Visual Cues For Semi-autonomous Control Of Transradial Prosthetics

Upper-limb prosthetics are typically driven exclusively by biological signals, mainly electromyography (EMG), where electrodes are placed on the residual part of an amputated limb. In this approach, amputees must control each arm joint iteratively, in a proportional manner. Research has shown that sequential control of prosthetics usually imposes a cognitive burden on amputees, leading to high abandonment rates. This thesis presents a control system for upper-limb prosthetics, leveraging a computer vision module capable of simultaneously predicting objects in a scene, their segmentation mask, and a ranked list of the optimal grasping locations. The proposed system shares control with an amputee, allowing them to only play a supervisory role, and offloads most of the work required to configure the wrist to the computer vision module. The overall system is evaluated in an object pick up, transport, and drop off experiment in realistic, cluttered environments. Results show that the proposed system enables the subject to successfully complete 95% of the trials, and confirms the benefit of having the user in the control loop

Micro-affordances during lexical processing: considerations on the nature of object-knowledge representations

Micro-affordance effects have been reported for several different components of the reach-to-grasp action during both on-line and off-line visual processing. The presence of such effects represents a strong demonstration of the close relationship between perception, action, and cognition. In this thesis 7 experiments are described, which investigate different aspects of that relationship, with particular attention on the nature of object representations. In 5 behavioural experiments as well as in 1 Transcranial Magnetic Stimulation (TMS) experiment a stimulus-response compatibility paradigm is employed to examine the presence of micro-affordance effects arising during language processing of object names. The power and precision component of the reach-to-grasp action is investigated in relation to the compatibility of an object for grasping with either a power or a precision grasp. Overall, the results of the experiments discussed in the present thesis suggest that: a) object representations activated during language processing of object names are able to potentiate actions arising from the component of the reach-to-grasp action under investigation; b) such representations might be more semantic or „propositional‟ than depictive in nature, therefore more related to stored semantic knowledge of the object and its associated actions than to its detailed visual properties; c) this semantic information about objects seems to be automatically translated into specific motor activity, even in the absence of any intention to act; d) finally, such semantic, non-visual motor potentiation seems to be rapid and relatively short lived

Characterizing Tool-Selective Areas With Human Neuroimaging

Humans, unlike any other species, use tools to achieve complex goals. New Caledonian Crows, among the best of avian tool-makers, use twigs to retrieve food in crevices, and veined octopuses use coconut shells as shelters. Humans, however, go above and beyond these simple behaviours. Even when compared to orders that are evolutionarily closest to humans such as non-human primates, tool use is indisputably more advanced in humans. Conventionally, neuroimaging researchers who have studied complex tool use in humans do so by presenting pictures of tools and measuring the brain activity evoked by actions potentiated by the tools. This method has revealed tool-selective regions that activate in response to pictures of tools but, critically, also activate in response to real actions with real tools. Though there is overlap between regions that respond to both pictures of tools and to real tool use, it is unclear whether tool pictures are indeed an effective proxy for real tool use. In light of this, the overarching goals of this thesis were, 1) from a methodological perspective, to determine whether different proxies for studying tool use are more effective than using pictures but less technically challenging than using real actions on real tools; and 2) from a theoretical perspective, to determine what these proxies can reveal about tool-related processing, particularly in brain regions involved in visuomotor control. In sum, the results from this thesis revealed, 1) that presenting videos of familiar tool actions is an optimal proxy to study tool use, and 2) that tool-selective regions are areas selective for actions afforded by tools, for the characteristic motion associated with tools, and for familiar tools of which functional associations are well-established. Taken together, this thesis offers support to the notion that tool-selective regions process information with the purpose of predicting upcoming actions and reasoning possible ways to use a tool to interact with a target. In agreement with the affordance perspective, tool-selective regions do so even when there is no intent to act on a tool

Probabilistic Models of Student Learning and Forgetting

This thesis uses statistical machine learning techniques to construct predictive models of human learning and to improve human learning by discovering optimal teaching methodologies. In Chapters 2 and 3, I present and evaluate models for predicting the changing memory strength of material being studied over time. The models combine a psychological theory of memory with Bayesian methods for inferring individual differences. In Chapter 4, I develop methods for delivering efficient, systematic, personalized review using the statistical models. Results are presented from three large semester-long experiments with middle school students which demonstrate how this \u22big data\u22 approach to education yields substantial gains in the long-term retention of course material. In Chapter 5, I focus on optimizing various aspects of instruction for populations of students. This involves a novel experimental paradigm which combines Bayesian nonparametric modeling techniques and probabilistic generative models of student performance. In Chapters 6 and 7, I present supporting laboratory behavioral studies and theoretical analyses. These include an examination of the relationship between study format and the testing effect, and a parsimonious theoretical account of long-term recency effects

Conceptualization and cognitive relativism on result in Mandarin Chinese: the case study of Mandarin Chinese bǎ construction using a cognitive and centering approach

This work adopts Langacker\u27s cognitive grammar approach and addresses the cognitive significance of result in Mandarin Chinese, as expressed in resultant construals in the Mandarin Chinese bă construction: X bă Y Z. I identify the semantic prime of result in Mandarin Chinese, and discuss its role in the resultative verbal compound construction, the V-de-EXT resultative construction, and the bèi construction, with particular focus on the bă construction. I provide evidence for the resultant nature of segment Z in the bă construction in (1) aspectual markers, (2) resultative suffixes, (3) resultative verbal compounds, (4) locative complements, (5) directional complements, (6) the double object gěi \u27give\u27 construction, (7) inalienable possession; (8) durative and frequentative markers; and (9) the regard predicate. I consider the semantic category of result in the Mandarin Chinese bă construction to be grounded in the conceptualization of the morpheme bă \u27to take, to hold.\u27 The manipulative sense of holding an object is transformed into a metaphorical resultative sense of holding a grammatical event. Comparisons with the English get/have + p.p. construction and the German inseparable prefixes reveal the shared cross-linguistic nature of agency and result. I utilize Grosz, Joshi, and Weinstein\u27s (1995) centering discourse approach to analyze the Mandarin Chinese bă construction X bă Y Z, and determine that segment Y is the backward-looking center. Prince\u27s assumed familiarity accounts for the cognitive constraints of segment Y. I ascribe the cognitive significance of result to the claim of construal differences. I apply cognitive relativism to pedagogical implications for SLA instruction of the Mandarin Chinese bă construction

The Selective Attention for Action Model (SAAM). An exploration of affordances in a computational and experimental study

In this thesis a connectionist model for affordance-guided selective attention for action is presented. The selective attention for action model (SAAM) is aimed at modelling the direct route from vision to action using Gibson's affordances to describe actions. In the model complex affordances are encoded in grasp postures. It is shown that this is a viable method to realise aordances. By deriving complex affordances from grasp postures which in turn are derived from grasp affordances and invariants in the visual information, the model implements a hierarchical structure of affordances as postulated in Gibson's affordance concept. This is a novel way of implementing affordances in a computational model. Three studies were conducted to explore the model. The grasp postures generated by SAAM are verified in Study 1 by comparing them with human grasp postures. These grasps were collected in an experiment which used the same stimulus shapes as the model. In Study 2 the attentional behaviour of SAAM is investigated. It is shown that the model is able to select only one of the objects in visual inputs showing multiple objects as well as selecting the appropriate action category (described by a grasp type). Furthermore, it is shown that the bottom-up selection of the model can be influenced by top-down feedback of action intentions. In Study 3 the fndings of Study 2 are applied to stimuli showing two hand-tools (pliers and hammer) to clarify how the findings of Study 2 link to complex affordances and action intentions. The results demonstrate that SAAM offers a novel and powerful way to implement complex affordances. Possibilities for further experimentation and extensions of the model are discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Affordances In The Design Of Virtual Environments

Human-computer interaction design principles largely focus on static representations and have yet to fully incorporate theories of perception appropriate for the dynamic multimodal interactions inherent to virtual environment (VE) interaction. Theories of direct perception, in particular affordance theory, may prove particularly relevant to enhancing VE interaction design. The present research constructs a conceptual model of how affordances are realized in the natural world and how lack of sensory stimuli may lead to realization failures in virtual environments. Implications of the model were empirically investigated by examining three affordances: passability, catchability, and flyability. The experimental design involved four factors for each of the three affordances and was implemented as a 2 [subscript IV] [superscript 4-1] fractional factorial design. The results demonstrated that providing affording cues led to behavior closely in-line with real-world behavior. More specifically, when given affording cues participants tended to rotate their virtual bodies when entering narrow passageways, accurately judge balls as catchable, and fly when conditions warranted it. The results support the conceptual model and demonstrate 1) that substituting designed cues via sensory stimuli in available sensory modalities for absent or impoverished modalities may enable the perception of affordances in VEs; 2) that sensory stimuli substitutions provide potential approaches for enabling the perception of affordances in a VE which in the real world are cross-modal; and 3) that affordances relating to specific action capabilities may be enabled by designed sensory stimuli. This research lays an empirical foundation for a science of VE design based on choosing and implementing design properties so as to evoke targeted user behavio

Designing enriched aesthetic interaction for garment comfort

This thesis describes a research through design approach to identifying comfort factors within the kinaesthetic experiences of human sensory activities and perceptions. The research explores the experience of women through the way they touch, move and feel when interacting with wool garments. The research provides (1) a body of creative work, (2) a framework of ‘enriched aesthetic interaction’ and (3) the development of design principles for the comfort and related aesthetic qualities of clothing