Memory is something we rely on throughout our lives. But, how does it first develop? In this lesson, we will explore the first signs of memory in infants and how memory changes over our lives.
Memory Development During Infancy
Are babies able to remember things? When does memory start to kick in?
Babies exhibit observable short-term memory the first year of life and further into the second. This can be seen by what's called deferred imitation, or the baby mimicking nonverbal tasks moments after they are demonstrated. For example, let's say a mother gives her baby a rattle for the first time. She shakes it and then puts it down. A couple minutes later, her baby is able to pick up that rattle, shake it and put it down. This shows that there is some memory at work in the child.
Between 6 and 12 months, infants remember familiar faces and places. Eleven-month-old Danny, for example, is visiting the doctor's office again. He has some recollection of the office and the doctor and starts immediately crying. However, when he sees his grandmother later that day, he recognizes her face and immediately starts to smile and giggle.
It is not until around two years that infants begin to exhibit long-term memory. An experiment was done where twelve 9-month-olds and the same number of 17- to 24-month-olds were shown how to play with new toys and expected to imitate the process. For example, the researcher gave them a toy truck, put a driver in the front seat, put a rock in the truck bed and then rolled the truck.
Four months later, the researcher returned to see if they remembered what to do with the truck. The nine now 13-month-olds did not remember what to do. The now 21- to 28-month-olds, however, exhibited strong recollection. This has been attributed to significant cell development in the hippocampus and frontal lobes of the brain, the areas in charge of memory.
We go through a lot as babies, but why is it we often can't remember anything earlier than around age four? The tendency to forget events the first few years of our lives is referred to as childhood amnesia.
Sunny, for example, is being asked in her psychology class what her earliest memories are. She can only remember back to about age four. Her professor explains that this is most likely due to the brain's lack of development and weak long-term memory the first few years.
Memory During Childhood and Adolescence
Between the ages of two and five, most children are able to focus their attention in order to pick up information in their present and then recall it later on. Their episodic memory increases in this time, which means they are able to remember personal experiences. A child who has been away for Christmas vacation is able to come back to school after a week or two and tell her classmates about what she did with her family.
These first several years also include the formation of their long-term memory. In order to get events into their long-term memory, children utilize scripts, or a viewpoint of events happening in a sequence of steps. This perspective helps children both remember and understand happenings.
For example, Sandra went to the ice skating rink yesterday with her dad. When asked about it today, she remembers it happening in stages. Dad and I drove to the place, put on skates, skated around the rink several times and then drove home.
At the start of adolescence, the brain begins developing more fully, leading to swifter incoming information, better storage and recall. This can be reflected in the amount of information teens remember as they go through their school and extracurricular schedules and study for cumulative exams. The end of adolescence marks a considerable improvement in memory.
Memory During Adulthood
Young adulthood is the peak timespan for memory. Even into middle adulthood, new brain cells and connections between them are being formed, providing absorption and retrieval of information. Memories decline in various ways during older adulthood. This occurrence is referred to as Age-Related Memory Impairment (AMI) or Age-Associated Memory Impairment (AAMI).
First, the speed of processing information steadily declines. When 75-year-old Ben is driving, it takes him longer to judge if he can turn left as the cars are approaching. His short- and long-term memories have also declined. He often forgets what he did earlier that week. If asked about certain events from middle adulthood, he often forgets names, places or times things happened.
Lastly, episodic memory decreases in older adults. Meaning, when Ben is asked about what his first year in college was like, he may only remember a few details of what took place. Doing mental exercises, like card games or those online as well as helping others solve life problems, can lessen normal memory loss in older adulthood, provided there are not other issues like dementia or Alzheimer's. Dementia refers to symptoms of memory loss that could be caused by any number of physical issues. Alzheimer's is a disease of the brain that includes dementia and accounts for 60-80% of dementia cases.
Let's review. Babies exhibit short-term memory in their first year and further into their second as shown through copying others, or deferred imitation. They remember faces and places between 6-9 months and exhibit long-term memory at about 17-24 months.
Memory continues to grow the first several years of childhood as children show episodic memory, or recalling of personal experiences. They do this through the use of scripts, or a sequence of steps that portray events. Adolescence is a time for significant brain development in the areas of memory, and both short- and long-term memory increase until they peak in young adulthood.
New brain cells are continually formed into adulthood until a gradual decline in memory and information processing takes place into later years. This is worsened by dementia, or memory loss caused by physical illnesses, and Alzheimer's, the brain disease that accounts for most dementia cases.
After you've completed this lesson, you'll be able to:
- Identify the ages that babies exhibit short-term memory and start to develop long-term memory
- Describe episodic memory and the use of scripts during childhood
- Explain how memory changes from adolescence into late adulthood
- Define dementia and Alzheimer's