Children begin to abstract semantic features (bonds) in the Perceptual-Motor Stage
Another important process is occurring at that time. The child is tackling the problem of why different objects are given the same name.
At this point, the word “shoe” may refer to just a particular shoe. This is a concrete level of meaning.
But this is not how the adults use the term. They use if for many types of shoes. What do they all have in common?
Please switch to the graphic version to see an illustration of a concrete concept of A SHOE which BY ANY OTHER NAME IS SOMETHING ELSE.