Answer: 
Emerging adulthood 
Explanation: 
Emerging adulthood is the period between adolescence and adulthood. It is the period where a person is at the end of adolescence and the starting stage of adulthood. It is a type of feeling in-between. 
There are different features of emerging adulthood: 
- It is the age of exploring the identity of a person. 
 - It is the stage of feeling about instability in life. 
 - It is the age self-focus 
 - It is the age of self-fulfilling 
 - It is the age of possibilities 
 
Thus here in the above context, findings from the longitudinal od Seattle on different ages in the cross-sectional study, most of the cognitive abilities are highest in the emerging adulthood compared with middle adulthood.