Browsing by Author "Nunez, David"

Now showing 1 - 6 of 6
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    Applying the contact hypothesis to a study of intergroup relations in a postgraduate class at a South African university
    (2008) Bonhomme, L; Louw-Potgieter, Joha; Nunez, David
    Includes abstract. Includes bibliographical references (leaves 53-61).
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    A capacity limited, cognitive constructionist model of virtual presence
    (2007) Nunez, David
    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 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.
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    A connectionist explanation of presence in virtual environments
    (2003) Nunez, David; Blake, Edwin H
    Presence has various definitions, but can be understood as the sensation that a virtual environment is a real place, that the user is actually in the virtual environment rather than at the display terminal, or that the medium used to display the environment has disappeared leaving only the environment itself. We present an attempt to unite various presence approaches by reducing each to what we believe is a common basis – the psychology of behaviour selection and control – and re-conceptualizing presence in these terms by defining cognitive presence – the mental state where the VE rather than the real environment is acting as the basis for behaviour selection. The bulk of this work represents the construction of a three-layer connectionist model to explain and predict this concept of cognitive presence. This model takes input from two major sources: the perceptual modalities of the user (bottom-up processes), and the mental state of the user (top-down processes). These two basic sources of input competitively spread activation to a central layer which competitively determines which behaviour script will be applied to regulate behaviour. We demonstrate the ability of the model to cope with current notions of presence by using it to successfully predict two published findings: one (Hendrix & Barfield, 1995) showing that presence increases with an increase in the geometric field of view of the graphical display, and another (Salln?s, 1999), which demonstrates the positive relationship between presence and the stimulation of more than one sensory modality. Apart from this theoretical analysis, we also perform two experiments to test the central tenets of our model. The first experiment aimed to show that presence is affected by both perceptual inputs (bottom-up processes), conceptual inputs (top-down processes), and the interaction of these. We collected 103 observations from a 2x2 factorial design with stimulus quality (2 levels) and conceptual priming (2 levels) as independent variables, and as dependent variable we used three measures of presence (Slater, Usoh & Steed's scale (1995), Witmer & Singer's (1998) Presence Questionnaire and our own cognitive presence measure) for the dependent variable. We found a significant main effect for stimulus quality and a significant interaction, which created a striking effect: priming the subject with material related in theme to the content of the VE increased the mean presence score for those viewing the high quality display, but decreased the mean of those viewing the low quality display. For those not primed with material related to the VE, no mean presence difference was discernible between those using high and low quality displays. The results from this study suggest that both top-down and bottom-up activation should be taken into account when explaining the causality of presence. Our second study aimed to show that presence comes about as a result not of raw sensory information, but rather due to partly-processed perceptual information. To do this we created a simple three group comparative design, with 78 observations. Each one of the three groups viewed the same VE under three display conditions: high-quality graphical, low-quality graphical, and text-only. Using the model, we predicted that the text and low-quality graphics displays would produce the same presence levels, while the high-quality display would outperform them both. The results were mixed, with the Slater, Usoh & Steed scale showing the predicted pattern, but the Presence Questionnaire showing each condition producing a significantly different presence score (in the increasing order: text, low-quality graphics, high-quality graphics). We conclude from our studies that the model shows the correct basic structure, but that it requires some refinement with regards to its dealings with non-immersive displays. We examined the performance our presence measure, which was found to not perform satisfactorily. We conclude by proposing some points relevant to the methodology of presence research, and by suggesting some avenues for future expansion of our model.
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    Epistemic action and language : a cross-linguistic study
    (2008) King, Warren; Malcolm-Smith, Susan; Nunez, David
    Epistemic actions are physical actions which increase the speed, accuracy, and/or robustness of internal computation by allowing cognitive work to be off-loaded to the environment, thus simplifying internal computation. Previous studies on epistemic action are limited in that they demonstrate that epistemic actions may only improve task performance within tasks which are inherently spatial in nature. In this regard, a cross-linguistic replication of an experiment by Maglio et al. (1999) which required participants to produce as many words as possible within five minutes from a string of seven random letters was performed in order to investigate epistemic actions in a verbal task domain.
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    The persistence of attitudes following violent and non-violent video game play using conventional versus embodied controls
    (2010) Koloko, Muya; Malcolm-Smith, Susan; Nunez, David
    The effects of violent video game play on hostility and support for violence are unclear. Previous studies have shown increases, decreases or no effect at all. At the time of the first study (2007) it was unclear if attitudes and opinions within a game persisted after game play. Also unknown was how long any such effects would last, and if they would be affected by using embodied versus conventional controls in the game. 3 experiments were run on university students to investigate these points. It was hypothesised that violent play would increase hostility and support for violence, and that these effects would be short term and increased by the use of embodied controls. Study 1 investigated whether attitudes and opinions persisted immediately after game play by having participants play either a nonviolent or violent version of a computer game and then measuring their support for violence. The hypothesis was tentatively supported in males, who showed higher support for violence in the violent version group. Study 2 aimed to pilot a behavioural measure of hostility to be used in Study 3 by having participants watch either a non-violent (non-violent group) or violent clip (violent group) before completing the behavioural measure and the violence questionnaire used in Study 1. The hypothesis was not well supported in that the attitudinal scores were almost equal. However, the expected trend occurred in the behavioural measure. Study 3 investigated how long the effects on hostility and support for violence would last, and if they were affected by the use of embodied versus conventional controls. Participants played a non-violent and violent game on either the Playstation 2 or Nintendo Wii. Violent play did not increase support for violence and hostile decision making, it marginally decreased them. Also, the participants' responses did not completely return to baseline after 24 hours. Lastly, embodied controls were not found to have a greater effect on support for violence. Therefore, the 3 predictions of this study were not supported. Overall, the central tenet that video games can affect players' attitudes, opinions, cognition and behaviour post play and that this will be especially true in games wherein an in-game character mimics the physical actions of the player is not well supported.
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    Preserving spatial and temporal dimensions in observational data of segregation
    (2005) Tredoux, Colin; Dixon, John; Underwood, Stephen; Nunez, David; Finchilescu, Gillian
    Recent approaches to the study of intergroup contact have emphasised the need for naturalistic studies and the importance of paying attention to the spatiality of contact. In this article it is argued that it is important to preserve both spatiality and temporality when studying inter-group contact in naturalistic settings. This is not easy to do with existing observational methods, and a novel approach is proposed. Photographs are taken of a public space with a fixed periodicity and vantage point, and with knowledge of the physical layout of the space, three-dimensional, time-marked data points are recorded for each inhabitant. A public space on a university campus was used as a test bed, and data are reported that show it to be very useful, giving fresh insights into the nature of segregation and integration in informal leisure spaces, as well as providing evidence of the importance of taking temporality into account when studying naturalistic instances of inter-group contact.