Information processing researchers have focused on several issues in cognitive development for this age group, including improvements in attention skills, changes in capacity, and the emergence of executive functions in working memory. Additionally, in early childhood memory strategies, memory accuracy and autobiographical memory emerge. Early childhood is seen by many researchers as a crucial time period in memory development (Posner & Rothbart, 2007).

7.4.1 Types of Memory

Based on studies of adults, people with amnesia, and neurological research on memory, researchers have proposed several “types” of memory (see Figure 7.1). 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, 2 seconds in 3-year-olds, more than 2 seconds in 4-year-olds, and 3–5 seconds in 6-year-olds (Glass et al., 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 memory, also known as working memory. Working memory is the component of memory in which current conscious mental activity occurs. Working memory often requires conscious effort and adequate attention to function effectively. As you read earlier, children in this age group struggle with many aspects of attention, which greatly diminishes their ability to consciously juggle several pieces of information in memory.

The capacity of working memory, 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 7.1. A child thinking.

Changes in attention and the working memory system also involve changes in executive function. These self-regulatory processes, such as the ability to inhibit a behavior or cognitive flexibility, enable adaptive responses to new situations or to reach a specific goal. 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 et al., 2014). For instance, scaffolding was positively correlated with greater cognitive flexibility at age 2 and inhibitory control at age 4 (Bibok et al., 2009). In Schneider et al.’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 compared to their abilities as they aged and started using more effective memory strategies.

The third type of memory is long-term memory, which is also known as permanent memory. A basic division of long-term memory is between declarative and nondeclarative memory. Declarative memories, sometimes referred to as explicit memories, are memories of facts or events that we can consciously recollect. Declarative memory is further divided into semantic and episodic memory. Semantic memories are memories of facts and knowledge that are not tied to a timeline. Episodic memories are tied to specific events in time. Nondeclarative memories, sometimes referred to as implicit memories, are typically automated skills that do not require conscious recollection.