From birth, babies experience sensations that make them react in one way or another. However, until they start talking, the parents have no idea about what they are thinking. They laugh for no apparent reason, for instance, or throw their toys onto the floor repeatedly.
Babies do not think like adults, as their brains are still developing up to the age of six. 90% of neural connections are made before the age of three, with the remaining 10% occurring between the ages of three and six.
However, while they may not think like an older person, babies think from the time they are born. These first thoughts, called protothoughts, are based on sensations, as children this young are not capable of specifying everything they perceive with words or images. Children's minds are sensitive to what is occurring around them but are not conscious, as they are not yet able to reason or memorise like an adult. The first ideas that enter a baby's head are linked to bodily experiences: hunger, cold, comfort, sleep, etc.
From month four, babies start to make voluntary movements and can observe their environments from a position of a little more awareness. In this stage, they begin to become aware of what their bodies are capable of and to learn to take advantage of them. This new interest in movement starts their cognitive development. In other words, the psychological development of children evolves in parallel with their biological development and one needs the other for optimum infant development.
Babies' mental capacities increase with sensory stimulation and the experiences to which their bodies are subject. The more they discover of the world, the more these lived experiences increase.
Humans are born with very few skills and are totally dependent on their parents during their early months. However, their brains have a large capacity to produce response to environmental stimuli. Babies' minds are like sponges and between four and five months they have already learnt the cause and effect relationship.
Between six and seven months their memory starts to develop and they become aware of the results of their actions. They start to associate certain activities with pleasant sensations or with things they do not like. For example, when they play they feel good but when they are hungry they feel uncomfortable. They begin to remember different experiences that make them feel a similar way.
From the age of one, children start learning to talk. As their language abilities grow, neural connections between words and objects form. They start to investigate the cause and effect relationships of their actions and begin acting intentionally. They will throw toys to the floor repeatedly to see how they fall and shake a rattle to hear the noise it makes. These are behaviours that involve an action that they now recognise and they repeat it over and again to check that it happens the same way every time.
At around a year and a half they start to develop the capacity for representation or symbolic function. By now they are associating words with certain objects. For example, they will say "bow-wow" to signify a dog and will imitate behaviours they see, like putting a teddy bear to bed. During this stage, they start to develop sympathy and show empathy for others.
From the age of three they are aware of certain basic rules and can do what they are told. They continue to perceive things through their senses but are yet to start thinking logically because they do not know how to work out why things happen. They think symbolically, based on creativity and fantasy.
Between the ages of five and six, children develop a capacity for reasoning similar to that of adults.