Hierarchical forms processing in adults and children

Two experiments examined child and adult processing of hierarchical stimuli composed of geometric forms. Adults (ages 18-23 years) and children (ages 7-10 years) performed a forced-choice task gauging similarity between visual stimuli consisting of large geometric objects (global level) composed of small geometric objects (local level). The stimuli spatial arrangement was manipulated to assess child and adult reaction times and predisposition toward local or global form categorization under two distinct trial conditions, with varied density of the local forms comprising the global forms. In Experiment 1, children and adults were presented with common, simple geometric shape hierarchical forms composed of ovals and rectangles. In Experiment 2, adults were presented with hierarchical forms composed of the simple geometric shapes, ovals and rectangles, and additional novel complex geometric shapes, “posts” and “arches.” Results show a clear increase of global processing bias across the age ranges of the individuals in the study, with children at 10 years performing similarly to adults on the simple stimuli. In addition, adults presented with the novel complex geometric shapes showed a significant reduction in global processing bias, indicating that form novelty and complexity lead to additional attention to local features in categorization tasks.     

The effects of varying attentional demands on the word retrieval skills of adults with aphasia, right hemisphere brain damage, or no brain damage

Adults with mild aphasia, right hemisphere brain damage (RBD), or no brain damage (NBD) provided one-word phrase completions under isolation, focused attention, and divided attention conditions and in response to relatively constrained or unconstrained phrase stems. Despite comparable word retrieval accuracy among groups during the isolation condition, aphasic and RBD groups performed less accurately than the NBD group during focused and divided attention conditions. Across conditions, there were no significant differences between aphasic and RBD groups. Only aphasic subjects demonstrated a significant effect of phrase type, responding more accurately when completing constrained versus unconstrained stimuli. For aphasic and RBD groups, error type analysis indicated that semantic and phonological aspects of word retrieval were influenced by increased attentional demands. These findings suggest that for adults with aphasia or RBD, there is a negative relation between attention impairments and word retrieval abilities.     

Plasticity of brain and cognition in older adults

Aging is typically related to changes in brain and cognition, but the aging process is heterogeneous and differs between individuals. Recent research has started investigating the influence of cognitive and physical training on cognitive performance, functional brain activity, and brain structure in old age. The functional relevance of neural changes and the interactions among these changes following interventions is still a matter of debate. Here we selectively review research on structural and functional brain correlates of training-induced performance changes in healthy older adults and present exemplary longitudinal intervention studies sorted by the type of training applied (i.e., strategy-based training, process-specific training, and physical exercise). Although many training studies have been conducted recently, within each task domain, the number of studies that used comparable methods and techniques to assess behavioral and neural changes is limited. We suggest that future studies should include a multimodal approach to enhance the understanding of the relation between different levels of brain changes in aging and those changes that result from training. Investigating inter-individual differences in intervention-induced behavioral and neuronal changes would provide more information about who would benefit from a specific intervention and why. In addition, a more systematic examination of the time course of training-related structural and functional changes would improve the current level of knowledge about how learning is implemented in the brain and facilitate our understanding of contradictory results.     

Spiral aftereffect in assessment of brain damage

The potential role of the Archimedes spiral aftereffect, an illusory negative aftereffect of apparent movement, in the assessment of brain damage has been the subject of investigation by clinicians for over thirty years. The results bearing on its utility have been highly equivocal. This paper reviews the more important studies, identifies salient issues, and suggests directions for research into brain damage using this intriguing procedure.     

Clinical and statistical approaches to the assessment of brain damage in children

In an attempt at innovation in the clinical versus statistical prediction controversy, the present research examined three methods of assessing organic brain damage in a sample of sixty-eight 9- to 14-year-old children. Methods compared were clinical judgment (CP); existing actuarial norms (EAN); and derived statistical prediction (DSP), based on three psychological tests. The results were as follows: (a) None of the methods classified subjects significantly better than chance (p<.05); (b) there was no significant difference (p<.05) among the methods in terms of their rates of accurate classification; (c) CP based on combined tests did not result in higher predictive accuracy than those based on an individual test; (d) CP made after receiving feedback on accuracy showed an increase in number of correct classifications over prior CP; and (e) CP based on knowledge of the statistical prediction in addition to test data showed a higher rate of correct classification than DSP alone.