Understanding Strategic Adaptation in Dual-Task Situations as Cognitively Bounded Rational Behavior

In this thesis I explored when people interleave attention in dual-task settings. The hypothesis is that people try to perform in a cognitively bounded rational way. Performance is limited by constraints that come from the task environment and cognition. If, given these constraints, multiple strategies for interleaving tasks are available, then people will interleave tasks in a way that aligns with their local priority objective (Chapter 3), or which maximizes the value of an objective payoff function that evaluates performance (Chapter 4). This hypothesis was tested using a combination of experimental studies and computational cognitive models. Across a series of studies, the interplay between different constraints was investigated. In Chapters 5 and 6, I developed mathematical models to study what task combinations in general allowed for “ideal payoff manipulations” to study task interleaving. The work contributed to the existing literature in four ways: (1) it provided an overarching theory of skilled human dual-task performance and tested this in relatively applied settings, (2) the theory was formalized in computational cognitive models that can predict performance of unobserved strategies and that can bracket the (optimal) performance space, (3) linear and logarithmic tasks were identified as an ideal combination for achieving ideal payoff manipulations, and (4) results demonstrated that in multitasking situations attention is not necessarily interleaved solely at chunk boundaries and other “natural breakpoints”, but that this depends on a person’s priorities. The work has implications for driver distraction research, in that it helps in systematically understanding the performance trade-offs that people face when multitasking. Moreover, the modeling framework could be used for model-based evaluation of new mobile interfaces. Finally, the demonstration that priorities can strongly influence multitasking performance highlights the importance of public safety campaigns that emphasize awareness of driver safety. Limitations and further implications are discussed

Dividing Attention Between Tasks: Testing Whether Explicit Payoff Functions Elicit Optimal Dual-Task Performance

We test people's ability to optimize performance across two concurrent tasks. Participants performed a number entry task while controlling a randomly moving cursor with a joystick. Participants received explicit feedback on their performance on these tasks in the form of a single combined score. This payoff function was varied between conditions to change the value of one task relative to the other. We found that participants adapted their strategy for interleaving the two tasks, by varying how long they spent on one task before switching to the other, in order to achieve the near maximum payoff available in each condition. In a second experiment, we show that this behavior is learned quickly (within 2-3 min over several discrete trials) and remained stable for as long as the payoff function did not change. The results of this work show that people are adaptive and flexible in how they prioritize and allocate attention in a dual-task setting. However, it also demonstrates some of the limits regarding people's ability to optimize payoff functions

Infrared-active optical phonons in LiFePO4 single crystals

Infrared-active optical phonons were studied in olivine LiFePO4 oriented single crystals by means of both rotating analyzer and rotating compensator spectroscopic ellipsometry in the spectral range between 50 and 1400 cm-1. The eigenfrequencies, oscillator strengths, and broadenings of the phonon modes were determined from fits of the anisotropic harmonic oscillator model to the data. Optical phonons in a heterosite FePO4 crystal were measured from the delithiated ab-surface of the LiFePO4 crystal and compared with the phonon modes of the latter. Good agreement was found between experimental data and the results of solid-state hybrid density functional theory calculations for the phonon modes in both LiFePO4 and FePO4

Perception of perspective in augmented reality head-up displays

Augmented Reality (AR) is emerging fast with a wide range of applications, including automotive AR Head-Up Displays (AR HUD). As a result, there is a growing need to understand human perception of depth in AR. Here, we discuss two user studies on depth perception, in particular the perspective cue. The fi rst experiment compares the perception of the perspective depth cue (1) in the physical world, (2) on a at-screen, and (3) on an AR HUD. Our AR HUD setup provided a two-dimensional vertically oriented virtual image projected at a fi xed distance. In each setting, participants were asked to estimate the size of a perspective angle. We found that the perception of angle sizes on AR HUD differs from perception in the physical world, but not from a at-screen. The underestimation of the physical world's angle size compared to the AR HUD and screen setup might explain the egocentric depth underestimation phenomenon in virtual environments. In the second experiment, we compared perception for different graphical representations of angles that are relevant for practical applications. Graphical alterations of angles displayed on a screen resulted in more variation between individuals' angle size estimations. Furthermore, the majority of the participants tends to underestimate the observed angle size in most conditions. Our results suggest that perspective angles on a vertically oriented fixed-depth AR HUD display mimics more accurately the perception of a screen, rather than the perception of the 3D environment. On-screen graphical alteration does not help to improve the underestimation in the majority of cases

Exploring the concept of the (future) mobile office

This video shows a concept of a future mobile office in a semi-automated vehicle that uses augmented reality. People perform non-driving tasks in current, non-automated vehicles even though that is unsafe. Moreover, even for passengers there is limited space, it is not social, and there can be motion sickness. In future cars, technology such as augmented reality might alleviate some of these issues. Our concept shows how augmented reality can project a remote conversant onto the dashboard. Thereby, the driver can keep an occasional eye on the road while the automated vehicle drives, and might experience less motion sickness. Potentially, this concept might even be used for group calls or for group activities such as karaoke, thereby creating a social setting. We also demonstrate how integration with an intelligent assistant (through speech and gesture analysis) might save the driver from having to grab a calendar to write things down, again allowing them to focus on the road

History and future of human-automation interaction

We review the history of human-automation interaction research, assess its current status and identify future directions. We start by reviewing articles that were published on this topic in the International Journal of Human-Computer Studies during the last 50 years. We find that over the years, automated systems have been used more frequently (1) in time-sensitive or safety-critical settings, (2) in embodied and situated systems, and (3) by non-professional users. Looking to the future, there is a need for human-automation interaction research to focus on (1) issues of function and task allocation between humans and machines, (2) issues of trust, incorrect use, and confusion, (3) the balance between focus, divided attention and attention management, (4) the need for interdisciplinary approaches to cover breadth and depth, (5) regulation and explainability, (6) ethical and social dilemmas, (7) allowing a human and humane experience, and (8) radically different human-automation interaction

ABJM Baryon Stability and Myers effect

We consider magnetically charged baryon vertex like configurations in AdS^4 X CP^3 with a reduced number of quarks l. We show that these configurations are solutions to the classical equations of motion and are stable beyond a critical value of l. Given that the magnetic flux dissolves D0-brane charge it is possible to give a microscopical description in terms of D0-branes expanding into fuzzy CP^n spaces by Myers dielectric effect. Using this description we are able to explore the region of finite 't Hooft coupling.Comment: 29 pages, Latex; minor changes; version to appear in JHE

Integrating knowledge of multitasking and interruptions across different perspectives and research methods

Multitasking and interruptions have been studied using a variety of methods in multiple fields (e.g., HCI, cognitive science, computer science, and social sciences). This diversity brings many complementary insights. However, it also challenges researchers to understand how seemingly disparate ideas can best be integrated to further theory and to inform the design of interactive systems. There is therefore a need for a platform to discuss how different approaches to understanding multitasking and interruptions can be combined to provide insights that are more than the sum of their parts. In this article we argue for the necessity of an integrative approach. As part of this argument we provide an overview of articles in this special issue on multitasking and interruptions. These articles showcase the variety of methods currently used to study multitasking and interruptions. It is clear that there are many challenges to studying multitasking and interruptions from different perspectives and using different techniques. We advance a six-point research agenda for the future of multi-method research on this important and timely topic

Fractional branes, warped compactifications and backreacted orientifold planes

The standard extremal p-brane solutions in supergravity are known to allow for a generalisation which consists of adding a linear dependence on the world-volume coordinates to the usual harmonic function. In this note we demonstrate that remarkably this generalisation goes through in exactly the same way for p-branes with fluxes added to it that correspond to fractional p-branes. We relate this to warped orientifold compactifications by trading the Dp-branes for Op-planes that solve the RR tadpole condition. This allows us to interpret the worldvolume dependence as due to lower-dimensional scalars that flow along the massless directions in the no-scale potential. Depending on the details of the fluxes these flows can be supersymmetric domain wall flows. Our solutions provide explicit examples of backreacted orientifold planes in compactifications with non-constant moduli.Comment: 20 pages, incl. references. v2: small changes required for JHEP publication. v3: few equation typos correcte

The problematic backreaction of SUSY-breaking branes

In this paper we investigate the localisation of SUSY-breaking branes which, in the smeared approximation, support specific non-BPS vacua. We show, for a wide class of boundary conditions, that there is no flux vacuum when the branes are described by a genuine delta-function. Even more, we find that the smeared solution is the unique solution with a regular brane profile. Our setup consists of a non-BPS AdS_7 solution in massive IIA supergravity with smeared anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.Comment: 27 pages, Latex2e, 5 figure