The Cognitive Ecology of Problem Solving

This chapter examines the first goal: understanding real-world problem solving. It is particularly concerned with issues of representativeness and what has been called ecological validity. In addition, because there is considerable evidence that there are differences across the adult life span in solving problems, as reviewed by Botwinick (1978), Giambra and Arenberg (1980), and Rabbitt (1977), it will be important to ask whether or not age is an important qualifier to the conclusions that are reached. The first section discusses the problems people actually face and reviews the paradigms used in scientific investigations to represent problems, including studies of age differences and changes in problem solving. The second section explores the extent to which the lay and scientific domains overlap and finds that there is little overlap. The final section describes an explanatory study of problems representative of those people report facing in everyday life

Acquisition and Application of Expertise at Computer Text Editing by Younger and Older Adults

Groups of younger and older adults learned to use a computer text editor. Measures of both knowledge and performance were collected at regular intervals. Better recall of material learned was correlated with better performance; there were no age group differences in recalled knowledge or in performance. Models of more skilled individuals showed richer knowledge representations and more sophisticated performance rules than models of less skilled individuals. Age accounted for very little of the variation in skilled performance

A neural network and rule based system application in water demand forecasting

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.This thesis describes a short term water demand forecasting application that is based upon a combination of a neural network forecast generator and a rule based system that modifies the resulting forecasts. Conventionally, short term forecasting of both water consumption and electrical load demand has been based upon mathematical models that aim to either extract the mathematical properties displayed by a time series of historical data, or represent the causal relationships between the level of demand and the key factors that determine that demand. These conventional approaches have been able to achieve acceptable levels of prediction accuracy for those days where distorting, non cyclic influences are not present to a significant degree. However, when such distortions are present, then the resultant decrease in prediction accuracy has a detrimental effect upon the controlling systems that are attempting to optimise the operation of the water or electricity supply network. The abnormal, non cyclic factors can be divided into those which are related to changes in the supply network itself, those that are related to particular dates or times of the year and those which are related to the prevailing meteorological conditions. If a prediction system is to provide consistently accurate forecasts then it has to be able to incorporate the effects of each of the factor types outlined above. The prediction system proposed in this thesis achieves this by the use of a neural network that by the application of appropriately classified example sets, can track the varying relationship between the level of demand and key meteorological variables. The influence of supply network changes and calendar related events are accounted for by the use of a rule base of prediction adjusting rules that are built up with reference to past occurrences of similar events. The resulting system is capable of eliminating a significant proportion of the large prediction errors that can lead to non optimal supply network operation

Megaloblastic anaemia, diabetes and deafness in a 2-year-old child

Megaloblastic anaemia in childhood usually occurs as a result of dietary folate deficiency or, rarely, congenital disorders of vitamin B12 metabolism. We present a 2-year-old girl with megaloblastic anaemia and insulin-dependent diabetes mellitus, both of which proved responsive to pharmacological doses of thiamine. She was also found to have sensorineural hearing loss. Also known as Rogers\' syndrome, thiamine-responsive megaloblastic anaemia is the result of inactivating mutations in a gene encoding a thiamine transporter. A clinical diagnosis is supported by characteristic bone marrow findings and can be confirmed by demonstrating apoptosis in skin fibroblasts cultured in thiamine-depleted medium. Where available, DNA sequencing is definitive. There is rapid reticulocytosis after thiamine administration. We recommend a trial of therapy for megaloblastic anaemia not responding to folate and vitamin B12, especially in a deaf and/or diabetic child.Journal of Endocrinology, Metabolism and Diabetes of South Africa Vol. 10(2) 2005: 62-6

Attention\u27s Grasp: Early and Late Hand Proximity Effects on Visual Evoked Potentials

Behavioral studies suggest that visual attention is biased toward stimuli in the region of space near the palm of the hand, but it is unclear whether this effect is universal or selective for goal/task-related stimuli. We examined event-related potentials (ERPs) using a visual detection task in which the hand was placed near or kept far from target and non-target stimuli that were matched for frequency and visual features to avoid confounding factors. Focusing on attention-sensitive ERP components, we found that P3 (350–450 ms) amplitudes were increased for Hand Near conditions for targets only, demonstrating a selective effect consistent with the P3\u27s cross-modal and task-relevance influences. An N1 variant implicated in visuo-tactile integration (central Nd1; 120–190 ms) showed similar target-specific effects. P1 (80–110 ms) effects for target stimuli were also apparent, but may have applied to non-targets as well, which would be consistent with the P1\u27s association with early, pre-categorical increases in sensory gain. Collectively, these findings suggest that by the time stimuli are categorized as relevant/irrelevant for action, the proprioceptive effects of the hand on visual attention are selective for goal/task-related stimuli. At the same time, hand proximity appears to bias attention early, starting with a facilitation of processing for perhaps any visual stimuli near the hand, and continuing with enhancements that are selective to those stimuli categorized as task-relevant

Interactions of Cbl with Grb2 and phosphatidylinositol 3\u27-kinase in activated Jurkat cells

T-cell receptor (TCR) cross-linking increases tyrosine phosphorylation of multiple proteins, only a few of which have been identified. One of the most rapidly tyrosine-phosphorylated polypeptides is the 120-kDa product of the proto-oncogene c-cbl, a cytosolic and cytoskeletal protein containing multiple proline-rich motifs that are potential binding sites for proteins containing Src homology 3 (SH3) domains. We report here that in cultured Jurkat T cells, Cbl is coprecipitated with antibody against the adapter protein Grb2. Upon activation of Jurkat T cells via the TCR-CD3 complex, we find that high-affinity binding of Cbl requires the N-terminal SH3 domain of GST-Grb2 fusion protein but after cross-linking of the TCR-CD3 and CD4 receptors, Cbl binds equally to its SH2 domain. Grb2 antisera also precipitated p85 from serum-starved cells, while TCR activation increased p85 and tyrosine-phosphorylated Cbl but not Cbl protein in Grb2 immunocomplexes. Phosphatidylinositol (PI) 3-kinase activity was immunoprecipitated from serum-starved cells with Cbl and to a lesser extent with Grb2 antisera, and TCR cross-linking increased this activity severalfold. The PI 3-kinase activity associated with Cbl amounted to 5 to 10% of the total cellular activity that could be precipitated by p85 antisera. The Ras exchange factor Son-of-sevenless 1 (Sos-1) was not found in anti-Cbl immunoprecipitates from activated cells, and Cbl was not detectable in anti-Sos-1 precipitates, supporting the likelihood that Sos-Grb2 and Cbl-Grb2 are present as distinct complexes. Taken together, these data suggest that Cbl function in Jurkat T cells involves its constitutive association with Grb2 and its recruitment of PI 3-kinase in response to TCR activation

Megaloblastic anaemia, diabetes and deafness in a two-year old child

Megaloblastic anaemia in childhood usually occurs as a result of dietary folate deficiency or, rarely, congenital disorders of vitamin B12 metabolism. We present a 2-year-old girl with megaloblastic anaemia and insulin-dependent diabetes mellitus, both of which proved responsive to pharmacological doses of thiamine. She was also found to have sensorineural hearing loss. Also known as Rogers’ syndrome, thiamine-responsive megaloblastic anaemia is the result of inactivating mutations in a gene encoding a thiamine transporter. A clinical diagnosis is supported by characteristic bone marrow findings and can be confirmed by demonstrating apoptosis in skin fibroblasts cultured in thiamine-depleted medium. Where available, DNA sequencing is definitive. There is rapid reticulocytosis after thiamine administration. We recommend a trial of therapy for megaloblastic anaemia not responding to folate and vitamin B12, especially in a deaf and/or diabetic child