Biomedical subjects
Publications and source records attributed to Harlene Hayne.
Using a Visual Recognition Memory (VRM) procedure, we examined the effect of encoding time on retention by 1- and 4-year olds. Irrespective of age, shorter familiarization time reduced retention, and longer familiarization time prolonged retention. The amount of familiarization that yielded retention after a given delay decreased as a function of age.
In three experiments, we examined the effect of a single reactivation treatment on retention by 1- and 2-year-old human infants who were tested in the visual recognition memory (VRM) paradigm. In all experiments, infants were familiarized with a visual stimulus and were tested after a delay. In the absence of a reactivation treatment, infants of both ages exhibited forgetting but exposure to a reactivation treatment alleviated forgetting after the same delay. When the duration of the original familiarization period was only 10 s, the minimum duration of an effective reminder treatment was 1 s for 2-year-olds, but was 5 s for 1-year-olds. When the duration of the original familiarization period was increased to 30 s, however, a 1-s reminder also alleviated forgetting by 1-year-olds.
Six- and 9-month-old human infants were tested in a deferred imitation paradigm in which an experimenter performed a single action with a novel object. Although infants of both ages imitated the action when tested immediately, only the 9-month-olds exhibited imitation after a 24-h delay.
In a series of three experiments, we examined the effects of familiarization time, retention interval, and changes in environmental context on adults' performance in the visual paired-comparison (VPC) task. The magnitude of adults' novelty preference increased as familiarization time increased, decreased as retention interval increased, and was impaired by a change in context after a delay. These data are highly consistent with data obtained in prior studies using the VPC task with infants and suggest that the VPC task could be used to measure memory across the life span.
Two alternative hypotheses have been generated to account for seasonal variation in the birth weight of human infants born in industrialized countries. First, it has been hypothesized that low ambient temperature during the second trimester of gestation decreases birth weight. Second, it has been hypothesized that exposure to bright sunshine during the first trimester increases birth weight. We tested these two hypotheses to determine which, if either, accounted for seasonal variation in birth weight of full-term infants. Birth weight data, collected over a 5-year period, were analyzed as a function of peak and trough sunshine and ambient temperature. Although there was no effect of ambient temperature during any trimester on birth weight, infants whose mothers were exposed to peak sunshine during their first trimester were born significantly heavier than infants whose mothers experienced trough levels of sunshine during the same trimester. Furthermore, infants whose mothers were exposed to trough levels of sunshine during their second and third trimesters were born significantly heavier than infants whose mothers were exposed to peak levels of sunshine during the same trimesters. We hypothesize that high levels of sunshine during early gestation may increase the level of insulin-like growth factor (IGF)-1, facilitating prenatal growth.
In three experiments, 18-month-olds were tested in a deferred imitation paradigm. Some infants received verbal information during the demonstration and at the time of the test (full narration), and some did not (empty narration). When tested after a 4-week delay, infants given full narration exhibited superior retention relative to infants given empty narration (Experiment 1). This retention advantage appears to be due to the effects of verbal cues at the time of memory retrieval. There was no effect of verbal cues that were presented only at the time of original encoding (Experiment 2A). Furthermore, infants who received verbal cues only at the time of retrieval exhibited superior retention relative to infants who received verbal cues only at the time of original encoding (Experiment 2B). These findings demonstrate that verbal cues can enhance memory retrieval by participants who are not yet fluent speakers themselves.
In the present experiment, age-related changes in verbal and nonverbal memory performance by 2- to 4-year-old children were assessed. All children participated in the same unique event, and their memory of that event was assessed after a 24-hr delay. Overall, children's performance on each memory measure increased as a function of age. Furthermore, children's performance on both the verbal and nonverbal memory tests was related to their language ability; children with more advanced language skills reported more during the verbal interview and exhibited superior nonverbal memory relative to children with less advanced language skills. Finally, children's verbal recall of the event lagged behind both their nonverbal recall and their general verbal skill. It is hypothesized that despite large strides in language acquisition. preschool-age children continue to rely primarily on nonverbal representations of past events. The findings have important implications for the phenomenon of childhood amnesia.
In the courtroom, child witnesses must undergo cross-examination. Prior research has shown that children change their original testimony under cross-examination, but the effect of these changes on the accuracy of children's testimony is unknown. The authors examined the effect of cross-examination on the accuracy of 5- and 6-year-old children's (N=46) reports of a contrived event. Consistent with prior research, children made changes to their original responses during cross-examination. Furthermore, these changes occurred irrespective of original accuracy. Finally, prior exposure to misleading information did not affect children's responses to cross-examination. Even children with no prior exposure to misinformation altered their original responses, decreasing their ultimate levels of accuracy. These findings demonstrate that cross-examination style questioning is inappropriate for young children.
Although the mobile conjugate reinforcement, deferred imitation, and visual attention paradigms are commonly used to test memory processing by infants, there is often debate about the comparability of memory measured by these three procedures. In a series of experiments, we systematically compared 6-month-old infants' performance across all three procedures. Contrary to current claims, measures of memory obtained using the mobile conjugate reinforcement and deferred imitation paradigms were more similar than those obtained using the deferred imitation and visual attention paradigms.
We examined children's ability to translate their preverbal memories into language following a period of substantial language development. Children participated in a unique event, and their memory was assessed 6 months or 1 year later. At the time of the event and at the time of the test, their language skills were also assessed. Children of all ages exhibited evidence of verbal and nonverbal memory. Their language skills also improved over the delay. By the time of the test, children of all ages had acquired most of the vocabulary necessary to describe the target event. Despite this, they did not translate preverbal aspects of their memory into language during the test. In no instance did a child verbally report information about the event that was not part of his or her productive vocabulary at the time of encoding. We conclude that language development plays a pivotal role in childhood amnesia.
Three experiments examined the effect of practice on memory performance by 18-month-old infants. Infants were tested using an imitation paradigm; an adult demonstrated a series of actions with objects and infants were given the opportunity to reproduce those actions following a delay. Some infants practiced the target actions before the retention interval (practice) and some did not (no practice). In Experiment 1, a reminder treatment alleviated forgetting by infants who practiced but failed to alleviate forgetting by infants who did not practice. In Experiments 2A and 2B, infants who practiced generalized to novel test stimuli after a 24-hr delay, whereas infants without practice did not. Results suggest practice influences the accessibility and generality of infants' memories.