The philosophy of perception is concerned with the nature of perceptual experience and the status of perceptual data, in particular how they relate to beliefs about, or knowledge of, the world. Any explicit account of perception requires a commitment to one of a variety of ontological or metaphysical views. Philosophers distinguish internalist accounts, which assume that perceptions of objects, and knowledge or beliefs about them, are aspects of an individual's mind, and externalist accounts, which state that they constitute real aspects of the world external to the individual. The position of naïve realism—the 'everyday' impression of physical objects constituting what is perceived—is to some extent contradicted by the occurrence of perceptual illusions and hallucinations and the relativity of perceptual experience as well as certain insights in science. Realist conceptions include phenomenalism and direct and indirect realism. Anti-realist conceptions include idealism and skepticism. Recent philosophical work have expanded on the philosophical features of perception by going beyond the single paradigm of vision.
In visual perception, an optical illusion is an illusion caused by the visual system and characterized by a visual percept that arguably appears to differ from reality. Illusions come in a wide variety; their categorization is difficult because the underlying cause is often not clear but a classification proposed by Richard Gregory is useful as an orientation. According to that, there are three main classes: physical, physiological, and cognitive illusions, and in each class there are four kinds: Ambiguities, distortions, paradoxes, and fictions. A classical example for a physical distortion would be the apparent bending of a stick half immerged in water; an example for a physiological paradox is the motion aftereffect. An example for a physiological fiction is an afterimage. Three typical cognitive distortions are the Ponzo, Poggendorff, and Müller-Lyer illusion. Physical illusions are caused by the physical environment, e.g. by the optical properties of water. Physiological illusions arise in the eye or the visual pathway, e.g. from the effects of excessive stimulation of a specific receptor type. Cognitive visual illusions are the result of unconscious inferences and are perhaps those most widely known.
Sleight of hand refers to fine motor skills when used by performing artists in different art forms to entertain or manipulate. It is closely associated with close-up magic, card magic, card flourishing and stealing. Because of its heavy use and practice by magicians, sleight of hand is often confused as a branch of magic; however, it is a separate genre of entertainment and many artists practice sleight of hand as an independent skill. Sleight of hand pioneers with worldwide acclaim include Dan and Dave, Ricky Jay, Derek DelGaudio, David Copperfield, Yann Frisch, Norbert Ferré, Dai Vernon, Cardini, Tony Slydini, Helder Guimarães and Tom Mullica.
In theatrical magic, misdirection is a form of deception in which the performer draws audience attention to one thing to distract it from another. Managing audience attention is the aim of all theater, and the foremost requirement of all magic acts. Whether the magic is of a "pocket trick" variety or a large stage production, misdirection is the central secret. The term describes either the effect or the sleight of hand or patter that creates it.
Smoke and mirrors is a classic technique in magical illusions that makes an entity appear to hover in empty space. It was documented as early as 1770 and spread widely after its use by the charlatan Johann Georg Schröpfer, who claimed the apparitions to be conjured spirits. It subsequently became a fixture of 19th-century phantasmagoria shows. The illusion relies on a hidden projector the beam of which reflects off a mirror into a cloud of smoke, which in turn scatters the beam to create an image.
Microsaccades are a kind of fixational eye movement. They are small, jerk-like, involuntary eye movements, similar to miniature versions of voluntary saccades. They typically occur during prolonged visual fixation, not only in humans, but also in animals with foveal vision. Microsaccade amplitudes vary from 2 to 120 arcminutes. The first empirical evidence for their existence was provided by Robert Darwin, the father of Charles Darwin.
Jamy Ian Swiss is an American magician, author, speaker, historian of magic, essayist, book reviewer, and scientific skeptic. He is known for sleight-of-hand with playing cards.
Fixation or visual fixation is the maintaining of the gaze on a single location. An animal can exhibit visual fixation if it possess a fovea in the anatomy of their eye. The fovea is typically located at the center of the retina and is the point of clearest vision. The species in which fixational eye movement has been verified thus far include humans, primates, cats, rabbits, turtles, salamanders, and owls. Regular eye movement alternates between saccades and visual fixations, the notable exception being in smooth pursuit, controlled by a different neural substrate that appears to have developed for hunting prey. The term "fixation" can either be used to refer to the point in time and space of focus or the act of fixating. Fixation, in the act of fixating, is the point between any two saccades, during which the eyes are relatively stationary and virtually all visual input occurs. In the absence of retinal jitter, a laboratory condition known as retinal stabilization, perceptions tend to rapidly fade away. To maintain visibility, the nervous system carries out a procedure called fixational eye movement, which continuously stimulates neurons in the early visual areas of the brain responding to transient stimuli. There are three categories of fixational eye movement: microsaccades, ocular drifts, and ocular microtremor. At small amplitudes the boundaries between categories become unclear, particularly between drift and tremor.
Apparition of Face and Fruit Dish on a Beach (1938) is a painting by the Spanish surrealist Salvador Dalí. This work belongs to a group of paintings by Dalí that instantiate an optical illusion called the double, multiple, or ambiguous image.
Magic, which encompasses the subgenres of illusion, stage magic, and close-up magic, among others, is a performing art in which audiences are entertained by tricks, effects, or illusions of seemingly impossible feats, using natural means. It is to be distinguished from paranormal magic which are effects claimed to be created through supernatural means. It is one of the oldest performing arts in the world.
The book test is a classic mentalism demonstration used by mentalists to demonstrate telepathy-like effects. The name refers to its early use as a test of mental powers.
The Best Illusion of the Year Contest is an annual recognition of the world's illusion creators awarded by the Neural Correlate Society. The contest was created in 2005 by professors Susana Martinez-Conde and Stephen Macknik as part of the European conference on Visual Perception in La Coruna, Spain. It has since transitioned to an online contest where everyone in the world is invited to submit illusions and vote for the winner.
Jerry Andrus was an American magician and writer known internationally for his original close-up, sleight of hand tricks, such as the famous "Linking Pins", and optical illusions.
The SUNY Downstate Health Sciences University is a public medical school in Brooklyn, New York City. The university includes the College of Medicine, College of Nursing, School of Health Professions, School of Graduate Studies and School of Public Health.
Susana Martinez-Conde is a Spanish-American neuroscientist and science writer. She is a professor of ophthalmology, neurology, physiology, and pharmacology at the SUNY Downstate Medical Center, where she directs the Laboratory of Integrative Neuroscience. She directed laboratories previously at the Barrow Neurological Institute and University College London. Her research bridges perceptual, cognitive, and oculomotor neuroscience. She is best known for her studies on illusions, eye movements and perception, neurological disorders, and attentional misdirection in stage magic.
Stephen Louis Macknik is an American neuroscientist and science writer. He is a Professor of Ophthalmology, Neurology, and Physiology & Pharmacology at the State University of New York, Downstate Medical Center, where he directs the Laboratory of Translational Neuroscience. He directed laboratories previously at the Barrow Neurological Institute and University College London. He is best known for his studies on illusions, consciousness, attentional misdirection in stage magic, and cerebral blood flow.
Phantoms in the Brain: Probing the Mysteries of the Human Mind is a 1998 popular science book by neuroscientist V.S. Ramachandran and New York Times science writer Sandra Blakeslee, discussing neurophysiology and neuropsychology as revealed by case studies of neurological disorders.
Sandra Blakeslee is an American science correspondent of over four decades for The New York Times and science writer, specializing in neuroscience. Together with neuroscientist V. S. Ramachandran, she authored the 1998 popular science book Phantoms in the Brain: Probing the Mysteries of the Human Mind.
Shepard tables are an optical illusion first published in 1990 as "Turning the Tables," by Stanford psychologist Roger N. Shepard in his book Mind Sights, a collection of illusions that he had created. It is one of the most powerful optical illusions, typically creating length miscalculations of 20–25%.
Researchers study the reactions of animals observing humans performing magic tricks in order to better understand animal cognition. Using these studies, evolutionary psychologists aim to gain insights into the evolution of perception and attention by comparing responses of different species, including humans.
