Spearman's two-factor theory.: Spearman's two-factor theory. Dr. Manoj Praveen G. Farook Training college Slide 2: Born into a well established family in London in 1863. As an adolescent, his deepest urge was to probe further into the nature of existence, knowledge and goodness. Engineer by profession……: Engineer by profession…… In college, he majored in engineering, and because he had become interested in the philosophies of India, he secured a commission in the Royal Engineers of the British Army in hopes that he might be stationed in India. Becoming a philosopher……: Becoming a philosopher…… Instead, he was sent to Burma, where his distinguished service in civil engineering won him a medal and promotion to the rank of major. His continuing study of philosophy led him to believe that the debated issues in philosophy could be properly dealt with only through the development of psychology as an empirically testable science. Ph D at the age of 41…….: Ph D at the age of 41……. Hence, at the age of 34, he resigned his commission and went to Germany, to study experimental psychology in the laboratory of Wilhelm Wundt. (founder of experimental psychology) Life is short…….: Life is short……. Spearman wrote of his 14 years of army service as “¼ the greatest mistake of my life ¼ [based on] the youthful delusion that life is long. For these almost wasted years, I have since mourned as bitterly as ever Tiberius did for his lost legions. Searching foot prints of Galton….: Searching foot prints of Galton…. Though Wundt was the guide of Spearman, Spearman’s thinkings were influenced by reading Galton’s book Inquiries into Human Faculty and Its Development (1883) Francis Galton, Founder of Differential Psychology. The two factor theory……: The two factor theory…… Spearman’s two-factor theory of intelligence states that any cognitive performance is a function of two ‘factors’-the general ability common to most cognitive performances and an ability specific to a given test. Slide 9: This common and general factor associated with every intellectual performance was called g . ALSO Every intellectual activity involve a specific ability pertaining to that particular activity, s . Slide 10: There is only one g factor but many s factors. One energy but different engines. (analogy) Slide 11: Every one starts with general mental ability, later specialises into one chosen field. One has to be a master of all trades and jack of one. Slide 12: People have varied proportions of g and s factors. g is not itself an ability, but some property of the brain that causes all forms of mental abilities to be positively correlated. The great variety of mental tests, however diverse in information content, skills, and task demands, all measure something in common, but to varying degrees. The common factor is g . Slide 13: Some of the well-known intelligence tests are designed to measure Spearman’s “g.” It is said that Raven’s Progressive Matrices, which is a non-verbal, cross-cultural test of intelligence is one of the best measures of Spearman’s ‘g.’ John Raven worked closely with Charles Spearman in constructing this test. Slide 14: Spearman never discovered the neuro-physiological cause(s) of g . He could only refer to g metaphorically as some form of “mental energy” in which people differ and which various mental tests elicit to different degrees. The underlying physiological causes of individual differences in g are still largely a mystery, but we now know that g is more genetically heritable than are any other ability factors measurable by mental tests and that g has more anatomical and physiological brain correlates than any other psychometric factors. Slide 15: Variables such as brain size, nerve conduction velocity, the amplitude of evoked brain waves, and the brain’s glucose metabolic rate while performing mental tasks are all correlated with g . One of the liveliest fields of research in the cognitive neurosciences today is the search for the physical basis of g . Spearman himself foresaw this development, but he knew it could be realised only with a technology far in advance of his time. Slide 16: During his career, Spearman received many academic honors, including Fellow of the Royal Society and membership in the United States National Academy of Science. Slide 17: He became a Fellow of the Eugenics Society of London (later renamed The Galton Institute) early in his career, And expressed his eugenic opinions in a more hard boiled fashion than ever did Galton himself, writing in 1912, for example, “One can conceive the establishment of a minimum index [of general intelligence] to qualify for parliamentary vote, and above all, for the right to have offspring.” In 1945, with failing health at age 82, he committed suicide by jumping from the top story of the London University Hospital, where he was a patient.