The effects of age and professional expertise on working memory performance

Differences in professional choice and experience may explain age differences in working memory performance of elderly people. The aim of this study was to examine whether expertise and prolonged practice in verbal and visuo‐spatial abilities reduce age differences in laboratory working memory tasks. The effects of age and expertise on working memory performance were examined in three age groups in two different experiments. Firstly, the role of visuo‐spatial expertise was analysed by examining age differences in architects. Secondly, people with extensive experience in verbal abilities (literary people) were tested in order to evaluate the effect of professional verbal experience. Architects and literary people outperformed a group of unselected age peers on tasks related to professional expertise only, but not on general working memory tests. There was no interaction between age and experience, suggesting that professional experience does not increase differences between experts and non experts and cannot modulate age‐related effects. Copyright © 2008 John Wiley & Sons, Ltd.     

Cognitive profiles and deviation patterns of dyslexic children.

Cognitive profiles of 20 dyslexic children were examined using a battery of neuropsychological tests. Their ages ranged from 90 to 114 mo. (M = 106.6 mo.). Intelligence and reading comprehension were normal, but the subjects had specific problems in decoding written material. These subjects were matched with a control group of same age, sex, and sociocultural status. The dyslexic children presented specific patterns of response on WISC-R subtests and failed a battery of cognitive tests examining subcomponents of reading. For each child, a deviation score was computed which represented the imbalance among the different cognitive functions. Greater imbalance was observed among the dyslexic children in development of cognitive functions than among the normal children.     

An experimental comparison of three- versus four-surface phenomenal transparency

The three-surface transparency occurs when an object seen through a transparency does not jut out under the transparent surface. The four-surface transparency occurs when the object juts out. Observers rated the density of the transparent surface in both kinds of transparency. The results seem to show that the topological diversity between the two kinds of transparency has no functional significance. The stimulus conditions ruling the generation of judgments were detected and expressed in terms of an algebraic model.     

An experimental check on Stevens’s explanation of the partition paradox by successive doubling and bisecting

Scaling methods based on direct estimation of sensory ratios and intervals give discrepant results (the partition paradox). Stevens’s explanation of this discrepancy was tested here. Given a psychological magnitude, ψ, observers were required to select a magnitude 2ψ, and subsequently to bisect the interval between ψ and 2ψ. Stevens’s hypothesis predicts that the bisected psychological magnitude falls between 1.41ψ and 1.50ψ. The hypothesis is not substantiated, since a bisected magnitude of 1.55ψ was obtained. Furthermore, observers had to bisect the interval between ψ and an imagined magnitude of 2ψ. The results show that observers are able to producereliably both a visual and a representational double.     

The effects of imagery instructions on total congenital blind recall

Abstract

Research on the performance of total congenital blind subjects in imagery tasks is of particular interest because it helps to evaluate the consequences of their lack of visual experience. The present paper examines some points which remained unclear in the preceding research on the effects of imagery instructions on the recall of blind subjects. In Experiment 1 it is shown that, in a free recall task of unrelated nouns, the blind may take advantage of imagery instructions, independently of the particular requirement to form either common or bizarre images. In Experiment 2 the multiple image processing deficit of the blind found by De Beni and Cornoldi (1988) was again observed, but the effect was not found when the same quantity of material had to be processed verbally. Results are interpreted as showing that, although the blind may follow imagery instructions, their visual handicap creates specific difficulties in creating interactive images involving several items at the same time.     

Passive and active processes in visuo-spatial memory: double dissociation in developmental learning disabilities

The distinction between passive and active visuo-spatial memory has been useful to interpret various pattern of deficits reported in individual differences studies. However, this interpretation raises the issue of task difficulty, since active tasks could be failed simply because more complex and the corresponding deficit could reflect a reduced capacity of the system. We describe two children with Nonverbal Learning Disability whose performance provides evidence of a dissociation between passive and active memory processes. One of the children showed a selective impairment in passive tasks and performed flawlessly in active tasks, whereas the second child displayed the opposite pattern. These data suggest that a qualitative difference between passive and active processes does exist and that differences in performance do not reflect a lower/higher level of task difficulty. Further, these data underlie the importance of formulating theoretical models of visuo-spatial memory including both material-related (i.e., visual vs spatial) and process-related (i.e., passive vs active) distinctions.     

Test of models of achromatic transparency

Consider an achromatic disk transparent on an achromatic background formed by two adjoining rectangles, with the common border of the rectangles dividing the disk in half. Current models of achromatic transparency contend that the perceived extent of transparency of the disk depends on the luminance contrast inside the disk and on the luminance contrast in the background outside the disk. Here, a model is proposed which contends that this perceived extent is determined only by the luminance contrasts inherent in the disk: inside the disk and between the disk and the background. Two experiments were designed to determine which luminance contrasts influence transparency. In the first experiment, subjects rated the perceived extent of transparency of the disk for different combinations of the luminances of the disk and of the background. The results strengthen the view that the perceived extent of transparency depends on the luminance contrasts inherent in the disk. In the second experiment, a test was made of the possibility that luminance contrasts between adjoining areas of the background outside the disk are nonessential for transparency. The results show that transparency occurred both when the areas of the background outside the transparent region adjoined one another and when they were separated, confirming that the perceived extent of transparency depended only on luminance contrasts between adjoining areas inherent in the disk.     

Intrusion errors in visuospatial working memory performance

This study tested the hypothesis that failure in active visuospatial working memory tasks involves a difficulty in avoiding intrusions due to information that is already activated. Two experiments are described, in which participants were required to process several series of locations on a 4 x 4 matrix and then to produce only the final location of each series. Results revealed a higher number of errors due to already activated locations (intrusions) compared with errors due to new locations (inventions). Moreover, when participants were required to pay extra attention to some irrelevant (non-final) locations by tapping on the table, intrusion errors increased. Results are discussed in terms of current models of working memory functioning.