Humans use active touch to gain behaviourally relevant information from their environment, includ... more Humans use active touch to gain behaviourally relevant information from their environment, including information about contained objects. Although most common, the perceptual basis of interacting with containers remains largely unexplored. The first aim of this study was to determine how accurately people can sense, by touch only, the location of a contained rolling object. Experiment 1 used tubes containing physical balls and demonstrated a considerable degree of accuracy in estimating the rolled distance. The second aim was to identify the relative effectiveness of the various available physical cues. Experiment 2 employed virtual reality technology to present, in isolation and in various combinations, the constituent haptic cues produced by a rolling ball, which are, the mechanical noise during rolling, the jolts from an impact with an internal wall, and the intensity and timing of the jolts resulting from elastic bounces. The rolling noise was of primary importance to the percep...
Proceedings of the 2020 Conference on Human Information Interaction and Retrieval, 2020
This research investigates the information behavior of undergraduate students in the context of a... more This research investigates the information behavior of undergraduate students in the context of academic and three everyday-life information domains (health, news, leisure). Data was collected using an online survey of all undergraduates at McGill University, with 3565 usable responses obtained (response rate 15.6%). Results-to-date show that there is variation by domain in the choice of resource, choice of search tool, and judgment of credibility. The results also show that while the students are able to make good judgements regarding the credibility of resources, that judgement is not always reflected in the resources they actually choose to use.
The aim of the presented research is to quantify how sensitive the human ear is to subtle changes... more The aim of the presented research is to quantify how sensitive the human ear is to subtle changes in reverberation. We quantified the discrimination thresholds for reverberations that are representative for large rooms such as concert halls (reverberation times around 1.8 s). For exponential decays, simulating an ideal simple room, thresholds are around 6% (Experiment 1). We found no difference in thresholds between a short noise burst and a male voice spoken word, suggesting that discrimination is not dependent on the type, or spectral content, of the sound source (Experiment 2). In a final experiment we matched coupled room, non-exponential decay stimuli to exponential ones, and vice versa, in an attempt to quantify the complex former in terms of the simpler latter.
We evaluate the efficiency of a 3D spatialization software named Transpan in the context of mixin... more We evaluate the efficiency of a 3D spatialization software named Transpan in the context of mixing acoustic recordings on a 5.1 reproduction system. The study aims to investigate if the use of the binaural with cross-talk cancellation (XTC) processing implemented in Transpan can improve the localization of lateral sources and their stability through listeners' movements. We administered a listening test to 22 expert listeners in Paris and in Berlin. The test consisted in comparisons among two mixes with and without binaural/XTC panning, for four classical music excerpts under five listening conditions, i.e., at the sweet spot and while performing specific movements. Quantitative analysis of multiple choice questions showed that Transpan can enlarge the 5.1 sweet spot area toward the rear speakers. From qualitative analysis of participants' feedback emerged five main categories of comments, namely Localization stability; Precise localization accuracy; Vague localization accuracy; Timbral and spectral artifacts; and Spatial differences. Together the results show that Transpan allows for better source lateralization in 5.1 mixing.
Extended Abstracts of the 2020 CHI Conference on Human Factors in Computing Systems, 2020
Despite much discussion in HCI research about how individual differences likely determine compute... more Despite much discussion in HCI research about how individual differences likely determine computer users' personal information management (PIM) practices, the extent of the influence of several important factors remains unclear, including users' personalities, spatial abilities, and the different software used to manage their collections. We therefore analyse data from prior CHI work to explore (1) associations of people's file collections with personality and spatial ability, and (2) differences between collections managed with different operating systems and file managers. We find no notable associations between users' attributes and their collections, and minimal predictive power, but do find considerable and surprising differences across operating systems. We discuss these findings and how they can inform future research.
The focus of this study was to investigate the ability to discriminate between melodic intervals ... more The focus of this study was to investigate the ability to discriminate between melodic intervals of the equal tempered scale based solely on vibrotactile stimulation. In music, a melodic interval is the musical distance between two pitches, or notes, that are played sequentially. This paper tests the hypothesis that people can detect melodic intervals that are presented to different body sites such as the fingertip of the index finger of the non-dominant hand, as well as to the flank, the lateral region between the ribcage and the hip bone. Vibrotactile stimuli on the flank were displayed through voice coils of different diameters (0 13 mm and 0 25 mm respectively), while those at the finger were displayed with a 0 13 mm diameter voice coil. Six melodic intervals ranging from a minor second (A/=100 cents) to a perfect fifth (A/=700 cents) were compared to the reference interval of a perfect prime (A/=0 cents) at a fundamental frequency (/) of 65 Hz. Discrimination was significant for intervals as small as a major second (A/=200 cents; i.e. 8Hz, or 12.3%), depending on the location of the body. Overall, results tend to suggest that larger intervals are less difficult to detect than smaller intervals.
Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems, 2019
Although many challenges of managing computer files have been identified in past studies -- and m... more Although many challenges of managing computer files have been identified in past studies -- and many alternative prototypes made -- the scale and structure of personal file collections remain relatively unknown. We studied 348 such collections, and found they are typically considerably larger in scale (30-190 thousand files) and structure (folder trees twice taller and many times wider) than previously thought, which suggests files and folders are used now more than ever despite advances in Web storage, desktop search, and tagging. Data along many measures within and across collections were log normally distributed, indicating that personal collections resemble imbalanced, group-made collections and confirming the intuition that personal information management behaviour varies greatly. Directions for the generation of test collections and other future research are discussed.
Journal of Information & Knowledge Management, 2018
Many organisations are confronted with challenges in getting employees to effectively participate... more Many organisations are confronted with challenges in getting employees to effectively participate in information and knowledge sharing (IKS). Further, IKS is embedded in multifaceted social contexts, which are influenced by several different social and cognitive factors. This study is in support of the hypothesis that perceived trustworthiness is widely implicated as a mediating factor between those social–cognitive factors and IKS. Previous work, however, uncovered only a handful of such mediating effects. It is argued here that the paucity may have been due to limitations of the statistical methods. This study employs PROCESS, a more powerful current method for mediation analysis in an attempt to uncover previously hidden relationships. Analyses were performed on data collected from 275 knowledge workers (legal professionals and paralegals) engaged in shared legal project work, at one of Canada’s largest multijurisdictional law firms. Social–cognitive factors that were considered ...
Proceedings of the Association for Information Science and Technology, 2016
In this paper we describe the design and trial use of Cardinal, novel software that overcomes the... more In this paper we describe the design and trial use of Cardinal, novel software that overcomes the limitations of existing research tools used in personal information management (PIM) studies focusing on file management (FM) behavior. Cardinal facilitates large-scale collection of FM behavior data along an extensive list of file system properties and additional relevant dimensions (e.g., demographic, software and hardware, etc). It enables anonymous, remote, and asynchronous participation across the 3 major operating systems, uses a simple interface, and provides value to participants by presenting a summary of their file and folder collections. In a 15-day trial implementation, Cardinal examined over 2.3 million files across 46 unsupervised participants. To test its adaptability we extended it to also collect psychological questionnaire responses and technological data from each participant. Participation sessions took an average of just over 10 minutes to complete, and participants reported positive impressions of their interactions. Following the pilot, we revised Cardinal to further decrease participation time and improve the user interface. Our tests suggest that Cardinal is a viable tool for FM research, and so we have made its source freely available to the PIM community.
When landing a plane, pilots could face several landing illusions that are accentuated at night o... more When landing a plane, pilots could face several landing illusions that are accentuated at night or in a featureless environment. In the current study, we compare participants landing trajectories in a featureless environment with and without haptic feedback. We asked the participants to land a virtual object during featured (F+) and featureless night conditions (F−); with (H+) and without haptic feedback (H−). The results showed that the haptic feedback facilitated lateral and up-down movements. This benefit was less evident between the visual conditions suggesting that participants were relying on haptic cues during the task. This attentional shift could reduce visual illusions during night landings, where they are accentuated by the fact that experienced pilots rely mainly on visual inputs.
Proceedings of the 28th Annual ACM Symposium on User Interface Software & Technology, 2015
Many variables have been shown to impact whether a vibra tion stimulus will be perceived. We pres... more Many variables have been shown to impact whether a vibra tion stimulus will be perceived. We present a user study that takes into account not only previously investigated predictors such as vibration intensity and duration along with the age of the person receiving the stimulus, but also the amount of mo tion, as measured by an accelerometer, at the site of vibration immediately preceding the stimulus. This is a more specific measure than in previous studies showing an effect on per ception due to gross conditions such as walking. We show that a logistic regression model including prior acceleration is significantly better at predicting vibration perception than a model including only vibration intensity, duration and par ticipant age. In addition to the overall regression, we discuss individual participant differences and measures of classifica tion performance for real-world applications. Our expecta tion is that haptic interface designers will be able to use such results to design better vibrations that are perceivable under the user's current activity conditions, without being annoy ingly loud or jarring, eventually approaching "perceptually equivalent" feedback independent of motion.
Rumble strips (RS) offer ideal conditions for multimodality research. Designed to reduce crashes ... more Rumble strips (RS) offer ideal conditions for multimodality research. Designed to reduce crashes and alert drowsy or inattentive drivers, their effectiveness in crash reduction is not questioned but little is known regarding how information from tactile vibrations and auditory rumbling is integrated during low-vision driving conditions. In this paper, we report descriptive data related to participants' perceptual experience while driving on a RS road during a snow storm, as well as data collected from participants driving in a simulated snow storm environment, and suggest future research perspectives.
The aim of the presented research is to determine whether the perception of reverberation is depe... more The aim of the presented research is to determine whether the perception of reverberation is dependent on the type of sound stimuli used. We quantified the discrimination thresholds for reverberations that are representative for large rooms such as concert halls (reverberation times around 1.8 s). For exponential decays, simulating an ideal simple room, thresholds are around 6% (Experiment 1). We
We determined velocity discrimination thresholds and Weber fractions for sounds revolving around ... more We determined velocity discrimination thresholds and Weber fractions for sounds revolving around the listener at very high velocities. Sounds used were a broadband white noise and two harmonic sounds with fundamental frequencies of 330 Hz and 1760 Hz. Experiment 1 used velocities ranging between 288 /s and 720 /s in an acoustically treated room and Experiment 2 used velocities between 288 /s and 576 /s in a highly reverberant hall. A third experiment addressed potential confounds in the first two experiments. The results show that people can reliably discriminate velocity at very high velocities and that both thresholds and Weber fractions decrease as velocity increases. These results violate Weber's law but are consistent with the empirical trend observed in the literature. While thresholds for the noise and 330 Hz harmonic stimulus were similar, those for the 1760 Hz harmonic stimulus were substantially higher. There were no reliable differences in velocity discrimination between the two acoustical environments, suggesting that auditory motion perception at high velocities is robust against the effects of reverberation.
Traditional models of face recognition view identity and recognition of expression as implemented... more Traditional models of face recognition view identity and recognition of expression as implemented in separate systems, a view reinforced by the notion that prosopagnosia is a selective loss of the ability to recognize facial identity and is due to a loss of configuralprocessing ability. Yet, not much attention has been devoted to investigating the role of configural processing in recognition of facial expressions either in normal viewers or in prosopagnosics. We investigated the influence of facial organization on discrimination of a local facial feature, using a feature-matching task and comparing matching performance for either upright or inverted target presentation. Stimuli consisted of faces and face parts with or without expression, but task requirements were identical in both conditions. Normal viewers are equally sensitive to the face configuration whether the stimuli are neutral faces of face expressions. In contrast, prosopagnosic patients present an effect of the configuration only when there is a facial expression present
In order to assist the human operator modern auditory interfaces increasingly rely on sound spati... more In order to assist the human operator modern auditory interfaces increasingly rely on sound spatialization to display auditory information and warning signals all around the listener. However, we often operate in environments that apply vibrations to the whole body, e.g., when driving a vehicle. So there is a concern that vibrations impair spatial hearing and thereby the efficacy of sound spatialization. While effects of whole-body vibrations have been found to impair simple front-back discrimination, their effect on sound localization per se has received scant attention. Here we report three experiments that used a variety of sound localization performance measures and vibration manipulations. The first was a free-field localization experiment that compared performance under conditions with and without vibration (a 5 Hz sinusoidal movement along the vertical axis). The other experiments used classical psychophysical forced choice procedures and sound lateralization tasks in which stimuli were presented over headphones and position was manipulated through interaural time differences. In experiment 2 we used two vibrations (4 and 8 Hz) at two magnitudes (0.084 and 0.169 ms-2). In experiment 3, sound lateralization was assessed at central and more peripheral locations. In none of the experiment did we observe an effect of whole-body vibrations on localization performance.
The CyberWalk treadmill is the first truly omnidirectional treadmill of its size that allows for ... more The CyberWalk treadmill is the first truly omnidirectional treadmill of its size that allows for near natural walking through arbitrarily large Virtual Environments. The platform represents advances in treadmill and virtual reality technology and engineering, but it is also a major step towards having a single setup that allows the study of human locomotion and its many facets. This chapter focuses on the human behavioral research that was conducted to understand human locomotion from the perspective of specifying design criteria for the CyberWalk. The first part of this chapter describes research on the biomechanics of human walking, in particular, the nature of natural unconstrained walking and the effects of treadmill walking on characteristics of gait. The second part of this chapter describes the multisensory nature of walking, with a focus on the integration of vestibular and proprioceptive information during walking. The third part of this chapter describes research on large-scale human navigation and identifies possible causes for the human tendency to veer from a straight path, and even walk in circles when no external references are made available. The chapter concludes with a summary description of the features of the CyberWalk platform that were informed by this collection of research findings and briefly highlights the current and future scientific potential for this platform.
Humans use active touch to gain behaviourally relevant information from their environment, includ... more Humans use active touch to gain behaviourally relevant information from their environment, including information about contained objects. Although most common, the perceptual basis of interacting with containers remains largely unexplored. The first aim of this study was to determine how accurately people can sense, by touch only, the location of a contained rolling object. Experiment 1 used tubes containing physical balls and demonstrated a considerable degree of accuracy in estimating the rolled distance. The second aim was to identify the relative effectiveness of the various available physical cues. Experiment 2 employed virtual reality technology to present, in isolation and in various combinations, the constituent haptic cues produced by a rolling ball, which are, the mechanical noise during rolling, the jolts from an impact with an internal wall, and the intensity and timing of the jolts resulting from elastic bounces. The rolling noise was of primary importance to the percep...
Proceedings of the 2020 Conference on Human Information Interaction and Retrieval, 2020
This research investigates the information behavior of undergraduate students in the context of a... more This research investigates the information behavior of undergraduate students in the context of academic and three everyday-life information domains (health, news, leisure). Data was collected using an online survey of all undergraduates at McGill University, with 3565 usable responses obtained (response rate 15.6%). Results-to-date show that there is variation by domain in the choice of resource, choice of search tool, and judgment of credibility. The results also show that while the students are able to make good judgements regarding the credibility of resources, that judgement is not always reflected in the resources they actually choose to use.
The aim of the presented research is to quantify how sensitive the human ear is to subtle changes... more The aim of the presented research is to quantify how sensitive the human ear is to subtle changes in reverberation. We quantified the discrimination thresholds for reverberations that are representative for large rooms such as concert halls (reverberation times around 1.8 s). For exponential decays, simulating an ideal simple room, thresholds are around 6% (Experiment 1). We found no difference in thresholds between a short noise burst and a male voice spoken word, suggesting that discrimination is not dependent on the type, or spectral content, of the sound source (Experiment 2). In a final experiment we matched coupled room, non-exponential decay stimuli to exponential ones, and vice versa, in an attempt to quantify the complex former in terms of the simpler latter.
We evaluate the efficiency of a 3D spatialization software named Transpan in the context of mixin... more We evaluate the efficiency of a 3D spatialization software named Transpan in the context of mixing acoustic recordings on a 5.1 reproduction system. The study aims to investigate if the use of the binaural with cross-talk cancellation (XTC) processing implemented in Transpan can improve the localization of lateral sources and their stability through listeners' movements. We administered a listening test to 22 expert listeners in Paris and in Berlin. The test consisted in comparisons among two mixes with and without binaural/XTC panning, for four classical music excerpts under five listening conditions, i.e., at the sweet spot and while performing specific movements. Quantitative analysis of multiple choice questions showed that Transpan can enlarge the 5.1 sweet spot area toward the rear speakers. From qualitative analysis of participants' feedback emerged five main categories of comments, namely Localization stability; Precise localization accuracy; Vague localization accuracy; Timbral and spectral artifacts; and Spatial differences. Together the results show that Transpan allows for better source lateralization in 5.1 mixing.
Extended Abstracts of the 2020 CHI Conference on Human Factors in Computing Systems, 2020
Despite much discussion in HCI research about how individual differences likely determine compute... more Despite much discussion in HCI research about how individual differences likely determine computer users' personal information management (PIM) practices, the extent of the influence of several important factors remains unclear, including users' personalities, spatial abilities, and the different software used to manage their collections. We therefore analyse data from prior CHI work to explore (1) associations of people's file collections with personality and spatial ability, and (2) differences between collections managed with different operating systems and file managers. We find no notable associations between users' attributes and their collections, and minimal predictive power, but do find considerable and surprising differences across operating systems. We discuss these findings and how they can inform future research.
The focus of this study was to investigate the ability to discriminate between melodic intervals ... more The focus of this study was to investigate the ability to discriminate between melodic intervals of the equal tempered scale based solely on vibrotactile stimulation. In music, a melodic interval is the musical distance between two pitches, or notes, that are played sequentially. This paper tests the hypothesis that people can detect melodic intervals that are presented to different body sites such as the fingertip of the index finger of the non-dominant hand, as well as to the flank, the lateral region between the ribcage and the hip bone. Vibrotactile stimuli on the flank were displayed through voice coils of different diameters (0 13 mm and 0 25 mm respectively), while those at the finger were displayed with a 0 13 mm diameter voice coil. Six melodic intervals ranging from a minor second (A/=100 cents) to a perfect fifth (A/=700 cents) were compared to the reference interval of a perfect prime (A/=0 cents) at a fundamental frequency (/) of 65 Hz. Discrimination was significant for intervals as small as a major second (A/=200 cents; i.e. 8Hz, or 12.3%), depending on the location of the body. Overall, results tend to suggest that larger intervals are less difficult to detect than smaller intervals.
Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems, 2019
Although many challenges of managing computer files have been identified in past studies -- and m... more Although many challenges of managing computer files have been identified in past studies -- and many alternative prototypes made -- the scale and structure of personal file collections remain relatively unknown. We studied 348 such collections, and found they are typically considerably larger in scale (30-190 thousand files) and structure (folder trees twice taller and many times wider) than previously thought, which suggests files and folders are used now more than ever despite advances in Web storage, desktop search, and tagging. Data along many measures within and across collections were log normally distributed, indicating that personal collections resemble imbalanced, group-made collections and confirming the intuition that personal information management behaviour varies greatly. Directions for the generation of test collections and other future research are discussed.
Journal of Information & Knowledge Management, 2018
Many organisations are confronted with challenges in getting employees to effectively participate... more Many organisations are confronted with challenges in getting employees to effectively participate in information and knowledge sharing (IKS). Further, IKS is embedded in multifaceted social contexts, which are influenced by several different social and cognitive factors. This study is in support of the hypothesis that perceived trustworthiness is widely implicated as a mediating factor between those social–cognitive factors and IKS. Previous work, however, uncovered only a handful of such mediating effects. It is argued here that the paucity may have been due to limitations of the statistical methods. This study employs PROCESS, a more powerful current method for mediation analysis in an attempt to uncover previously hidden relationships. Analyses were performed on data collected from 275 knowledge workers (legal professionals and paralegals) engaged in shared legal project work, at one of Canada’s largest multijurisdictional law firms. Social–cognitive factors that were considered ...
Proceedings of the Association for Information Science and Technology, 2016
In this paper we describe the design and trial use of Cardinal, novel software that overcomes the... more In this paper we describe the design and trial use of Cardinal, novel software that overcomes the limitations of existing research tools used in personal information management (PIM) studies focusing on file management (FM) behavior. Cardinal facilitates large-scale collection of FM behavior data along an extensive list of file system properties and additional relevant dimensions (e.g., demographic, software and hardware, etc). It enables anonymous, remote, and asynchronous participation across the 3 major operating systems, uses a simple interface, and provides value to participants by presenting a summary of their file and folder collections. In a 15-day trial implementation, Cardinal examined over 2.3 million files across 46 unsupervised participants. To test its adaptability we extended it to also collect psychological questionnaire responses and technological data from each participant. Participation sessions took an average of just over 10 minutes to complete, and participants reported positive impressions of their interactions. Following the pilot, we revised Cardinal to further decrease participation time and improve the user interface. Our tests suggest that Cardinal is a viable tool for FM research, and so we have made its source freely available to the PIM community.
When landing a plane, pilots could face several landing illusions that are accentuated at night o... more When landing a plane, pilots could face several landing illusions that are accentuated at night or in a featureless environment. In the current study, we compare participants landing trajectories in a featureless environment with and without haptic feedback. We asked the participants to land a virtual object during featured (F+) and featureless night conditions (F−); with (H+) and without haptic feedback (H−). The results showed that the haptic feedback facilitated lateral and up-down movements. This benefit was less evident between the visual conditions suggesting that participants were relying on haptic cues during the task. This attentional shift could reduce visual illusions during night landings, where they are accentuated by the fact that experienced pilots rely mainly on visual inputs.
Proceedings of the 28th Annual ACM Symposium on User Interface Software & Technology, 2015
Many variables have been shown to impact whether a vibra tion stimulus will be perceived. We pres... more Many variables have been shown to impact whether a vibra tion stimulus will be perceived. We present a user study that takes into account not only previously investigated predictors such as vibration intensity and duration along with the age of the person receiving the stimulus, but also the amount of mo tion, as measured by an accelerometer, at the site of vibration immediately preceding the stimulus. This is a more specific measure than in previous studies showing an effect on per ception due to gross conditions such as walking. We show that a logistic regression model including prior acceleration is significantly better at predicting vibration perception than a model including only vibration intensity, duration and par ticipant age. In addition to the overall regression, we discuss individual participant differences and measures of classifica tion performance for real-world applications. Our expecta tion is that haptic interface designers will be able to use such results to design better vibrations that are perceivable under the user's current activity conditions, without being annoy ingly loud or jarring, eventually approaching "perceptually equivalent" feedback independent of motion.
Rumble strips (RS) offer ideal conditions for multimodality research. Designed to reduce crashes ... more Rumble strips (RS) offer ideal conditions for multimodality research. Designed to reduce crashes and alert drowsy or inattentive drivers, their effectiveness in crash reduction is not questioned but little is known regarding how information from tactile vibrations and auditory rumbling is integrated during low-vision driving conditions. In this paper, we report descriptive data related to participants' perceptual experience while driving on a RS road during a snow storm, as well as data collected from participants driving in a simulated snow storm environment, and suggest future research perspectives.
The aim of the presented research is to determine whether the perception of reverberation is depe... more The aim of the presented research is to determine whether the perception of reverberation is dependent on the type of sound stimuli used. We quantified the discrimination thresholds for reverberations that are representative for large rooms such as concert halls (reverberation times around 1.8 s). For exponential decays, simulating an ideal simple room, thresholds are around 6% (Experiment 1). We
We determined velocity discrimination thresholds and Weber fractions for sounds revolving around ... more We determined velocity discrimination thresholds and Weber fractions for sounds revolving around the listener at very high velocities. Sounds used were a broadband white noise and two harmonic sounds with fundamental frequencies of 330 Hz and 1760 Hz. Experiment 1 used velocities ranging between 288 /s and 720 /s in an acoustically treated room and Experiment 2 used velocities between 288 /s and 576 /s in a highly reverberant hall. A third experiment addressed potential confounds in the first two experiments. The results show that people can reliably discriminate velocity at very high velocities and that both thresholds and Weber fractions decrease as velocity increases. These results violate Weber's law but are consistent with the empirical trend observed in the literature. While thresholds for the noise and 330 Hz harmonic stimulus were similar, those for the 1760 Hz harmonic stimulus were substantially higher. There were no reliable differences in velocity discrimination between the two acoustical environments, suggesting that auditory motion perception at high velocities is robust against the effects of reverberation.
Traditional models of face recognition view identity and recognition of expression as implemented... more Traditional models of face recognition view identity and recognition of expression as implemented in separate systems, a view reinforced by the notion that prosopagnosia is a selective loss of the ability to recognize facial identity and is due to a loss of configuralprocessing ability. Yet, not much attention has been devoted to investigating the role of configural processing in recognition of facial expressions either in normal viewers or in prosopagnosics. We investigated the influence of facial organization on discrimination of a local facial feature, using a feature-matching task and comparing matching performance for either upright or inverted target presentation. Stimuli consisted of faces and face parts with or without expression, but task requirements were identical in both conditions. Normal viewers are equally sensitive to the face configuration whether the stimuli are neutral faces of face expressions. In contrast, prosopagnosic patients present an effect of the configuration only when there is a facial expression present
In order to assist the human operator modern auditory interfaces increasingly rely on sound spati... more In order to assist the human operator modern auditory interfaces increasingly rely on sound spatialization to display auditory information and warning signals all around the listener. However, we often operate in environments that apply vibrations to the whole body, e.g., when driving a vehicle. So there is a concern that vibrations impair spatial hearing and thereby the efficacy of sound spatialization. While effects of whole-body vibrations have been found to impair simple front-back discrimination, their effect on sound localization per se has received scant attention. Here we report three experiments that used a variety of sound localization performance measures and vibration manipulations. The first was a free-field localization experiment that compared performance under conditions with and without vibration (a 5 Hz sinusoidal movement along the vertical axis). The other experiments used classical psychophysical forced choice procedures and sound lateralization tasks in which stimuli were presented over headphones and position was manipulated through interaural time differences. In experiment 2 we used two vibrations (4 and 8 Hz) at two magnitudes (0.084 and 0.169 ms-2). In experiment 3, sound lateralization was assessed at central and more peripheral locations. In none of the experiment did we observe an effect of whole-body vibrations on localization performance.
The CyberWalk treadmill is the first truly omnidirectional treadmill of its size that allows for ... more The CyberWalk treadmill is the first truly omnidirectional treadmill of its size that allows for near natural walking through arbitrarily large Virtual Environments. The platform represents advances in treadmill and virtual reality technology and engineering, but it is also a major step towards having a single setup that allows the study of human locomotion and its many facets. This chapter focuses on the human behavioral research that was conducted to understand human locomotion from the perspective of specifying design criteria for the CyberWalk. The first part of this chapter describes research on the biomechanics of human walking, in particular, the nature of natural unconstrained walking and the effects of treadmill walking on characteristics of gait. The second part of this chapter describes the multisensory nature of walking, with a focus on the integration of vestibular and proprioceptive information during walking. The third part of this chapter describes research on large-scale human navigation and identifies possible causes for the human tendency to veer from a straight path, and even walk in circles when no external references are made available. The chapter concludes with a summary description of the features of the CyberWalk platform that were informed by this collection of research findings and briefly highlights the current and future scientific potential for this platform.
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Papers by Ilja Frissen