Development of episodic and autobiographical memory: The importance of remembering forgetting

Abstract

Some memories of the events of our lives have a long shelf-life-they remain accessible to recollection even after long delays. Yet many other of our experiences are forgotten, sometimes very soon after they take place. In spite of the prevalence of forgetting, theories of the development of episodic and autobiographical memory largely ignore it as a potential source of variance in explanation of age-related variability in long-term recall. They focus instead on what may be viewed as positive developmental changes, that is, changes that result in improvements in the quality of memory representations that are formed. The purpose of this review is to highlight the role of forgetting as an important variable in understanding the development of episodic and autobiographical memory. Forgetting processes are implicated as a source of variability in long-term recall due to the protracted course of development of the neural substrate responsible for transformation of fleeting experiences into memory traces that can be integrated into long-term stores and retrieved at later points in time. It is logical to assume that while the substrate is developing, neural processing is relatively inefficient and ineffective, resulting in loss of information from memory (i.e., forgetting). For this reason, focus on developmental increases in the quality of representations of past events and experiences will tell only a part of the story of how memory develops. A more complete account is afforded when we also consider changes in forgetting.

Keywords: autobiographical memory; forgetting; long-term recall.

Figure 1

Schematic depiction of the length of time over which infants retain memories of specific past events from ages 6 to 36 months. The retention interval that infants tolerate increases dramatically over the first two years of life.

Figure 2

Schematic depiction of the number of memories in the corpus that survive over each hypothetical unit of time (T1–T5) in distributions characterized by the power function (dark bars) and the exponential function (dappled bars).

Figure 3

Schematic depiction of the distribution of memories across the first decade of life from a traditional perspective, suggesting a gradually increasing number of memories with age (Panel a); and from the complementary processes perspective, suggesting a residual number of early memories remaining after forgetting (Panel b).