Agency in mid-air interfaces

Touchless interfaces allow users to view, control and manipulate digital content without physically touching an interface. They are being explored in a wide range of application scenarios from medical surgery to car dashboard controllers. One aspect of touchless interaction that has not been explored to date is the Sense of Agency (SoA). The SoA refers to the subjective experience of voluntary control over actions in the external world. In this paper, we investigated the SoA in touchless systems using the intentional binding paradigm. We first compare touchless systems with physical interactions and then augmented different types of haptic feedback to explore how different outcome modalities influence users’ SoA. From our experiments, we demonstrated that an intentional binding effect is observed in both physical and touchless interactions with no statistical difference. Additionally, we found that haptic and auditory feedback help to increase SoA compared with visual feedback in touchless interfaces. We discuss these findings and identify design opportunities that take agency into consideration

Examining the sense of agency in human-computer interaction

Humans are agents, we feel that we control the course of events on our everyday life. This refers to the Sense of Agency (SoA). This experience is not only crucial in our daily life, but also in our interaction with technology. When we manipulate a user interface (e.g., computer, smartphone, etc.), we expect that the system responds to our input commands with feedback, as we desire to feel that we are in charge of the interaction. If this interplay elicits a SoA, then the user will perceive an instinctive feeling of “I am controlling this”. Although research in Human-Computer Interaction (HCI) pursuits the design of intuitive and responsive systems, most of the current studies have been focussed mainly on interaction techniques (e.g., software-hardware) and User Experience (UX) (e.g., comfort, usability, etc.), and very little has been investigated in terms of the SoA i.e., the conscious experience of being in control regarding the interaction. In this thesis, we present an experimental exploration of the role of the SoA in interaction paradigms typical of HCI. After two chapters of introduction and related work, we describe a series of studies that explore agency implication in interaction with systems through human senses such as vision, audio, touch and smell. Chapter 3 explores the SoA in mid-air haptic interaction through touchless actions. Then, Chapter 4 examines agency modulation through smell and its application for olfactory interfaces. Chapter 5 describes two novel timing techniques based on auditory and haptic cues that provide alternative timing methods to the traditional Libet clock. Finally, we conclude with a discussion chapter that highlights the importance of our SoA during interactions with technology as well as the implications of the results found, in the design of user interfaces

Substance-specific modulation of the affective and neurobiological effects of heroin and cocaine in human addicts

This dissertation investigates how the settings of drug use influence the affective and neurobiological response to heroin versus cocaine in addicts. Chapter 1 reviews the neuropharmacology of heroin and cocaine and the theoretical background for drugs-settings interactions, including a detailed discussion of findings from previous studies in animals and humans that show how the same settings can influence in opposite directions the reinforcing effect of heroin and cocaine. Cocaine self-administration, for example, was greatly facilitated when rats were tested outside the home environment relative to rats test at home. The opposite pattern was found for heroin. Translational studies in humans yielded similar results. Indeed, heroin and cocaine co-abusers reported using the two drugs in distinct settings: heroin preferentially at home and cocaine preferentially outside the home. The aim of this dissertation is to determine whether the setting could also influence in opposite manner the affective and neurobiological response to heroin and cocaine in human addicts. Chapter 2 illustrates the findings of a study aimed at testing the hypothesis that the affective state experienced under cocaine or heroin is the result of an interaction between central and peripheral drug effects and the surroundings of drug use. According to this hypothesis, when cocaine is taken at home there is a mismatch between the familiar environment and the peripheral effects such as arousal, increased heart rate, increased respiratory rate, and increased muscular tension (which are usually produced in stressful situations). This mismatch dampens cocaine-rewarding effects. A mismatch would also occurs when heroin (which produces sedation and decreases heart rate, respiratory rate, and muscular tension) is used outside the home in contexts requiring vigilance. We found indeed that co-abusers subjectively experienced opposite changes in arousal, heart rate, respiratory rate, and muscular tension in response to cocaine (increase) versus heroin (decrease). Most important, using a novel two-dimensional visual test, we found that in agreement with the working hypothesis the valence of the affective state produced by heroin and cocaine shifted in opposite directions as a function of the setting of drug use: heroin was reported to be more pleasant at home than outside the home, and vice versa for cocaine. Chapter 3 illustrates the results of in which emotional imagery was combined with fMRI to investigation the neurobiological underpinnings of drug and setting interactions in addicts. Heroin and cocaine co-abusers were asked to recreate real-world settings of drug use during fMRI. In agreement with the working hypothesis, we found that heroin and cocaine imagery produced opposite changes in BOLD in the prefrontal cortex and in the striatum, regions implicated in brain reward in humans. Furthermore the same pattern of dissociation was observed in the cerebellum, suggesting that that a fronto-triatal-cerebellar network is implicated in processing drug-setting interactions. Chapter 4 includes a summary of the results, a general discussion, and suggestions for future research and implication. The major finding is that the environment surrounding drug use can influence in opposite manner the affective and neurobiological response to heroin and cocaine, suggesting that therapeutic approaches to the treatment of drug addiction should take into account the distinctive effects of different classes of drugs as well as the contexts of drug use. The Appendix includes reprints of two papers reporting on additional studies conducted during the course of the Ph.D. program, which are not directly germane to the aims of the dissertation. Other three papers are in the pre-submission stage