Range and variability in gesture-based interactions with medical images : do non-stereo versus stereo visualizations elicit different types of gestures?

The current paper presents a study into the range and variability of natural gestures when interacting with medical images, using traditional non stereo and stereoscopic modes of presentation. The results have implications for the design of computer-vision algorithms developed to support natural gesture-based interactions in a medical context

Smoothness and flicker perception of temporal color transitions

\u3cp\u3eWe present results from two experiments designed to explore temporal properties of human color vision relevant to dynamic lighting applications. Sensitivity for smoothness perception of linear temporal transitions and flicker visibility was tested. Stimuli in the first experiment were linear color transitions, varying in either lightness, chroma or hue, around a base color represented in CIE LCh. Results show a significantly lower smoothness threshold for lightness changes than for chroma and hue changes. Moreover, the thresholds for lightness change show independence from the chroma and hue of the base color in contrast to thresholds for chroma and hue changes. A difference between the sensitivity for chroma and hue changes was also demonstrated. In the second experiment, the sensitivity for linear transitions is compared to flicker sensitivity for the same base colors. Results show that visibility thresholds for flicker are significantly lower than the thresholds smoothness of linear changes, demonstrating an influence of the type of change to the temporal sensitivity. The results from the flicker experiment show the same tendencies as the linear changes. The results from these experiments show a need for a model of perceived smoothness to control temporal changes in dynamic lighting systems and give the first steps towards building such a model.\u3c/p\u3

Effectiveness of stereoscopic displays in medicine : a review

In this paper we review empirical studies concerning the effectiveness of stereoscopic displays in medicine. The domains covered in this review are: diagnosis, pre-operative planning, minimally invasive surgery (MIS) and training/teaching. For diagnosis, stereoscopic viewing of medical data has been shown to improve the sensitivity of tumor detection in breast imaging, and to improve the visualization of internal structures in 3D ultrasound. For MRI and CT data, where images are frequently rendered in 3D perspective, the added value of binocular depth has not yet been convincingly demonstrated. For MIS, stereoscopic displays decrease surgery time and increase accuracy of surgical procedures when the resolution of the stereoscopic displays is comparable to that of 2D displays. Training and surgical planning already use computer simulations; more research however is needed to assess the potential benefits of stereoscopic displays in those applications. Overall, there is a clear need for more empirical evidence that quantifies the added value of stereoscopic displays in medical domains

User experience of gesture based interfaces:A comparison with traditional interaction methods on pragmatic and hedonic qualities

Studies into gestural interfaces - and interfaces in general - typically focus on pragmatic or usability aspects (e.g., ease of use, learnability). Yet the merits of gesture-based interaction likely go beyond the purely pragmatic and impact a broader class of experiences, involving also qualities such as enjoyment, stimulation, and identification. The current study compared gesture-based interaction with device-based interaction, in terms of both their pragmatic and hedonic qualities. Two experiments were performed, one in a near-field context (mouse vs. gestures), and one in a far-field context (Wii vs. gestures). Results show that, whereas device-based interfaces generally scored higher on perceived performance, and the mouse scored higher on pragmatic quality, embodied interfaces (gesture-based interfaces, but also the Wii) scored higher in terms of hedonic quality and fun. A broader perspective on evaluating embodied interaction technologies can inform the design of such technologies and allow designers to tailor them to the appropriate application.</p

Time perception and timed decision task performance during passive heat stress

This study investigates the hypotheses that during passive heat stress, the change in perception of time and change in accuracy of a timed decision task relate to changes in thermophysiological variables gastrointestinal temperature and heart rate (HR), as well as subjective measures of cognitive load and thermal perception. Young adult males (N = 29) participated in two 60-min head-out water immersion conditions (36.5°C-neutral and 38.0°C-warm). Cognitive task measurements included accuracy (judgment task), response time (judgment ask), and time estimation (interval timing task). Physiological measurements included gastrointestinal temperature and heart rate. Subjective measurements included cognitive task load (NASA-TLX), rate of perceived exertion, thermal sensation, and thermal comfort. Gastrointestinal temperature and HR were significantly higher in warm versus neutral condition (gastrointestinal temperature: 38.4 ± 0.2°C vs. 37.2 ± 0.2°C, p < 0.01; HR: 105 ± 8 BPM vs. 83 ± 9 BPM, p < 0.01). The change in accuracy was significantly associated with the change in gastrointestinal temperature, and attenuated by change in thermal sensation and change in HR (r2=0.40, p< 0.01). Change in response time was significantly associated with the change in gastrointestinal temperature (r2=0.26, p< 0.002), and change in time estimation was best explained by a change in thermal discomfort (r2=0.18, p< 0.01). Changes in cognitive performance during passive thermal stress are significantly associated with changes in thermophysiological variables and thermal perception. Although explained variance is low (<50%), decreased accuracy is attributed to increased gastrointestinal temperature, yet is attenuated by increased arousal (expressed as increased HR and warmth thermal sensation)

Time perception and timed decision task performance during passive heat stress

This study investigates the hypotheses that during passive heat stress, the change in perception of time and change in accuracy of a timed decision task relate to changes in thermophysiological variables gastrointestinal temperature and heart rate (HR), as well as subjective measures of cognitive load and thermal perception. Young adult males (N = 29) participated in two 60-min head-out water immersion conditions (36.5°C-neutral and 38.0°C-warm). Cognitive task measurements included accuracy (judgment task), response time (judgment ask), and time estimation (interval timing task). Physiological measurements included gastrointestinal temperature and heart rate. Subjective measurements included cognitive task load (NASA-TLX), rate of perceived exertion, thermal sensation, and thermal comfort. Gastrointestinal temperature and HR were significantly higher in warm versus neutral condition (gastrointestinal temperature: 38.4 ± 0.2°C vs. 37.2 ± 0.2°C, p < 0.01; HR: 105 ± 8 BPM vs. 83 ± 9 BPM, p < 0.01). The change in accuracy was significantly associated with the change in gastrointestinal temperature, and attenuated by change in thermal sensation and change in HR (r2=0.40, p< 0.01). Change in response time was significantly associated with the change in gastrointestinal temperature (r2=0.26, p< 0.002), and change in time estimation was best explained by a change in thermal discomfort (r2=0.18, p< 0.01). Changes in cognitive performance during passive thermal stress are significantly associated with changes in thermophysiological variables and thermal perception. Although explained variance is low (<50%), decreased accuracy is attributed to increased gastrointestinal temperature, yet is attenuated by increased arousal (expressed as increased HR and warmth thermal sensation)

User experience of gesture based interfaces: A comparison with traditional interaction methods on pragmatic and hedonic qualities

Studies into gestural interfaces - and interfaces in general - typically focus on pragmatic or usability aspects (e.g., ease of use, learnability). Yet the merits of gesture-based interaction likely go beyond the purely pragmatic and impact a broader class of experiences, involving also qualities such as enjoyment, stimulation, and identification. The current study compared gesture-based interaction with device-based interaction, in terms of both their pragmatic and hedonic qualities. Two experiments were performed, one in a near-field context (mouse vs. gestures), and one in a far-field context (Wii vs. gestures). Results show that, whereas device-based interfaces generally scored higher on perceived performance, and the mouse scored higher on pragmatic quality, embodied interfaces (gesture-based interfaces, but also the Wii) scored higher in terms of hedonic quality and fun. A broader perspective on evaluating embodied interaction technologies can inform the design of such technologies and allow designers to tailor them to the appropriate application

Core body temperature speeds up temporal processing and choice behavior under deadlines

Evidence suggests that human timing ability is compromised by heat. In particular, some studies suggest that increasing body temperature speeds up an internal clock, resulting in faster time perception. However, the consequences of this speed-up for other cognitive processes remain unknown. In the current study, we rigorously tested the speed-up hypothesis by inducing passive hyperthermia through immersion of participants in warm water. In addition, we tested how a change in time perception affects performance in decision making under deadline stress. We found that participants underestimate a prelearned temporal interval when body temperature increases, and that their performance in a two-alternative forced-choice task displays signatures of increased time pressure. these results show not only that timing plays an important role in decision-making, but also that this relationship is mediated by temperature. the consequences for decision-making in job environments that are demanding due to changes in body temperature may be considerable