Thinking consists of the process of manipulating some form of representation or meaning for a goal or purpose. Thinking is a basic psychological process that undergoes transformation over the life span. To understand thinking, it is thus necessary to understand the concept of representation. A representation is something that is used to stand for or refer to something else. There are many forms of representation, including signs (e.g., words), symbols (i.e., pictorial representations such as ↗, ⚥, or ∅), mental images (e.g., imagining a duck), gestures (e.g., pointing), and objects when they are used to stand for something else (e.g., a flag representing a nation; fingers used to represent quantity). This entry begins with an analysis of issues related to the origins of thinking in ...