E.L Thorndike (1874 - 1949), American Psychologist was the exponent of the theory of connectionism or trial and error theory. 

• Thorndike's study on animal behavior and the learning process of cats founded trial and error theory or theory of connectionism.
• He stated that connections are formed in the nervous system between stimuli and response, illustrated by the symbols S-R. It is meant that Learning is the product between stimulus and response. "Bond" is also used to describe these connections, so this theory is sometimes called as "Bond Theory of Learning".
• According to the theory, when no solution to the problem is available, then the learner adopts the method of trial and error. He first tries a solution, if it does not help him, he rejects it and switches to another solution of the problem. This process helps to reduce error and in the end, discovers the correct solution. 
  • Connection is established by following these three laws.
    • Law of Readiness: Readiness means preparation for action. It stated that learning occurs when an action tendency is present. If one is not ready to learn, learning can not be processed further.
    • Law of Exercise: This law stated that drill or practice helps in increasing efficiency or connection are strengthened with trial or practice. For example; learning to type, learning to drive needs repetition of several actions.
    • Law of Effect: This law suggested that when satisfaction follows an association, it is more likely to be repeated.

Thorndike also proposed five secondary laws for the learning process. These are as follows:

• Law of Multiple Responses: means a change in response till appropriate behavior is known.
• Law of Attitude or Set: means learner performs the task well if he has attitude set in the task.
• Law of Response by Analogy: means utilizing previous experiences in new situations.
• Pre- Potency of elements: means learner reacts only to essential situation and neglect other irrelevant features.
• Law of Associative Shifting: means learner may get a response, of which a learner is capable.

Hence, it can be concluded that when children learn a concept and use it, practice helps in reducing the errors committed by them, this idea was given by E.L Thorndike.

 According to Piaget’s Cognitive Development Theory:

• Cognitive development takes place at different rates at different stages of development.
• Cognition develops through the interaction between the child and the environment.
• Piaget’s theory focuses not only on understanding how children acquire knowledge but also on understanding the nature of the child’s intelligence.

J.B Watson's learning theory

• It explained that behaviour can be explained in terms of S-R connection in the brain. It is because the contiguity of the brain was enough to establish a connection between stimulus and response.
• Watson conducted an experiment on his eleven-year-old son. Watson presented him a white rat. His son Albert started loving that white rat. After this, Watson produced a loud sound at the time of his playing with a white rat. After this process, the child started fearing this white rat. In this way, the response of fear got conditioned along with the white rat.

Lev Vygotsky', a Soviet psychologist, has propounded the "Socio-cultural Theory". This theory implies the idea that social interaction plays a crucial role in the development of a learner's cognitive ability. 

• According to Vygotsky, social interaction is the primary cause of cognitive development as his theory emphasizes that children learn through interaction and collaboration with skilled and knowledgeable people.
• In fact, as per Vygotsky’s sociocultural perspective, interaction with adults and abler peers is influence language development.