The Role of Fixation Position in Detecting Scene Changes Across Saccades

Target objects presented within color images of naturalistic scenes were deleted or rotated during a saccade to or from the target object or to a control region of the scene. Despite instructions to memorize the details of the scenes and to monitor for object changes, viewers frequently failed to notice the changes. However, the failure to detect change was mediated by three other important factors: First, accuracy generally increased as the distance between the changing region and the fixation immediately before or after the change decreased. Second, changes were sometimes initially missed, but subsequently noticed when the changed region was later refixated. Third, when an object disappeared from a scene, detection of that disappearance was greatly improved when the deletion occurred during the saccade toward that object. These results suggest that fixation position and saccade direction play an important role in determining whether changes will be detected. It appears that more information can be retained across views than has been suggested by previous studies.     

Gender Differences in Population Versus Media Body Sizes: A Comparison over Four Decades

Mean body mass indices (BMIs, kg/m²)of North Americans aged 18 to 24 collected from 11national health surveys were compared to: Playboycenterfold models, Miss America Pageant winners,andPlaygirl models. The survey samples were representative of themix of different ethnic and racial groups in Canada andthe USA. No racial or ethnic information was availablefor either the Playboy women or the Miss America Pageant winners. Ninety percent of the Playgirlmen were white; 10%, black; 1.5%, Hispanic black; and.8%, American Samoan. From the 1950s to the present,while the body sizes of Miss America Pageant winners decreased significantly and the body sizes ofPlayboy centerfold models remained below normal bodyweight, the body sizes of Playgirl models and youngadult North American women and men increasedsignificantly. The increase in body size of Playgirl modelsappears to be due to an increase in muscularity, whereasthe increase in body size of young North American menand women is more likely due to an increase in body fat. Thus, in the 1990s, the body size andshape of the average young adult North American becameincreasingly different from the ideal being promoted bythe media. Furthermore the difference in male and female body sizes depicted by the media inthe 1990s was huge, whereas the difference between thebody sizes of 18- to 24-year-old North American womenand men was actually quite small. These discrepancies are discussed in relation to the differentsociocultural expectations for the two genders and theincreasing prevalence of body dissatisfaction reportedby both women and men.     

Simple reaction time and predictive tracking in Parkinson's disease: do they converge on a single, fixed impairment of preparation?

Patients with Parkinson's disease exhibit a number. of abnormalities that seem more marked in circumstances in which stimulus and response are predictable in advance. In this article, we consider the prolonged movement onset latencies exhibited by Parkinsonian subjects in the tracking of predictable targets and in the simple reaction time (RT) task. It has been suggested that the performance impairments on both these tasks stem from a common planning deficit. We argue that the Parkinsonian tendency to refrain from predictive tracking cannot be ascribed to an inability to anticipate due to a planning deficit. The data are better accommodated by our alternative thesis that when Parkinsonians' response initiation lags behind that of normal subjects, this is a result of a strategic adaptation to an impairment of the accuracy of movements guided by an internal representation of the target. Our conclusion, that the primary impairment of predictive tracking is one of inaccurate movement execution rather than delayed response initiation, precludes postulation of the same deficit as a source of the selective prolongation of simple RT sometimes found in Parkinson's disease. Moreover, an analysis of the processing demands of the two tasks shows that the predictability that characterizes each of them is quite different in nature. Hence, the impairments in predictive tracking and simple RT tasks are unlikely to stem from a single mechanism that is defective in Parkinson's disease.     

Stimulus discrimination following covert attentional orienting to an exogenous cue.

Five experiments explored exogenous covert visual-attentional orienting following a brief peripheral cue. On each trial an attentional cue was followed by a stimulus in an empty field at 1 of 8 locations on an imaginary circle centered on the fixation point. The cued area size and the cue-target spatial relation were manipulated. Accuracy and response time were affected by the exogenous cue validity. Attention was allocated to a specific location in a visual quadrant: A target at an uncued location in a quadrant was not facilitated as much as target at the cued location, and a target in a different quadrant was inhibited in relation to a neutral condition. Cuing 2 locations in a quadrant was not as facilitative for targets at the cued locations or as inhibitive for targets at other locations compared with cuing a single location in a quadrant. Results are discussed in the context of several extent models of covert visual-spatial attention.     

The Egyptian Coptic Christians: the conflict between identity and equality

This essay will endeavor to explore the identity and situation of the Coptic Christian community in Egypt, which constitutes the largest Christian community in the Middle East. I will start with a brief background of the community's history and introduction to modern Coptic life in the form of its liturgy, art, and music in order that those of us in the West might better grasp the richness and heritage in which Coptic Christianity grounds its worldview. The essay will proceed to explore the present situation in which Coptic Christians find themselves as a minority within the borders of a nation that officially designates itself Islamic. In the late 1960s and 1970s the Sunday School Movement brought about an age of reform in the Coptic Church that continues to this day. A large part of the reform has been to identify their origins as apostolic, monastic and marked by martyrdom and persecution. Under Pope Shenouda III, the Coptic Church has undergone some organizational changes that are clearly perceived as a threat to the Egyptian government under President Mubarak, despite groundbreaking progress towards ecumenism and cooperation between Muslims and Christians at large. This essay will explore the tension between Muslims and Christians in Egypt and the ways in which the minority status of the Copts is simultaneously defining and sustaining their tradition and self-image.     

Opinion leadership in a computer‐mediated environment

This paper investigates the characteristics of opinion leaders within the computer‐mediated environment, analyses the differences between online opinion leaders and online non‐leaders and examines the implications of opinion leadership theory for e‐commerce. This study finds that opinion leaders in computer‐mediated environments possess significantly higher levels of enduring involvement, innovativeness, exploratory behaviour and self‐perceived knowledge than non‐leaders. Online opinion leaders also possess greater computer skills, have used the internet for a longer period of time and use the internet more frequently for longer sessions than non‐leaders. Copyright © 2005 John Wiley & Sons, Ltd.     

Age differences in what is viewed and remembered in complex conjunction search

Older and younger adults searched arrays of 12 unique real-world photographs for a specified object (e.g., a yellow drill) among distractors (e.g., yellow telephone, red drill, and green door). Eye-tracking data from 24 of 48 participants in each age group showed generally similar search patterns for the younger and older adults but there were some interesting differences. Older adults processed all the items in the arrays more slowly than the younger adults (e.g., they had longer fixation durations, gaze durations, and total times), but this difference was exaggerated for target items. We also found that older and younger adults differed in the sequence in which objects were searched, with younger adults fixating the target objects earlier in the trial than older adults. Despite the relatively longer fixation times on the targets (in comparison to the distractors) for older adults, a surprise visual recognition test revealed a sizeable age deficit for target memory but, importantly, no age differences for distractor memory.     

Motivated contextualism

The concept of knowledge is used to certify epistemic agents as good sources (on a certain point or subject matter) for an understood audience. Attributions of knowledge and denials of knowledge are used in a kind of epistemic gate keeping for (epistemic or practical) communities with which the attributor and interlocutors are associated. When combined with reflection on kinds of practical and epistemic communities, and their situated epistemic needs for gate keeping, this simple observation regarding the point and purpose of the concept of knowledge has rich implications. First, it gives one general reason to prefer contextualism over various forms of sensitive invariantism. Second, when gate keeping for a select community of experts or authorities, with an associated body of results on which folk generally might then draw (when gate keeping for a general source community) the contextual demands approximate those with which insensitive invariantists would be comfortable.