11.1: Memory and Executive Function Development

If we want to remember something tomorrow, we have to consolidate it into long-term memory today. Long-term memory is the final, semi-permanent stage of memory. Unlike sensory and short-term memory, long-term memory has a theoretically infinite capacity, and information can remain there indefinitely. Long-term memory has also been called reference memory, because an individual must refer to the information in long-term memory when performing almost any task. Long-term memory can be broken down into two categories: explicit and implicit memory.

Explicit Memory

Explicit memory, also known as conscious or declarative memory, involves memory of facts, concepts, and events that require conscious recall of the information. In other words, the individual must actively think about retrieving the information from memory. This type of information is explicitly stored and retrieved—hence its name. Explicit memory can be further subdivided into semantic memory, which concerns facts, and episodic memory, which concerns primarily personal or autobiographical information.

Semantic Memory

Semantic memory refers to the facts that a child begins to acquire in the form of language and other knowledge. When I used to ask our youngest child how they knew some fact they had spouted off they would say "I just knowed it mommy!" This is certainly an example of explicit memory since they could declare it was something they knew (therefore declarative or explicit memory). Also it is an example of semantic memory if it was something like a description of a fact like "Airplanes are big and blue"

Episodic Memory

Episodic memory is used for more contextualized memories. They are generally memories of specific moments, or episodes, in one's life. As such, they include sensations and emotions associated with the event, in addition to the who, what, where, and when of what happened. An example of an episodic memory would be recalling your family's trip to the beach. Autobiographical memory (memory for particular events in one's own life) is generally viewed as either equivalent to, or a subset of, episodic memory. One specific type of autobiographical memory is a flashbulb memory, which is a highly detailed, exceptionally vivid "snapshot" of the moment and circumstances in which a piece of surprising and consequential (or emotionally arousing) news was heard. For example, many people remember exactly where they were and what they were doing when they heard of the terrorist attacks on September 11, 2001. This is because it is a flashbulb memory.

Semantic and episodic memory are closely related; memory for facts can be enhanced with episodic memories associated with the fact, and vice versa. For example, the answer to the factual question "Are all apples red?" might be recalled by remembering the time you saw someone eating a green apple. Likewise, semantic memories about certain topics, such as football, can contribute to more detailed episodic memories of a particular personal event, like watching a football game. A person that barely knows the rules of football will remember the various plays and outcomes of the game in much less detail than a football expert.

Implicit Memory

In contrast to explicit (conscious) memory, implicit (also called "unconscious" or "procedural") memory involves procedures for completing actions. These actions develop with practice over time. Athletic skills are one example of implicit memory. You learn the fundamentals of a sport, practice them over and over, and then they flow naturally during a game. Rehearsing for a dance or musical performance is another example of implicit memory. Everyday examples include remembering how to tie your shoes, drive a car, or ride a bicycle. These memories are accessed without conscious awareness—they are automatically translated into actions without us even realizing it. As such, they can often be difficult to teach or explain to other people. Implicit memories differ from the semantic scripts described above in that they are usually actions that involve movement and motor coordination, whereas scripts tend to emphasize social norms or behaviors.

Figure \(\PageIndex{1}\): A normal toddler’s experiences walking outdoors and playing may not necessarily be remembered for long.[1]

Short-Term Memory Storage

Short-term memory is the ability to hold information for a short duration of time (on the order of seconds). In the process of encoding, information enters the brain and can be quickly forgotten if it is not stored further in the short-term memory. George A. Miller suggested that the capacity of short-term memory storage is approximately seven items plus or minus two, but modern researchers are showing that this can vary depending on variables like the stored items' phonological properties. When several elements (such as digits, words, or pictures) are held in short-term memory simultaneously, their representations compete with each other for recall, or degrade each other. Thereby, new content gradually pushes out older content, unless the older content is actively protected against interference by rehearsal or by directing attention to it.

Information in the short-term memory is readily accessible, but for only a short time. It continuously decays, so in the absence of rehearsal (keeping information in short-term memory by mentally repeating it) it can be forgotten.

Figure \(\PageIndex{2}\): Diagram of the memory storage process – where sensory information is transferred to short term memory, and retained there through rehearsal, but also moved into longterm memory in a process called consolidation.[2]

Long-Term Memory Storage

In contrast to short-term memory, long-term memory is the ability to hold semantic information for a prolonged period of time. Items stored in short-term memory move to long-term memory through rehearsal, processing, and use. The capacity of long-term memory storage is much greater than that of short-term memory, and perhaps unlimited. However, the duration of long-term memories is not permanent; unless a memory is occasionally recalled, it may fail to be recalled on later occasions. This is known as forgetting.

Long-term memory storage can be affected by traumatic brain injury or lesions. Amnesia, a deficit in memory, can be caused by brain damage. Anterograde amnesia is the inability to store new memories; retrograde amnesia is the inability to retrieve old memories. These types of amnesia indicate that memory does have a storage process[3].

Infantile amnesia

Autobiographical memory is our personal narrative. Adults rarely remember events from the first few years of life. In other words, we lack autobiographical memories from our experiences as an infant, toddler and very young preschooler. Several factors contribute to the emergence of autobiographical memory including brain maturation, improvements in language, opportunities to talk about experiences with parents and others, the development of theory of mind, and a representation of “self” (Nelson & Fivush, 2004). Two-year-olds do remember fragments of personal experiences, but these are rarely coherent accounts of past events (Nelson & Ross, 1980). Between 2 and 2 1⁄2 years of age children can provide more information about past experiences. However, these recollections require considerable prodding by adults (Nelson & Fivush, 2004). Over the next few years children will form more detailed autobiographical memories and engage in more reflection of the past.

Memory in early childhood

Based on studies of adults, people with amnesia, and neurological research on memory, researchers have proposed several “types” of memory (see Figure). Sensory memory (also called the sensory register) is the first stage of the memory system, and it stores sensory input in its raw form for a very brief duration; essentially long enough for the brain to register and start processing the information. Studies of auditory sensory memory show that it lasts about one second in 2 year-olds, two seconds in 3-year-olds, more than two seconds in 4-year-olds, and three to five seconds in 6-year-olds (Glass, Sachse, & von Suchodoletz, 2008). Other researchers have also found that young children hold sounds for a shorter duration than do older children and adults, and that this deficit is not due to attentional differences between these age groups, but reflects differences in the performance of the sensory memory system (Gomes et al., 1999). The second stage of the memory system is called short-term or working memory. Working memory is the component of memory in which current conscious mental activity occurs.

Working memory often requires conscious effort and adequate use of attention to function effectively. In early childhood, children struggle with many aspects of attention and this greatly diminishes their ability to consciously juggle several pieces of information in memory. The capacity of working memory, that is the amount of information someone can hold in consciousness, is smaller in young children than in older children and adults. The typical adult and teenager can hold a 7 digit number active in their short-term memory. The typical 5-year-old can hold only a 4 digit number active. This means that the more complex a mental task is, the less efficient a younger child will be in paying attention to, and actively processing, information in order to complete the task.

Figure \(\PageIndex{3}\): Much research has examined the elements and processes of children’s thinking.[4]

Executive function

Changes in attention and the working memory system also involve changes in executive function. Executive function (EF) refers to self-regulatory processes, such as the ability to inhibit a behavior or cognitive flexibility, that enable adaptive responses to new situations or to reach a specific goal.

"EF covers a set of both unique and overlapping cognitive processes which are required for problem solving and goal achievement (Miyake et al., 2000; Diamond et al., 2007). The core components of EF are working memory (mentally holding and using information), inhibitory control (deliberate, controlled suppression of prepotent responses), and cognitive flexibility (adjusting to change and shifting of mental sets)." (Spiegler & Leyendecker, 2017)

Executive function skills gradually emerge during early childhood and continue to develop throughout childhood and adolescence. Like many cognitive changes, brain maturation, especially the prefrontal cortex, along with experience influence the development of executive function skills.

A child shows higher executive functioning skills when the parents are more warm and responsive, use scaffolding when the child is trying to solve a problem, and provide cognitively stimulating environments for the child (Fay-Stammbach, Hawes & Meredith, 2014). For instance, scaffolding was positively correlated with greater cognitive flexibility at age two and inhibitory control at age four (Bibok, Carpendale & Müller, 2009). In Schneider, Kron-Sperl and Hunnerkopf’s (2009) longitudinal study of 102 kindergarten children, the majority of children used no strategy to remember information, a finding that was consistent with previous research. As a result, their memory performance was poor when compared to their abilities as they aged and started to use more effective memory strategies.

The role of culture

Both bilingualism, and biculturalism require the ability to effectively alternate the use of culturally appropriate behaviors (LaFromboise et al., 1993). Therefore, Spiegler and Leyendecker (2027) assumed that biculturals who endorse both cultures with equal strength will perform better on EF tasks than individuals who favor one culture over the other. In addition, we expect performance differences to be most pronounced in tasks that require cognitive flexibility as the successful navigation of cultures involves the ability to switch between different mind sets (Hong et al., 2000).

Their study's focus was on Turkish-German children of immigrant origin. This allowed them to investigate the consequences of immersion into two markedly distant cultures in terms of interdependence—independence, family obligations, religious values and traditions, and gender role expectations. The acculturation complexity model argues that the immersion into conflicting and dissonant cultures is most likely to promote cognitive skills (Tadmor and Tetlock, 2006). Their focus on children is of immediate societal relevance as Turkish-German children are the largest immigrant-origin group in Germany and among the least successful in the German school system compared to native Germans and other immigrant groups, and because EF performance is strongly correlated with academic achievement (Best et al., 2011).

Their study is the first to demonstrate that immigrant-origin children who identify equally strong with their ethnic heritage and host-national groups perform better on a switching task that demands cognitive flexibility than their peers who prefer one culture over the other. The immersion into two cultures is highly demanding, especially if both cultures are markedly distinct. Individuals who endorse such distinct cultures with relatively equal strength are expected to switch more often between cultural mindsets and behavioral repertoires than individuals who make a commitment to one of the cultures (Hong et al., 2000). Their results indicate that the more frequent cultural frame switching experiences of biculturals can generalize to greater switching abilities in non-cultural tasks. This complements research on the positive effects of bilingualism and is a valuable contribution to prior research on biculturals’ advanced cognitive complexity.

It is of interest to note that children who reported relatively low identity as both Turkish and German also performed well. Similar findings were reported by Tadmor et al. (2009) who studied cognitive complexity among Asian American college students and Israelis in the United States. They argued that it is the equal preference for two cultures, rather than high levels of identification, that creates dissonance, an internal conflict due to respected, discordant cultural values, and cognitions. Resolving this conflict repeatedly increases cognitive ability.

Attributions:

Child Growth and Development by Jennifer Paris, Antoinette Ricardo, and Dawn Rymond, 2019, is licensed under CC BY 4.0

[1] Image on Public Domain Pictures

[2] Image by Wikipedia is licensed under CC BY-SA 3.0

[3] Children’s Development by Ana R. Leon is licensed under CC BY 4.0

[4] Image by Leonid Mamchenkov is licensed under CC BY 2.0

Balanced Cultural Identities Promote Cognitive Flexibility among Immigrant Children. Spiegler, O. and Leyendecker, B. (2017). In Front. Psychol. 8:1579. doi: 10.3389/fpsyg.2017.01579 Licensed CC BY 4.0