Human factors and performance considerations of visual spatial skills in medical context tasks

In the medical field, stereoscopic applications are present in diagnosis, pre-operative planning, minimally invasive surgery, instruction, and training. The use of stereoscopic applications has afforded new ways to interact with patient data, such as immersive virtual environments. This increased usage of stereoscopic applications also raises many basic research questions on human perception and performance. Current studies show mixed results on the benefits of stereoscopic applications with regards to general performance. The benefits depend on the specific task as well as the application domain. The work presented here attempts to answer the general question: How would adding the stereopsis depth cue affect the performance of visual spatial tasks in a medical context? Visual spatial tasks are needed in medicine to understand the relationships between shapes and organs for a variety of activities in patient diagnosis and treatment. The general research question was decomposed into specific hypotheses and three studies were conducted to study them. These studies measured performance of a visual spatial computer task using medical imaging data. Participants assessed the relative positions of three different objects located inside a 3D volumetric representation of a patient\u27s anatomy. The first study consisted of static views and recognition of the position of color objects. The second study consisted of static views using gray objects. The third study consisted of animated views of color objects. In all three studies the task was basically the same: To select which of two objects was closest to a reference object. In all three studies participants were first and second year medical students. Thirty-four participants completed the first study. The results of this study showed some emerging patterns in which the stereoscopic display condition had a positive benefit on performance. The stereoscopic condition had a positive effect on performance for the most difficult cases but did not yield higher results under every case and condition. The second study, completed by 44 participants, showed the stereoscopic condition had a positive benefit on performance in 20 out of the 40 tasks completed. These 40 tasks were divided into four cases, with varying degrees of difficulty, depending on the distances between the objects being judged (i.e. cylinders in this study). At distances between 5-15 mm, the stereoscopic condition yielded statistically significant higher performance. At other distance ranges, while stereopsis showed improvement it was not statistically significant. Thirty-one participants completed the third study. These participants completed a visual spatial task with the addition of an animation to the volume. This allowed the representation to be viewed from multiple angles before the task was completed. Overall the stereoscopic condition had a benefit in performance over the monoscopic condition. As in the previous studies tasks that had the objects between 5 - 15 mm apart had higher performance in the stereoscopic condition. Females performance in the stereoscopic condition was higher and statistically significant than for the monoscopic condition. Participants over 25 years also had a statistically significant higher performance under the stereoscopic condition. It was also observed that the stereoscopic condition did not outperform the monoscopic one in every condition. The results of these studies show that, in general, stereopsis has a positive benefit in performance for visual spatial tasks in medical contexts. This benefit certainly has a relationship with the difficulty of the task as well as age and gender. These initial insights are a step into further work to help generate design guidelines when developing stereoscopic applications

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

Multi-touch 3D Exploratory Analysis of Ocean Flow Models

Modern ocean flow simulations are generating increasingly complex, multi-layer 3D ocean flow models. However, most researchers are still using traditional 2D visualizations to visualize these models one slice at a time. Properly designed 3D visualization tools can be highly effective for revealing the complex, dynamic flow patterns and structures present in these models. However, the transition from visualizing ocean flow patterns in 2D to 3D presents many challenges, including occlusion and depth ambiguity. Further complications arise from the interaction methods required to navigate, explore, and interact with these 3D datasets. We present a system that employs a combination of stereoscopic rendering, to best reveal and illustrate 3D structures and patterns, and multi-touch interaction, to allow for natural and efficient navigation and manipulation within the 3D environment. Exploratory visual analysis is facilitated through the use of a highly-interactive toolset which leverages a smart particle system. Multi-touch gestures allow users to quickly position dye emitting tools within the 3D model. Finally, we illustrate the potential applications of our system through examples of real world significance

Operator vision aids for space teleoperation assembly and servicing

This paper investigates concepts for visual operator aids required for effective telerobotic control. Operator visual aids, as defined here, mean any operational enhancement that improves man-machine control through the visual system. These concepts were derived as part of a study of vision issues for space teleoperation. Extensive literature on teleoperation, robotics, and human factors was surveyed to definitively specify appropriate requirements. This paper presents these visual aids in three general categories of camera/lighting functions, display enhancements, and operator cues. In the area of camera/lighting functions concepts are discussed for: (1) automatic end effector or task tracking; (2) novel camera designs; (3) computer-generated virtual camera views; (4) computer assisted camera/lighting placement; and (5) voice control. In the technology area of display aids, concepts are presented for: (1) zone displays, such as imminent collision or indexing limits; (2) predictive displays for temporal and spatial location; (3) stimulus-response reconciliation displays; (4) graphical display of depth cues such as 2-D symbolic depth, virtual views, and perspective depth; and (5) view enhancements through image processing and symbolic representations. Finally, operator visual cues (e.g., targets) that help identify size, distance, shape, orientation and location are discussed