Biomedical subjects

G S Halford

Publications and source records attributed to G S Halford.

8 recordsLinked to original sources

PubMed1998

Induction of relational schemas: common processes in reasoning and complex learning.

Five experiments were performed to test whether participants induced a coherent representation of the structure of a task, called a relational schema, from specific instances. Properties of a relational schema include: An explicit symbol for a relation, a binding that preserves the truth of a relation, potential for higher-order relations, omnidirectional access, potential for transfer between isomorphs, and ability to predict unseen items in isomorphic problems. However relational schemas are not necessarily coded in abstract form. Predictions from relational schema theory were contrasted with predictions from configural learning and other nonstructural theories in five experiments in which participants were taught a structure comprised of a set of initial-state,operator-->end-state instances. The initial-state,operator pairs were presented and participants had to predict the correct end-state. Induction of a relational schema was achieved efficiently by adult participants as indicated by ability to predict items of a new isomorphic problem. The relational schemas induced showed the omnidirectional access property, there was efficient transfer to isomorphs, and structural coherence had a powerful effect on learning. The "learning to learn" effect traditionally associated with the learning set literature was observed, and the long-standing enigma of learning set acquisition is explained by a model composed of relational schema induction and structure mapping. Performance was better after reversal of operators than after shift to an alternate structure, even though the latter entailed more overlap with previously learned tasks in terms of the number of configural associations that were preserved. An explanation for the reversal shift phenomenon in terms of induction and mapping of a relational schema is proposed. The five experiments provided evidence supporting predictions from relational schema theory, and no evidence was found for configural or nonstructural learning theories.

Adult↗

PubMed1998

Processing capacity defined by relational complexity: implications for comparative, developmental, and cognitive psychology.

Working memory limits are best defined in terms of the complexity of the relations that can be processed in parallel. Complexity is defined as the number of related dimensions or sources of variation. A binary relation has one argument and one source of variation; its argument can be instantiated in only one way at a time. A binary relation has two arguments, two sources of variation, and two instantiations, and so on. Dimensionality is related to the number of chunks, because both attributes on dimensions and chunks are independent units of information of arbitrary size. Studies of working memory limits suggest that there is a soft limit corresponding to the parallel processing of one quaternary relation. More complex concepts are processed by "segmentation" or "conceptual chunking." In segmentation, tasks are broken into components that do not exceed processing capacity and can be processed serially. In conceptual chunking, representations are "collapsed" to reduce their dimensionality and hence their processing load, but at the cost of making some relational information inaccessible. Neural net models of relational representations show that relations with more arguments have a higher computational cost that coincides with experimental findings on higher processing loads in humans. Relational complexity is related to processing load in reasoning and sentence comprehension and can distinguish between the capacities of higher species. The complexity of relations processed by children increases with age. Implications for neural net models and theories of cognition and cognitive development are discussed.

Cognition↗

PubMed1994

The development of memory and processing capacity.

The assumption of some developmental theories that short-term memory is the workspace of higher cognitive processes, and consequently that span measures processing capacity, is claimed to be inconsistent with the working memory literature. 4 experiments, using children aged 5 to 12 years, contrast this theory with a model in which short-term memory and the processing space component of working memory are at least partly distinct. Experiments 1 and 2 varied processing load, holding duration constant. The processing load manipulation had little effect on recall of a short-term memory preload. Experiments 3 and 4 failed to support the prediction that the greater processing efficiency of older children would be associated with slower loss of information from short-term memory. Although counting and rehearsal rates increased with age, and correlated with span, they did not predict the rate of loss of memory preload due to intervening counting. The data suggest that effects obtained with short-term memory span do not provide clear indications of overall working memory development, because short-term memory span and the processing space component of working memory entail distinct systems.

Age Factors↗

PubMed1988