
David Martin Ward PowersFlinders University · College of Science and Engineering
David Martin Ward Powers
B.Sc.(Hons), Ph.D. (UNSW)
About
367
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Introduction
I work in Computational Cognitive Psycholinguistics: systems with sensors, heads and bodies to learn language, learn about the world, learn to interact, learn to communicate - modeling on how children do! I am as much interested in how babies learn as how to get computers to learn, and I use what I learn about one to help with the other: bioplausible computer programs, psycholinguistic models, unsupervised learning, multimodal learning, self-organization neural nets, similarity and metaphor, ...
Additional affiliations
January 1994 - June 2017
December 2011 - present
February 1983 - July 1984
Publications
Publications (367)
The Expanding Hole Illusion is a compelling visual phenomenon in which a static, concentric pattern evokes a strong perception of continuous forward motion. Despite its simplicity, this illusion challenges our understanding of how the brain processes visual information, particularly motion derived from static cues. While the neural basis of this il...
Objective
Rehabilitation for adults with traumatic brain injury (TBI) incorporates client-centred goal-setting and motivational support to achieve goals. However, face-to-face rehabilitation is time-limited. New therapy approaches which leverage care are warranted. Conversational agents (CAs) offer a human–computer interface with which a person can...
Supporting behaviour change is important in health promotion and disease prevention. Motivational Interviewing (MI) is a core behaviour change counselling skill for health professionals to support people to make and maintain behaviour changes. MI is taught across many university courses and as continuing professional development. There is a need to...
High variability between individual subjects and recording sessions is a known fact about scalp recorded EEG signal. While some do, the majority of the EEG based machine learning studies do not attempt to assess performance of algorithms across recording sessions or across subjects, instead studies use the whole data-set available for training and...
From early childhood through to adulthood, ECAs are already being used for a range of education and training applications. In early childhood the focus so far has been on literacy, however social skills are also a promising emergent area.
Reviews by Rao et al. (2008) and Neely et al. (2016) identified a range of recommendations to improve the experimental methods used to evaluate social skills interventions. These include but are not limited to inclusion of control groups, sample sizes of over ten participants, use of blinded observer ratings, longitudinal data collection, and expli...
When developing educational content in any context, the educational process that takes place and the ressources used must be carefully considered. Existing research has shown that one-on-one tutoring produces greater understanding and a higher level of motivation in students than traditional classroom situations, with students also able to progress...
To investigate the potential of virtual human-based educational software for teaching social skills to children with autism, the Thinking Head Whiteboard was produced. The Thinking Head Whiteboard provides a mechanism to control multiple instances of the virtual human software ‘Head X’ (Luerssen and Lewis 2009), and is also used to display interact...
There are a multitude of reasons why virtual tutors, or pedagogical agents as they are often known, are appealing for use in an educational context. They not only provide an opportunity for one-on-one interaction, but importantly they allow the learner to work through material at their own pace rather than being subjected to the constraints of a cl...
Technology is continually evolving, and this presents us with new and exciting options for incorporating more realistic learning activities and providing an increasingly dynamic and personalised experience in future virtual teaching systems.
Many factors go into creating an ECA that is engaging, appropriate for the intended purpose and educationally beneficial. The persona of the ECA is a major consideration and covers not only the appearance and voice of the ECA but also their responses and mannerisms. Another factor is perceived availability versus interference of the ECA—should it b...
When designing a tutoring system for any population, the needs and characteristics of the specific audience need to be carefully considered. In this chapter we discuss some of the challenges individuals with specific needs may experience and suggest strategies to support these users and lead to positive educational outcomes.
Prior to developing the Social Tutor software discussed in the remainder of this book, an investigation into existing social skills interventions, both traditional and technology-based, was conducted. Technology-based interventions include hardware and software, with some incorporating virtual and augmented reality. Here, a brief overview of some o...
Prioritization and selection of requirements are an essential component of software development. The process, however, often leads to ignoring some requirements due to the budget limitations, without considering the impact of those requirements on the values of the selected requirements. That may lead to user dissatisfaction and financial losses in...
Software products have become an integral part of human lives, and therefore need to account for human values such as privacy, fairness, and equality. Ignoring human values in software development leads to biases and violations of human values: racial biases in recidivism assessment and facial recognition software are well-known examples of such is...
This book highlights current research into virtual tutoring software and presents a case study of the design and application of a social tutor for children with autism. Best practice guidelines for developing software-based educational interventions are discussed, with a major emphasis on facilitating the generalisation of skills to contexts outsid...
Over the last decade, a variety of new neurophysiological experiments have deepened our understanding about retinal cells functionality, leading to new insights as to how, when and where retinal processing takes place, and the nature of the retinal representation and encoding sent to the cortex for further processing. Based on these neurobiological...
Over the last decade, a variety of new neurophysiological experiments have led to new insights as to how, when and where retinal processing takes place, and the nature of the retinal representation encoding sent to the cortex for further processing. Based on these neurobiological discoveries, in our previous work, we provided computer simulation ev...
Both empirical and mathematical demonstrations of the importance of chance-corrected measures are discussed, and a new model of learning is proposed based on empirical psychological results on association learning. Two forms of this model are developed, the Informatron as a chance-corrected Perceptron, and AdaBook as a chance-corrected AdaBoost pro...
There has been considerable interest in boosting and bagging, including the combination of the adaptive techniques of AdaBoost with the random selection with replacement techniques of Bagging. At the same time there has been a revisiting of the way we evaluate, with chance-corrected measures like Kappa, Informedness, Correlation or ROC AUC being ad...
Commonly used evaluation measures including Recall, Precision, F-Measure and Rand Accuracy are biased and should not be used without clear understanding of the biases, and corresponding identification of chance or base case levels of the statistic. Using these measures a system that performs worse in the objective sense of Informedness, can appear...
Considering user preferences is a determining factor in optimizing the value of a software release. This is due to the fact that user preferences for software features specify the values of those features and consequently determine the value of the release. Certain features of a software however, may encourage or discourage users to prefer (select...
One of the critical activities in software development is Requirements Selection, which is to find an optimal subset of the software requirements (features) with the highest value for a given budget. The values of the requirements, however, may depend on one another. Such Value Dependencies have not been considered by the existing requirements sele...
Advances in hardware technology have facilitated more integration of sophisticated software toward augmenting the development of Unmanned Vehicles (UVs) and mitigating constraints for onboard intelligence. As a result, UVs can operate in complex missions where continuous trans-formation in environmental condition calls for a higher level of situati...
This paper describes a reflexive multilayered mission planner with a mounted energy efficient local path planner for Unmanned Underwater Vehicle's (UUV) navigation throughout the complex subsea volume in a time-variant semi-dynamic operation network. The UUV routing protocol in Underwater Wireless Sensor Network (UNSW) is generalized with a homogen...
The Café Wall illusion is one of a class of tilt illusions where lines that are parallel appear to be tilted. We demonstrate that a simple Differences of Gaussian model provides an explanatory mechanism for the illusory tilt perceived in a family of Café Wall illusion generalizes to the dashed versions of Café Wall. Our explanation models the visua...
Software requirement selection aims to find an optimal subset of the requirements with the highest value while respecting the budget. But the value of a requirement may depend on the presence or absence of other requirements in the optimal subset. Existing requirement selection methods, however, do not consider Value Dependencies, thus increasing t...
Software requirements selection aims to find an optimal subset of the requirements with the highest value while respecting the project constraints. But the value of a requirement may depend on the presence or absence of other requirements in the optimal subset. Such Value Dependencies, however, are imprecise and hard to capture. In this paper, we p...
Software requirement selection is to find an optimal set of requirements that gives the highest value for a release of software while keeping the cost within the budget. However, value-related dependencies among software requirements may impact the value of an optimal set. Moreover, value-related dependencies can be of varying strengths. Hence, it...
Software Release Planning (SRP) is to find, for the software, a subset of the requirements with the highest value while respecting the budget. The value of a requirement however may, to various degrees, depend on selecting or ignoring other requirements. However, existing SRP models ignore either Value-Related Dependencies altogether or the strengt...
Introduction
Motivating behavioural change during client consultations is of crucial importance across all health professions to address the growing burden of chronic conditions. Yet health professionals often lack the skills and confidence to use evidence-based counselling interventions to support clients’ behavioural change and mobilise clients’...
Storytelling is fundamental to language, including culture, conversation and communication in their broadest senses. It thus emerges as an essential component of intelligent systems, including systems where natural language is not a primary focus or where we do not usually think of a story being involved. In this paper we explore the emergence of s...
This paper presents a hybrid route-path planning model for an Autonomous Underwater Vehicle’s task assignment and management while the AUV is operating through the variable littoral waters. Several prioritized tasks distributed in a large scale terrain is defined first; then, considering the limitations over the mission time, vehicle’s battery, unc...
In Computer Vision, finding simple features is performed using classifiers called interest point (IP) detectors, which are often utilised to track features as the scene changes. For 2D based classifiers it has been intuitive to measure repeated point reliability using 2D metrics given the difficulty to establish ground truth beyond 2D. The aim is t...
Illusions are fascinating and immediately catch people's attention and interest, but they are also valuable in terms of giving us insights into human cognition and perception. A good theory of human perception should be able to explain the illusion, and a correct theory will actually give quantifiable results. We investigate here the efficiency of...
Illusions are fascinating and immediately catch people's attention and interest, but they are also valuable in terms of giving us insights into human cognition and perception. A good theory of human perception should be able to explain the illusion, and a correct theory will actually give quantifiable results. We investigate here the efficiency of...
The Caf\'e Wall illusion is one of a class of tilt illusions where lines that are parallel appear to be tilted. We demonstrate that a simple Differences of Gaussian model provides an explanatory mechanism for the illusory tilt perceived in a family of Caf\'e Wall illusion generalizes to the dashed versions of Caf\'e Wall. Our explanation models the...
Advancing the decision autonomy is a real challenge in the development of today AUVs as their operation is still restricted to very particular tasks that usually supervised by the human operator(s). Having a robust decision-making system along with an accurate motion planning mechanism facilitates a single vehicle to manage its restricted energy re...
Avoid colliding static and uncertain mobile-motile objects;
Nowadays underwater missions and scenarios have been expanded and this will bold out the demands for having more powerful decision making of the AUV; thus, increasing mission productivity and reliability, concerning time and resource restrictions, are the target of interest in this chapter as the crucial factors of designing an efficient decision-m...
The subject of autonomy and mission planning have been comprehensively investigated on various frameworks over the past decades. It has been briefly discussed in previews chapters that among attempted scopes of autonomous operations, the underwater exploration remained still restricted to particular tasks with a low-level of autonomy. Underwater ro...
Autonomous mission management is closely related to the accuracy of the navigation system. Path planning is an essential component in the UV’s development, which determines the vehicle’s level of autonomy in dealing with environmental changes and it is considered as a premise of mission reliability and success Statheros et al. (J Navig 61:129–142,...
The purpose of this chapter is to review some of the recent advancements in the autonomous mission management and mission planning systems in UV studies concentrating on UAVs and AUVs individual and swarm operations. In recent years, increasing attention has been concentrated on extending the ranges of missions and UVs’ endurance, increasing UVs’ a...
Increasing the level of autonomy allows reducing reliance on the human supervisor. Addressing autonomy in the real world with unknown events, it is strongly critical to instantaneous adaptation to the continuously changing situations. Autonomous adaptation relies on the understanding of the surrounding environment. Complicated missions that cannot...
In Computer Vision, finding simple features is performed using classifiers called interest point (IP) detectors, which are often utilised to track features as the scene changes. For 2D based classifiers it has been intuitive to measure repeated point reliability using 2D metrics given the difficulty to establish ground truth beyond 2D. The aim is t...
Robust and efficient AUV path planning is a key element for persistence AUV maneuvering in variable underwater environments. To develop such a path planning system, in this study, differential evolution (DE) algorithm is employed. The performance of the DE-based planner in generating time-efficient paths to direct the AUV from its initial condition...
Existing research involving children with autism suggests that autonomous (self directed) virtual humans can be used successfully to improve language skills, and that authorable (researcher controlled) virtual humans can be used to improve social skills. This research combines these ideas and investigates the use of autonomous virtual humans for te...
In an empirical user study, we assessed two approaches to ranking the results from a keyword search using semantic contextual match based on Latent Semantic Analysis. These techniques involved searches initiated from words found in a seed document within a corpus. The first approach used the sentence around the search query in the document as conte...
This paper describes a reflexive multilayered mission planner with a mounted energy efficient local path planner for unmanned underwater vehicle's (UUV) navigation throughout complex subsea volume in a time variant semi-dynamic operation network. The UUV routing protocol in underwater wireless sensor network is generalized with a homogeneous dynami...
Expansion of today's underwater scenarios and missions necessitates the requestion for robust decision making of the Autonomous Underwater Vehicle (AUV); hence, design an efficient decision making framework is essential for maximizing the mission productivity in a restricted time. This paper focuses on developing a deliberative conflict-free-task a...
Our study aims to develop an engaging interaction system that assists dementia patients who have frequent memory loss. The system features include: videoing patients' daily social encounters, then replaying their key events at arranged or appropriate times, which not only functions to give patients reminders, but also motivates human machine intera...
This paper provides a hierarchical dynamic mission planning framework for an AUV to accomplish task-assign process in a restricted time operating in uncertain undersea environment. A high-level reactive mission planner is developed for task priority assignment, guiding the vehicle toward a target of interest, and managing on-time mission completion...
Geometrical illusions are a subclass of optical illusions in which the geometrical characteristics of patterns such as orientations and angles are distorted and misperceived as the result of low- to high-level retinal/cortical processing. Modelling the detection of tilt in these illusions and their strengths as they are perceived is a challenging t...
In this paper, we introduce a novel mechanism for pronunciation evaluation for use in a computer-based application for the reduction of vowel errors. Unlike modern pronunciation feedback, which relies on the charts used by linguists or simply highlighting of incorrect segments, our two-dimensional maps situate the utterances produced by the learner...
Why does our visual system fail to reconstruct reality, when we look at certain patterns? Where do Geometrical illusions start to emerge in the visual pathway? How far should we take computational models of vision with the same visual ability to detect illusions as we do? This study addresses these questions, by focusing on a specific underlying ne...
Motion vectors extracted from a compressed video file can be used to track objects in the video and it could be efficient as motion vectors provide trajectory information of the objects. However, tracking objects represented by the motion vectors can be inaccuracy because of camera movement, small size sets of motion vectors acting as noise, unmovi...
Geometrical illusions are a subclass of optical illusions in which the geometrical characteristics of patterns such as orientations and angles are distorted and misperceived as the result of low- to high-level retinal/cortical processing. Modelling the detection of tilt in these illusions and their strengths as they are perceived is a challenging t...
Software requirement selection is to find an optimal set of requirements that gives the highest value for a release of software while keeping the cost within the budget. However, value-related dependencies among software requirements may impact the value of an optimal set. Moreover, value-related dependencies can be of varying strengths. Hence, it...
Binary Knapsack Problem (BKP) is to select a subset of items with the highest value while keeping the size within the capacity of the knapsack. This paper presents an Integer Linear Programming (ILP) model for a variation of BKP where the value of an item may depend on presence or absence of other items in the knapsack. Strengths of such Value-Rela...
This paper explores the tilt illusion effect in the Cafe Wall pattern using a classical Gaussian Receptive Field model. In this illusion, the mortar lines are misperceived as diverging or converging rather than horizontal. We examine the capability of a simple bioplausible filtering model to recognize different degrees of tilt effect in the Cafe Wa...
This paper presents a model explaining tilt illusion effect in the Café Wall pattern. In this geometric illusion, we perceive horizontal edges as tilted. We explain this as the result of innate retinal/gangliar visual processing of the pattern. Our bioplausible model is based on a simple early layer using Difference of Gaussian over simple ON-cente...
Why does our visual system fail to reconstruct reality, when we look at certain patterns? Where do Geometrical illusions start to emerge in the visual pathway? Should computational models of vision have the same visual ability to detect illusions as we do? This study addresses these questions, by focusing on a specific underlying neural mechanism i...
Binary Knapsack Problem (BKP) is to select a subset of an element (item) set with the highest value while keeping the total weight within the capacity of the knapsack. This paper presents an integer programming model for a variation of BKP where the value of each element may depend on selecting or ignoring other elements. Strengths of such Value-Re...
Considering user preferences is a determining factor in optimizing the value of a software release. This is due to the fact that user preferences for software features specify the values of those features and consequently determine the value of the release. Certain features of a software however, may encourage or discourage users to prefer (select...
Training Brain Computer Interface (BCI) systems to understand the intention of a subject through Electroencephalogram (EEG) data currently requires multiple training sessions with a subject in order to develop the necessary expertise to distinguish signals for different tasks. Conventionally the task of training the subject is done by introducing a...
Affective computing is an increasingly important outgrowth of Artificial Intelligence, which is intended to deal with rich and subjective human communication. In view of the complexity of affective expression, discriminative feature extraction and corresponding high-performance classifier selection are still a big challenge. Specific features/class...
We report investigations into speaker classification of larger quantities of unlabelled speech data using small sets of manually phonemically annotated speech. The Kohonen speech typewriter is a semi-supervised method comprised of self-organising maps (SOMs) that achieves low phoneme error rates. A SOM is a 2D array of cells that learn vector repre...
Optical illusions highlight sensitivities and limitations of human visual processing and studying them leads to insights about perception that can potentially help computer vision match or exceed human performance. Geometric illusions are a subclass of illusions in which orientations and angles are distorted and misperceived. In this paper, a quant...
It has been widely recognized that uncertainty is an inevitable aspect of diagnosis and treatment of medical disorders. Such uncertainties hence, need to be considered in computerized medical models. The existing medical modeling techniques however, have mainly focused on capturing uncertainty associated with diagnosis of medical disorders while ig...
Background
Two experiments investigated the effect of features of human behaviour on the quality of interaction with an Embodied Conversational Agent (ECA). Methods
In Experiment 1, visual prominence cues (head nod, eyebrow raise) of the ECA were manipulated to explore the hypothesis that likeability of an ECA increases as a function of interperson...
Optical illusions highlight sensitivities and limitations of human visual processing and studying them leads to insights about perception that can potentially help computer vision match or exceed human performance. Geometric illusions are a subclass of illusions in which orientations and angles are distorted and misperceived. In this paper, a quant...
Limitations and sensitivities of human visual processing can be investigated through the study of optical illusions and their perception, leading to insights that can potentially help computer vision match or exceed human performance. Geometric illusions are a specific subfamily in which orientations and angles are misperceived. This paper reports...
This paper presents a model explaining tilt illusion effect in the Café Wall pattern. In this geometric illusion, we perceive horizontal edges as tilted. We explain this as the result of innate retinal/gangliar visual processing of the pattern. Our bioplausible model is based on a simple early layer using Difference of Gaussian over simple ON-cente...
Edge detection is a long standing but still challenging problem. Although there are many effective edge detectors, none of them can obtain ideal edges in every situation. To make the results robust for any image, we propose a new edge detection algorithm based on a two-level fusion model that combines several typical edge detectors together with ne...
An Autonomous Underwater Vehicle (AUV) needs to acquire a certain degree of autonomy for any particular underwater mission to fulfill the mission objectives successfully and ensure its safety in all stages of the mission in a large scale operating filed. In this paper, a novel combinatorial conflict-free-task assignment strategy consisting an inter...
Purpose of this study was to understand the effect of automatic muscle pruning of electroencephalograph on cognitive work load prediction. Pruning was achieved using an automatic Independent Component Analysis (ICA) based component classification. Initially, raw data from EEG recording was used for prediction, this result was then compared with men...