What psychology studies

Biology tells you how your body works: the heart pumps, hormones carry messages. Psychology tells you how your mind works: why your friend behaves differently from you, why one person is cheerful and another irritable, how you learn, remember and think.

The word comes from two Greek words: psyche (once taken to mean soul, today taken to mean mind) and logos (study). So psychology began as 'the study of the mind'.

Today it is defined as the science that studies mental processes, experiences and behaviour in different contexts. Because of the mind you can do all three:

• Mental processes (also called cognition): thinking, remembering, learning, reasoning, imagining, solving problems. Most chapters of this book are about one of them.
• Experiences: how something feels to you. They are subjective, different for each person, and they live in your consciousness (awareness). Heavy rain feels like a treat to a child at home with hot snacks and like a loss to a rickshaw driver who cannot earn that day. Same rain, two experiences.
• Behaviour: your responses to the world outside and to your own inner needs. Answering when someone calls your name is a response to the outside; drinking water because you are thirsty is a response to an inner need.

Behaviour comes in two kinds:

• Overt: others can see it, like running, smiling or speaking.
• Covert: it happens inside and others cannot easily see it, like silently repeating a poem in your head to calm your nerves.
• Psychologists often describe behaviour as a stimulus (what happens) and a response (what the person does).

Psychology as a subject grew out of philosophy. It became a separate science in 1879, when Wilhelm Wundt set up the first psychology laboratory in Leipzig, Germany.

It runs in two parallel streams:

• A natural science. Like physics or biology, it uses the hypothetico-deductive model: start with a hypothesis, a tentative answer to a question, then collect real-world (empirical) data to test it, and keep it or reject it. Theories of learning, memory, attention and motivation were built this way.
• A social science. People are not studied in a closed room. Psychology studies them in their social and cultural setting: how your family, friends and culture shape the way you think and act, and how you in turn shape them.