Quantifying accuracy on distance estimation tasks: A Monte Carlo study.

An important aspect of perceptual learning involves understanding how well individuals can perceive distances, sizes, and time-to-contact. Oftentimes, the primary goal in these experiments is to assess participants' errors (i.e.

Effects of arm-support exoskeletons on pointing accuracy and movement.

Exoskeletons are wearable devices that support or augment users' physical abilities. Previous studies indicate that they reduce the physical demands of repetitive tasks such as those involving heavy material handling, work performed with arms elevated, and the use of heavy tools. However, there have been concerns about exoskeletons hindering movement and reducing its precision.

Investigating the Effects of Avatarization and Interaction Techniques on Near-field Mixed Reality Interactions with Physical Components.

Mixed reality (MR) interactions feature users interacting with a combination of virtual and physical components. Inspired by research investigating aspects associated with near-field interactions in augmented and virtual reality (AR & VR), we investigated how avatarization, the physicality of the interacting components, and the interaction technique used to manipulate a virtual object affected performance and perceptions of user experience in a mixed reality fundamentals of laparoscopic peg-transfer task wherein users had to transfer a virtual ring from one peg to another for a number of trials. We employed a 3 (Physicality of pegs) X 3 (Augmented Avatar Representation) X 2 (Interaction Technique) multi-factorial design, manipulating the physicality of the pegs as a between-subjects factor, the type of augmented self-avatar representation, and the type of interaction technique used for object-manipulation as within-subjects factors.

Generalizing the optic flow equalization control law to an asymmetrical person-plus-object system.

Visually guided action in humans occurs in part through the use of control laws, which are dynamical equations in which optical information modulates an actor's interaction with their environment. For example, humans locomote through the center of a corridor by equalizing the speed of optic flow across their left and right fields of view. This optic flow equalization control law relies on a crucial assumption: that the shape of the body relative to the eyes is laterally symmetrical.

Gone Fishin': Perceiving the length of one object that is non-rigidly attached to a wielded object.

We performed four experiments to investigate whether people can perceive the length of a target object (a "fish") that is attached to a freely wielded object (the "fishing pole") by a length of string, and if so, whether this ability is grounded in the sensitivity of the touch system to invariant mechanical parameters that describe the forces and torques required to move the target object. In particular, we investigated sensitivity to mass, static moment, and rotational inertia-the forces required to keep an object from falling due to gravity, the torque required to keep an object from rotating due to gravity, and the torques required to actively rotate an object in different directions, respectively. We manipulated the length of the target object (Experiment 1), the mass of the target object (Experiment 2), and the mass distribution of the target object (Experiments 3 and 4).

Can I Squeeze Through? Effects of Self-Avatars and Calibration in a Person-Plus-Virtual-Object System on Perceived Lateral Passability in VR.

With the popularity of Virtual Reality (VR) on the rise, creators from a variety of fields are building increasingly complex experiences that allow users to express themselves more naturally. Self-avatars and object interaction in virtual worlds are at the heart of these experiences. However, these give rise to several perception based challenges that have been the focus of research in recent years.

Give Me a Hand: Improving the Effectiveness of Near-field Augmented Reality Interactions By Avatarizing Users' End Effectors.

Inspired by previous works showing promise for AR self-avatarization - providing users with an augmented self avatar, we investigated whether avatarizing users' end-effectors (hands) improved their interaction performance on a near-field, obstacle avoidance, object retrieval task wherein users were tasked with retrieving a target object from a field of non-target obstacles for a number of trials. We employed a 3 (Augmented hand representation) X 2 (density of obstacles) X 2 (size of obstacles) X 2 (virtual light intensity) multi-factorial design, manipulating the presence/absence and anthropomorphic fidelity of augmented self-avatars overlaid on the user's real hands, as a between subjects factor across three experimental conditions: (1) No-Augmented Avatar (using only real hands); (2) Iconic-Augmented Avatar; (3) Realistic Augmented Avatar. Results indicated that self-avatarization improved interaction performance and was perceived as more usable regardless of the anthropomorphic fidelity of avatar.

Comparing the Effects of Visual Realism on Size Perception in VR versus Real World Viewing through Physical and Verbal Judgments.

Virtual Reality (VR) is well-known for its use in interdisciplinary applications and research. The visual representation of these applications could vary depending in their purpose and hardware limitation, and in those situations could require an accurate perception of size for task performance. However, the relationship between size perception and visual realism in VR has not yet been explored.

How Virtual Hand Representations Affect the Perceptions of Dynamic Affordances in Virtual Reality.

User representations are critical to the virtual experience, and involve both the input device used to support interactions as well as how the user is virtually represented in the scene. Inspired by previous work that has shown effects of user representations on the perceptions of relatively static affordances, we attempt to investigate how end-effector representations affect the perceptions of affordances that dynamically change over time. Towards this end, we empirically evaluated how different virtual hand representations affect users' perceptions of dynamic affordances in an object retrieval task wherein users were tasked with retrieving a target from a box for a number of trials while avoiding collisions with its moving doors.

Did I Hit the Door? Effects of Self-Avatars and Calibration in a Person-Plus-Virtual-Object System on Perceived Frontal Passability in VR.

The availability of new and improved display, tracking and input devices for Virtual Reality experiences has facilitated the use of partial and full body self-avatars in interaction with virtual objects in the environment. However, scaling the avatar to match the user's body dimensions remains to be a cumbersome process. Moreover, the effect of body-scaled self-avatars on size perception of virtual handheld objects and related action capabilities has been relatively unexplored.

The effects of testing environment, experimental design, and ankle loading on calibration to perturbed optic flow during locomotion.

Calibration is the process by which the execution of actions becomes scaled to the (changing) relationship between environmental features and the actor's action capabilities. Though much research has investigated how individuals calibrate to perturbed optic flow, it remains unclear how different experimental factors contribute to the magnitude of calibration transfer. In the present study, we assessed how testing environment (Experiment 1), an adapted pretest-calibration-posttest design (Experiment 2), and bilateral ankle loading (Experiment 3) affected the magnitude of calibration to perturbed optic flow.

Predicting aperture crossing behavior from within-trial metrics of motor control reliability.

Actors utilize intrinsically scaled information about their geometric and dynamic properties when perceiving their ability to pass through openings. Research about dynamic factors of affordance perception have shown that the reliability of a given movement, or the precision of one's motor control for that movement, increase the buffer space used when interacting with the environment. While previous work has assessed motor control reliability as a person-level variable (i.

Examining the effects of altered avatars on perception-action in virtual reality.

In virtual reality (VR), avatars are graphical representations of people. Previous research highlights benefits of having a self-avatar when perceiving-acting while embedded in a virtual environment. We studied the effect that an altered avatar had on the perception of one's action capabilities.

Calibration to tool use during visually-guided reaching.

In studying human perception and performance researchers must understand how the body schema is modified to accurately represent one's capabilities when tools are used, as humans use tools that alter their capabilities frequently. The present work tested the idea that calibration is responsible for modifying an embodied action schema during tool use. We investigated calibration in the context of manual activity in near space through a behavioral measure.

Learning to perceive haptic distance-to-break in the presence of friction.

Two experiments employed attunement and calibration training to investigate whether observers are able to identify material break points in compliant materials through haptic force application. The task required participants to attune to a recently identified haptic invariant, distance-to-break (DTB), rather than haptic stimulation not related to the invariant, including friction. In the first experiment participants probed simulated force-displacement relationships (materials) under 3 levels of friction with the aim of pushing as far as possible into the materials without breaking them.

Investigating haptic distance-to-break using linear and nonlinear materials in a simulated minimally invasive surgery task.

Accurate detection of mediated haptic information in minimally invasive surgery (MIS) is critical for applying appropriate force magnitudes onto soft tissue with the aim of minimising tissue trauma. Force perception in MIS is a dynamic process, with surgeons' administration of force into tissue revealing information about the remote surgical site which further informs the surgeons' haptic interactions. The relationship between applied force and material deformation rate provides biomechanical information specifying the deformation distance remaining until a tissue will fail: which is termed distance-to-break (DTB).

Simulator-based assessment of haptic surgical skill: a comparative study.

The aim of this study was to examine if the forces applied by users of a haptic simulator could be used to distinguish expert surgeons from novices. Seven surgeons with significant operating room expertise and 9 novices with no surgical experience participated in this study. The experimental task comprised exploring 4 virtual materials with the haptic device and learning the precise forces required to compress the materials to various depths.

Endovascular seldinger needle placement: a simulator for examining haptic skills.

In this work, we develop an affordable haptic simulator for examining haptic skills required for endovascular Seldinger needle placement.

The effect of instructions on potential slide-out failures during portable extension ladder angular positioning.

Accidents involving portable ladders are a common cause of serious occupational and non-occupational injuries throughout the industrialized world. Many of these injuries could be prevented with better instruction on the proper usage of portable ladders. Research is reported that focused on both the human factors and engineering aspects of portable extension ladder usage based on common ladder setup procedures.

Velocity-dependent changes of rotational axes during the control of unconstrained 3D arm motions depend on initial instruction on limb position.

The velocity-dependent change in rotational axes observed during the control of unconstrained 3D arm rotations may obey the principle of minimum inertia resistance (MIR). Rotating the arm around the minimum inertia tensor axis (e3) reduces the contribution of muscle torque to net torque by employing interaction torque. The present experiment tested whether the MIR principle still governs rotational movements when subjects were instructed to maintain the humeral long axis (SH-EL) as closely as possible to horizontal.

A haptic simulator to increase laparoscopic force application sensitivity.

Laparoscopic surgery demands perceptual-motor skills that are fundamentally different from open surgery, and laparoscopists must be adept at perceiving tissue interaction at the surgical site and then applying precise amounts of forces through instruments without damaging tissues. A haptic simulator that emulates multiple salient laparoscopic tasks and renders differing degrees of forces was created. Two of the haptic skills tasks were evaluated in two studies to determine their ability to distinguish and then train laparoscopic force application sensitivity.

Salient haptic skills trainer: initial validation of a novel simulator for training force-based laparoscopic surgical skills.

Background: There is an increasing need for efficient training simulators to teach advanced laparoscopic skills beyond those imparted by a box trainer. In particular, force-based or haptic skills must be addressed in simulators, especially because a large percentage of surgical errors are caused by the over-application of force. In this work, the efficacy of a novel, salient haptic skills simulator is tested as a training tool for force-based laparoscopic skills.

Objective differentiation of force-based laparoscopic skills using a novel haptic simulator.

Background: There is a growing need for effective surgical simulators to train the novice resident with a core skill set that can be later used in advanced operating room training. The most common simulator-based laparoscopic skills curriculum, the Fundamentals of Laparoscopic Skills (FLS), has been demonstrated to effectively teach basic surgical skills; however, a key deficiency in current surgical simulators is lack of validated training for force-based or haptic skills. In this study, a novel haptic simulator was examined for construct validity by determining its ability to differentiate between the force skills of surgeons and novices.

Haptic tasks for physical laparoscopic ("Box") trainers to differentiate surgeon skill.

In this work, we present four tasks, primarily testing haptic laparoscopic skill that can be simulated in a conventional box trainer. Results from examining expert surgeon and novice performance is presented as evidence that these tasks can be used for training haptic skills for laparoscopy in a box trainer.

Assessing surgeon and novice force skill on a haptic stiffness simulator for laparoscopic surgery.

Though several simulators and training methods are available for basic laparoscopic skills, few have addressed force-based skills. In this work, we discuss a haptic simulator that renders virtual materials of different stiffness profiles to be used for haptic skills differentiation. A force-based task was designed on the simulator and the performance of surgeons and novices was analyzed.