The broken escalator phenomenon, also known as the Walker effect, is the sensation of losing balance or dizziness reported by some people when stepping onto an escalator which is not working. It is said that there is a brief, odd sensation of imbalance, despite full awareness that the escalator is not going to move.
It has been shown that this effect causes people to step inappropriately fast onto a moving platform that is no longer moving, even when this is obvious to the participant.
Even though subjects are fully aware that the platform or escalator is not moving now, parts of their brains still act on previous experience gained when it was moving, and so misjudge how to step onto it. Thus, this effect demonstrates the separateness of the declarative and procedural functions of the brain.
Dizziness is an impairment in spatial perception and stability. The term dizziness is imprecise: it can refer to vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness.One can induce dizziness by engaging in disorientating activities such as spinning.
Vertigo is the sensation of spinning or having one's surroundings spin about them. Many people find vertigo very disturbing and often report associated nausea and vomiting. It represents about 25% of cases of occurrences of dizziness.
Disequilibrium is the sensation of being off balance and is most often characterized by frequent falls in a specific direction. This condition is not often associated with nausea or vomiting.
Presyncope is lightheadedness, muscular weakness, and feeling faint as opposed to a syncope, which is actually fainting.
Non-specific dizziness is often psychiatric in origin. It is a diagnosis of exclusion and can sometimes be brought about by hyperventilation.A stroke is the cause of isolated dizziness in 0.7% of people who present to the emergency department.Illusions of self-motion
Illusions of self-motion refers to a phenomenon that occurs when someone feels like their body is moving when no movement is taking place. One can experience illusory movements of the whole body or of individual body parts, such as arms or legs.Proprioception
Proprioception ( PROH-pree-o-SEP-shən), is the sense of the relative position of one's own parts of the body and strength of effort being employed in movement. It is sometimes described as the "sixth sense".In humans, it is provided by proprioceptors in skeletal striated muscles (muscle spindles) and tendons (Golgi tendon organ) and the fibrous membrane in joint capsules. It is distinguished from exteroception, by which one perceives the outside world, and interoception, by which one perceives pain, hunger, etc., and the movement of internal organs.
The brain integrates information from proprioception and from the vestibular system into its overall sense of body position, movement, and acceleration. The word kinesthesia or kinæsthesia (kinesthetic sense) strictly means movement sense, but has been used inconsistently to refer either to proprioception alone or to the brain's integration of proprioceptive and vestibular inputs.
Proprioception has also been described in other animals such as vertebrates, and in some invertebrates such as arthropods. More recently proprioception has also been described in flowering land plants (angiosperms).Sense of balance
The sense of balance or equilibrioception is one of the physiological senses related to balance. It helps prevent humans and animals from falling over when standing or moving. Balance is the result of a number of body systems working together: the eyes (visual system), ears (vestibular system) and the body's sense of where it is in space (proprioception) ideally need to be intact. The vestibular system, the region of the inner ear where three semicircular canals converge, works with the visual system to keep objects in focus when the head is moving. This is called the vestibulo-ocular reflex (VOR). The balance system works with the visual and skeletal systems (the muscles and joints and their sensors) to maintain orientation or balance. Visual signals sent to the brain about the body's position in relation to its surroundings are processed by the brain and compared to information from the vestibular, visual and skeletal systems.Spatial disorientation
Spatial disorientation, spatial unawareness, or "Spatial-D" is the inability to determine one’s position, location, and motion relative to their environment. This phenomenon most commonly affects aircraft pilots and underwater divers, but also can be induced in normal conditions—or reproduced in the lab with instruments such as the Barany Chair. In aviation, the term means the inability to correctly interpret aircraft attitude, altitude or airspeed, in relation to the ground or point of reference. This most commonly occurs after a reference point (e.g., the horizon) has been lost. Spatial disorientation, often referred to as 'Spatial-D' by aviators occurs when aircrew's sensory interpretation of their position or motion conflicts with reality. Spatial disorientation is often separated into 3 main categories by mishap investigators:
Type 1: Unrecognized
Type 2: Recognized
Type 3: IncapacitatingA pilot who enters such conditions will quickly lose spatial orientation if there has been no training in flying with reference to instruments. Approximately 80% of the private pilots in the United States do not have an instrument rating, and therefore are prohibited from flying in conditions where instrument skills are required. Not all pilots abide by this rule and approximately 40% of the NTSB fatal general aviation accident reports list "continuation of flight into conditions for which the pilot was not qualified" as a cause.Vertigo
Vertigo is a symptom where a person feels as if they or the objects around them are moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties walking. It is typically worse when the head is moved. Vertigo is the most common type of dizziness.The most common diseases that result in vertigo are benign paroxysmal positional vertigo (BPPV), Ménière's disease, and labyrinthitis. Less common causes include stroke, brain tumors, brain injury, multiple sclerosis, migraines, trauma, and uneven pressures between the middle ears. Physiologic vertigo may occur following being exposed to motion for a prolonged period such as when on a ship or simply following spinning with the eyes closed. Other causes may include toxin exposures such as to carbon monoxide, alcohol, or aspirin. Vertigo typically indicates a problem in a part of the vestibular system. Other causes of dizziness include presyncope, disequilibrium, and non-specific dizziness.Benign paroxysmal positional vertigo is more likely in someone who gets repeated episodes of vertigo with movement and is otherwise normal between these episodes. The episodes of vertigo should last less than one minute. The Dix-Hallpike test typically produces a period of rapid eye movements known as nystagmus in this condition. In Ménière's disease there is often ringing in the ears, hearing loss, and the attacks of vertigo last more than twenty minutes. In labyrinthitis the onset of vertigo is sudden and the nystagmus occurs without movement. In this condition vertigo can last for days. More severe causes should also be considered. This is especially true if other problems such as weakness, headache, double vision, or numbness occur.Dizziness affects approximately 20–40% of people at some point in time, while about 7.5–10% have vertigo. About 5% have vertigo in a given year. It becomes more common with age and affects women two to three times more often than men. Vertigo accounts for about 2–3% of emergency department visits in the developed world.