Read the article below quickly and say if developmental psychologists are successful in exploring differences between people of certain ages

CONTINUITY AND DISCONTINUITY IN DEVELOPMENTAL PSYCHOLOGY

We can all agree that from birth to death, people change along several parallel pathways, including movement, cognition, and social skills and emotion. But how exactly do these changes take place? Are they sudden and abrupt or gradual? This article explains how developmental psychologists explore differences between people of certain ages based on how gradually or abruptly those differences seem to emerge.

The continuity approach. If you have spent any significant amounts of time with young children, there are some aspects of their behavior that seem to change so gradually that you hardly notice. We can compare these aspects of development to the growth of a mighty oak from its beginnings as a little acorn.

For example, young parents are unlikely to notice the gradual weight gain of the young infant. From day to day, the parents will respond to lifting the growing child by becoming stronger themselves, so they hardly notice any change in weight. What makes this truly astonishing is that the child is growing at a remarkable rate, especially during the first year of life. If a human child continued his or her growth rate during the first year of life over the next nine years as well, the child at age 10 years would be about the size of a jumbo jet!

Another gradual change that seems to sneak up on parents is the child's increasing vocabulary. Once children start speaking, their vocabularies begin to increase on a daily basis. The typical 18-month-old child might have between 10 and 50 words, but by the time children reach kindergarten age, they have a very mature sounding vocabulary of about 2000 words. Because these are the types of words even adults use most frequently (as opposed to the types of words we learn in high school or college, like hippocampus), you can have a rather sophisticated conversation with a 5-year-old.

Children's social skills might also proceed in a very gradual manner. As they are exposed to more diverse social experiences when moving from the home to perhaps a daycare provider to preschool to school, the child's social skills must keep pace. Once in awhile, however, we observe rather dramatic changes in a child's behavior in which a behavior that wasn't there the day before now appears. This type of observation has led to a different way of viewing some aspects of development.

Discontinuity approach. Discontinuous development occurs when differences between individuals of one age and either previous or subsequent ages appear rather abruptly rather than gradually. Unlike the acorn to oak analogy we made for continuous development, we might think of discontinuous development as being like a caterpillar changing into a butterfly. We tend to see discontinuity when children hit "milestones," such as walking alone and speaking a first word. The day before, these behaviors are absent, but they seem to emerge in some cases with little warning.

In some cases, we are able to identify biological correlates of some abrupt developmental changes. For example, in both infant rhesus monkeys and humans, development in the frontal lobes is strongly predictive of the achievement of object permanence. Object permanence occurs at about the same stage of development in both species, and is demonstrated when the infant searches for an object once it is removed from sight. At a previous stage of development, objects for infants are literally "out of sight – out of mind."

Some developmental theories, such as Jean Piaget and Erik Erikson, propose stage theories of development that are largely discontinuous. According to these theories, behavior in one stage is qualitatively different than behavior in the previous or next stages, and movement from one stage to the next can occur rather suddenly.