Preoperational children cannot solve conservation tasks, because they focus on only one dimension of an object. This type of thought is referred to as:

Intuitive thinking

Explanation:

Intuitive thinking: In psychology, the term "intuitive thinking" is determined as one of the two sub-stages of the preoperational stage of the cognitive development theory which was proposed by Jean Piaget. This stage generally starts at the two years of age and lasts through seven years of a child's life.

Intuitive thinking is determined as a kind of thinking that ought to help a child to understand reality in any specific moment in the absence of analysis or logical thinking.

because the early people found out about it.