Mental retardation (MDA) is a delay in mental development that is more commonly found on entry to school and is expressed as a lack of general knowledge, limited perceptions, immature thinking, predominantly playful interests and an inability to engage in intellectual activities. Thinking is the highest regulatory and cognitive process. It is a form of creative human reflection of reality, which generates a result, which in reality itself or figure does not exist at this point in time. Thinking operations are mental actions to transform objects (mental states, ideas, images) represented in the form of concepts.