Vijay Shankar Sharma
Textbook neuroscience, philosophy of mind, and clinical terms. Not a reinterpretation of Vijay's Law or the Consciousness Index. 148 terms. Textbook meanings only.
148 terms. Page 3 of 3.
sleep-and-altered-states · intro
Also called: nrem sleep
The stages of sleep other than REM sleep, comprising light sleep and deep, slow-wave sleep, characterised by progressively slower brain waves and reduced responsiveness to external stimuli. Deep non-REM sleep is considered particularly important for physical restoration and for certain forms of memory consolidation.
consciousness-theories · intermediate
Also called: Orch-OR
A speculative theory of consciousness proposed by physicist Roger Penrose and anaesthesiologist Stuart Hameroff, which holds that consciousness arises from quantum computations occurring within microtubules inside brain neurons. It remains a minority position, and most neuroscientists consider the brain too warm and noisy for the specific quantum coherence the theory requires to be sustained meaningfully.
consciousness-theories · intermediate
A variant of panpsychism holding that the fundamental constituents of physical reality possess proto-experiential or precursor properties, which combine to give rise to full-blown consciousness in complex systems like brains, rather than each fundamental particle already possessing rich, fully-formed experience. It is offered as an attempt to soften some of the more counterintuitive commitments of standard panpsychism.
philosophy-of-mind · intermediate
The view that consciousness, or some very basic form of experience, is a fundamental and ubiquitous feature of physical reality, present in some minimal form even in simple physical systems, rather than something that only emerges at a certain level of biological complexity. Its proponents argue it avoids the hard problem by not needing consciousness to emerge from non-conscious matter at all; critics raise the combination problem, the difficulty of explaining how simple instances of experience combine into a unified complex mind.
perception · intermediate
The process by which the brain combines separately processed sensory features, such as an object's colour, shape, location, and motion, into a single, unified perceptual experience of that object. It is closely related to the broader neural binding problem in theories of consciousness.
perception · intermediate
The tendency to perceive objects as having stable properties, such as size, shape, and colour, despite changes in the raw sensory input caused by viewing angle, distance, or lighting conditions. For example, a door is perceived as rectangular even when viewed at an angle that projects a trapezoidal shape onto the retina.
perception · intro
A perceptual experience that differs systematically from the actual physical properties of a stimulus, arising not from a fault in the senses but from the normal, often useful inferential processes the brain uses to interpret sensory data. Illusions are valuable to researchers precisely because they reveal the assumptions and shortcuts the perceptual system relies on when interpreting ambiguous or incomplete information.
clinical-and-disorders · intermediate
Also called: unresponsive wakefulness syndrome
A condition, now more often termed 'unresponsive wakefulness syndrome' in clinical settings, in which a patient shows cycles of eye-opening that resemble wakefulness and sleep, along with basic reflexes, but no evidence of awareness of self or environment. It is distinguished from coma by the presence of these wake-sleep cycles, and from a minimally conscious state by the complete absence of any behavioural sign of awareness.
philosophy-of-mind · intermediate
The subjective, experiential aspect of a mental state, capturing what it is like to be in that state, as distinguished from its functional role in guiding behaviour or reasoning. Philosopher Ned Block introduced the distinction between phenomenal consciousness and access consciousness to separate the raw felt quality of an experience from its availability for reasoning, report, and action.
philosophy-of-mind · intermediate
Also called: p-zombie
A hypothetical being physically identical to a conscious person, behaving exactly the same way in every respect, but lacking any subjective experience whatsoever. The thought experiment is used to argue that physical and functional facts alone may not fully determine facts about consciousness, though critics argue such a being is not actually conceivable once physical facts are fully specified.
philosophy-of-mind · intro
Also called: materialism
The view that everything that exists, including the mind and conscious experience, is ultimately physical, or wholly determined by physical facts. It is the dominant position among contemporary philosophers of mind and scientists, though physicalists disagree among themselves about how exactly mental states relate to physical brain states.
consciousness-theories · intermediate
Also called: predictive coding
A framework in cognitive science and neuroscience proposing that the brain constantly generates predictions about incoming sensory input and updates its internal models based on the difference, or prediction error, between what was predicted and what actually arrives. On this view, perception itself is partly a controlled hallucination, constrained and corrected by sensory input rather than a passive readout of the world.
neuroscience · intro
The front-most region of the frontal lobe, associated with planning, decision-making, working memory, and the regulation of social and emotional behaviour. It matures later than most other brain regions, continuing development into a person's twenties. Damage to this area, as in the historical case of Phineas Gage, can dramatically alter personality while leaving basic perception and movement intact.
cognitive-science · intermediate
A phenomenon in which exposure to one stimulus influences the response to a later, related stimulus, typically without conscious awareness of the connection. For example, seeing the word 'nurse' can speed recognition of the related word 'doctor' shortly afterward. It is widely used as an experimental tool for probing unconscious mental associations.
philosophy-of-mind · intermediate
The view that there is only one kind of substance in the world, which is physical, but that this physical substance can give rise to two fundamentally distinct kinds of properties: physical properties and irreducible mental properties. It is offered as a middle position between substance dualism, which posits two separate kinds of stuff, and physicalism, which holds mental properties are nothing over and above physical ones.
perception · intro
The sense of the relative position and movement of one's own body parts, allowing a person to know, without looking, where their limbs are in space. It relies on specialised receptors in muscles, tendons, and joints, and is essential for coordinated movement; its loss, as in rare medical cases, makes even simple movements require constant visual monitoring.
sleep-and-altered-states · intermediate
An altered state of consciousness induced by psychedelic substances such as psilocybin or LSD, often characterised by altered perception, intensified emotion, and, at higher doses, a temporary dissolution of the ordinary sense of self. Clinical research into supervised psychedelic use for certain psychiatric conditions has expanded substantially in recent years, alongside continued regulatory restrictions on most such substances.
philosophy-of-mind · intro
Also called: quale
The subjective, felt qualities of individual conscious experiences, such as the particular redness of red or the specific taste of coffee, considered independently of any behaviour or function they enable. The concept is used to isolate the purely experiential aspect of a mental state, and debates over whether qualia exist, and if so how they relate to physical brain states, are central to philosophy of mind.
self-and-social-cognition · intermediate
A gradual buildup of electrical activity recorded over the motor cortex in the period leading up to a voluntary movement, first described well before the Libet experiment made it central to debates over free will. Its precise significance, whether it reflects an unconscious decision already made or simply a rising general readiness to act, remains an active subject of research and interpretation.
consciousness-theories · intermediate
A theory of consciousness, associated with neuroscientist Victor Lamme, proposing that conscious perception requires recurrent, or feedback, signalling between higher and lower areas of the visual cortex, as distinguished from purely feedforward processing, which the theory holds can support sophisticated unconscious processing but not conscious experience on its own.
sleep-and-altered-states · intro
Also called: rapid eye movement sleep
A stage of sleep characterised by rapid eye movement, low muscle tone, and heightened brain activity resembling wakefulness, during which most vivid dreaming occurs. It alternates with non-REM sleep in cycles of roughly ninety minutes throughout the night, with REM periods generally lengthening toward morning.
neuroscience · intermediate
Also called: RAS
A network of neurons in the brainstem that regulates wakefulness and the transition between sleep and arousal, projecting broadly to the thalamus and cortex. Damage to this system can produce coma even when the cerebral cortex itself is undamaged, which is part of why it is considered central to maintaining a conscious, wakeful state rather than the content of consciousness itself.
neuroscience · intermediate
A group of interconnected brain structures, centrally involving dopamine signalling between the midbrain and regions including the nucleus accumbens and prefrontal cortex, that produces feelings of pleasure and reinforces behaviours associated with survival and reproduction, such as eating and social bonding. Its dysregulation is central to most current models of addiction.
cognitive-science · intermediate
Also called: mental schema
A cognitive framework or mental structure that organises and interprets information based on prior knowledge and experience, helping people quickly process new information by fitting it into existing categories. Schemas make cognition efficient but can also produce systematic distortions in memory and perception when new information is forced to fit a pre-existing, imperfect framework.
cognitive-science · intermediate
The ability to focus cognitive processing on one source of information while filtering out competing, simultaneous information. The classic 'cocktail party effect', in which a person can follow one conversation in a noisy room yet still notice their own name spoken elsewhere, is a well-studied example of how selective attention operates alongside residual, low-level processing of unattended input.
self-and-social-cognition · intro
The capacity to recognise oneself as an individual, distinct from the environment and other individuals, and to reflect on one's own mental states, traits, and behaviour. It is often studied experimentally through tasks like the mirror self-recognition test, and is considered a foundational, though not sufficient, component of many theories of self-consciousness.
consciousness-theories · intermediate
A theory, associated with philosopher Thomas Metzinger, proposing that the subjective sense of being a self is generated by the brain constructing and continuously updating an internal model of itself, and that this self-model, rather than corresponding to any actual persisting entity, is simply the most useful representation the organism has for coordinating its behaviour.
self-and-social-cognition · intermediate
The subjective experience of being the author of one's own actions and of controlling events in the external world through one's own will. It can be experimentally weakened or disrupted, for example when an action's normal sensory consequences are delayed or altered, revealing that the felt sense of agency depends on specific, measurable predictive processes rather than being a simple, unmediated given.
self-and-social-cognition · intermediate
The subjective experience that a particular body, or body part, belongs to oneself. It can be experimentally manipulated, most famously in the rubber hand illusion, in which synchronised visual and tactile stimulation can cause a person to briefly experience an artificial rubber hand as part of their own body.
perception · intermediate
The neurological process by which the brain filters out redundant or unimportant sensory stimuli, preventing sensory overload and allowing attention to be directed toward more relevant information. Impairments in sensory gating have been studied in relation to certain psychiatric conditions, including schizophrenia, where filtering of sensory input appears to function less effectively.
perception · intro
The process by which raw sensory input from the eyes, ears, skin, and other sense organs is organised and interpreted by the nervous system to produce a coherent experience of the external world. Perception is not a passive recording of sensory data but an active process of inference, which is why the same physical stimulus can sometimes be perceived differently depending on context and expectation.
neuroscience · intro
Also called: 5-HT
A neurotransmitter involved in regulating mood, appetite, sleep, and social behaviour. Many antidepressant medications, including selective serotonin reuptake inhibitors, work by increasing the availability of serotonin at synapses. Most of the body's serotonin is actually found in the gut rather than the brain, where it regulates intestinal movement.
sleep-and-altered-states · intro
The recurring pattern of alternating REM and non-REM sleep stages that a person progresses through during a night's sleep, typically completing four to six cycles of roughly ninety minutes each. Disruption of normal sleep cycles, whether through sleep disorders or lifestyle factors, is associated with impairments in mood, cognition, and physical health.
sleep-and-altered-states · intermediate
A temporary inability to move or speak that occurs when a person becomes consciously aware while the muscle paralysis characteristic of REM sleep is still active, often accompanied by vivid, sometimes frightening hallucinations. It is a widely reported phenomenon that occurs at least once for a substantial fraction of the general population.
self-and-social-cognition · intro
The set of mental processes involved in perceiving, interpreting, and responding to information about other people and social situations, including recognising emotions, inferring intentions, and navigating social relationships. It draws on a broad network of brain regions and is studied across psychology, neuroscience, and psychiatry.
clinical-and-disorders · intermediate
A condition, most often resulting from a surgical procedure to sever the corpus callosum as a treatment for severe epilepsy, in which the brain's two hemispheres can no longer directly exchange information. Experiments with split-brain patients, who can show each hemisphere information independently, have provided influential evidence about hemispheric specialisation and raised deep questions about the unity of conscious experience.
self-and-social-cognition · intermediate
A term, coined by psychologist and philosopher William James, describing the continuous, ever-flowing, and constantly changing nature of subjective experience and thought, as opposed to a series of discrete, separable mental states. James used the metaphor to emphasise that ordinary conscious experience does not naturally divide into neat, separate units the way early psychological theories often assumed.
perception · intermediate
The processing of sensory information below the threshold of conscious awareness, such that a stimulus can influence behaviour or judgement without a person being consciously aware of having perceived it. Rigorous laboratory studies have found genuine but generally modest and short-lived subliminal effects, in contrast to the exaggerated claims made about subliminal advertising in popular culture.
philosophy-of-mind · intermediate
The view, most associated with René Descartes, that mind and body are two fundamentally different kinds of substance: an unextended, thinking substance and an extended, non-thinking physical substance. It faces the long-standing interaction problem of explaining how an entirely non-physical mind could causally affect, or be affected by, a physical body.
neuroscience · intro
The junction between two neurons, or between a neuron and a target cell, where signals are transmitted, most commonly through the release of chemical neurotransmitters across a small gap. Synaptic strength can increase or decrease with use, a property called synaptic plasticity that underlies learning and memory. A single neuron may have thousands of synaptic connections.
neuroscience · intermediate
The ability of synapses to strengthen or weaken over time in response to increases or decreases in their activity, widely considered the primary cellular mechanism underlying learning and memory. Long-term potentiation, a long-lasting increase in synaptic strength following repeated stimulation, is the most extensively studied form of synaptic plasticity.
perception · intermediate
A neurological condition in which stimulation of one sensory or cognitive pathway automatically triggers an involuntary experience in another, such as perceiving specific colours when hearing particular sounds, or associating numbers with distinct colours or spatial positions. It is estimated to occur in a small percentage of the population and tends to run in families, suggesting a genetic component.
cognitive-science · intro
Terms popularised by psychologist Daniel Kahneman for the two modes of thought described by dual-process theory: System 1 is fast, automatic, and intuitive, while System 2 is slower, deliberate, and effortful. Many cognitive biases arise when System 1's quick judgements are accepted without the more effortful checking that System 2 could, in principle, provide.
neuroscience · intermediate
A paired, egg-shaped structure near the centre of the brain that relays nearly all sensory information (except smell) to the cerebral cortex, and also participates in regulating consciousness, arousal, and sleep. Because of its central relay role, damage to the thalamus can produce profound disturbances of awareness. Some theories of consciousness assign it a key role in synchronising cortical activity.
self-and-social-cognition · intro
The cognitive capacity to attribute mental states, such as beliefs, desires, and intentions, to oneself and to others, and to understand that others can hold beliefs different from one's own. It typically develops through early childhood, and its impairment is a defining feature studied extensively in autism spectrum research, though the two are not simply equivalent.
perception · intro
A mode of perceptual processing in which prior knowledge, expectations, and context shape the interpretation of incoming sensory information, rather than perception being built up purely from raw sensory data. Predictive processing theories of the brain place particular emphasis on the pervasive role of top-down expectation in shaping everyday perception.
self-and-social-cognition · intermediate
The observation that, despite processing many different kinds of sensory and cognitive information simultaneously through many different, partly independent brain systems, ordinary conscious experience is normally felt as a single, unified perspective rather than as a fragmented collection of separate experiences. Split-brain research is among the most direct empirical challenges to a simple picture of this unity.
cognitive-science · intro
A limited-capacity cognitive system that temporarily holds and manipulates information needed for ongoing mental tasks such as reasoning, comprehension, and learning. Classic estimates put its capacity at around seven items, though more recent research suggests the true limit for many types of information is closer to three or four. It is distinguished from long-term memory by its limited capacity and short duration.