Real Presence

Phenomenology and the Cognitive Sciences, 2011

In his book Action in Perception, Alva Noë poses what he refers to as the “problem of perceptual presence” and develops his enactive view as solution to the problem. Noë describes the problem of perceptual presence as the problem of how to conceive of the presence of that which, “strictly speaking,” we do not perceive. I argue that the “problem of perceptual presence” is ambiguous between two problems that need to be addressed by invoking very different resources. On one hand, there is the problem of how to conceive of the presence of objects as wholes, front side and back, and their constant properties. On the other hand, there is the problem of how to account for the presence of unattended detail. I focus on the first problem, which Noë approaches by invoking Husserlian ideas. I argue that Noë’s enactive view encounters difficulties, which can be dealt with by complementing it with Edmund Husserl’s idea of fulfillment and generally restoring the view to its original Husserlian context. Contrary to Noë’s purport, this involves regarding the view not as a theory of perception and perceptual content but as part of a descriptive-clarificatory project of conceptual analysis. The Husserlian phenomenologist analyzes, e.g., the concept of shape or color by investigating the fulfillment conditions pertinent to shape or color. In general, my critique of Noë’s enactive view serves to caution philosophers against unprincipled uses of Husserlian ideas.

Annals of Biomedical Engineering, 2008

Accommodation has been suspected as a contributor to size illusions in virtual environments (VE) due to the lack of appropriate accommodative stimuli in a VE for the objects displayed. Previous experiments examining size-constancy in VE have shown that monocular cues to depth that accompany the object are a major contributor to correct size perception. When these accompanying cues are removed perceived size varied with the object's distance from the subject, i.e., visual angle. If accommodation were the dominant mechanism contributing to a visual angle response [due to its action to keep physical objects clear] in this condition, an open-loop accommodation viewing condition might restore size-constancy to this condition. Pinhole apertures were used to open-loop accommodation and examine if size-constancy might be restored when few accompanying monocular cues to depth were present. Visual angle performance when viewing a low cue environment was found with and without the use of the pinhole apertures. Thus, these results signify that accommodation does not play a dominate role in the loss of size-constancy in sparse visual environments often used in VE. These results suggest that size-constancy is driven by the inclusion of the remaining monocular cues to depth in VE as it is in the physical world.

Discussion of spatial-perceptual constancies has loomed large in recent philosophy, due in part to and . To evaluate lessons drawn from constancy achievements it is important to understand what perceptual constancy is and how and when it is gained. I start by clarifying the subtle picture of perceptual constancy at work in perception science. As an illustrative example, I work through the empirical study of perceived object or surface shape. I then address the question of whether non-view-defined, 'objective' spatial (shape, size, slant, etc.) properties are represented in perceptual experience (the view of many perception scientists), or whether 'objective' shape, size, slant etc. are only represented post-perceptually--in (say) perceptual judgments derived from shifting shape (size, slant, etc.) 'appearances' (the view of many philosophers). I close by considering how accurate spatial-perceptual experience is-addressing methodological challenges faced in assessing spatial experience accuracy.

2006

This paper describes an experiment that examines the influence of visual realism on reported presence. 33 participants experienced two different renderings of a virtual environment that depicts a pit in the centre of a room, in a head-tracked head-mounted display. The environment was rendered using parallel ray tracing at 15fps, but in one condition ray casting (RC) was used achieving a result equivalent to OpenGL based per-pixel local illumination, and in the second full recursive ray tracing (RT). The participants were randomly allocated to two groups -one that experienced RC first followed by RT, and the second group in the opposite order. Reported presence was obtained by questionnaires following each session. The results indicate that reported presence, in terms of the 'sense of being there' was significantly higher for the RT than for the RC condition.

Constructivist Foundations , 2021

Context • Perceptual presence is the experience wherein veridical objects are experienced as belonging to an observer-independent world. > Problem • Experimental investigations of perceptual presence are rare. It may be that the standard conceptualizations of perceptual presence are not suitable for experimental operationalization. > Method • Using the framework of constructivist grounded theory, three observational perspectives (engaged, nearecological, and receptive) are employed to discern method-invariant phenomenological properties of perceptual presence. Inductive coding is used as a main analytical instrument. > Results • Four phenomenological properties of perceptual presence are constructed: perceptually present objects (a) appear inexhaustible in the amount of modal detail they contain; (b) are experienced as a particular arrangement of lived space; (c) allow for some and preclude other bodily interactions; and (d) are marked by a specific feeling of coupling. > Implications • Descriptions of lived experience of perceptual presence, in particular the structure of lived space, may further allow for the design of experiments that more precisely target individual properties of this phenomenon. > Constructivist content • Perceptual presence is conceived of as one of the main properties of consciousness: it is the experience of objects as belonging to an observer-independent world. Phenomenological properties contributing to how this sense of veridicality is constructed are presented.

Constructivist Foundations , 2021

In our response, we demonstrate how theoretical constructs of philosophical phenomenology do not correspond to findings from lived experience. We provide additional subjective reports illustrating the active nature of perceptual presence, and how this phenomenon can be considered a socially reinforced mastery of veridicality. Finally, we outline future directions for computational modelling.

Presence Connect, 2003

Progress in understanding presence is inhibited by the fact that we are unable to agree what it is we are talking about. What one researcher means by presence is not the same as what another means, and from this stems confusion about how to evaluate models of presence, how to measure it, and how it relates to other psychological phenomena such as mental imagery, attention and emotional engagement. If presence is a phenomenon worthy of investigation, it has at least to be characterised in a way that differentiates it from other phenomena already under long-term investigation (such as those listed above). And this characterisation should lead to ways of measurement that can, in the best case, cleanly discriminate between changes in presence and changes in other phenomena. Over the two decades of increasingly active presence research, several definitions of what characterises presence have been put forward. We suggest that, of these, there is one that meets the needs of future progress in the field: electronically mediated presence is the perceptual illusion of being in an external environment. The key word here is perceptual, not least because of the implications it carries for measurement. We know how to measure the effectiveness of perceptual illusions objectively, and we can expect to be able to distinguish presence defined in this way from other psychological phenomena.

2004

Abstract This paper describes reports on the results of an experiment designed to study the impact of realism on the reported presence in an immersive virtual environment. An experiment was carried out with 40 participants who were asked to walk through a virtual street, which had virtual characters walking through it. Two factors were varied–texture quality (2 levels) and virtual character realism (2 levels). 10 participants were assigned to each cell, which was also balanced for gender.

Philosophy of Science, 2014

Some experiments in perceptual psychology measure perceivers’ phenomenal experiences of objects versus their cognitive assessments of object properties. Analyzing such experiments, this article responds to Pizlo’s claim that much work on shape constancy before 1985 confused problems of shape ambiguity with problems of shape constancy. Pizlo fails to grasp the logic of experimental designs directed toward phenomenal aspects of shape constancy. In the domain of size perception, Granrud’s studies of size constancy in children and adults distinguish phenomenal from cognitive factors.