cognitive psychology Branch of psychology devoted to the study of human cognition, particularly as it affects learning and behaviour. The field grew out of advances in Gestalt, developmental, and comparative psy¬ chology and in computer science, particularly information-processing research. Cognitive psychology shares many research interests with cog¬ nitive science, and some experts classify it as a branch of the latter. Con¬ temporary cognitive theory has followed one of two broad approaches: the developmental approach, derived from the work of Jean Piaget and concerned with “representational thought” and the construction of men¬ tal models (“schemas”) of the world, and the information-processing approach, which views the human mind as analogous to a sophisticated computer system.
cognitive science Interdisciplinary study that attempts to explain the cognitive processes of humans and some higher animals in terms of the manipulation of symbols using computational rules. The field draws par¬ ticularly on the disciplines of artificial intelligence, psychology (see cog¬ nitive psychology), linguistics, neuroscience, and philosophy. Some chief areas of research in cognitive science have been vision, thinking and rea¬ soning, memory, attention, learning, and language processing. Early theo¬ ries of cognitive function attempted to explain the evident compositionality of human thought (thoughts are built up of smaller units put together in a certain way), as well as its productivity (the process of putting together a thought from smaller units can be repeated indefinitely to produce an infinite number of new thoughts), by assuming the exist¬ ence of discrete mental representations that can be put together or taken apart according to rules that are sensitive to the representations’ syntac¬ tic, or structural, properties. This “language of thought” hypothesis was later challenged by an approach, variously referred to as connectionism, parallel-distributed processing, or neural-network modeling, according to which cognitive processes (such as pattern recognition) consist of adjust¬ ments in the activation strengths of neuronlike processing units arranged in a network.
cognitivism In metaethics, the thesis that the function of moral sen¬ tences (e.g., sentences in which moral terms such as “right,” “wrong,”
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and “ought” are used) is to describe a domain of moral facts existing independently of our subjective thoughts and feelings, and that moral statements can accordingly be thought of as objectively true or false. Cognitivists typically try to support their position by seeking out analo¬ gies between moral discourse, on the one hand, and scientific and every¬ day factual discourse, on the other. Cognitivism is opposed by various forms of noncognitivism, all of which have in common the denial of the cognitivist claim that the function of moral sentences is to state or describe facts.
Cohan \'ko- l han\ / George M(ichael) (b. July 3, 1878, Providence, R.I., U.S.—d. Nov. 5, 1942, New York, N.Y.) U.S. actor, songwriter, playwright, and producer. Cohan with his parents and sister performed in vaudeville as The Four Cohans.
He began writing for the New York stage in the early 1900s; his musical Little Johnny Jones (1904; film,
1930) included the classics “Give My Regards to Broadway” and “Yankee Doodle Dandy.” Among his later productions were The Gover¬ nor’s Son (1901), The Talk of New York (1907), Broadway Jones (1912), Seven Keys to Baldpate (1913), and American Born (1925).
He later appeared in shows such as Ah, Wilderness! (1933) and I’d Rather Be Right (1937). His best- known songs include “You’re a Grand Old Flag,” “Mary’s a Grand Old Name,” and the famous World War I recruiting song “Over There,” for which he was awarded a special Congressional medal in 1940. Cohan was the subject of the film Yankee Doodle Dandy (1942) and the musical George M! (1968).
cohen \'ko-3n\ or kohen \ko-'han, ko-'hen\ (Hebrew: “priest”) Jewish priest descended from Zadok (a descendant of Aaron), priest at the First Temple of Jerusalem. The biblical priesthood was hereditary and male. Before King Josiah’s reign (7th century bc), the high priest alone could enter the Holy of Holies on Yom Kippur. Lower-ranking priests accompa¬ nied the army in war or administered the Temple. The priestly class was strongest during the period of the Second Temple and was curtailed after its destruction. The rabbinate has replaced the kohanim as authorities on the Law, but kohanim retain some privileges (except in Reform Judaism).
coherentism Theory of truth according to which a belief is true just in case, or to the extent that, it coheres with a system of other beliefs. Philosophers have differed over the relevant sense of “cohere,” though most agree that it must be stronger than mere consistency. Among rival theories of truth, perhaps the oldest is the correspondence theory, which holds that the truth of a belief consists in its correspondence with inde¬ pendently existing facts. In epistemology, coherentism contrasts with foundationalism, which asserts that ordinary beliefs are justified if they are inferrable from a set of basic beliefs that are justified immediately or directly. Coherentism often has been combined with the idealist doctrine that reality consists of, or is knowable only through, ideas or judgments (see idealism).
Cohn, Edwin Joseph (b. Dec. 17, 1892, New York, N.Y, U.S.—d. Oct. 1, 1953, Boston, Mass.) U.S. biochemist. He received his Ph.D. from the University of Chicago and taught at Harvard 1922-53. He studied the components of protein molecules, correlating their structures with their physical properties and determining basic principles that became the foun¬ dation for the further study of proteins. In World War II he headed a team that devised methods of large-scale production of human plasma fractions for treatment of the wounded.
Cohn, Ferdinand (Julius) (b. Jan. 24, 1828, Breslau, Silesia, Prussia—d. June 25, 1898, Breslau) German naturalist and botanist, con¬ sidered one of the founders of bacteriology. He received a Ph.D. from the University of Berlin at age 19. His early research centred on the single- celled algae, and his accounts of the life histories of various algae spe¬ cies are of permanent value. He was among the first to attempt to arrange bacteria into genera and species on a systematic basis. Among his most striking contributions was his discovery of the formation and germination
of spores in certain bacteria. During his lifetime Cohn was recognized as the foremost bacteriologist of his day.
Cohn, Harry (b. July 23, 1891, New York, N.Y., U.S.—d. Feb. 27, 1958, Phoenix, Ariz.) U.S. film producer and cofounder of Columbia Pic¬ tures. He worked for a film distributor before cofounding C.B.C. Film Sales Co. (1920), later named Columbia Pictures Corp. In 1932 he became president of the company, which he built into a major studio. Though he came to epitomize the ruthless philistine movie mogul, he was credited with discovering many stars, including Rita Hayworth, and promoting such directors as Frank Capra.
Cohnheim, Julius Friedrich (b. July 20, 1839, Demmin, Prussia—d. Aug. 15, 1884, Leipzig) German pioneer of experimental pathology. While assisting Rudolf Virchow, he confirmed that inflammation results from passage of leukocytes through capillary walls into tissues and that pus is mainly debris from their disintegration. His induction of tubercu¬ losis in a rabbit’s eye led to Robert Koch’s discovery of the tuberculosis bacillus. His Lectures on General Pathology (2 vol., 1877-80) far out¬ lasted contemporary texts. His method of freezing tissue for thin slicing for microscopic examination is a standard clinical procedure.