Perception of illumination direction in images of 3-D convex objects: influence of surface materials and light fields

We investigated the perception of illumination direction in images of 3-D convex objects under variations of light field and surface material properties. In a first experiment, we used an illumination-matching procedure in order to measure observers' ability to estimate the direction of illumination in images of 3-D polyhedra rendered under different light fields and illumination directions. Match deviations were larger in frontal direction than in rear directions, mainly counterclockwise in azimuth component, and diverged, in elevation component, from the image plane. In a second experiment, we examined whether the direction estimate was affected by the surface material type (BRDF), the light field, and the illumination direction. Angular deviations varied with material surface type and were largest in the test elevation direction 0 degrees. Elevation component deviations also differed with surface type and were larger in hemispherical diffuse lighting than in collimated lighting. These results suggest that the direction estimation is better with images of evenly distributed intensity gradients than with those of drastically varying gradients, and that the visual system may not take intensity variations due to the surface material or the light field into account in estimating the direction of illumination.     

Accuracy of drawing in a dual-task and resistance-to-distraction study: motor or attention deficit?

To determine whether manual incoordination is caused by attention deficit or not, we used an accuracy drawing task as a primary task in dual-task and resistance-to-distraction studies, and examined if thus measured attention could differentiate inattention (IA) and combined (CO) subtypes of ADHD. The secondary tasks and distractions failed to lower the primary task performance in IA, CO and control groups. We also compared the impairment scores of the accuracy drawing tasks from the Movement Assessment Battery for Children [Henderson, S. E., & Sugden, D. A. (1992). Movement assessment battery for children. London: Psychological Corporation.] between the groups with attention deficit hyperactivity disorder (ADHD) and/or developmental coordination disorder-inaccurate drawing type (DCD-ID). There were no group differences in the impairment score between the control and the ADHD groups, and between ADHD and ADHD plus DCD-ID groups. We concluded that inaccurate drawing is not caused by attention deficit, but that it is a manifestation of a motor deficit as a separate entity from attention deficit.     

Vanishing white matter disease: a review with focus on its genetics

Leukoencephalopathy with vanishing white matter (VWM) is an autosomal recessive brain disorder, most often with a childhood onset. Magnetic resonance imaging and spectroscopy indicate that, with time, increasing amounts of cerebral white matter vanish and are replaced by fluid. Autopsy confirms white matter rarefaction and cystic degeneration. The process of localization and identification of the first two genes related to VWM, EIF2B5 and EIF2B2, was facilitated by two founder effects in the Dutch population. EIF2B5 and EIF2B2 encode the epsilon and beta subunits of translation initiation factor eIF2B. Soon it was shown that mutations in all five eIF2B subunit genes can cause VWM. EIF2B is essential for the initiation of translation of RNA into protein and is involved in regulation of the process, especially under stress conditions, which may explain the sensitivity to stress conditions observed in VWM patients. The pathophysiology of the disease is still poorly understood.     

Auditory temporal information processing in preschool children at family risk for dyslexia: relations with phonological abilities and developing literacy skills

In this project, the hypothesis of an auditory temporal processing deficit in dyslexia was tested by examining auditory processing in relation to phonological skills in two contrasting groups of five-year-old preschool children, a familial high risk and a familial low risk group. Participants were individually matched for gender, age, non-verbal IQ, school environment, and parental educational level. Psychophysical thresholds were estimated for gap-detection, frequency modulation detection, and tone-in-noise detection using a three-interval forced-choice adaptive staircase paradigm embedded within a computer game. Phonological skills were measured by tasks assessing phonological awareness, rapid serial naming, and verbal short-term memory. Significant group differences were found for phonological awareness and letter knowledge. In contrast, none of the auditory tasks differentiated significantly between both groups. However, both frequency modulation and tone-in-noise detection were significantly related to phonological awareness. This relation with phonological skills was not present for gap-detection.     

When is search for a static target among dynamic distractors efficient?

Intuitively, dynamic visual stimuli, such as moving objects or flashing lights, attract attention. Visual search tasks have revealed that dynamic targets among static distractors can indeed efficiently guide attention. The present study shows that the reverse case, a static target among dynamic distractors, allows for relatively efficient selection in certain but not all cases. A static target was relatively efficiently found among distractors that featured apparent motion, corroborating earlier findings. The important new finding was that static targets were equally easily found among distractors that blinked on and off continuously, even when each individual item blinked at a random rate. However, search for a static target was less efficient when distractors abruptly varied in luminance but did not completely disappear. The authors suggest that the division into the parvocellular pathway dealing with static visual information, on the one hand, and the magnocellular pathway common to motion and new object onset detection, on the other hand, allows for efficient filtering of dynamic and static information.     

Analogical reasoning in handling emerging technologies: the case of umbilical cord blood biobanking

How are we individually and as a society to handle new and emerging technologies? This challenging question underlies much of the bioethical debates of modern times. To address this question we need suitable conceptions of the new technology and ways of identifying its proper management and regulation. To establish conceptions and to find ways to handle emerging technologies we tend to use analogies extensively. The aim of this article is to investigate the role that analogies play or may play in the processes of understanding and managing new technology. More precisely we aim to unveil the role of analogies as analytical devices in exploring the "being" of the new technology as well the normative function of analogies in conceptualizing the characteristics and applications of new technology. Umbilical cord blood biobanking will be used as a case to investigate these roles and functions.     

Oppel-Kundt illusion in three-dimensional space

A three-dimensional form of the Oppel-Kundt illusion was examined. Subjects viewed arrays consisting of two parallel rows of lights. For one group the rows consisted of equal numbers of lights (2, 3, or 4), while for a second group the row nearest the subject always had the greater number of lights. Subjects viewed these arrays from two vantage points, one directly in front of the array and the other displaced laterally. For each array subjects adjusted the extent of the far array until they felt the two rows were the same length. Both the nature of the array and the viewpoint had a significant influence on the perceived length of the far row. The size of the near row was overestimated significantly more when the array was viewed from the central position and also when the number of lights in the near row exceeded that of the far row. These results confirm that a lateral viewing position decreases the perspective effect and indicate that the Oppel-Kundt illusion can occur with three-dimensional stimuli.     

Automaticity: a theoretical and conceptual analysis

Several theoretical views of automaticity are discussed. Most of these suggest that automaticity should be diagnosed by looking at the presence of features such as unintentional, uncontrolled/uncontrollable, goal independent, autonomous, purely stimulus driven, unconscious, efficient, and fast. Contemporary views further suggest that these features should be investigated separately. The authors examine whether features of automaticity can be disentangled on a conceptual level, because only then is the separate investigation of them worth the effort. They conclude that the conceptual analysis of features is to a large extent feasible. Not all researchers agree with this position, however. The authors show that assumptions of overlap among features are determined by the other researchers' views of automaticity and by the models they endorse for information processing in general.     

Reasoning rats: forward blocking in Pavlovian animal conditioning is sensitive to constraints of causal inference

Forward blocking is one of the best-documented phenomena in Pavlovian animal conditioning. According to contemporary associative learning theories, forward blocking arises directly from the hardwired basic learning rules that govern the acquisition or expression of associations. Contrary to this view, here the authors demonstrate that blocking in rats is flexible and sensitive to constraints of causal inference, such as violation of additivity and ceiling considerations. This suggests that complex cognitive processes akin to causal inferential reasoning are involved in a well-established Pavlovian animal conditioning phenomenon commonly attributed to the operation of basic associative processes.