Gayathri Narasimham

Updating orientation in large virtual environments using scaled translational gain

Navigating through large virtual environments using a head-mounted display (HMD) is difficult due to the spatial limitations of the tracking system. We conducted two experiments to examine methods of exploring large virtual spaces with an HMD under translation conditions different than normal walking. Experiment 1 compares locomotion in the virtual environment using two different motor actions to translate the subject. The study contrasts user learning and orientation of two different translational gains of bipedal locomotion (not scaled and scaled by ten) with joystick locomotion, where rotation in both locomotion interfaces is accomplished by physically turning. Experiment 2 looks further at the effects of increasing the translational gain of bipedal locomotion in a virtual environment. A subjects spatial learning and orientation were evaluated in three gain conditions where each physical step was: not scaled, scaled by two, or scaled by ten (1:1, 2:1, 10:1, respectively). A sub-study of this experiment compared the performance of people who played video games against people who did not.

Evaluation of walking in place on a Wii balance board to explore a virtual environment

In this work, we present a method of “Walking In Place” (WIP) on the Nintendo Wii Fit Balance Board to explore a virtual environment. We directly compare our method to joystick locomotion and normal walking. The joystick proves inferior to physically walking and to WIP on the Wii Balance Board (WIP--Wii). Interestingly, we find that physically exploring an environment on foot is equivalent in terms of spatial orientation to exploring an environment using our WIP--Wii method. This implies that the WIP--Wii is a good inexpensive alternative to exploring a virtual environment and it may be well--suited for exploring large virtual environments.

Representations as mediators of adolescent deductive reasoning.

In Experiment 1, preadolescents, middle adolescents, and late adolescents were presented 3 deductive reasoning tasks. With some important exceptions, conditional reasoning improved with age on problems containing permission conditional relations, and reasoning fallacies increased with age on problems containing causal conditional relations. The results of Experiments 2a and 2b indicated that problem type (i.e., permission or causal) does not mediate the activation of conditional reasoning skills. Rather, valid conditional inferences are more common on problems for which plausible alternative antecedents can be generated than on problems for which alternative antecedent generation is difficult. Conditional rules for which alternative antecedent generation is difficult may be misrepresented as biconditionals, resulting in biconditional rather than conditional reasoning.

Distance estimation in virtual and real environments using bisection

Systematic error in judging distances in virtual environments is one of the most interesting problems in perceptual studies of virtual environments. The causes of this error are not known. This paper presents an experiment designed to investigate distance perception in virtual environments using the method of distance bisection (fractionation). Most other studies of distance perception in virtual environment rely on measures involving motor responses or time judgments. Unlike these, the method used in this study depends purely on visually perceived distances. Our experiment compares distance bisection judgments in virtual environments, bisection judgments in the real-world, and bisection judgments in the real-world with limited field of view. We also perform the judgments in two environmental contexts, an outdoor environment and an indoor environment. We find evidence that nonlinear distance compression occurs in virtual environments, but judgments in real-world conditions are accurate. We do not find an effect of environmental context.

A system for exploring large virtual environments that combines scaled translational gain and interventions

This paper evaluates the combination of two methods for adapting bipedal locomotion to explore virtual environments displayed on head-mounted displays (HMDs) within the confines of limited tracking spaces. We combine a method of changing the optic flow of locomotion, effectively scaling the translational gain, with a method of intervening and manipulating a users locations in physical space while preserving their spatial awareness of the virtual space. This latter technique is called resetting. In two experiments, we evaluate both scaling the translational gain and resetting while a subject locomotes along a path and then turns to face a remembered object. We find that the two techniques can be effectively combined, although there is a cognitive cost to resetting.

Egocentric distance perception in real and HMD-based virtual environments: the effect of limited scanning method

We conducted four experiments on egocentric depth perception using blind walking with a restricted scanning method in both the real and a virtual environment. Our viewing condition in all experiments was monocular. We varied the field of view (real), scan direction (real), blind walking method (real and virtual), and self-representation (virtual) over distances of 4 meters to 7 meters. The field of view varied between 21.1° and 13.6°. The scan direction varied between near-to-far scanning and far-to-near scanning. The blind walking method varied between direct blind walking and an indirect method of blind walking that matched the geometry of our laboratory. We varied self-representation between having a self-avatar (a fully tracked, animated, and first-person perspective of the user), having a static avatar (a mannequin avatar that did not move), to having no avatar (a disembodied camera view of the virtual environment). In the real environment, we find an effect of field of view; participants performed more accurately with larger field of view. In both real and virtual environments, we find an effect of blind walking method; participants performed more accurately in direct blind walking. We do not find an effect of distance underestimation in any environment, nor do we find an effect of self-representation.

Distance perception in virtual environments: a closer look at the horizon and the error

Distances are systematically underestimated in the virtual environments. In this work we explore the possibility of shifting the angular the angular declination from the horizon as a way of manipulating perceived distances in a head-mounted display (HMD). We find that shifting the horizon upward 11.5° upward does not have an effect on distance perception. Blind walking tasks at 1.5m, 2.5m, 3.5m, 4.5m and 5.5m show an overestimation of perceived distances less than 2.5m and an underestimation of perceived distances greater than 3.5m. Absolute distance and errors in estimating distance are linearly related.

Behavior Prediction in MOOCs using Higher Granularity Temporal Information

In this paper, we present early research evaluating the predictive power of a variety of temporal features across student subpopulations with distinctive behaviors at the beginning of the course. Initial results illustrate that these features predict important differences across the subpopulations and over time in the courses. Ultimately, these results have implications for effectively targeting adaptive scaffolding tailored to the particular intentions and goals of subpopulations in MOOCs.

Young Children's Flexible Use of Semantic Cues to Word Meanings: Converging Evidence of Individual and Age Differences.

A new test of childrens flexible use of semantic cues for word learning extended previous results. In Experiment 1, three- to five-year-olds (N = 51) completed two tests of interpreting several novel words for the same stimulus arrays. Within-sentence phrasal cues implied different stimulus referent properties. Childrens cue-using flexibility in the new Flexible Induction of Meanings [Words for Animates] test (FIM-An) was strongly correlated with an established test (Flexible Induction of Meanings [Words for Objects]; Deák, 2000). Individual children showed between-test consistency in using cues to flexibly assign words to different referent properties. There were large individual differences, as well as limited age differences, in the distribution of flexible and inflexible response patterns. The comprehensibility of specific cues, and perceptual salience of specific properties, explained much of the variance. Proportions of flexible and inflexible patterns shifted with age. Experiment 2 replicated these results in N=36 three- and four-year-olds, using a modified FIM-An with more distinctive cues.

Pass the Idea Please: The Relationship between Network Position, Direct Engagement, and Course Performance in MOOCs

Extant research suggests that learner engagement in discussion forums is positively correlated with learner performance. In this paper we investigate which types of forum engagement are most strongly associated with final performance in MOOC courses. In particular, we compare the correlation between course final grade and two types of learner engagement: direct measures, which count the number of interactions, and indirect measures, which capture learners position in a social network. We found that direct measures have stronger correlations with final grade. However, in preliminary analyses, we also found that course instructors score higher than learners on some indirect measures. We discuss the implications of these findings and our plans for developing the work further in the future.