What moves behaviour

Motivation is the concept that explains what moves behaviour. The word comes from the Latin 'movere', meaning to move. Knowing a person's motives helps us explain why they act as they do and predict what they will do next. Motivated behaviour is goal-directed: it keeps going until the goal is reached.

Our behaviour can be moved by instincts (inborn patterns, such as curiosity drawing a crowd around an unusual event), needs, drives, and goals or incentives (working extra hours for a bonus).

The motivational cycle:

• A need arises: a lack of something necessary, such as water.
• The need produces a drive: a state of tension or arousal that pushes us to act.
• We carry out goal-directed behaviour: you go to the water cooler.
• Reaching the goal (drinking) brings relief, and the drive and arousal are reduced.
• Soon a new need arises, so the cycle keeps turning.

There are two types of motives:

• Biological motives come from the body's needs and are found in everyone, though their strength varies.
• Psychosocial motives are learnt from our family, friends and society.
• No motive is purely one or the other. Even hunger is shaped by learning: what we feel like eating, and when, depends on our culture and habits.

Hunger is controlled by several signals working together:

• Stomach contractions and the feeling of an empty stomach.
• A fall in blood glucose (sugar), sensed partly by the liver.
• The hypothalamus in the brain: one area signals hunger and another signals fullness, together regulating how much we eat.
• External cues: the smell of fresh food, a plate of snacks in front of you, or the clock showing dinner time can make you feel hungry even when your body does not need food.

Thirst is also controlled by more than a dry mouth:

• When cells lose water, they shrink. Osmoreceptors in the hypothalamus detect this and trigger thirst.
• A drop in blood volume (for example after heavy sweating or bleeding) also triggers thirst.
• A dry mouth is felt, but simply wetting the mouth does not stop thirst for long: the body's water balance must be restored.