Hendrik Knoche - Academia.edu (original) (raw)
Papers by Hendrik Knoche
EAI Endorsed Transactions on Pervasive Health and Technology, 2017
We designed and evaluated a whack-a-mole (WAM) style game (see Figure 1) in a clinical randomized... more We designed and evaluated a whack-a-mole (WAM) style game (see Figure 1) in a clinical randomized controlled trial (RCT) with reminder-assisted but self-initiated use over the period of a month with 43 participants from a post-lesion pool. While game play did not moderate rehabilitative progress indices of standard neuropsychological control tests, it did significantly improve in-game performance when compared to the control group. Its performance indicators and interaction data were highly accurate in predicting neglect and which hand the patients used for input. Patients found playing beneficial to their rehabilitation and attributed gains in the attention training properties of the game. The game showed potential for bedside assessment, insight support, and motivation by providing knowledge about rehabilitative progress.
Previous studies have found mobile TV usage durations to be shorter than 10 minutes [1]. News pro... more Previous studies have found mobile TV usage durations to be shorter than 10 minutes [1]. News programmes fit this requirement and were identified by mobile phone users in focus groups and surveys as the most interesting content type [2]. This paper presents two studies that investigate human requirements on the delivery and presentation of TV news footage at different video and audio encoding bitrates. The effects of resolution, picture size, different mobile presentation devices, encoding schemes and audio on the news content are presented. To ensure validity both studies were carried out on mobile devices. Study 1 examined video and audio encoding bitrates on a 3G phone and an IPAQ PDA whereas study 2 looked at various resolutions and picture sizes ranging from 120x90 to 240x180 on an IPAQ.
Broadcast (SDMB) project aims to deliver multimedia services to West European mobile phone users ... more Broadcast (SDMB) project aims to deliver multimedia services to West European mobile phone users in a cost efficient manner. To understand the service requirements for SDMB, a series of focus groups were conducted in three countries. These explored users ’ needs and expectations of next generation mobile multimedia services by probing seven different service types. The results illustrate different demand spectrums in different countries and give an interesting insight into the services people really want. Index Terms — mobile phone usage, user expectations, user needs, SDMB T
Universal Access in the Information Society
AbstractWe designed a vibrotactile vest and The Humming Wall, a vibroacoustic interactive furnitu... more AbstractWe designed a vibrotactile vest and The Humming Wall, a vibroacoustic interactive furniture set in an urban environment to interact with each other. We developed the vibrotactile patterns in the vest as a form of vibrotactile language to convey information to the wearer. In addition, we designed a set of interactive movements on The Humming Wall that would trigger patterns on the vest and elicit sensations and encourage body movements onto the wearer’s body. We invited people to interact in pairs at The Humming Wall, with one at the wall and one wearing the vest (they later swapped roles). Actions by the one at the wall, such as swiping or knocking on the wall were repeated on the vest wearer’s body. In addition, participants could ‘feel’ (vibroacoustically) and hear their own heartbeats and breath rates at the wall. We conducted a field trial with 39 participants over a 5-week period. Participants wearing the vest (and their pair) completed a set of tasks. We logged use and responses, recorded all activities on video and conducted post-experiment interviews and questionnaires. The results depicted the participants’ experience, communication and connection while wearing the vibrotactile vest and interacting with the wall. The findings show convincing, strong and positive responses to novel interactions between the responsive vibroacoustic environment and the vibrotactile vest. This work constitutes the first field trial with people ‘working’ in pairs with a vibrotactile wearable responding to and driving vibroacoustic displays with an interactive vibroacoustic environment.
ACM Transactions on Multimedia Computing, Communications, and Applications, 2009
The migration of media consumption to personal computers retains distributed social viewing, but ... more The migration of media consumption to personal computers retains distributed social viewing, but only via nonsocial, strictly personal interfaces. This article presents an architecture, and implementation for media sharing that allows for enhanced social interactions among users. Using a mixed-device model, our work allows targeted, personalized enrichment of content. All recipients see common content, while differentiated content is delivered to individuals via their personal secondary screens. We describe the goals, architecture, and implementation of our system in this article. In order to validate our results, we also present results from two user studies involving disjoint sets of test participants.
Common emotional effects following a stroke include depression, apathy and lack of motivation. We... more Common emotional effects following a stroke include depression, apathy and lack of motivation. We conducted a longitudinal case study to investigate if enabling a post-stroke former guitarist re-learn to play guitar would help increase motivation for self rehabilitation and quality of life after suffering a stroke. The intervention lasted three weeks during which the participant had a fully functional electrical guitar fitted with a strumming device controlled by a foot pedal at his free disposal. The device replaced right strumming of the strings, and the study showed that the participant, who was highly motivated, played 20 sessions despite system latency and reduced musical expression. He incorporated his own literature and equipment into his playing routine and improved greatly as the study progressed. He was able to play alone and keep a steady rhythm in time with backing tracks that went as fast as 120bpm. During the study he was able to lower his error rate to 33%, while his ...
The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to... more The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to identifying quality requirements for audio and video quality in the context of novel multimedia services. We advocate an approach that maximizes ecological validity. It is important to recruit participants from the expected user population, create realistic tasks and using real material, and use an assessment method that creates minimal load on study participants. Finally, it is important to replicate all physical factors that affect quality in the eventual context of use. We present an example of how we apply this approach to identifying video quality requirements for mobile TV viewing. 1.
This paper describes the challenges faced in ICT-D by reviewing the lessons learned from a projec... more This paper describes the challenges faced in ICT-D by reviewing the lessons learned from a project geared at improving the livelihood of marginal farmers in India through wireless sensor networks. Insufficient user participation, lack of attention to user needs and a primary focus on technology in the design process led to unconvinced target users who were not interested in adopting the new technology. We present some of the benefits ICTD can reap from incorporating human-centered design (HCD) principles and holistic user involvement and methods that have been shown to improve the design of socio-technical systems in the field of human computer interaction (HCI). In turn, to meet the challenges in the development arena HCI and HCD have to incorporate well established (participatory) action research and rural appraisal approaches that help achieving sustainable outcomes. Categories and Subject Descriptors H.5.2 [Information Interfaces and Presentation]: User-centered design
Mobile TV services are available in an increasing number of countries. For cost reasons, most of ... more Mobile TV services are available in an increasing number of countries. For cost reasons, most of these services offer material directly recoded for mobile consumption (i.e. without additional editing). This paper reports the findings of a study on the influence of text legibility and quality on the perceived video quality of mobile TV content. The study, with 64 participants, examined responses to news footage presented at four image resolutions and seven video encoding bitrates. The results showed that a simulated separate delivery of a news ticker and other textual information significantly increased the perceived video quality of the entire screen for native speakers. In addition, some automatable changes to the layout of news content resulted in substantial increases in perceived video quality. The results can be used to quantify the perceived quality gains when considering text delivery separately from the video stream and in the development of more accurate multimedia quality ...
Speech is one of the promising candidates to convey information to illiterate users through non-t... more Speech is one of the promising candidates to convey information to illiterate users through non-text user interfaces. This paper describes the challenges that marginal farmers in India face in terms of ICT accessibility on mobile phones in an ICT4D project. The central question is how to submit and convey information through low end mobile phones in ways that illiterate or semiliterate farmers will find trustworthy and help them adapt their farming practices.
: This paper describes the design considerations for a mobile television service from a user-cent... more : This paper describes the design considerations for a mobile television service from a user-centred perspective. Results from previous research on interface design, traditional TV consumption, and focus groups on user expectations and needs in a mobile context are taken into account. 1. Introduction This paper explains the design considerations for a demonstrator for a mobile TV service, which will be part of and accessed through mobile phone devices. More specifically, this demonstrator emulates the service of the Satellite Digital Multimedia Broadcast (SDMB) system. The cost-efficient country-wide distribution of the multimedia content will be achieved by integrating satellite broadcast capacities with existing terrestrial 3G and beyond 3G infrastructures [1]. The SDMB service assumes the use of mobile phones with extensive storage that allows the consumption of previously cached content at opportune times as well as the watching of live streams and receipt of alerts. The interfa...
Recent advances in mobile device technology have freed augmented reality (AR) applications from t... more Recent advances in mobile device technology have freed augmented reality (AR) applications from the constraints of desktops, laptops and head-mounted displays. But they are met with a lack of guidelines on the design and user interactions of mobile device-based AR systems. The situation for developers is further exacerbated by closed-license environments and inflexible solutions. We provide an overview of the design of AR applications on handheld devices, the necessary building blocks and problems that future AR systems need to overcome. This experience was gathered during the design and development of an AR framework for the AndroidTM platform. User experience evaluations showed a great demand for overlay collision avoidance and the value of being able to freeze AR screens. These will be valuable for the design of future mobile device based AR applications.
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](Mobile TV can deliver up-to-date content to users on the move. But it is currently unclear how to... more Mobile TV can deliver up-to-date content to users on the move. But it is currently unclear how to best adapt higher resolution TV content. In this paper, we describe a laboratory study with 35 participants who watched short clips of different content and shot types on a 200ppi PDA display at a resolution of either 120x90 or 168x128. Participants selected their preferred size and rated the acceptability of the visual experience. The preferred viewing ratio depended on the resolution and had to be at least 9.8H. The minimal angular resolution people required and which limited the up-scaling factor was 14 pixels per degree. Extreme long shots were best when depicted actors were at least 0.7 ° high. A second study researched the ecological validity of previous lab results by comparing them to results from the field. Image size yielded more value for users in the field than was apparent from lab results. In conclusion, current prediction models based on preferred viewing distances for TV...
Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems
The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to... more The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to identifying quality requirements for audio and video quality in the context of novel multimedia services. We advocate an approach that maximizes ecological validity. It is important to recruit participants from the expected user population, create realistic tasks and using real material, and use an assessment method that creates minimal load on study participants. Finally, it is important to replicate all physical factors that affect quality in the eventual context of use. We present an example of how we apply this approach to identifying video quality requirements for mobile TV viewing.
Converging Clinical and Engineering Research on Neurorehabilitation III
Proceedings of the ACM on Human-Computer Interaction, 2021
To reduce frustration while performing no-risk tasks (e.g. in training and games) for BCI users, ... more To reduce frustration while performing no-risk tasks (e.g. in training and games) for BCI users, we propose increasing their perceived level of control through fabricated input - system-generated positive task outcomes. Two surrogate BCI studies injected fabricated input creating additional positive task outcomes to a 50% baseline. Users' perceived control increased significantly compared to the 50% baseline. In turn, frustration levels decreased. Fabricated input worked equally well in a game story context that provided an emotional stake in the protagonist's success and a simpler task lacking such incentives. People's number of input attempts during the tasks determined perceived control more than our controlled ratios of positive to negative task outcomes. Delays between users' input attempts and subsequent fabricated inputs further moderated their perceived control.
Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems
Universal Access in the Information Society
EAI Endorsed Transactions on Pervasive Health and Technology, 2017
We designed and evaluated a whack-a-mole (WAM) style game (see Figure 1) in a clinical randomized... more We designed and evaluated a whack-a-mole (WAM) style game (see Figure 1) in a clinical randomized controlled trial (RCT) with reminder-assisted but self-initiated use over the period of a month with 43 participants from a post-lesion pool. While game play did not moderate rehabilitative progress indices of standard neuropsychological control tests, it did significantly improve in-game performance when compared to the control group. Its performance indicators and interaction data were highly accurate in predicting neglect and which hand the patients used for input. Patients found playing beneficial to their rehabilitation and attributed gains in the attention training properties of the game. The game showed potential for bedside assessment, insight support, and motivation by providing knowledge about rehabilitative progress.
Previous studies have found mobile TV usage durations to be shorter than 10 minutes [1]. News pro... more Previous studies have found mobile TV usage durations to be shorter than 10 minutes [1]. News programmes fit this requirement and were identified by mobile phone users in focus groups and surveys as the most interesting content type [2]. This paper presents two studies that investigate human requirements on the delivery and presentation of TV news footage at different video and audio encoding bitrates. The effects of resolution, picture size, different mobile presentation devices, encoding schemes and audio on the news content are presented. To ensure validity both studies were carried out on mobile devices. Study 1 examined video and audio encoding bitrates on a 3G phone and an IPAQ PDA whereas study 2 looked at various resolutions and picture sizes ranging from 120x90 to 240x180 on an IPAQ.
Broadcast (SDMB) project aims to deliver multimedia services to West European mobile phone users ... more Broadcast (SDMB) project aims to deliver multimedia services to West European mobile phone users in a cost efficient manner. To understand the service requirements for SDMB, a series of focus groups were conducted in three countries. These explored users ’ needs and expectations of next generation mobile multimedia services by probing seven different service types. The results illustrate different demand spectrums in different countries and give an interesting insight into the services people really want. Index Terms — mobile phone usage, user expectations, user needs, SDMB T
Universal Access in the Information Society
AbstractWe designed a vibrotactile vest and The Humming Wall, a vibroacoustic interactive furnitu... more AbstractWe designed a vibrotactile vest and The Humming Wall, a vibroacoustic interactive furniture set in an urban environment to interact with each other. We developed the vibrotactile patterns in the vest as a form of vibrotactile language to convey information to the wearer. In addition, we designed a set of interactive movements on The Humming Wall that would trigger patterns on the vest and elicit sensations and encourage body movements onto the wearer’s body. We invited people to interact in pairs at The Humming Wall, with one at the wall and one wearing the vest (they later swapped roles). Actions by the one at the wall, such as swiping or knocking on the wall were repeated on the vest wearer’s body. In addition, participants could ‘feel’ (vibroacoustically) and hear their own heartbeats and breath rates at the wall. We conducted a field trial with 39 participants over a 5-week period. Participants wearing the vest (and their pair) completed a set of tasks. We logged use and responses, recorded all activities on video and conducted post-experiment interviews and questionnaires. The results depicted the participants’ experience, communication and connection while wearing the vibrotactile vest and interacting with the wall. The findings show convincing, strong and positive responses to novel interactions between the responsive vibroacoustic environment and the vibrotactile vest. This work constitutes the first field trial with people ‘working’ in pairs with a vibrotactile wearable responding to and driving vibroacoustic displays with an interactive vibroacoustic environment.
ACM Transactions on Multimedia Computing, Communications, and Applications, 2009
The migration of media consumption to personal computers retains distributed social viewing, but ... more The migration of media consumption to personal computers retains distributed social viewing, but only via nonsocial, strictly personal interfaces. This article presents an architecture, and implementation for media sharing that allows for enhanced social interactions among users. Using a mixed-device model, our work allows targeted, personalized enrichment of content. All recipients see common content, while differentiated content is delivered to individuals via their personal secondary screens. We describe the goals, architecture, and implementation of our system in this article. In order to validate our results, we also present results from two user studies involving disjoint sets of test participants.
Common emotional effects following a stroke include depression, apathy and lack of motivation. We... more Common emotional effects following a stroke include depression, apathy and lack of motivation. We conducted a longitudinal case study to investigate if enabling a post-stroke former guitarist re-learn to play guitar would help increase motivation for self rehabilitation and quality of life after suffering a stroke. The intervention lasted three weeks during which the participant had a fully functional electrical guitar fitted with a strumming device controlled by a foot pedal at his free disposal. The device replaced right strumming of the strings, and the study showed that the participant, who was highly motivated, played 20 sessions despite system latency and reduced musical expression. He incorporated his own literature and equipment into his playing routine and improved greatly as the study progressed. He was able to play alone and keep a steady rhythm in time with backing tracks that went as fast as 120bpm. During the study he was able to lower his error rate to 33%, while his ...
The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to... more The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to identifying quality requirements for audio and video quality in the context of novel multimedia services. We advocate an approach that maximizes ecological validity. It is important to recruit participants from the expected user population, create realistic tasks and using real material, and use an assessment method that creates minimal load on study participants. Finally, it is important to replicate all physical factors that affect quality in the eventual context of use. We present an example of how we apply this approach to identifying video quality requirements for mobile TV viewing. 1.
This paper describes the challenges faced in ICT-D by reviewing the lessons learned from a projec... more This paper describes the challenges faced in ICT-D by reviewing the lessons learned from a project geared at improving the livelihood of marginal farmers in India through wireless sensor networks. Insufficient user participation, lack of attention to user needs and a primary focus on technology in the design process led to unconvinced target users who were not interested in adopting the new technology. We present some of the benefits ICTD can reap from incorporating human-centered design (HCD) principles and holistic user involvement and methods that have been shown to improve the design of socio-technical systems in the field of human computer interaction (HCI). In turn, to meet the challenges in the development arena HCI and HCD have to incorporate well established (participatory) action research and rural appraisal approaches that help achieving sustainable outcomes. Categories and Subject Descriptors H.5.2 [Information Interfaces and Presentation]: User-centered design
Mobile TV services are available in an increasing number of countries. For cost reasons, most of ... more Mobile TV services are available in an increasing number of countries. For cost reasons, most of these services offer material directly recoded for mobile consumption (i.e. without additional editing). This paper reports the findings of a study on the influence of text legibility and quality on the perceived video quality of mobile TV content. The study, with 64 participants, examined responses to news footage presented at four image resolutions and seven video encoding bitrates. The results showed that a simulated separate delivery of a news ticker and other textual information significantly increased the perceived video quality of the entire screen for native speakers. In addition, some automatable changes to the layout of news content resulted in substantial increases in perceived video quality. The results can be used to quantify the perceived quality gains when considering text delivery separately from the video stream and in the development of more accurate multimedia quality ...
Speech is one of the promising candidates to convey information to illiterate users through non-t... more Speech is one of the promising candidates to convey information to illiterate users through non-text user interfaces. This paper describes the challenges that marginal farmers in India face in terms of ICT accessibility on mobile phones in an ICT4D project. The central question is how to submit and convey information through low end mobile phones in ways that illiterate or semiliterate farmers will find trustworthy and help them adapt their farming practices.
: This paper describes the design considerations for a mobile television service from a user-cent... more : This paper describes the design considerations for a mobile television service from a user-centred perspective. Results from previous research on interface design, traditional TV consumption, and focus groups on user expectations and needs in a mobile context are taken into account. 1. Introduction This paper explains the design considerations for a demonstrator for a mobile TV service, which will be part of and accessed through mobile phone devices. More specifically, this demonstrator emulates the service of the Satellite Digital Multimedia Broadcast (SDMB) system. The cost-efficient country-wide distribution of the multimedia content will be achieved by integrating satellite broadcast capacities with existing terrestrial 3G and beyond 3G infrastructures [1]. The SDMB service assumes the use of mobile phones with extensive storage that allows the consumption of previously cached content at opportune times as well as the watching of live streams and receipt of alerts. The interfa...
Recent advances in mobile device technology have freed augmented reality (AR) applications from t... more Recent advances in mobile device technology have freed augmented reality (AR) applications from the constraints of desktops, laptops and head-mounted displays. But they are met with a lack of guidelines on the design and user interactions of mobile device-based AR systems. The situation for developers is further exacerbated by closed-license environments and inflexible solutions. We provide an overview of the design of AR applications on handheld devices, the necessary building blocks and problems that future AR systems need to overcome. This experience was gathered during the design and development of an AR framework for the AndroidTM platform. User experience evaluations showed a great demand for overlay collision avoidance and the value of being able to freeze AR screens. These will be valuable for the design of future mobile device based AR applications.
Mobile TV can deliver up-to-date content to users on the move. But it is currently unclear how to... more Mobile TV can deliver up-to-date content to users on the move. But it is currently unclear how to best adapt higher resolution TV content. In this paper, we describe a laboratory study with 35 participants who watched short clips of different content and shot types on a 200ppi PDA display at a resolution of either 120x90 or 168x128. Participants selected their preferred size and rated the acceptability of the visual experience. The preferred viewing ratio depended on the resolution and had to be at least 9.8H. The minimal angular resolution people required and which limited the up-scaling factor was 14 pixels per degree. Extreme long shots were best when depicted actors were at least 0.7 ° high. A second study researched the ecological validity of previous lab results by comparing them to results from the field. Image size yielded more value for users in the field than was apparent from lab results. In conclusion, current prediction models based on preferred viewing distances for TV...
Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems
The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to... more The paper presents an overview of Quality of Service (QoS) definitions, and reviews approaches to identifying quality requirements for audio and video quality in the context of novel multimedia services. We advocate an approach that maximizes ecological validity. It is important to recruit participants from the expected user population, create realistic tasks and using real material, and use an assessment method that creates minimal load on study participants. Finally, it is important to replicate all physical factors that affect quality in the eventual context of use. We present an example of how we apply this approach to identifying video quality requirements for mobile TV viewing.
Converging Clinical and Engineering Research on Neurorehabilitation III
Proceedings of the ACM on Human-Computer Interaction, 2021
To reduce frustration while performing no-risk tasks (e.g. in training and games) for BCI users, ... more To reduce frustration while performing no-risk tasks (e.g. in training and games) for BCI users, we propose increasing their perceived level of control through fabricated input - system-generated positive task outcomes. Two surrogate BCI studies injected fabricated input creating additional positive task outcomes to a 50% baseline. Users' perceived control increased significantly compared to the 50% baseline. In turn, frustration levels decreased. Fabricated input worked equally well in a game story context that provided an emotional stake in the protagonist's success and a simpler task lacking such incentives. People's number of input attempts during the tasks determined perceived control more than our controlled ratios of positive to negative task outcomes. Delays between users' input attempts and subsequent fabricated inputs further moderated their perceived control.
Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems
Universal Access in the Information Society
In this study we investigate the experience for participants while wearing a vibrotactile vest th... more In this study we investigate the experience for participants while wearing a vibrotactile vest that interacts with a vibroacoustic architecture The Humming Wall, set in an urban space. This public large scale artefact is built to exchange vibrotactile and physiological interactions with a vibrotactile wearable vest. The heart beats and breath rates of the vest wearers are vibroacoustically displayed at The Humming Wall. In addition, participants can swipe and knock on The Humming Wall and the vest wearer is effectively swiped and knocked upon. We work with overlapping vibrotactile outputs in order that the wearers experience a flow of sensations similar to a touch gesture. The communication advan-taged vibroacoustic and vibrotactile as the primary interaction modalities for both vest wearers as well as for a passing public. The participants found the experience favourable and analysis reveals some patterns on the vest and zones at the wall impact relaxation in the form of calming and feel-good sensations, (even therapeutic) as well as activation and warning on the vest. We contribute to this research field by adding a large scale public object and visibly responsive interactive wall that was positively received as the partner responder for the wearers of a vibrotac-tile vest set in an urban environment. Participants reported calming, therapeutic, feel good sensations in response to the patterns.