Statistical analysis of subjective preferences for video enhancement

ABSTRACT Traditional Thurstone scaling (1927) constructs a perceptual scale from pairwise comparisons without providing statistical inferences. We show that subjective preferences for moving video using pairwise comparisons can be analyzed to construct a perceptual scale and provide the statistical significance of preference differences. Two statistical methods (binary logistic regression and linear regression) are described. Data sets from two studies are used to demonstrate the perceptual scale construction from the traditional Thurstone method and from the described statistical methods. Both the studies showed videos on two side-by-side TVs. Four enhancement levels (Off, Low, Medium and High) were applied to the videos using a commercial device. Subjects made pairwise comparisons to indicate their preference of one video over another. The perceptual scales constructed from the three methods were comparable, except when there were cells missing from the preference matrix. Binary logistic regression easily permitted modeling of additional factors, such as side bias. Video quality can be systematically assessed using pairwise comparisons and statistical methods that permits construction of a perceptual scale and provide statistical significance for the compared levels

Emotions and the Environment: The Variable Effect of Environmental Complexity on Pleasure and Interest

This dissertation establishes a more comprehensive examination of the often discussed environmental complexity effect on emotional response by addressing four specific considerations. First, positive emotional response was considered as composed of many distinct emotions, thus interest was gauged alongside the commonly explored emotion of pleasure. Second, a systematic approach to quantifying environmental complexity was developed where the environment possessed complexity through either the diversity or numerosity of its geometric and featural elements. Third, a cognitive component was introduced to the formation of emotional response, where the bottom-up effect of environmental properties is mediated by subjective, perceived complexity. Fourth, by arguing that emotions are functional, the degree of agreement between subjective emotional responses and navigation behaviour was examined. In Experiments 1.1 and 1.2, complexity was generated by manipulating the numerosity of featural and geometric elements of virtual environments. In Experiments 2.1 and 2.2 complexity was generated by manipulating diversity of featural elements and quantified using information entropy, while Experiment 3.0 employed a similar approach but with real-world environments. Participants rated complexity, interest and pleasure in every experiment, while Experiments 2.1 and 2.2 introduced a virtual reality navigation task and Experiment 3.0 measured behavioural intention using approach-avoidance ratings. Results demonstrated that environmental complexity had a dissociable effect on pleasure and interest; where the effect was positive on interest it was negative on pleasure. Regardless of whether it affected pleasure or interest, the direct effect of environmental complexity on emotion was either partially or fully mediated by perceived complexity. Environmental complexity itself was successfully manipulated using diversity and numerosity of both featural and geometric elements of the environment. Finally, there was a consistent relationship between feelings of displeasure and avoidance behaviour. These novel perspectives suggest that environmental complexity has a variable effect on emotional response, where the exact relationship is dependent both on the emotion probed and factors beyond complexity such as the processing dynamics of environmental features. By arguing for a more nuanced and exhaustive examination of emotional response, this dissertation repositions the research to better assist in the design of more effective, people-centred, built environments

Designing a Value Centred Inspection Method for Children

There are currently several evaluation methods suited to children within the Child-Computer Interaction (CCI) community. However, these methods are user based leaving a gap in inspection method suited to children, that is, where children will act as the inspection method evaluators. This research focused on how to design an effective and easy to use inspection method where children will perform the evaluation based on their values. To ensure that the above is met, a user centred approach and a mixed methodology was explored and finally resulted in the creation of the Inspection Method for Children (IMCH) with an accompanying guideline. This six stages method could be used by CCI researchers as a guide to develop similar methods for children, by industries to perform inspection method evaluation with children on technologies designed for children and could be used by designers to gather design criteria for children’s technology. The process undertaken within this research to develop the new method is also novel and could be adapted by new and old researchers when adapting method to suit children. Future work will focus on carrying out evaluation with wider age range of children in the method to ensure suitability of the method for more children. Comparative studies of the method with other usability method to determine the effectiveness of the method and as a refinement process to produce a validated and refined IMCH method