How the eye measures reality and virtual reality

If virtual reality systems are to make good on their name, designers must know how people perceive space in natural environments, in photographs, and in cinema. Perceivers understand the layout of a cluttered natural environment through the use of nine or more sources of information, each based on different assumptions—occlusion, height in the visual field, relative size, relative density, aerial perspective, binocular disparities, accommodation, convergence, and motion perspective. The relative utility of these sources at different distances is compared, using their ordinal depth-threshold functions. From these, three classes of space around a moving observer are postulated: personal space, action space, and vista space. Within each, a smaller number of sources act in consort, with different relative strengths. Given the general ordinality of the sources, these spaces are likely to be affine in character, stretching and collapsing with viewing conditions. One of these conditions is controlled by lens length in photography and cinematography or by field-of-view commands in computer graphics. These have striking effects on many of these sources of information and, consequently, on how the layout of a scene is perceived.     

Sex differences in cerebral laterality of language and visuospatial processing

Sex differences on language and visuospatial tasks are of great interest, with differences in hemispheric laterality hypothesized to exist between males and females. Some functional imaging studies examining sex differences have shown that males are more left lateralized on language tasks and females are more right lateralized on visuospatial tasks; however, findings are inconsistent. Here we used functional magnetic resonance imaging to study thirty participants, matched on task performance, during phonological and visuospatial tasks. For each task, region-of-interest analyses were used to test differences in cerebral laterality. Results indicate that lateralization differences exist, with males more left lateralized during the phonological task and showing greater bilateral activity during the visuospatial task, whereas females showed greater bilateral activity during the phonological task and were more right lateralized during the visuospatial task. Our data provide clear evidence for differences in laterality between males and females when processing language versus visuospatial information.     

The Association of Neurofibromatosis Type 1 and Attention Deficit Hyperactivity Disorder

Some research and clinical observations have linked Neurofibromatosis Type 1 (NF-1) and Attention Deficit Hyperactivity Disorder (ADHD). In order to investigate whether ADHD is part of the phenotype of NF-1 or is a separate, unrelated disorder within families, we compared the ADHD status of children affected with NF-1 to that of their unaffected-NF-1 siblings and to that of their biological parents. Results of matched-pair analyses were calculated and revealed a significant with-in pair discordance, when comparing children with NF-1 and their siblings and when comparing children with NF-1 and their biological parents (in families with a sporadic, non-familial NF-1 child). These findings suggest that ADHD may occur as a component of the NF-1 phenotype.     

Effects of IQ on Executive Function Measures in Children with ADHD

The present study compared children with Attention-Deficit Hyperactivity Disorder (ADHD) and controls on a selected set of clinical measures of executive function (EF). A total of 92 children (51 ADHD, 41 control), ages 6-16, completed measures chosen from a larger neuropsychological battery to illustrate diverse components of the EF construct (planning, inhibitory control, response preparation, memory search). The selected measures were moderately correlated with one another, and moderately correlated with IQ. After controlling for age, sex, presence of learning disability (LD), ADHD, and IQ test version, Full Scale IQ was significantly related to four of the five selected EF measures. A second analysis showed group differences on the EF measures at different IQ levels. After covarying for age, there was a significant multivariate effect for IQ level (average, high average, superior) and a significant multivariate interaction between group (ADHD vs. control) and IQ level. Three of the five selected EF measures showed significant univariate group effects (controls performing better than ADHD) at the average IQ level; however, there were no significant group differences between children with ADHD and controls at high average or superior IQ levels. These results suggest that clinical measures of EF may differ among children with ADHD and controls at average IQ levels, but there is poorer discriminatory power for these measures among children with above average IQ.     

Semantic and phonological information flow in the production lexicon

When speakers produce words, lexical access proceeds through semantic and phonological levels of processing. If phonological processing begins based on partial semantic information, processing is cascaded; otherwise, it is discrete. In standard models of lexical access, semantically processed words exert phonological effects only if processing is cascaded. In 3 experiments, speakers named pictures of objects with homophone names (ball), while auditory distractor words were heard beginning 150 ms prior to picture onset. Distractors speeded picture naming (compared with controls) only when related to the nondepicted meaning of the picture (e.g., dance), exhibiting an early phonological effect, thereby supporting the cascaded prediction. Distractors slowed picture naming when categorically (e.g., frisbee) related to the depicted picture meaning, but not when associatively (e.g., game) related to it. An interactive activation model is presented.     

The effect of culture and self‐construals on predispositions toward verbal communication

This study tested the effects of culture and self‐construals (i.e., independence and interdependence) on predispositions toward verbal communication. For the purpose of this study, we focused on two main areas of verbal communication predispositions: (a) communication apprehension and (b) argumentativeness. In our path model, we expected that culture‐level individualism increases one's construal of self as independent, which, in turn, leads to a higher degree of argumentativeness and a lower level of communication apprehension. We also expected that culture‐level individualism decreases one's construal of self as interdependent, which, in turn, leads to a lower degree of argumentativeness and a higher level of communication apprehension. Data to test the model were drawn from undergraduates (N=539) studying in Korea, Hawaii, and mainland U.S. The data were partially consistent with the theoretical predictions made. The implications of the results for theory and practice are discussed.     

Why do children lack the flexibility to innovate tools?

Despite being proficient tool users, young children have surprising difficulty in innovating tools (making novel tools to solve problems). Two experiments found that 4- to 7-year-olds had difficulty on two tool innovation problems and explored reasons for this inflexibility. Experiment 1 (N = 51) showed that children’s performance was unaffected by the need to switch away from previously correct strategies. Experiment 2 (N = 92) suggested that children’s difficulty could not easily be explained by task pragmatics or permission issues. Both experiments found evidence that some children perseverated on a single incorrect strategy, but such perseveration was insufficient to explain children’s tendency not to innovate tools. We suggest that children’s difficulty lies not with switching, task pragmatics, or behavioral perseveration but rather with solving the fundamentally “ill-structured” nature of tool innovation problems.     

Effects of IQ on executive function measures in children with ADHD.

The present study compared children with Attention-Deficit Hyperactivity Disorder (ADHD) and controls on a selected set of clinical measures of executive function (EF). A total of 92 children (51 ADHD, 41 control), ages 6-16, completed measures chosen from a larger neuropsychological battery to illustrate diverse components of the EF construct (planning, inhibitory control, response preparation, memory search). The selected measures were moderately correlated with one another, and moderately correlated with IQ. After controlling for age, sex, presence of learning disability (LD), ADHD, and IQ test version, Full Scale IQ was significantly related to four of the five selected EF measures. A second analysis showed group differences on the EF measures at different IQ levels. After covarying for age, there was a significant multivariate effect for IQ level (average, high average, superior) and a significant multivariate interaction between group (ADHD vs. control) and IQ level. Three of the five selected EF measures showed significant univariate group effects (controls performing better than ADHD) at the average IQ level; however, there were no significant group differences between children with ADHD and controls at high average or superior IQ levels. These results suggest that clinical measures of EF may differ among children with ADHD and controls at average IQ levels, but there is poorer discriminatory power for these measures among children with above average IQ.     

Walking,looking to the side,and taking curved paths

In two experiments, viewers judged heading from displays simulating locomotion through tree-filled environments, with gaze off to the side. They marked their heading with a mouse-controlled probe at three different depths. When simulated eye or head rotation generally exceeded 0.5 deg/sec, there was reliable curvature in perceived paths toward the fixated object. This curvature, however, was slight even with rotation rates as great as 2.6 deg/sec. Best-fit paths to circular arcs had radii of 1.8 km or greater. In a third experiment, pedestrians walked with matched gaze to the side. Measured curvature in the direction of gaze corresponded to a circular radius of about 1.3 km. Thus, at minimum, vision scientists need not worry about perceived path curvature in this situation; real path curvatures are about the same. However, at present, we can make no claim that the same mechanisms necessarily govern the two results.