The proposed research aims to study the developmental origins of chunking, the process by which short-term memory representations are reorganized to enable greater storage capacity. Previous research has found that both adults and infants are limited to storing approximately 3 items in short-term memory. For example, infants can remember up to 3 hidden objects but fail to remember larger numbers. Adults can overcome this 3-item memory limit by grouping items into meaningful units or chunks. Doing so can vastly increase short-term memory capacity. Recently, my lab demonstrated that this ability is present early in development: untrained 14-month old infants can also chunk items (Feigenson & Halberda, 2004). When shown object arrays that were then hidden, infants remembered more objects if they were initially presented in two spatially-defined sets of 2 than when no such grouping cues were present and the objects appeared as a single set of 4. Hence, infants can use spatial cues to chunk items into sets, thereby increasing the total number of items they can remember. Several important questions arise regarding the nature of this fundamental memory computation. First, can infants use other, non-spatial cues to chunk individual items into sets? Perceptual features such as color or size are also strong Gestalt grouping cues for adults. It is unknown whether these perceptual cues can also support chunking in infants. Second, can infants chunk items based on semantic knowledge? Evidence for such an endogenous computation, driven by previously-acquired knowledge about object kinds, would more closely align infant and adult chunking. Third, what are the parametric limits on infants' chunking abilities? While infants can remember up to 4 hidden objects via chunking, it is unclear whether they can also represent more items. Specifically, is open how many chunks, and how many individual items within each chunk, infants can store. Taken together, the proposed project aims to elucidate the origins of an essential memory computation. The experiments will reveal the ways in which the limits on infants' short-term memory, and mechanisms that can allow those limits to be overcome, are similar to and different from those of mature adults. Ultimately, the proposed studies will contribute to the broader goal of understanding continuities and discontinuities in memory development, and may have repercussions for studying disorders of memory computations or for strategies for improving memory. The proposed project aims to contribute to the larger goal of understanding memory development by investigating short-term memory in a normally-developing population of infants. In documenting the early appearance of memory computations such as chunking, the project may have repercussions for understanding disorders of memory, difficulties in skills such as reading or math that rely on short-term memory, or strategies for improving memory. ? ? ?
| Zosh, Jennifer M; Feigenson, Lisa (2015) Array heterogeneity prevents catastrophic forgetting in infants. Cognition 136:365-80 |
| Moher, Mariko; Feigenson, Lisa (2013) Factors influencing infants' ability to update object representations in memory. Cogn Dev 28:272-289 |
| Moher, Mariko; Tuerk, Arin S; Feigenson, Lisa (2012) Seven-month-old infants chunk items in memory. J Exp Child Psychol 112:361-77 |
| Feigenson, Lisa; Halberda, Justin (2008) Conceptual knowledge increases infants'memory capacity. Proc Natl Acad Sci U S A 105:9926-30 |
