Mental image

A mental image or mental picture is an experience that, on most occasions, significantly resembles the experience of perceiving some object, event, or scene, but occurs when the relevant object, event, or scene is not actually present to the senses. There are sometimes episodes, particularly on falling asleep (hypnagogic imagery) and waking up (hypnopompic), when the mental imagery, being of a rapid, phantasmagoric and involuntary character, defies perception, presenting a kaleidoscopic field, in which no distinct object can be discerned. Mental imagery can sometimes produce the same effects as would be produced by the behavior or experience imagined.The visual pathway is not a one-way street. Higher areas of the brain can also send visual input back to neurons in lower areas of the visual cortex. As humans, we have the ability to see with the mind's eye—to have a perceptual experience in the absence of visual input. For example, PET scans have shown that when subjects, seated in a room, imagine they are at their front door starting to walk either to the left or right, activation begins in the visual association cortex, the parietal cortex, and the prefrontal cortex—all higher cognitive processing centers of the brain. A mental image or mental picture is an experience that, on most occasions, significantly resembles the experience of perceiving some object, event, or scene, but occurs when the relevant object, event, or scene is not actually present to the senses. There are sometimes episodes, particularly on falling asleep (hypnagogic imagery) and waking up (hypnopompic), when the mental imagery, being of a rapid, phantasmagoric and involuntary character, defies perception, presenting a kaleidoscopic field, in which no distinct object can be discerned. Mental imagery can sometimes produce the same effects as would be produced by the behavior or experience imagined. The nature of these experiences, what makes them possible, and their function (if any) have long been subjects of research and controversy in philosophy, psychology, cognitive science, and, more recently, neuroscience. As contemporary researchers use the expression, mental images or imagery can comprise information from any source of sensory input; one may experience auditory images, olfactory images, and so forth. However, the majority of philosophical and scientific investigations of the topic focus upon visual mental imagery. It has sometimes been assumed that, like humans, some types of animals are capable of experiencing mental images. Due to the fundamentally introspective nature of the phenomenon, there is little to no evidence either for or against this view. Philosophers such as George Berkeley and David Hume, and early experimental psychologists such as Wilhelm Wundt and William James, understood ideas in general to be mental images. Today it is very widely believed that much imagery functions as mental representations (or mental models), playing an important role in memory and thinking. William Brant (2013, p. 12) traces the scientific use of the phrase 'mental images' back to John Tyndall's 1870 speech called the 'Scientific Use of the Imagination'. Some have gone so far as to suggest that images are best understood to be, by definition, a form of inner, mental or neural representation; in the case of hypnagogic and hypnapompic imagery, it is not representational at all. Others reject the view that the image experience may be identical with (or directly caused by) any such representation in the mind or the brain, but do not take account of the non-representational forms of imagery. In 2010, IBM applied for a patent on a method to extract mental images of human faces from the human brain. It uses a feedback loop based on brain measurements of the fusiform face area in the brain that activates proportionate with degree of facial recognition. It was issued in 2015. The notion of a 'mind's eye' goes back at least to Cicero's reference to mentis oculi during his discussion of the orator's appropriate use of simile. In this discussion, Cicero observed that allusions to 'the Syrtis of his patrimony' and 'the Charybdis of his possessions' involved similes that were 'too far-fetched'; and he advised the orator to, instead, just speak of 'the rock' and 'the gulf' (respectively)—on the grounds that 'the eyes of the mind are more easily directed to those objects which we have seen, than to those which we have only heard'. The concept of 'the mind's eye' first appeared in English in Chaucer's (c. 1387) Man of Law's Tale in his Canterbury Tales, where he tells us that one of the three men dwelling in a castle was blind, and could only see with 'the eyes of his mind'; namely, those eyes 'with which all men see after they have become blind'. The phrase remained rarely used and the OED incorrectly ascribes it to Shakespeare, as the first time the literally introspective phrase ‘the mind's eye’ is used in English was in Hamlet. As an example of introspection, it demonstrates that the internal life of the mind rarely came into focus in literature until the introspective realism movement in the 19th century. The biological foundation of the mind's eye is not fully understood. Studies using fMRI have shown that the lateral geniculate nucleus and the V1 area of the visual cortex are activated during mental imagery tasks. Ratey writes: The rudiments of a biological basis for the mind's eye is found in the deeper portions of the brain below the neocortex, or where the center of perception exists. The thalamus has been found to be discrete to other components in that it processes all forms of perceptional data relayed from both lower and higher components of the brain. Damage to this component can produce permanent perceptual damage, however when damage is inflicted upon the cerebral cortex, the brain adapts to neuroplasticity to amend any occlusions for perception. It can be thought that the neocortex is a sophisticated memory storage warehouse in which data received as an input from sensory systems are compartmentalized via the cerebral cortex. This would essentially allow for shapes to be identified, although given the lack of filtering input produced internally, one may as a consequence, hallucinate—essentially seeing something that isn't received as an input externally but rather internal (i.e. an error in the filtering of segmented sensory data from the cerebral cortex may result in one seeing, feeling, hearing or experiencing something that is inconsistent with reality).