A number of emerging technologies including virtual reality, simulation rides, video conferencing, home theater, and high definition television are designed to provide media users with an illusion that a mediated experience is not mediated, a perception defined here as presence. Traditional media such as the telephone, radio, television, film, and many others offer a lesser degree of presence as well. This article examines the key concept of presence. It begins by noting practical and theoretical reasons for studying this concept. Six conceptualizations of presence found in a diverse set of literatures are identified and a detailed explication of the concept that incorporates these conceptualizations is presented. Existing research and speculation about the factors that encourage or discourage a sense of presence in media users as well as the physiological and psychological effects of presence are then outlined. Finally, suggestions concerning future systematic research about presence are presented.

At the Heart of It All: The Concept of Presence

Let's read! We will often find out this sentence everywhere. When still being a kid, mom used to order us to always read, so did the teacher. Some books are fully read in a week and we need the obligation to support reading. What about now? Do you still love reading? Is reading only for you who have obligation? Absolutely not! We here offer you a new book enPDFd the perception of the visual world to read.

The Perception of the Visual World. By James J. Gibson. U.S.A.: Houghton Mifflin Company, 1950 (George Allen & Unwin, Ltd., London). Price 35s.

Publisher Summary
This chapter discusses three questions: Why are there so many sources of information about layout? How is it that one perceives layout with near-metric accuracy when none of these sources yields metric information about it? Can one not do better, theoretically, in understanding the perception of layout than simply make a list? The answer to the first question begins with Todd's answer. Perceiving layout is extremely important to human beings, so important that it must be redundantly specified so that the redundancy can guard against the failure of any given source or the failure of any of the assumptions on which a given source is based. However, information redundancy is only part of the answer. Different sources of information about layout metrically reinforce and contrast with each other, providing a powerful network of constraints. The answer to the second proceeds from this idea. Through the analysis of depth-threshold functions for nine different sources of information about layout, one can begin to understand how those sources of information sharing the same-shaped functions across distances can help ramify judgments of layout by serving to correct measurement errors in each. Third, on the basis of the analyses and the pattern of functions, it suggests that list making has misled about space and layout. Psychologists and other vision scientists have generally considered layout, space, and distance as a uniform commodity in which observers carry out their day-to-day activities.

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Perceiving Layout and Knowing Distances: The Integration, Relative Potency, and Contextual Use of Different Information about Depth*

A necessary condition for visually guided action is that an organism perceive what actions are afforded by a given environmental situation. Warren (1984) proposed that an affordance such as the climbability of a stairway is determined by the fit between properties of the environment and the organism and can be characterized by optimal points, where action is most comfortable or efficient, and critical points, where a phase transition to a new action occurs. Perceiving an affordance, then, implies perceiving the relation between the environment and the observer's own action system. The present study is an extension of this analysis to the visual guidance of walking through apertures. We videotaped large and small subjects walking through apertures of different widths to determine empirically the critical aperture-to-shoulder-width ratio (A/S) marking the transition from frontal walking to body rotation. These results were compared with perceptual judgments of "passability" under static and moving viewing conditions. Finally, we tested the hypothesis that such judgments are based on intrinsic or body-scaled information specifying aperture width as a ratio of the observer's eyeheight. We conclude (a) that the critical point in free walking occurs at A/S = 1.30, (b) that static monocular information is sufficient for judging passability, and (c) that the perception of passability under such conditions is based on body-scaled eyeheight information.

http://www.cog.brown.edu/Research/ven_lab/Publications/WarrenWhang_Aperture_JEP87.pdf

Visual guidance of walking through apertures: body-scaled information for affordances.

In this article, past consumer research dealing with advertising images is analyzed and critiqued for its underlying assumption: that pictures are reflections of reality. The case against this assumption is presented, and an alternative view, in which visuals are a convention-based symbolic system, is formulated. In this alternative view, pictures must be cognitively processed, rather than absorbed peripherally or automatically. The author argues that current conceptualizations of advertising images are incommensurate with what ads are really like, and that many images currently dismissed as affect laden or information devoid are, in fact, complex figurative arguments. A new theoretical framework for the study of images is advanced in which advertising images are a sophisticated form of visual rhetoric. The process of consumer response implied by the new framework differs radically from past concepts in many ways, but also suggests new ways to approach questions currently open in the literature on the nature and processing of imagery. A pluralistic program for studying advertising pictures as persuasion is outlined.

Images in Advertising: The Need for a Theory of Visual Rhetoric

The Perception of Pictures

J. J. Gibson's new theory of picture perception is described, and a program of research within his framework is outlined. An analysis of pictorial information is proposed in which a systematic investigation of the structural components of pictures and their varying effects on perception is seen as preliminary to the postulation of hypothetical pickup mechanisms. The basic components of pictures are described, and literature is reviewed in the problem areas of distorted and impoverished information, observation from the wrong station point, coexisting flatness and depth information, and the ambiguity of .the source of a single projection. The feasibility of the Gibsonian enterprise is demonstrated, and further avenues for research into a structural analysis of pictorial information are pointed out. A picture is a delimited surface with markings on it that represent something. This article is concerned with pictures in the Western post-Renaissance mode; namely, that attempt to represent, by means of structural equivalence of some order, the layout of surfaces in the world. Alternative modes of representation, perhaps requiring alternative analyses, are beyond the scope of this article. By what means can a picture be said to represent, to bring clearly before the mind, the segment of the world pictured? The aim of this article is to demonstrate the feasibility of extending J. J. Gibson's theory of perception via motion-generated information to an adequate theory of frozen pictorial information and to explicate the problems that must be dealt with in any comprehensive theory of the perception of pictures. The problems to be dealt with herein are the use by artists of modified linear perspective, caricature, impoverishment of information in outline drawings and black-and-white photographs, the coexistence of flatness and depth information, observation from the wrong station point, and the ambiguity of a single projection (i.e., the same projected form can arise from an infinite variety of shapes).

http://psycnet.apa.org/journals/bul/81/8/471.pdf

Picture perception: Toward a theoretical model.

Varieties of Realism argues that it is not possible to represent the layout of objects and surfaces in space outside the dictates of formal visual geometry, the geometry of natural perspective. The book examines most of the world's coherent representational art styles, both in terms of the geometry of their creation and in terms of their perceptual effects on the viewer. A lucid exposition of modern geometrical principles and relations, accessible to the nonmathematical reader, is followed by an analysis of all known styles as variants of natural perspective, as true varieties of realism. Delineating the physical and mechanical constraints that determine the act of visual representation in painting and drawing, the author traces the intimate relations among seemingly distant styles and considers the kind of perceptual information about the world each can carry. Margaret Hagen is a perceptual psychologist with an ecological point of view. Her rigorous but readable presentation of visual theory and research offers provocative new insights into the connections among vision, geometry, and art.

Varieties of Realism: Geometries of Representational Art

Theoretical analyses of pictorial perception have concentrated on the consequences of conflicting flatness and depth information in pictures, but have failed to consider the perceptual effects of the truncation of the visual field attendant on any pictorial display. The importance of this variable both for methods of testing pictorial information and for theory building was demonstrated. Under four different viewing conditions, adults were asked to scale the size and distance of five isoceles triangles at five different distances. The four conditions were unobstructed static monocular view, peephole view, view through a rectangular frame, and view of all the stimuli photographed in a slide. The slopes of the peephole, truncation, and slide conditions’ scaling functions were all significantly smaller than the slope of the untruncated Monocular condition, and the Y-intercepts were all greater. A decrease in over-constancy in the size functions indicated a similar effect for all three truncated conditions. Results are interpreted as supporting the hypothesis that truncation of the visual field, both in pictures and in peephole views of the real world, causes a frontal shift in the localization of the visible field, with a resultant compression of perceived size and distance.

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On a neglected variable in theories of pictorial perception: truncation of the visual field.

A scathing expose of the fraud inherent in the use of "expert" psychological testimony in the courtroom. From the high-profile murder trials of the Menendez brothers and Jeffrey Dahmer to personal injury, product liability and child custody cases, lawyers across the country have increasingly turned to "expert" testimony from psychologists, psychiatrists and social workers to influence the decisions of judges and juries. Psychologist Margaret Hagen, a professor and medical industry insider, details the very real danger of this booming business. In every state, a child can be taken away from a parent on the strength of five minutes of "neutral" testimony from a social worker. A criminal suspect's freedom or incarceration can depend on a superficial psychological examination performed by an incompetent, overworked, or, at worst, paid-off psychologist. Parole hearings hinge on the testimony of similarly incomplete or fraudulent evaluations, allowing "rehabilitated" violent criminals back onto the street to commit more heinous crimes, with no accountability for the reviewing "expert." Unmasking some legal psycho-expertise as a total fraud, Dr. Hagen instructs readers to protect themselves and their families from being victimized by psychological testimony in the courtroom. In today's frenzied legal climate, her insight and wisdom make for provocative, compelling and invaluable reading."This sizzling expose by a courageous psychological scientist shines a brilliant light on the incalculable harm done to millions of Americans by the purveyors of psychological pseudoscience who have invaded our courtrooms."--Elizabeth Loftus, Ph.D., author of "The Myth of Repressed Memory" and "EyewitnessTestimony"

Margaret A. Hagen

Papers

The Perception of Pictures

Picture perception: Toward a theoretical model.

Varieties of Realism: Geometries of Representational Art

On a neglected variable in theories of pictorial perception: truncation of the visual field.

Whores of the Court: The Fraud of Psychiatric Testimony and the Rape of American Justice