Step 1: Understanding the Concept:
Growth and Development are often used interchangeably, but they represent different types of changes in an organism.
Step 2: Detailed Explanation:
Quantitative changes refer to measurable increases in size, such as height, weight, and the number of words in a vocabulary.
Qualitative changes refer to transformations in the nature of functioning, such as the transition from crawling to walking or the development of abstract reasoning.
Erikson's stages focus on qualitative psychosocial crises, but human development as a whole encompasses both physical growth and functional maturation.
Step 3: Final Answer:
Human development is the sum of both measurable physical changes and complex functional changes.