Language and cognition are closely connected, practically and conceptually, although there is considerable disagreement among experts about the precise nature of this connection. The debate among linguists and psychologists is much like the chicken-and-egg debate — they question whether the ability to think comes first or the ability to speak comes first. There are three main positions regarding the relationship between language and cognition: language develops largely independent of cognition, cognition influences both language and the pace of language development, and language precedes cognition and is the primary influence on thought development.
There is considered to be validity to all three theories concerning the nature of the connection between language and cognition. Considerable research and evidence exists to support each position. Much of the disagreement among child development experts, surrounds “when,” not “if.”
Language is the use of sounds, grammar and vocabulary according to a system of rules that is used to communicate knowledge and information. Although many non-human species have a communicative ability that might loosely be called language, only humans utilize a system of rules that incorporates grammar and vocabulary. The word "cognition" is often used synonymously with “thought” or “thinking,” but its general meaning is more complex. It refers to the process or act of obtaining knowledge through not only perceiving but through recognizing and judging. Cognition also includes such thinking processes as reasoning, remembering, categorizing, decision-making and problem-solving.
Linguistics is concerned with the scientific study of language in all its manifestations, and there are several branches of social sciences that focus on cognition. For example, cognitive anthropology studies the cultural differences in reasoning and perception. Cognitive science is the formal study of the mind, and the models and theories from this discipline were the basis for the originating theories of artificial intelligence.
The branch of psychology that studies mental processes such as memory and attention is called cognitive psychology. Within the realm of psychology, cognitive therapy is a behavior therapy based on the idea that the way a person cognitively perceives himself or herself in the world determines how he or she feels. Cognitive therapists believe that people can change their emotions by first changing their cognitive perceptions.
At its simplest, the connection between language and cognition for normal human adults, no matter their ethnicity or culture, is profound. Speech gives voice to thoughts. Although individual cognitive processes are internalized and therefore silent, language — whether spoken or written — allows for knowledge and information to be shared.