The detailed study of children allows us to fully appreciate the roots of the psychic and psychological life of young children, hence the reason why researchers study children in particular since during age of 0-2 years, which is childhood, as these changes are very widespread and rapid during childhood. A famous researcher named William James (1891), an eminent psychologist, identified that the world of childhood is a very high profile, lively and confusing subject as they do not grasp the world as adults do; They also do not recognize objects that have characteristics such as size and color. Subsequently, during the twentieth century, researchers devised fertile methods to study newborns and this challenged everything that William James (1891) had previously thought about newborns, so these researchers developed ideas/concepts that the abilities infants develop in some way, counting aspects such as cognition, emotion, etc. As children, the ability to take in new information and build on it continues to grow and develop. When investigating young children we use time-of-observation approaches, where it allows us to adapt if, for example, a child in the 3-5 age range can notice very precise changes in the video shown to them. The hypothesis of looking at time is for example; if the child finds the video clip stimulating then he will tend to watch it more. In one experiment, the child was shown the same video clip a given number of times. Therefore, as the number of times the child watches the video clip increases, he/she should find it boring after watching it for a while. As a result, this would lead to shorter viewing times; However, children are able to perceive a change in the video clip if it were in the center of the paper......recognize objects and surfaces such as size and color. Because proven new and innovative methods such as Object Permanence make use of children's natural behaviors, however critics have criticized Piaget's research studies due to the limited amount of samples and the use of artificial tasks and settings that lack external validity. Haith (1998) argued that there is overinterpretation of the child's behavior in experimental tests, related to this Scholl and Leslie (1999) found that researchers who rely on relatively rigid measures to assess the child's knowledge are sometimes accused of proposing "deflationary" bills". New technologies such as MRI and EEG are also being developed, so researchers will be able to find new ways to test children, which means new discoveries can be made, so researchers will build a bigger picture for the future development of the mind.