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Intelligence/Intelligence Quotient (IQ)

Intelligence has been a focus of research for over a century. Herbert Spencer, a late nineteenth century British philosopher, is often credited with first referring to general cognitive ability as intelligence. This long-standing interest in the construct of human intellectual capacity has resulted in numerous definitions and theories. Common definitions of intelligence describe it as including the ability to reason, plan, solve problems, think abstractly, comprehend ideas and language, and learn; effectively perceiving, interpreting and responding to the environment; or the ability to understand complex ideas, adapt effectively to the environment, learn from experience, engage in various forms of reasoning, and to overcome obstacles by taking thought. While there is a general consensus within all definitions and theories that individuals differ in their levels of this ability or construct, there are two major schools of thought on the nature of