Prospective Memory Impairment in Mild Cognitive Impairment: An Analytical Review

Mild cognitive impairment (MCI) is a heterogeneous condition characterized by the presence in an otherwise healthy elderly individual of cognitive deficits involving specific domains in the absence of significant functional impairments. Reports indicate that prospective memory (PM), that is, the ability to remember to execute delayed intentions, is impaired in individuals with MCI. The present review discusses the current debate in the literature on PM functioning in MCI by focusing on the relationship between prospective retrieval and retrospective memory functioning. Analysis of the reported evidence revealed that both the prospective component and the retrospective component of PM can be impaired in MCI. Declarative memory dysfunction may account for the retrospective memory impairment, while either reduced executive abilities or a deficit of reflexive mechanisms could explain the prospective component impairment.     

Bidirectional links in the network of multiplication facts

In three experiments, we tested the hypothesis that activation of multiplication operand nodes (e.g., 3 and 8) can occur through presentation of their product (e.g., 24). In Experiments 1 and 2 we found activation of the operands when the product was presented as a cue in a number-matching task. In Experiment 3, activation also occurred in a parity-matching task, where the product (24) was not relevant to the parity matching on its operands (3 and 8). We concluded that bidirectional links exist among the operands and their product for multiplication problems and these links can be activated in a purely stimulus-driven manner. We suggest this may constitute the basis for the solution of simple divisions by mediation through the complementary multiplication facts.     

Short-Term Memory Deficits Are Not Uniform in Down and Williams Syndromes

Neuropsychological investigation of the development of the mnesic function in mental retardation has primarily focused on evaluating short-term memory (STM). Studies have often documented a reduced verbal short-term memory span in individuals with mental retardation and with Down syndrome in particular, compared to groups of mental age-matched controls. However, recent evidence suggests that verbal short-term memory is not equally impaired in all individuals with mental retardation. Findings in children with Williams syndrome are particularly relevant in this regard. Also, data concerning STM for visual information suggest that visual-object and visual-spatial working memory may be differently compromised in people with mental retardation. In particular, individuals with Williams syndrome exhibit specific difficulties in visual-spatial but not in visual-object working memory tasks compared to typically-developing children matched for mental age. Instead, people with Down syndrome show reduced performance in both visual-spatial and visual-object tests. Taken together, these results reinforce the view that intellectual disability is not a unitary condition characterized by homogeneous slowness of cognitive development but a variety of conditions in which some cognitive functions may be more disrupted than others. The finding that the working memory deficit in individuals with Williams and Down syndrome may be qualitatively differentiated also supports the hypothesis that it is not simply a manifestation of general cognitive impairment but, rather, the expression of a specific deficit of a discrete cognitive ability.     

Number magnitude orients attention, but not against one’s will

Recent evidence has shown that uninformative numbers can trigger attention shifts congruent with the spatial representation of number magnitude (Fischer, Castel, Dodd, & Pratt, 2003). In the present study, three spatial-cuing experiments whose aim was to qualify the automaticity of this numbermediated orienting are described. Experiment 1 replicated the phenomenon, showing that uninformative numbers can evoke orienting in a simple detection task. In Experiment 2, target location was random, but the participants were encouraged to shift attention to the left in response to large numbers and to the right in response to small numbers. No evidence for strong automaticity was observed, since the participants’ performance was better when left-side targets were preceded by large numbers than when they were preceded by small numbers and vice versa. Experiment 3 corroborated this pattern by comparing gaze- and number-mediated cuing under conditions of real counterpredictiveness. The results indicate that unlike gaze-driven orienting, number-mediated orienting is not obligatory.     

Glowing greys and surface-white: the photo-geometric factors of luminosity perception

The perception of luminosity is thought to depend upon the intensity of the stimulus: a surface begins to appear self-luminous when it emits or reflects a certain amount of light. This is known as the luminosity threshold. It is a common opinion among vision scientists that such a threshold is correlated to the intensity of a perceptually white surface, in the sense that only an area of the visual field with luminance higher than perceived surface-white will appear luminous. Here we show grey colours that appear luminous in virtue of surrounding luminance ramps. These ramps are intended to mimic halos seen around light sources in natural environments. The results of three experiments indicate that the phenomenon is in direct contradiction to the aforementioned assumptions and suggest the existence of separate perceptual pathways for self-luminosity perception and for surface-colour perception.     

Context in selection of men and women in hiring decisions: gender composition of the applicant pool

The hypothesis that the sex composition of an applicant pool affects the hiring probabilities of individual job applicants was tested using gender-distinctive information on accepted and rejected job applicants in The Netherlands. The evidence supports this hypothesis, although the effect sizes are moderate. Both men and women have a lower probability of being hired when the applicant pool contains fewer applicants from their own sex.     

Is handedness recognition automatic? A study using a Simon-like paradigm

The authors used a modified Simon task (J. R. Simon, 1969) to assess the automatic recognition of handedness. Participants responded to the color of a circle in the center of the photograph of a right or a left hand, displayed in the center of the computer screen. A regular Simon effect was found for back views, whereas a reverse Simon effect was found for palm views. This pattern of results was found when the forearm was present (Experiment 2), when 1 finger at a time was rendered invisible (Experiment 3), and when the hands were connected to a body image (Experiment 4). When the hands were cut at the wrist, no effect emerged (Experiment 1). These findings suggest an automatic encoding of the relative position of the hand in relation to the body (imaginary or real) rather than the automatic encoding of handedness.     

Cerebellar ataxia: quantitative assessment and cybernetic interpretation

To assess neuromotor disorders clinicians often rely on rating scales. Unfortunately, these scales lack the sensitivity and accuracy needed to detect the small changes in motor coordination that reflect the clinical progression of the disease on the basis of which treatment programmes can be adjusted. As a contribution to this topic, the present paper proposes a straightforward kinematic and kinetic analysis of reaching movements of patients with cerebellar ataxia in conjunction with a cybernetic interpretation of the data. The aim of the approach is to capture key deficits in the underlying motor control processes. We suggest that cerebellar ataxia may be characterized by defective feedforward control.     

Haptic estimates of discordant visual—haptic size vary developmentally

In two size-conflict experiments, children viewed various squares through a reducing (1/2) lens while manually grasping them through a hand-concealing cloth. Then, using either vision or touch, they selected a match from a set of comparison squares. Forty 6-, 9-, and 12-year-olds participated in Experiment 1. Vision dominated the visual estimates of all three age groups; however, for the haptic estimates, the dominant modality varied developmentally: Vision dominated the 6-year-olds’ haptic estimates, whereas neither modality dominated the 9-year-olds’ haptic estimates, and touch dominated the 12-ear-olds’ haptic estimates. In Experiment 2, 24 six-year-olds were tested, as in Experiment 1; however, half of them were shown the size-distorting effects of the lens just prior to testing. Although this reduced the visual dominance of their haptic estimates, the effect was weak and short-lived. The haptic dominance seen in the data of the 12-year-olds was conspicuously absent.