Biomedical subjects

Kristin Hartshorn

Publications and source records attributed to Kristin Hartshorn.

3 recordsLinked to original sources

PubMed2003

Reinstatement maintains a memory in human infants for 1(1/2) years.

This study tested the proposition of Campbell and Jaynes (1966) that reinstatement is the mechanism by which early memories are maintained over a significant period of development. In four progressive replications, 6-month-old human infants learned to move a miniature train around a track by lever-pressing. They received a brief reinstatement at 7, 8, 9, 12, and 18 months of age and a final retention test at 2 years of age. Although 6-month-olds usually remember this task for only 2 weeks, after five reinstatements they exhibited significant retention 1(1/2) years later. Untrained yoked controls that received the same reinstatement regimen exhibited no retention after any delay. These findings reveal that the immaturity of the brain at the time of encoding is not the rate-limiting step in whether infants remember over the long term. Rather, as long as infants periodically encounter a nonverbal reminder, they can maintain early memories over a significant period of development.

Brain↗

PubMed2003

Does infant memory expression reflect age at encoding or age at retrieval?

Do human infants express a memory acquired earlier in ontogeny in a manner appropriate to their age at encoding or their age at the time of retrieval? To answer this, we exploited the fact that retention is highly context dependent at 6 months but not at 8-9 months of age. Six-month-olds learned an operant response in one context, and their memory was maintained by monthly reinstatements in the original context. At 8 or 9 months of age, 1 month after the last (or only) reinstatement, infants were tested in either the same or a different context. During testing, infants' retention was no longer context dependent; rather, they responded robustly in both test contexts. These results revealed that infants expressed a memory acquired when they were younger in a manner appropriate to their test age. They were interpreted in terms of changes in the functional significance of context before and after infants self-locomote.

Age Factors↗

PubMed2002

The development of explicit memory for basic perceptual features.

In three experiments with 164 individuals between 4 and 80 years old, we examined age-related changes in explicit memory for three perceptual features--item identity, color, and location. In Experiments 1-2, feature recognition was assessed in an incidental learning, gamelike task resembling the game Concentration. In Experiment 3, feature recognition was assessed using a pencil-and-paper task after intentional learning instructions. The form of the explicit memory function across the life span varied with the particular perceptual feature tested and the type of task. Item recognition was excellent at all ages but was significantly poorer for older adults than children, color recognition peaked in late childhood on the gamelike task, and location recognition peaked in early adulthood on the pencil-and-paper task. These findings indicate that performance on explicit memory tests is not a consistent inverted U-shaped function of age across various features. Explicit memory performance depends on what is measured and how. Because explicit memory typically reflects a composite of different features, age-related changes in explicit memory will not necessarily correspond to the function for any single one.

Adult↗