasoning. Experiment 1 examined the relation between different factors affecting retrieval. The test revealed high correlations between the number of possible alternative causes or disabling conditions and their strength of association and plausibility. Experiment 2 explored the hypothesis that due to a more extended search process, conditional inferences would last longer when many alternative causes or disabling conditions were available. Affirmation of the consequent (AC) and modus ponens (MP) latencies showed the hypothesized pattern. Denial of the antecedent (DA) and modus tollens (MT) inferences did not show latency effects. The experiment also identified an effect of the number of disabling conditions on AC and DA acceptance. Experiment 3 measured efficiency of disabler retrieval by a limited time, disabler generation task. As predicted, better disabler retrieval was related to lower acceptance of the MP and MT inferences.     

Satisfiability Testing for Boolean Formulas Using Δ-trees

The tree-based data structure of -tree for propositional formulas is introduced in an improved and optimised form. The -trees allow a compact representation for negation normal forms as well as for a number of reduction strategies in order to consider only those occurrences of literals which are relevant for the satisfiability of the input formula. These reduction strategies are divided into two subsets (meaning- and satisfiability-preserving transformations) and can be used to decrease the size of a negation normal form A at (at most) quadratic cost. The reduction strategies are aimed at decreasing the number of required branchings and, therefore, these strategies allow to limit the size of the search space for the SAT problem.