Intelligence, speech and emotion

Intelligence is the ability to understand links between objects and events and apply them in a new situation. A simpler form exists in higher animals: a chimpanzee stacks boxes to reach hanging fruit, a fox goes round a glass barrier and finds food, while some other animals find such a task harder. This ability is developed differently in different animals and depends on the structure and development of the brain. In humans intelligence is highly developed as thinking: thinking allows forming concepts, drawing conclusions and foreseeing new situations. A thought is expressed by words. A word is a sound or visual signal for an object or event (for example, the manual alphabet of deaf people, or writing), a conditional stimulus; the word “lemon” increases salivation. A word generalises: the word “table” fits many tables. Speech can be oral, written or by gestures, and passes experience to later generations. A human is born with the ability to speak but learns language through communication; a child without communication acquires speech late. Spoken-speech centres are mainly in the frontal and temporal regions of the left hemisphere, and written speech in the frontal, parietal and occipital regions.