Last week as I was having a video call with my mom and my sister, we touched upon an adult topic and then quickly changed the subject because my 1-year-old baby boy was playing next to me. It was just a few words but I wondered: are adult words that we use around our children recorded somewhere in their memories even if they don't remember them explicitly? Let's find out.
How does human memory build up?
Types of memory
Our memory is an information processing system with 3 main components – sensory, short-term, and long-term.
Sensory memory stores information that our senses collect from the environment for merely a few seconds. We don't notice all of the sensory memory our brain processes though. Of all the information that we attend to, only a small portion makes its way to our short-term memory.
Short-term memory lasts for 20-30 seconds. It's the type of memory that helps us remember a phone number while it is being told to us. It's also the type of memory that helps us remember where a ball that has been rolled towards us originated from.
Long-term memory can store information for up to a lifetime. Long-term memory has two distinct types: implicit and explicit.
Implicit memory is made up of memories that you don't consciously have to remember. Using our body parts or driving a bike are implicit memories. Explicit memories are those that you consciously recall.
Explicit memory is further split into two: episodic memory and semantic memory.
Episodic memories are your recollection of life experiences (i.e. visiting the Eiffel Tower) whereas semantic memories are general knowledge (i.e. the Eiffel Tower is located in Paris).
Development of memory in infancy
It used to be thought that humans did not build much memory before the age of 3 or 4 but recent research showed that infants build memories not much differently than adults.
The main difference is that a baby's brain is quarter the size of an adult's and neural connections are rapidly forming.
When we look at early infancy we see that the hippocampus (responsible for memory storage) and the prefrontal cortex (responsible for memory recall) are under massive development. Although all parts of the brain develop rapidly, the hippocampus is one of the few regions that keeps producing new neurons into adulthood.
Babies as young as 6-months-old can remember information 24 hours after it's been taught to them. Similarly, 9-month-olds can remember information after up to five weeks and 20-month-olds after twelve months.
When it comes to the order of information, babies cannot recall the order of a 2-step sequence in the correct order until 9 months of age. 6-month-olds can only recall one step of a 2-step sequence. This might be related to the development and neural connections in the hippocampus and the frontal lobe.
At around 9 months of age, babies start to notice when their mothers leave them. Around this time, separation anxiety kicks in. The 9-month mark is an important milestone in memory development too. Around 9-months babies start forming explicit memories.
When it comes to making episodic memories (a type of explicit memory), it requires bringing together different details of an event and recalling that information later.
The majority of people don't remember anything from before they are 3 or 4 years old. According to research, young children do form episodic memories but lose them later on through a process called childhood amnesia.
For example, 6-year-olds can remember events before the age of 3, but as they get older, those early episodic memories are lost. The starting point for amnesia is around age 7 and it's not even unique to humans. Rats and some other animals have it too.
Children do not capture the present as it happens. If we say that an adult's neural regions are made up of a fine mesh, children's neural regions is a colander with big holes, through which most information escapes. As neural regions develop, so does the child's memory. Around 2 years of age, children's memory starts resembling an adult's.
In spite of the loss of early episodic memories, it was found that encoding of an early stressful memory influenced social behavior in mice. This may explain how early trauma might influence behavior in adulthood.
How to support memory build-up
Children can form implicit and explicit memories.
But because of the developing neural structures and the lack of language skills, children cannot make sense of early experiences. It's only after 3 and a half years of age, most of us start forming a few long-term memories that are going to stick with us in adulthood.
How children start forming memories that stick has to do with our parenting style. Children who are given rich narratives of what happened (in the same day or a few days after) experience less childhood amnesia. In cultures such as Italians, where larger family settings are more common in comparison to the rest of Europe, first memories averaged at around 2 and a half years old, whereas the Europe average was 3 and a half. A similar average of 2 and a half year old was found in New Zealand's Maori populations where mothers were found to offer an elaborate narrative to children. One study found that training mothers in elaborative reminiscing enhances children's autobiographical memory and narrative.
How do children make sense of arguments?
Now that we know babies and toddlers lack the memory and language skills to decipher daily life as it happens, let's see how adult's dialogues affect them.
Babies and toddlers rely on the emotional tone in their environment to make sure they are safe. How their parents treat each other signals them whether they are safe or not. Research found that 15 month old toddlers make use of emotional information to guide their own behavior.
That's why, although the verbal content of our discussions is too complex for our children to process, they can pick up on tension and body language, causing them to feel abandoned, frustrated, scared, and sad.
However, this does not mean that families should keep all of their disagreements child-free. Children can benefit from constructive disagreement when parties express each other their emotions and extend empathy and compassion to resolve conflicts. This type of conflict handling teaches children that a disagreement is not going to break the relationships in the family and the world is a safe place where love and warmth can solve problems.
In fact, having a constructive disagreement in front of your children is better than trying to ignore the built-up tension, because children can sense emotional distance too. That's why, debating your strong emotions, even when they include anger towards your partner in front of your children is a lot healthier than passive or active aggression.
Babies and young children lack the neural structures and language processing skills to pick up and record inappropriate words in our conversations, and it is unlikely that they are going to be converted into memory. So, there is no need to freak out when we accidentally expose our child to a big word! What might have a long-term effect on children is the emotional tone in the room and how those emotions are handled by the adults around them.