Haptic perception in the context of "Mixed reality"

Augmented reality (AR), also known as mixed reality (MR), is a technology that overlays real-time 3D-rendered computer graphics onto a portion of the real world through a display, such as a handheld device or head-mounted display. This experience is seamlessly interwoven with the physical world such that it is perceived as an immersive aspect of the real environment. In this way, augmented reality alters one's ongoing perception of a real-world environment, compared to virtual reality, which aims to completely replace the user's real-world environment with a simulated one. Augmented reality is typically visual, but can span multiple sensory modalities, including auditory, haptic, and somatosensory.

The primary value of augmented reality is the manner in which components of a digital world blend into a person's perception of the real world, through the integration of immersive sensations, which are perceived as real in the user's environment. The earliest functional AR systems that provided immersive mixed reality experiences for users were invented in the early 1990s, starting with the Virtual Fixtures system developed at the U.S. Air Force's Armstrong Laboratory in 1992. Commercial augmented reality experiences were first introduced in entertainment and gaming businesses. Subsequently, augmented reality applications have spanned industries such as education, communications, medicine, and entertainment.

Haptic technology (also kinaesthetic communication or 3D touch) is technology that can create an experience of touch by applying forces, vibrations, or motions to the user. These technologies can be used to feel virtual objects and events in a computer simulation, to control virtual objects, and to enhance remote control of machines and devices (telerobotics). Haptic devices may incorporate tactile sensors that measure forces exerted by the user on the interface. The word haptic, from the Ancient Greek: ἁπτικός (haptikos), means "tactile, pertaining to the sense of touch". Simple haptic devices are common in the form of game controllers, joysticks, and steering wheels.

Haptic technology facilitates investigation of how the human sense of touch works by allowing the creation of controlled haptic virtual objects. Vibrations and other tactile cues have also become an integral part of mobile user experience and interface design. Most researchers distinguish three sensory systems related to sense of touch in humans: cutaneous, kinaesthetic and haptic. All perceptions mediated by cutaneous and kinaesthetic sensibility are referred to as tactual perception. The sense of touch may be classified as passive and active, and the term "haptic" is often associated with active touch to communicate or recognize objects.

Tickling is the act of touching a part of a person's body in a way that causes involuntary twitching movements or laughter. The word "tickle" evolved from the Middle English tikelen, perhaps frequentative of ticken, to touch lightly.

In 1897, psychologists G. Stanley Hall and Arthur Allin described a "tickle" as two different types of phenomena. One type is caused by very light movement across the skin. This type of tickle, called a knismesis, generally does not produce laughter and is sometimes accompanied by an itching sensation.

A cutaneous receptor is a sensory receptor found in the skin that provides information about temperature, touch (including vibration and pain), spatial orientation, pressure (stretching or squeezing), and metabolic circumstances (including those induced by external chemical substances). The main four types of cutaneous receptors are tactile corpuscles, bulbous corpuscles, Pacinian corpuscles, and Merkel nerve endings, although the latter do not qualify as sensory corpuscles in the narrow sense.

In perceptual psychology, a sensory cue is a statistic or signal that can be extracted from the sensory input by a perceiver, that indicates the state of some property of the world that the perceiver is interested in perceiving.

A cue is some organization of the data present in the signal which allows for meaningful extrapolation. For example, sensory cues include visual cues, auditory cues, haptic cues, olfactory cues and environmental cues. Sensory cues are a fundamental part of theories of perception, especially theories of appearance (how things look).

Surface roughness or simply roughness is the quality of a surface of not being smooth and it is hence linked to human (haptic) perception of the surface texture. From a mathematical perspective it is related to the spatial variability structure of surfaces, and inherently it is a multiscale property. It has different interpretations and definitions depending on the disciplines considered.

In surface metrology, surface roughness is a component of surface finish (surface texture). It is quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is smooth. Roughness is typically assumed to be the high-frequency, short-wavelength component of a measured surface. However, in practice it is often necessary to know both the amplitude and frequency to ensure that a surface is fit for a purpose.