Cognition is "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses many aspects of intellectual functions and processes such as attention, the formation of knowledge, memory and working memory, judgment and evaluation, reasoning and "computation", problem solving and decision making, comprehension and production of language. Cognitive processes use existing knowledge and generate new knowledge.
The processes are analyzed from different perspectives within different contexts, notably in the fields of linguistics, anesthesia, neuroscience, psychiatry, psychology, education, philosophy, anthropology, biology, systemics, logic, and computer science. These and other different approaches to the analysis of cognition are synthesised in the developing field of cognitive science, a progressively autonomous academic discipline.
The word cognition comes from the Latin verb cognosco (con, 'with', and gnōscō, 'know'; itself a cognate of the Greek verb γι(γ)νώσκω, gi(g)nόsko, meaning 'I know, perceive'), meaning 'to conceptualize' or 'to recognize'.
The word cognition dates back to the 15th century, when it meant "thinking and awareness". Attention to cognitive processes came about more than eighteen centuries earlier, however, beginning with Aristotle (384–322 BC) and his interest in the inner workings of the mind and how they affect the human experience. Aristotle focused on cognitive areas pertaining to memory, perception, and mental imagery. He placed great importance on ensuring that his studies were based on empirical evidence, that is, scientific information that is gathered through observation and conscientious experimentation. Two millennia later, as psychology emerged as a burgeoning field of study in Europe and then gained a following in America, other scientists like Wilhelm Wundt, Herman Ebbinghaus, Mary Whiton Calkins, and William James would offer their contributions to the study of human cognition.
Wilhelm Wundt (1832–1920) emphasized the notion of what he called introspection: examining the inner feelings of an individual. With introspection, the subject had to be careful to describe his or her feelings in the most objective manner possible in order for Wundt to find the information scientific. Though Wundt's contributions are by no means minimal, modern psychologists find his methods to be quite subjective and choose to rely on more objective procedures of experimentation to make conclusions about the human cognitive process.
Hermann Ebbinghaus (1850–1909) conducted cognitive studies that mainly examined the function and capacity of human memory. Ebbinghaus developed his own experiment in which he constructed over 2,000 syllables made out of nonexistent words, for instance EAS. He then examined his own personal ability to learn these non-words. He purposely chose non-words as opposed to real words to control for the influence of pre-existing experience on what the words might symbolize, thus enabling easier recollection of them. Ebbinghaus observed and hypothesized a number of variables that may have affected his ability to learn and recall the non-words he created. One of the reasons, he concluded, was the amount of time between the presentation of the list of stimuli and the recitation or recall of same. Ebbinghaus was the first to record and plot a "learning curve," and a "forgetting curve." His work heavily influenced the study of serial position and its effect on memory, discussed in subsequent sections.
Mary Whiton Calkins (1863–1930) was an influential American pioneer in the realm of psychology. Her work also focused on the human memory capacity. A common theory, called the recency effect, can be attributed to the studies that she conducted. The recency effect, also discussed in the subsequent experiment section, is the tendency for individuals to be able to accurately recollect the final items presented in a sequence of stimuli. Calkin's theory is closely related to the aforementioned study and conclusion of the memory experiments conducted by Hermann Ebbinghaus.
William James (1842–1910) is another pivotal figure in the history of cognitive science. James was quite discontent with Wundt's emphasis on introspection and Ebbinghaus' use of nonsense stimuli. He instead chose to focus on the human learning experience in everyday life and its importance to the study of cognition. James' most significant contribution to the study and theory of cognition was his textbook Principles of Psychology that preliminarily examines aspects of cognition such as perception, memory, reasoning, and attention.
In psychology, the term "cognition" is usually used within an information processing view of an individual's psychological functions (see cognitivism), and it is the same in cognitive engineering; in a branch of social psychology called social cognition, the term is used to explain attitudes, attribution, and group dynamics.
Human cognition is conscious and unconscious, concrete or abstract, as well as intuitive (like knowledge of a language) and conceptual (like a model of a language). It encompasses processes such as memory, association, concept formation, pattern recognition, language, attention, perception, action, problem solving and mental imagery. Traditionally, emotion was not thought of as a cognitive process, but now much research is being undertaken to examine the cognitive psychology of emotion; research is also focused on one's awareness of one's own strategies and methods of cognition, which is called metacognition.
While few people would deny that cognitive processes are a function of the brain, a cognitive theory will not necessarily make reference to the brain or to biological processes (compare neurocognitive). It may purely describe behavior in terms of information flow or function. Relatively recent fields of study such as neuropsychology aim to bridge this gap, using cognitive paradigms to understand how the brain implements the information-processing functions (see also cognitive neuroscience), or to understand how pure information-processing systems (e.g., computers) can simulate human cognition (see also artificial intelligence). The branch of psychology that studies brain injury to infer normal cognitive function is called cognitive neuropsychology. The links of cognition to evolutionary demands are studied through the investigation of animal cognition.
For years, sociologists and psychologists have conducted studies on cognitive development or the construction of human thought or mental processes.
Jean Piaget was one of the most important and influential people in the field of Developmental Psychology. He believed that humans are unique in comparison to animals because we have the capacity to do "abstract symbolic reasoning." His work can be compared to Lev Vygotsky, Sigmund Freud, and Erik Erikson who were also great contributors in the field of Developmental Psychology. Today, Piaget is known for studying the cognitive development in children. He studied his own three children and their intellectual development and came up with a theory that describes the stages children pass through during development.
|Stage||Age or Period||Description|
|Sensorimotor stage||Infancy (0–2 years)||Intelligence is present; motor activity but no symbols; knowledge is developing yet limited; knowledge is based on experiences/ interactions; mobility allows child to learn new things; some language skills are developed at the end of this stage. The goal is to develop object permanence; achieves basic understanding of causality, time, and space.|
|Pre-operational stage||Toddler and Early Childhood (2–7 years)||Symbols or language skills are present; memory and imagination are developed; nonreversible and nonlogical thinking; shows intuitive problem solving; begins to see relationships; grasps concept of conservation of numbers; egocentric thinking predominates.|
|Concrete operational stage||Elementary and Early Adolescence (7–12 years)||Logical and systematic form of intelligence; manipulation of symbols related to concrete objects; thinking is now characterized by reversibility and the ability to take the role of another; grasps concepts of the conservation of mass, length, weight, and volume; operational thinking predominates nonreversible and egocentric thinking|
|Formal operational stage||Adolescence and Adulthood (12 years and on)||Logical use of symbols related to abstract concepts; Acquires flexibility in thinking as well as the capacities for abstract thinking and mental hypothesis testing; can consider possible alternatives in complex reasoning and problem solving.|
The serial position experiment is meant to test a theory of memory that states that when information is given in a serial manner, we tend to remember information in the beginning of the sequence, called the primacy effect, and information in the end of the sequence, called the recency effect. Consequently, information given in the middle of the sequence is typically forgotten, or not recalled as easily. This study predicts that the recency effect is stronger than the primacy effect, because the information that is most recently learned is still in working memory when asked to be recalled. Information that is learned first still has to go through a retrieval process. This experiment focuses on human memory processes.
The word superiority experiment presents a subject with a word, or a letter by itself, for a brief period of time, i.e. 40ms, and they are then asked to recall the letter that was in a particular location in the word. By theory, the subject should be better able to correctly recall the letter when it was presented in a word than when it was presented in isolation. This experiment focuses on human speech and language.
In the Brown-Peterson experiment, participants are briefly presented with a trigram and in one particular version of the experiment, they are then given a distractor task, asking them to identify whether a sequence of words are in fact words, or non-words (due to being misspelled, etc.). After the distractor task, they are asked to recall the trigram from before the distractor task. In theory, the longer the distractor task, the harder it will be for participants to correctly recall the trigram. This experiment focuses on human short-term memory.
During the memory span experiment, each subject is presented with a sequence of stimuli of the same kind; words depicting objects, numbers, letters that sound similar, and letters that sound dissimilar. After being presented with the stimuli, the subject is asked to recall the sequence of stimuli that they were given in the exact order in which it was given. In one particular version of the experiment, if the subject recalled a list correctly, the list length was increased by one for that type of material, and vice versa if it was recalled incorrectly. The theory is that people have a memory span of about seven items for numbers, the same for letters that sound dissimilar and short words. The memory span is projected to be shorter with letters that sound similar and with longer words.
In one version of the visual search experiment, a participant is presented with a window that displays circles and squares scattered across it. The participant is to identify whether there is a green circle on the window. In the "featured" search, the subject is presented with several trial windows that have blue squares or circles and one green circle or no green circle in it at all. In the "conjunctive" search, the subject is presented with trial windows that have blue circles or green squares and a present or absent green circle whose presence the participant is asked to identify. What is expected is that in the feature searches, reaction time, that is the time it takes for a participant to identify whether a green circle is present or not, should not change as the number of distractors increases. Conjunctive searches where the target is absent should have a longer reaction time than the conjunctive searches where the target is present. The theory is that in feature searches, it is easy to spot the target, or if it is absent, because of the difference in color between the target and the distractors. In conjunctive searches where the target is absent, reaction time increases because the subject has to look at each shape to determine whether it is the target or not because some of the distractors if not all of them, are the same color as the target stimuli. Conjunctive searches where the target is present take less time because if the target is found, the search between each shape stops.
The semantic network of knowledge representation systems has been studied in various paradigms. One of the oldest paradigms is the leveling and sharpening of stories as they are repeated from memory studied by Bartlett. The semantic differential used factor analysis to determine the main meanings of words, finding that value or "goodness" of words is the first factor. More controlled experiments examine the categorical relationships of words in free recall. The hierarchical structure of words has been explicitly mapped in George Miller's Wordnet. More dynamic models of semantic networks have been created and tested with neural network experiments based on computational systems such as latent semantic analysis (LSA), Bayesian analysis, and multidimensional factor analysis. The semantics (meaning) of words is studied by all the disciplines of cognitive science.
An emergent field of research, referred to as "Team Cognition", is arising in military sciences. "Team cognition" indicates “an emergent property of teams that results from the interplay of individual cognition and team process behaviors [...] [Team cognition] underlies team performance” (Arizona State University East, 2005, Cooke NJ, 2005).
Metacognition is "cognition about cognition", "thinking about thinking", "knowing about knowing", becoming "aware of one's awareness" and higher-order thinking skills. The term comes from the root word meta, meaning "beyond". Metacognition can take many forms; it includes knowledge about when and how to use particular strategies for learning or problem-solving. There are generally two components of metacognition: (1) knowledge about cognition and (2) regulation of cognition.
Metamemory, defined as knowing about memory and mnemonic strategies, is an especially important form of metacognition. Academic research on metacognitive processing across cultures is in the early stages, but there are indications that further work may provide better outcomes in cross-cultural learning between teachers and students.
Some evolutionary psychologists hypothesize that humans use metacognition as a survival tool. Writings on metacognition date back at least as far as two works by the Greek philosopher Aristotle (384-322 BC): On the Soul and the Parva Naturalia.
Writings on metacognition can be traced back at least as far as De Anima and the Parva Naturalia of the Greek philosopher Aristotle (384-322 BC) [...].
Animal cognition describes the mental capacities of non-human animals and the study of those capacities. The field developed from comparative psychology, including the study of animal conditioning and learning. It has also been strongly influenced by research in ethology, behavioral ecology, and evolutionary psychology, and hence the alternative name cognitive ethology is sometimes used. Many behaviors associated with the term animal intelligence are also subsumed within animal cognition.Researchers have examined animal cognition in mammals (especially primates, cetaceans, elephants, dogs, cats, pigs, horses, cattle, raccoons and rodents), birds (including parrots, fowl, corvids and pigeons), reptiles (lizards and snakes), fish and invertebrates (including cephalopods, spiders and insects).Cognitive psychology
Cognitive psychology is the scientific study of mental processes such as "attention, language use, memory, perception, problem solving, creativity, and thinking". Much of the work derived from cognitive psychology has been integrated into various other modern disciplines such as Cognitive Science and of psychological study, including educational psychology, social psychology, personality psychology, abnormal psychology, developmental psychology, linguistics, and economics.Cognitive science
Cognitive science is the interdisciplinary, scientific study of the mind and its processes. It examines the nature, the tasks, and the functions of cognition (in a broad sense). Cognitive scientists study intelligence and behavior, with a focus on how nervous systems represent, process, and transform information. Mental faculties of concern to cognitive scientists include language, perception, memory, attention, reasoning, and emotion; to understand these faculties, cognitive scientists borrow from fields such as linguistics, psychology, artificial intelligence, philosophy, neuroscience, and anthropology. The typical analysis of cognitive science spans many levels of organization, from learning and decision to logic and planning; from neural circuitry to modular brain organization. The fundamental concept of cognitive science is that "thinking can best be understood in terms of representational structures in the mind and computational procedures that operate on those structures."Simply put: Cognitive Science is the interdisciplinary study of cognition in humans, animals, and machines. It encompasses the traditional disciplines of psychology, computer science, neuroscience, anthropology, linguistics and philosophy. The goal of cognitive science is to understand the principles of intelligence with the hope that this will lead to better comprehension of the mind and of learning and to develop intelligent devices.
The cognitive sciences began as an intellectual movement in the 1950s often referred to as the cognitive revolution.David Langford
David Rowland Langford (born 10 April 1953) is a British author, editor and critic, largely active within the science fiction field. He publishes the science fiction fanzine and newsletter Ansible.Embodied cognition
Embodied cognition is the theory that many features of cognition, whether human or otherwise, are shaped by aspects of the entire body of the organism. The features of cognition include high level mental constructs (such as concepts and categories) and performance on various cognitive tasks (such as reasoning or judgment). The aspects of the body include the motor system, the perceptual system, bodily interactions with the environment (situatedness) and the assumptions about the world that are built into the structure of the organism.
The embodied mind thesis challenges other theories, such as cognitivism, computationalism, and Cartesian dualism.
It is closely related to the extended mind thesis, situated cognition and enactivism. The modern version depends on insights drawn from recent research in psychology, linguistics, cognitive science, dynamical systems, artificial intelligence, robotics, animal cognition, plant cognition and neurobiology.Extrasensory perception
Extrasensory perception or ESP, also called sixth sense, includes claimed reception of information not gained through the recognized physical senses, but sensed with the mind. The term was adopted by Duke University psychologist J. B. Rhine to denote psychic abilities such as intuition, telepathy, psychometry, clairvoyance, and their trans-temporal operation as precognition or retrocognition.Second sight is a form of extrasensory perception, the supposed power to perceive things that are not present to the senses, whereby a person perceives information, in the form of a vision, about future events before they happen (precognition), or about things or events at remote locations (remote viewing). There is no scientific evidence that second sight exists. Reports of second sight are known only from anecdotal evidence given after the fact.Linguistic relativity
The hypothesis of linguistic relativity holds that the structure of a language affects its speakers' world view or cognition. Also known as the Sapir–Whorf hypothesis, or Whorfianism, the principle is often defined to include two versions: the strong hypothesis and the weak hypothesis:
The strong version says that language determines thought and that linguistic categories limit and determine cognitive categories.
The weak version says that linguistic categories and usage only influence thought and decisions.The term "Sapir–Whorf hypothesis" is considered a misnomer by linguists for several reasons: Edward Sapir and Benjamin Lee Whorf never co-authored any works, and never stated their ideas in terms of a hypothesis. The distinction between a weak and a strong version of this hypothesis is also a later invention; Sapir and Whorf never set up such a dichotomy, although often in their writings and in their views of this relativity principle are phrased in stronger or weaker terms.The idea was first clearly expressed by 19th-century thinkers, such as Wilhelm von Humboldt, who saw language as the expression of the spirit of a nation. Members of the early 20th-century school of American anthropology headed by Franz Boas and Edward Sapir also embraced forms of the idea to one degree or another, including in a 1928 meeting of the Linguistic Society of America, but Sapir in particular wrote more often against than in favor of anything like linguistic determinism. Sapir's student, Benjamin Lee Whorf, came to be seen as the primary proponent as a result of his published observations of how he perceived linguistic differences to have consequences in human cognition and behavior. Harry Hoijer, another of Sapir's students, introduced the term "Sapir–Whorf hypothesis", even though the two scholars never formally advanced any such hypothesis. A strong version of relativist theory was developed from the late 1920s by the German linguist Leo Weisgerber. Whorf's principle of linguistic relativity was reformulated as a testable hypothesis by Roger Brown and Eric Lenneberg who conducted experiments designed to find out whether color perception varies between speakers of languages that classified colors differently. As the study of the universal nature of human language and cognition came into focus in the 1960s the idea of linguistic relativity fell out of favor among linguists. A 1969 study by Brent Berlin and Paul Kay demonstrated the existence of universal semantic constraints in the field of colour terminology which were widely seen to discredit the existence of linguistic relativity in this domain, although this conclusion has been disputed by relativist researchers.
From the late 1980s, a new school of linguistic relativity scholars has examined the effects of differences in linguistic categorization on cognition, finding broad support for non-deterministic versions of the hypothesis in experimental contexts. Some effects of linguistic relativity have been shown in several semantic domains, although they are generally weak. Currently, a balanced view of linguistic relativity is espoused by most linguists holding that language influences certain kinds of cognitive processes in non-trivial ways, but that other processes are better seen as arising from connectionist factors. Research is focused on exploring the ways and extent to which language influences thought. The principle of linguistic relativity and the relation between language and thought has also received attention in varying academic fields from philosophy to psychology and anthropology, and it has also inspired and coloured works of fiction and the invention of constructed languages.Metacognition
Metacognition is "cognition about cognition", "thinking about thinking", "knowing about knowing", becoming "aware of one's awareness" and higher-order thinking skills. The term comes from the root word meta, meaning "beyond". Metacognition can take many forms; it includes knowledge about when and how to use particular strategies for learning or problem-solving. There are generally two components of metacognition: (1) knowledge about cognition and (2) regulation of cognition.Metamemory, defined as knowing about memory and mnemonic strategies, is an especially important form of metacognition. Academic research on metacognitive processing across cultures is in the early stages, but there are indications that further work may provide better outcomes in cross-cultural learning between teachers and students.Some evolutionary psychologists hypothesize that humans use metacognition as a survival tool. Writings on metacognition date back at least as far as two works by the Greek philosopher Aristotle (384-322 BC): On the Soul and the Parva Naturalia.Michael Tomasello
Michael Tomasello (born January 18, 1950) is an American developmental and comparative psychologist, as well as linguist. He is co-director of Max Planck Institute for Evolutionary Anthropology in Leipzig, co-director of the Wolfgang Kohler Primate Research CenterGermany, honorary professor at University of Leipzig's and at Manchester University's Department of Psychology, and professor of psychology at Duke University.
Earning many prizes and awards from the end of the 1990s onward, he is considered one of today's most authoritative developmental and comparative psychologists. He is "one of the few scientists worldwide who is acknowledged as an expert in multiple disciplines". His "pioneering research on the origins of social cognition has led to revolutionary insights in both developmental psychology and primate cognition."Molecular cellular cognition
Molecular cellular cognition (MCC) is a branch of neuroscience that involves the study of cognitive processes with approaches that integrate molecular, cellular and behavioral mechanisms. Key goals of MCC studies include the derivation of molecular and cellular explanations of cognitive processes, as well as finding mechanisms and treatments for cognitive disorders.
Although closely connected with behavioral genetics, MCC emphasizes the integration of molecular and cellular explanations of behavior, instead of focusing on the connections between genes and behavior.
Unlike cognitive neuroscience, which historically has focused on the connection between human brain systems and behavior, the field of MCC has used model organisms, such as mice, to study how molecular (i.e. receptor, kinase activation, phosphatase regulation), intra-cellular (i.e. dendritic processes), and inter-cellular processes (i.e. synaptic plasticity; network representations such as place fields) modulate cognitive function.
Methods employed in MCC include (but are not limited to) transgenic organisms (i.e. mice), viral vectors, pharmacology, in vitro and in vivo electrophysiology, optogenetics, in vivo imaging, and behavioral analysis. Modeling is becoming an essential component of the field because of the complexity of the multilevel data generated.Music psychology
Music psychology, or the psychology of music, may be regarded as a branch of both psychology and musicology. It aims to explain and understand musical behaviour and experience, including the processes through which music is perceived, created, responded to, and incorporated into everyday life. Modern music psychology is primarily empirical; its knowledge tends to advance on the basis of interpretations of data collected by systematic observation of and interaction with human participants. Music psychology is a field of research with practical relevance for many areas, including music performance, composition, education, criticism, and therapy, as well as investigations of human attitude, skill, performance, intelligence, creativity, and social behavior.
Music psychology can shed light on non-psychological aspects of musicology and musical practice. For example, it contributes to music theory through investigations of the perception and computational modelling of musical structures such as melody, harmony, tonality, rhythm, meter, and form. Research in music history can benefit from systematic study of the history of musical syntax, or from psychological analyses of composers and compositions in relation to perceptual, affective, and social responses to their music. Ethnomusicology can benefit from psychological approaches to the study of music cognition in different cultures.Nootropic
Nootropics ( noh-ə-TROP-iks) (colloquial: smart drugs and cognitive enhancers) are drugs, supplements, and other substances that may improve cognitive function, particularly executive functions, memory, creativity, or motivation, in healthy individuals. While many substances are purported to improve cognition, research is at a preliminary stage as of 2018, and the effects of the majority of these agents are not fully determined.
The use of cognition-enhancing drugs by healthy individuals in the absence of a medical indication spans numerous controversial issues, including the ethics and fairness of their use, concerns over adverse effects, and the diversion of prescription drugs for nonmedical uses, among others. Nonetheless, the international sales of cognition-enhancing supplements exceeded US$1 billion in 2015 when global demand for these compounds grew.The word nootropic was coined in 1972 by a Romanian psychologist and chemist, Corneliu E. Giurgea, from the Greek words νοῦς (nous), or "mind", and τρέπειν (trepein), meaning to bend or turn.Paranoia
Paranoia is an instinct or thought process believed to be heavily influenced by anxiety or fear, often to the point of delusion and irrationality. Paranoid thinking typically includes persecutory, or beliefs of conspiracy concerning a perceived threat towards oneself (e.g. the American colloquial phrase, "Everyone is out to get me"). Paranoia is distinct from phobias, which also involve irrational fear, but usually no blame. Making false accusations and the general distrust of others also frequently accompany paranoia. For example, an incident most people would view as an accident or coincidence, a paranoid person might believe was intentional. Paranoia is a central symptom of psychosis.Passive-aggressive behavior
Passive-aggressive behavior is characterized by indirect resistance to the demands of others and an avoidance of direct confrontation.Retrocognition
Retrocognition (also known as postcognition), from the Latin retro meaning "backward, behind" and cognition meaning "knowing," describes "knowledge of a past event which could not have been learned or inferred by normal means." The term was coined by Frederic W. H. Myers.Social cognition
Social cognition is "a sub-topic of social psychology that focuses on how people process, store, and apply information about other people and social situations. It focuses on the role that cognitive processes play in social interactions."More technically, social cognition refers to how people deal with conspecifics (members of the same species) or even across species (such as pet) information, include four stages: encoding, storage, retrieval, and processing. In the area of social psychology, social cognition refers to a specific approach in which these processes are studied according to the methods of cognitive psychology and information processing theory. According to this view, social cognition is a level of analysis that aims to understand social psychological phenomena by investigating the cognitive processes that underlie them. The major concerns of the approach are the processes involved in the perception, judgment, and memory of social stimuli; the effects of social and affective factors on information processing; and the behavioral and interpersonal consequences of cognitive processes. This level of analysis may be applied to any content area within social psychology, including research on intrapersonal, interpersonal, intragroup, and intergroup processes.
The term social cognition has been used in multiple areas in psychology and cognitive neuroscience, most often to refer to various social abilities disrupted in autism, schizophrenia and other disorders. In cognitive neuroscience the biological basis of social cognition is investigated. Developmental psychologists study the development of social cognition abilities.Social cognitive neuroscience
Social cognitive neuroscience is the scientific study of the biological processes underpinning social cognition. Specifically, it uses the tools of neuroscience to study "the mental mechanisms that create, frame, regulate, and respond to our experience of the social world". Social cognitive neuroscience uses the epistemological foundations of cognitive neuroscience, and is closely related to social neuroscience. Social cognitive neuroscience employs human neuroimaging, typically using functional magnetic resonance imaging (fMRI). Human brain stimulation techniques such as transcranial magnetic stimulation and transcranial direct-current stimulation are also used. In nonhuman animals, direct electrophysiological recordings and electrical stimulation of single cells and neuronal populations are utilized for investigating lower-level social cognitive processes.Unconsciousness
Unconsciousness is a state which occurs when the ability to maintain an awareness of self and environment is lost. It involves a complete or near-complete lack of responsiveness to people and other environmental stimuli.Loss of consciousness should not be confused with the notion of the psychoanalytic unconscious or cognitive processes (e.g., implicit cognition) that take place outside awareness, and with altered states of consciousness, such as delirium (when the person is confused and only partially responsive to the environment), normal sleep, hypnosis, and other altered states in which the person responds to stimuli.
Unconsciousness may occur as the result of traumatic brain injury, brain hypoxia (e.g., due to a brain infarction or cardiac arrest), severe poisoning with drugs that depress the activity of the central nervous system (e.g., alcohol and other hypnotic or sedative drugs), severe fatigue, anaesthesia, and other causes.Understanding
Understanding is a psychological process related to an abstract or physical object, such as a person, situation, or message whereby one is able to think about it and use concepts to deal adequately with that object.
Understanding is a relation between the knower and an object of understanding. Understanding implies abilities and dispositions with respect to an object of knowledge that are sufficient to support intelligent behaviour.Understanding is often, though not always, related to learning concepts, and sometimes also the theory or theories associated with those concepts. However, a person may have a good ability to predict the behaviour of an object, animal or system—and therefore may, in some sense, understand it—without necessarily being familiar with the concepts or theories associated with that object, animal or system in their culture. They may have developed their own distinct concepts and theories, which may be equivalent, better or worse than the recognised standard concepts and theories of their culture. Thus, understanding is correlated with the ability to make inferences.