Vision-fair neuropsychological assessment in normal aging, Parkinson's disease and Alzheimer's disease

We examined performance of healthy older and younger adults and individuals with Alzheimer's disease (AD) and Parkinson's disease (PD) on digit cancellation, a task putatively sensitive to cognitive impairment, but possibly affected by visual impairment, particularly in contrast sensitivity. Critical contrast thresholds were established to create custom stimulus arrays that were proximally matched across individuals. Age- and PD-related differences in search were fully accounted for by the sensory deficit. Increased contrast benefited AD patients, but could not override cognitive impairment. We conclude that visually fair neuropsychological testing can effectively compensate for normal age- and PD-related visual changes that affect cognitive performance. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Bingo! Externally supported performance intervention for deficient visual search in normal aging, Parkinson's disease, and Alzheimer's disease

External support may improve task performance regardless of an individual's ability to compensate for cognitive deficits through internally generated mechanisms. We investigated if performance of a complex, familiar visual search task (the game of bingo) could be enhanced in groups with suboptimal vision by providing external support through manipulation of task stimuli. Participants were 19 younger adults, 14 individuals with probable Alzheimer's disease (AD), 13 AD-matched healthy adults, 17 non-demented individuals with Parkinson's disease (PD), and 20 PD-matched healthy adults. We varied stimulus contrast, size, and visual complexity during game play. The externally supported performance interventions of increased stimulus size and decreased complexity resulted in improvements in performance by all groups. AD also obtained benefit from increasing contrast, presumably by compensating for their contrast sensitivity deficit. The general finding of improved performance across healthy and afflicted groups suggests the value of visual support as an easy-to-apply intervention to enhance cognitive performance.     

Age effects on a nonverbal auditory sustained attention task

A nonverbal auditory test of sustained attention was administered to 20 young and 20 elderly women, screened to ensure good health. Groups were matched for intelligence. Older subjects performed as accurately as younger subjects. Neither group showed increases in response latency as a function of time spent on test. Older subjects took longer to respond than younger subjects, but only for a particular combination of stimulus duration and order of presenting stimulus durations. When subjects were presented long tones first, there was no difference in response latency associated with age or stimulus duration. When short tones were presented first, older subjects were slower than younger subjects in both duration conditions and in response to long tones were slower than all other subjects.     

When are nonwords easy to see?

The influences of presentation mode (mixed vs. blocked trials) and target variability on the detection of targets in words and in random letter strings were examined. The results indicated that there was a substantial word superiority effect in mixed lists of words and nonwords, but that this effect was eliminated when pure lists of words and nonwords were compared. Also, target variability affected the shape of the serial position curve. When subjects searched repeatedly for a single target, the serial position curve had only a significant linear component. However, when the identity of the target varied from trial to trial, the serial position curve had a significant quartic component (i.e.. it was M-shaped). These results were interpreted in terms of strategies and feature learning.     

Application of two-dimensional Fourier transforms to problems of visual perception

Neurophysiological and psychophysical evidence indicates that the visual system performs a sort of Fourier analysis of retinal variations in brightness through multiple spatial frequency-tuned channels. Two types of applications of techniques of two-dimensional Fourier analysis are discussed: (1) modeling and simulation of visual functions, and (2) generation of stimuli in which the spatial frequency information is controlled. Examples of both these applications are presented.     

Seniority in the generational transition of laboratory groups: The effects of social familiarity and task experience

The determinants of leadership seniority in laboratory groups were investigated in two experiments. In both experiments a procedure was used in which individual group members were periodically replaced throughout 7 generations. The individuals within the groups folded origami products and traded with other groups so as to earn quarters. In the first experiment the effect of social familiarity on seniority was investigated by comparing a set of standard groups with a set of rotational groups in which the group members moved from group to group between generations and thus always interacted with strangers. There was less seniority in the rotational groups. In the second experiment the effect of experience on seniority was investigated by comparing a set of standard groups with a set of experienced groups in which the new group members were recruited from the standard groups. There was less seniority in the experienced groups. It was found in both experiments, in agreement with previous research, that over generations the subjects earned increasing amounts of money and worked with increasing speed and efficiency.     

Children’s mapping between symbolic and nonsymbolic representations of number

When children learn to count and acquire a symbolic system for representing numbers, they map these symbols onto a preexisting system involving approximate nonsymbolic representations of quantity. Little is known about this mapping process, how it develops, and its role in the performance of formal mathematics. Using a novel task to assess children’s mapping ability, we show that children can map in both directions between symbolic and nonsymbolic numerical representations and that this ability develops between 6 and 8 years of age. Moreover, we reveal that children’s mapping ability is related to their achievement on tests of school mathematics over and above the variance accounted for by standard symbolic and nonsymbolic numerical tasks. These findings support the proposal that underlying nonsymbolic representations play a role in children’s mathematical development.     

The Implicit Associations Between Religious and Nonreligious Supernatural Constructs

The present studies furthered understanding of the implicit relationships between traditional religious (RS) and nonreligious supernatural (NRS) concepts. Moving beyond the study of explicit beliefs, we accounted for the distinctions within NRS concepts, applying recent developments in the understanding of the correspondence in beliefs in these phenomena.     

Stability in young infants' discrimination of optic flow

Although considerable progress has been made in understanding how adults perceive their direction of self-motion, or heading, from optic flow, little is known about how these perceptual processes develop in infants. In 3 experiments, the authors explored how well 3- to 6-month-old infants could discriminate between optic flow patterns that simulated changes in heading direction. The results suggest that (a) prior to the onset of locomotion, the majority of infants discriminate between optic flow displays that simulate only large (> 22 deg.) changes in heading, (b) there is minimal development in sensitivity between 3 and 6 months, and (c) optic flow alone is sufficient for infants to discriminate heading. These data suggest that spatial abilities associated with the dorsal visual stream undergo prolonged postnatal development and may depend on locomotor experience.