UCT CS Research Document Archive

A Capacity Limited, Cognitive Constructionist Model of Virtual Presence

Nunez, David (2007) A Capacity Limited, Cognitive Constructionist Model of Virtual Presence. PhD, Department of Computer Science, University of Cape Town.

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Abstract

The Capacity Limited, Cognitive Constructionist (CLCC) model of presence is proposed as an information processing model of presence, which is demonstrated to have more theoretical power than extant models. The CLCC model defines information processing paths between attention, working memory, declarative memory and procedural memory, which operate to create and maintain a semantic context or bias. Bottom-up information entering the sensory cortices is filtered by attention into working memory where it forms temporary structures encoding the subject’s experience of the VE. These structures also receive top-down information, which arises in declarative memory. This interaction of top-down and bottom-up data gives the entire model a semantic bias which attempts to keep the subject’s construction of the environment semantically coherent. This allows for inferences and decision making, which translates into high presence. A semantically incoherent construction, or one which does not have enough working memory capacity allocated to it will result in poorer inferences about the environment, and reduced presence. If, as the CLCC model contends, presence involves information processing rather than simple perception, then one would expect to see working memory interference effects and semantic content effects in presence. Six studies were conducted to test these conjectures and validate the CLCC model. Studies 1 – 3 examined the role of working memory and attention on presence (the bottom half of the model), while Studies 4 – 6 examined semantic content and processing effects on presence (the top half of the model).

Study 1 manipulated working memory (WM) load during VE exploration. The CLCC prediction was that WM load would interfere with presence. Data from 177 subjects showed smaller effects than predicted: No WM effects on spatial presence, lower naturalness under spatial WM load, and lower engagement under verbal WM load. This suggests that spatial presence makes no use of WM, and that engagement and naturalness make limited use of it. While engagement seems to make use of semantic processing as predicted, naturalness seems to use spatial processing. Study 2 examined WM use by media decoders by repeating Study 1 with a text-based VE. Data from 114 subjects shows no WM effects exist on any of the four ITC-SOPI factors. This supports Study 1’s finding that spatial presence does not use WM, but 3 contradicts results engagement and naturalness. Study 3 examined the relative contribution of attention and WM. 46 subjects viewed VE walkthroughs in three conditions: Viewing one walkthrough only (baseline), viewing two walkthroughs simultaneously (WM load condition), or viewing one walkthrough and a jumbled video simultaneously (attention load condition). The CLCC model predicted the WM load condition would interfere with presence the most, followed by the attention load condition, followed by the baseline. No difference was found across conditions, although naturalness and engagement predicted task performance, indicating that spatial presence is distinct from these factors, in agreement with the findings of Study 1 and 2.

Study 4 was a survey of semantic and processing effects on presence. Data from 101 computer gamers indicate that it is how often gamers play presence games (and not how many years they have been playing) that predicts how important they consider presence to their gaming experience. This suggests a moderate term activation effect rather than a long term learning effect. Furthermore, gamers with a high thematic inertia rate presence as important to gaming, indicating a processing effect. Finally, gamers who are capable of integrating non-diegetic music into their experiences rate presence as more important, which supports the CLCC notion that information processing of both semantic and perceptual information is important to presence. Study 5 followed up Study 4 by focusing on one specific content area. 461 flight simulation gamers completed the survey. Findings largely agree with those of Study 4, and strongly support the CLCC model prediction that highly specific expectations of content will reduce presence, while generalized expectations will increase it. Thematic inertia and priming were are also positively associated with presence, as predicted by the CLCC model. Study 6 manipulated non-diegetic information (background music) and semantic priming to test semantic processing in presence. The CLCC model predicted that all VE related information (semantic or perceptual) contributes to presence, particularly engagement and naturalness. 181 subjects were primed with materials semantically relevant or irrelevant to VE content, and then experienced the VE with no background music (baseline), music which semantically fit the VE, or VE music which was not a semantic fit. Priming did not influence presence as predicted, but non-diegetic music which fit the VE increased naturalness as predicted. The no-fit music produced the same presence scores as the baseline 4 condition, indicating that it was filtered out by attention, as predicted by the CLCC model.

Overall, the CLCC model and data show that content effects occur in presence, and how these are mediated by declarative memory. It also shows that presence is a complex multi-level processing phenomenon. Spatial presence is at a cognitively low level, relying on perceptual (bottom-up) information, while engagement and naturalness are heavily dependent on conceptual (top-down) information, operating as a set of expectation-content comparisons which, when met by the content, lead to enhanced presence. These high and low cognitive forms of presence are largely independent, but do share some semantic effects, likely due to a reliance on common underlying cognitive processes such as priming and thematic inertia. The top half of the CLCC model (which encodes semantic meaning and explains content effects) is better supported that the bottom half (which predicted interference and attention effects). This finding is highly unexpected, as the literature on almost all extant models predicts an important role for attention in presence. From the data however, one must conclude that spatial presence makes no use of working memory, while cognitive higher forms of presence make use of limited amounts of working memory.

EPrint Type:Electronic Thesis or Dissertation
Keywords:Virtual Presence Reality Cognitive Science
Subjects:J Computer Applications: J.4 SOCIAL AND BEHAVIORAL SCIENCES
ID Code:454
Deposited By:Nunez, David
Deposited On:18 April 2008