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Details

  • Name

    Carlos Loureiro Silva
  • Cluster

    Computer Science
  • Role

    External Student
  • Since

    01st January 2012
Publications

2015

Immersiveness of Ubiquitous Computing Environments Prototypes: A Case Study

Authors
Abade, T; Campos, JC; Moreira, R; Silva, CCL; Silva, JL;

Publication
DISTRIBUTED, AMBIENT, AND PERVASIVE INTERACTIONS

Abstract
The development of ubiquitous computing (ubicomp) environments raises several challenges in terms of their evaluation. Ubicomp virtual reality prototyping tools enable users to experience the system to be developed and are of great help to face those challenges, as they support developers in assessing the consequences of a design decision in the early phases of development. Given the situated nature of ubicomp environments, a particular issue to consider is the level of realism provided by the prototypes. This work presents a case study where two ubicomp prototypes, featuring different levels of immersion (desktop-based versus CAVE-based), were developed and compared. The goal was to determine the cost/benefits relation of both solutions, which provided better user experience results, and whether or not simpler solutions provide the same user experience results as more elaborate one.

2014

Spatial limits for audiovisual unity assumption

Authors
Silva, CCL; Mouta, S; Santos, JA; Creissac, J;

Publication
PERCEPTION

Abstract

2013

Depth Cues and Perceived Audiovisual Synchrony of Biological Motion

Authors
Silva, CC; Mendonca, C; Mouta, S; Silva, R; Campos, JC; Santos, J;

Publication
PLOS ONE

Abstract
Background: Due to their different propagation times, visual and auditory signals from external events arrive at the human sensory receptors with a disparate delay. This delay consistently varies with distance, but, despite such variability, most events are perceived as synchronic. There is, however, contradictory data and claims regarding the existence of compensatory mechanisms for distance in simultaneity judgments. Principal Findings: In this paper we have used familiar audiovisual events - a visual walker and footstep sounds and manipulated the number of depth cues. In a simultaneity judgment task we presented a large range of stimulus onset asynchronies corresponding to distances of up to 35 meters. We found an effect of distance over the simultaneity estimates, with greater distances requiring larger stimulus onset asynchronies, and vision always leading. This effect was stronger when both visual and auditory cues were present but was interestingly not found when depth cues were impoverished. Significance: These findings reveal that there should be an internal mechanism to compensate for audiovisual delays, which critically depends on the depth information available.

2013

The social acceptability of intelligent transportation systems

Authors
Silva, C; Santos, J;

Publication
ICTIS 2013: Improving Multimodal Transportation Systems - Information, Safety, and Integration - Proceedings of the 2nd International Conference on Transportation Information and Safety

Abstract
Understanding how users will respond to new in-vehicle technologies can be a crucial factor in the success of future Intelligent Transportation Systems (ITS) implementations. This study's main goal was to evaluate the social acceptability of different ITS that varied in the control and monitoring levels over vehicle parameters and driver's performance and to describe the most common socio-psychological factors that influence ITS acceptability. We developed a novel ITS acceptability measure, composed by a 51-item questionnaire. The participants had generally high levels of acceptability, independently of the ITS control level over driver's performance. However ITS that exerted more control were regarded as more efficient. We also found gender differences, especially in a "Personal and Social Aims" dimension. Age is positively correlated with participants score on the acceptability index, while education level is showing an opposite tendency. Finally, and critical to ITS development, controlling the car velocity is evaluated as the least preferable ITS feature. © 2013 American Society of Civil Engineers.

2013

Reflection orders and auditory distance

Authors
Mendonca, C; Lamas, J; Barker, T; Campos, G; Dias, P; Pulkki, V; Silva, C; Santos, JA;

Publication
Proceedings of Meetings on Acoustics

Abstract
The perception of sound distance has been sparsely studied so far. It is assumed to depend on familiar loudness, reverberation, sound spectrum and parallax, but most of these factors have never been carefully addressed. Reverberation has been mostly analysed in terms of ratio between direct and indirect sound, and total duration. Here we were interested in assessing the impact of each reflection order on distance localization. We compared sound source discrimination at an intermediate and at a distant location with direct sound only, one, two, three, and four reflection orders in a 2AFC task. At the intermediate distances, normalized psychophysical curves reveal no differentiation between direct sound and up to three reflection orders, but sounds with four reflection orders have significantly lower thresholds. For the distant sources, sounds with four reflection orders yielded the best discrimination slopes, but there was also a clear benefit for sounds with three reflection orders. We conclude that at least three reflection orders are required so that reflection-related cues are accounted for in distance estimates. Also, these cues might interact differently with the direct sound pressure cues at different distances. © 2013 Acoustical Society of America.