Some psychologists suggest that cognitive development is not in a stage-like manner. From the information-processing approach, if we view cognitive development as the acquisition of several separate information processing skills, we would notice that a child may need several cognitive skills like attention and memory, apart from the critical skills which symbolyses the stages, to successfully do the tasks designed to test the critical skills. For example, in the study of object permanence, when an …showed first 75 words of 396 total…

…showed last 75 words of 396 total…in a memory test on random numbers. But the 10-year-old chess experts did better than the 18-year-old chess amateurs when they are asked to recall the positions of the chess pieces on the board. This shows that the domain-specific knowledge is the main difference between the two groups which affect their cognitive abilities, but not the stages of cognitive development. These two approaches provide evidence why cognitive development may not conform to a stage view.