Defining the boundary: Age-related changes in childhood amnesia.

Childhood amnesia refers to the inability of adults to recall events that occurred during their infancy and early childhood. Although it is generally assumed that children and adolescents also experience childhood amnesia, with limited exceptions, most empirical research on the phenomenon has focused exclusively on adults. Here, we developed a new Timeline procedure to directly compare the early memories reported by children, adolescents, and adults. Overall, the proportion of memories reported before the age of 3 years was greater for the children and adolescents relative to the adults. In addition, the single earliest memory reported by children and adolescents was at a younger age than that reported by adults. In fact, the earliest memories reported by the children and adolescents, but not the adults, were significantly younger than the traditional 3 ?-year-old boundary of childhood amnesia. Regardless of the age of the rememberer, participants' early memories had the same episodic characteristics. We conclude that the boundary and the density of childhood amnesia may increase over the course of human development and that age-related changes in basic memory mechanisms make an important contribution to our understanding of the source of childhood amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of drawing on memory performance in young children.

In Experiment 1, 32 5- to 6-year-old boys and girls participated in a unique event and were interviewed about that event 1 day later. Half of the children were asked to draw what happened during the event and half were asked to tell what happened. In both conditions, only children's verbal behavior was scored. Children in the draw group were as accurate and reported more information than children in the tell group, especially in response to direct questions. In Experiment 2, 32 5- to 6-year-olds and 32 3- to 4-year-olds participated in the same event used in Experiment 1 and were interviewed 1 month later. The 5- to 6-year-olds in the draw group reported more information than the 5- to 6-year-olds in the tell group after the 1-month delay. Drawing did not, however, increase the amount of information reported by 3- to 4-year-olds. These findings have important theoretical implications for memory development and important practical implications for children's eyewitness testimony. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Three-dimensional reconstruction from serial sections in PC-Windows platform by using 3D_Viewer

Three-dimensional (3D) reconstruction from serial sections allows identification of objects of interest in 3D and clarifies the relationship among these objects. 3D_Viewer, developed in our laboratory for this purpose, has four major functions: image alignment, movie frame production, movie viewing, and shift-overlay image generation. Color images captured from serial sections were aligned; then the contours of objects of interest were highlighted in a semi-automatic manner. These 2D images were then automatically stacked at different viewing angles, and their composite images on a projected plane were recorded by an image transform-shift-overlay technique. These composition images are used in the object-rotation movie show. The design considerations of the program and the procedures used for 3D reconstruction from serial sections are described. This program, with a digital image-capture system, a semi-automatic contours highlight method, and an automatic image transform-shift-overlay technique, greatly speeds up the reconstruction process. Since images generated by 3D_Viewer are in a general graphic format, data sharing with others is easy. 3D_Viewer is written in MS Visual Basic 6, obtainable from our laboratory on request.     

Age-related changes in verbal and nonverbal memory during early childhood.

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Roles of function, reminding, and variability in categorization by 3-month-old infants.

The roles of function, reminding, and exemplar variability in categorization of a physically dissimilar object were studied with 3-month-old infants trained to move a crib mobile by kicking. Performance on a transfer test with a motionless novel object provided evidence of categorization. In Experiments 1 and 2, infants, like adults, initially categorized novel objects on the basis of physical appearance, but only if trained with multiple exemplars, after delays of 1 and 7 days. In Experiment 3, prior knowledge of an object's functional properties overrode physical dissimilarity as the basis for categorization and enabled reminding of the classification response 2 weeks later. In Experiment 4, postevent contingency information overrode physical and functional properties as the basis for categorization. These findings indicate that expectations and goals influence infants' category decisions and raise the possibility that infants of 3 months respond by analogy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The development of declarative memory in human infants: Age-related changes in deffered imitation.

In 2 experiments, deferred imitation procedures were used to trace age-related changes in declarative memory by human infants over the first 2 years of life. An adult modeled 3 actions with an object, and infants' ability to reproduce those actions was assessed 24 hr later. Some infants were tested with a new object or in a new context relative to the original demonstration. Changes in the context disrupted the performance of 6-month-olds but had no effect on the performance of 12- and 18-month-olds. Changes in the object disrupted the performance of 6- and 12-month-olds but had no effect on the performance of 18-month-olds. This age-related increase in representational flexibility may account for the decline of childhood amnesia during the 3rd year of life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpreting visual preferences in the visual paired-comparison task.

Performance on the visual paired-comparison (VPC) task has typically been interpreted with E. Sokolov's (1963) comparator model of the orienting response; novelty preferences are interpreted as evidence of retention, whereas null preferences are interpreted as evidence of forgetting. Here the authors capitalized on the verbal nature of human adults to clarify the interpretation of visual preferences in VPC performance. In 2 experiments, adults were tested on either the VPC task or a forced-choice recognition task after delays of 3 min to 12 months. In Experiment 1, adults tested on the VPC task exhibited novelty preferences after short delays, null preferences after intermediate delays, and familiarity preferences after long delays. In Experiment 2, adults tested on the forced-choice recognition task exhibited high levels of accuracy irrespective of delay, but the latency with which they recognized the stimuli increased systematically over the retention interval. These data are inconsistent with a simple Sokolovian interpretation of VPC performance and instead suggest that memory may be expressed as a novelty preference, null preference, or familiarity preference depending on the accessibility of the representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory retrieval by 18–30-month-olds: Age-related changes in representational flexibility.

Deferred imitation was used to trace changes in memory retrieval by 18–30-month-olds. In all experiments, an adult demonstrated 2 sets of actions using 2 different sets of stimuli. In Experiments 1A and 1B, independent groups of infants were tested immediately or after a 24-hr delay. Each infant was tested with 1 set of stimuli from the original demonstration and 1 set of stimuli that was different. Recall of the target actions when tested with different stimuli increased as a function of age, particularly after a delay. In Experiment 2, infants were provided with a unique verbal label for the stimuli during the demonstration and the test. The verbal label facilitated performance by 24-month-olds tested with different stimuli but had no effect on performance by 18-month-olds. One hallmark of memory development appears to be an age-related increase in the range of effective retrieval cues for a particular memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)