Cognition: A general term used to refer to the ‘higher’ mental processes. Cognition would generally be taken to include such forms of mental activity as thinking and conceptualization, memory, representation, mental imagery, perception, attention, reasoning, and decision making.

Cognitive Development: The way in which cognitions develop during childhood. The major and most detailed theory of cognitive development is that produced by Piaget, although his theory is largely restricted to the ways in which thinking and understanding change through childhood. One of Piaget’s most important contributions was to establish that the thought and logic of young children is not an inferior version of adult thinking, but has its own rules and is well adapted to the needs of the child. Cognitive development is not just a process of getting better at adult modes of cognition, but it is a complex progression through different kinds of thinking and understanding. Other approaches to cognitive development include research into metacognition, social cognition, and the child’s theory of mind.

Development: The processes of change over the lifespan. One aspect is physical development, which is strongly influenced by genetic tendencies. The other is psychological development, which is much more directly influenced by environmental factors.

Intelligence: In general, the ability of an individual to understand the world and work out appropriate courses of action. Within psychology there is no more precise definition that is generally accepted, although the old claim that ‘intelligence is what intelligence tests measure’ is uncomfortably accurately.