Perceptual assignment of opacity to translucent surfaces: the role of image blur

In constructing the percept of transparency, the visual system must decompose the light intensity at each image location into two components one for the partially transmissivc surface, the other for the underlying surface seen through it. Theories of perceptual transparency have typically assumed that this decomposition is defined quantitatively in terms of the inverse of some physical model (typically, Metelli's 'episcotister model'). In previous work, we demonstrated that the visual system uses Michelson contrast as a critical image variable in assigning transmittance to transparent surfaces not luminance differences as predicted by Metelli's model [F Metelli, 1974 Scientific American 230(4) 90 98]. In this paper, we study the contribution of another variable in determining perceived transmittance, namely, the image blur introduced by the light-scattering properties of translucent surfaces and materials. Experiment 1 demonstrates that increasing the degree of blur in the region of transparency leads to a lowering in perceived transmittance, even if Michelson contrast remains constant in this region. Experiment 2 tests how this addition of blur affects apparent contrast in the absence of perceived transparency. The results demonstrate that, although introducing blur leads to a lowering in apparent contrast, the magnitude of this decrease is relatively small, and not sufficient to explain the decrease in perceived transmittance observed in experiment 1. The visual system thus takes the presence of blur in the region of transparency as an additional image cue in assigning transmittance to partially transmissive surfaces.     

"Clockness" in the detection of dementia: a semantic-conceptual effect

We studied aspects of clock cognition that might underlie the sensitivity of the CDT in screening for dementia of the Alzheimer type (DAT). Two groups, 15 patients with mild-moderate DAT and 15 controls, were assessed with the CDT and specially designed tests of clock-related cognition. Patients were impaired on the CDT, but they did not differ from controls in copying a clock face or selecting the correct representation of a given time. Patients were worse than controls at distinguishing between clock and nonclock objects, detecting anomalies in clocks, and in setting time irrespective of response format. These findings suggest that semantic-conceptual aspects of clock-related cognition are important in discriminating between patients with DAT and controls.     

Propagation of depth information from local regions in 3-D scenes

The effects of regions with local linear perspective on judgments of the depth separation between two objects in a scene were investigated for scenes consisting of a ground plane, a quadrilateral region, and two poles separated in depth. The poles were either inside or outside the region. Two types of displays were used: motion-parallax dot displays, and a still photograph of a real scene on which computer-generated regions and objects were superimposed. Judged depth separations were greater for regions with greater linear perspective, both for objects inside and outside the region. In most cases, the effect of the region's shape was reduced for objects outside the region. Some systematic differences were found between the two types of displays. For example, adding a region with any shape increased judged depth in motion-parallax displays, but only high-perspective regions increased judged depth in real-scene displays. We conclude that depth information present in local regions affects perceived depth within the region, and that these effects propagate, to a lesser degree, outside the region.     

Participation by women in developmental, social, cognitive, and general psychology: A context for interpreting trends in behavior analysis

We examined participation by women in journals devoted to social, developmental, cognitive, and general psychology. Authorship and first authorship by women increased from 1978 to 1997 for most journals. Participation by women on the editorial staff did not keep pace with their increased authorship for social and developmental psychology. Based on these trends, women's participation decreased with increases in the selectivity of the position for social and developmental psychology (a glass ceiling). The development of a glass ceiling suggests that the contributions of men and women are not always treated equally (gender inequity). Because a similar glass ceiling was reported for journals in behavior analysis (McSweeney, Donahoe, & Swindell, 2000; McSweeney & Swindell, 1998), the causes of this inequity appear to be relatively widespread. The failure to find a glass ceiling for general and cognitive psychology suggests that the inequity might be reduced by subtle pressure for diversity in editorial positions and by adopting actions that encourage women to pursue research positions.     

Recognition memory for single items and for associations is similarly impaired following damage to the hippocampal region

The formation of new associations between items is critical for establishing episodic memories. It has been suggested that the hippocampus is essential for creating such associations but is not involved, or is much less involved, in memory for single items. In Experiment 1, we tested controls and amnesic patients with bilateral lesions thought to be limited primarily to the hippocampal region in both single-item and associative recognition memory tasks. In the single-item task, a conventional recognition memory task was administered in which participants studied either houses or faces and were tested for their ability to recognize the individual items. In the associative task, participants studied paired pictures of houses and faces with instructions that encouraged associating the two stimuli, and were tested for their ability to recognize the specific pairings that were presented at study. Like the controls, the amnesic patients performed more poorly on the associative task. Relative to the controls, the amnesic patients were impaired to a similar extent on the single-item and associative tasks. In Experiment 2, the performance of the amnesic patients was improved by increasing the number of presentations of the study lists (eight presentations instead of one). On both the single-item and associative tests, the performance of the amnesic patients after eight presentations was now identical to the performance of the controls who had been given only one presentation of the study list. Thus, the associative condition was not disproportionally difficult for the amnesic patients. These results are consistent with the idea that the hippocampus is similarly involved in single-item and associative memory.     

The research subject as wage earner

Theoretical Medicine and Bioethics - The practice of paying research subjects for participating inclinical trials has yet to receive an adequate moral analysis.Dickert and Grady argue for a wage...     

Video games and aggressive thoughts, feelings, and behavior in the laboratory and in life

Two studies examined violent video game effects on aggression-related variables. Study 1 found that real-life violent video game play was positively related to aggressive behavior and delinquency. The relation was stronger for individuals who are characteristically aggressive and for men. Academic achievement was negatively related to overall amount of time spent playing video games. In Study 2, laboratory exposure to a graphically violent video game increased aggressive thoughts and behavior. In both studies, men had a more hostile view of the world than did women. The results from both studies are consistent with the General Affective Aggression Model, which predicts that exposure to violent video games will increase aggressive behavior in both the short term (e.g., laboratory aggression) and the long term (e.g., delinquency).     

The Relation of Perceived Neighborhood Danger to Childhood Aggression: A Test of Mediating Mechanisms

In the current study, two mediational mechanisms, parenting practices and children's beliefs about aggression, were hypothesized to account for the relationship between perceived neighborhood danger and childhood aggression. Using structural equation modeling, data were analyzed from an inner-city school-based sample of 732 predominantly African American 5th graders. Results suggested that perceived neighborhood danger was associated with strong positive beliefs about aggression, which in turn was associated with high levels of aggression. The hypothesized mediating role of parenting practices (restrictive discipline, parental monitoring, and parental involvement) on the relation between perceived neighborhood danger and child aggression was not supported. However, the current findings suggest that children's positive beliefs about aggression mediated the relationship between restrictive discipline and aggression. Directions for future research are discussed.     

Eye Movements and Lexical Access in Spoken-Language Comprehension: Evaluating a Linking Hypothesis between Fixations and Linguistic Processing

A growing number of researchers in the sentence processing community are using eye movements to address issues in spoken language comprehension. Experiments using this paradigm have shown that visually presented referential information, including properties of referents relevant to specific actions, influences even the earliest moments of syntactic processing. Methodological concerns about task-specific strategies and the linking hypothesis between eye movements and linguistic processing are identified and discussed. These concerns are addressed in a review of recent studies of spoken word recognition which introduce and evaluate a detailed linking hypothesis between eye movements and lexical access. The results provide evidence about the time course of lexical activation that resolves some important theoretical issues in spoken-word recognition. They also demonstrate that fixations are sensitive to properties of the normal language-processing system that cannot be attributed to task-specific strategies.     

Hypermnesia: Age-related differences between young and older adults

Hypermnesia is a net improvement in memory performance that occurs across tests in a multitest paradigm with only one study session. Our goal was to identify possible age-related differences in hypermnesic recall. We observed hypermnesia for young adults using verbal (Experiment 1) as well as pictorial (Experiment 2) material, but no hypermnesia for older adults in either experiment. We found no age-related difference in reminiscence (Experiments 1 and 2), though there was a substantial difference in intertest forgetting (Experiments 1 and 2). Older, relative to young, adults produced more forgetting, most of which occurred between Tests 1 and 2 (Experiments 1 and 2). Furthermore, older, relative to young, adults produced more intrusions. We failed to identify a relationship between intrusions and intertest forgetting. We suggest that the age-related difference in intertest forgetting may be due to less efficient reinstatement of cues at test by older adults. The present findings reveal that intertest forgetting plays a critical role in hypermnesic recall, particularly for older adults.