Moving toward a grand theory of development: in memory of Esther Thelen

This paper is in memory of Esther Thelen, who passed away while President of the Society for Research in Child Development. A survey of Esther Thelen's career reveals a trajectory from early work on simple movements like stepping, to the study of goal-directed reaching, to work on the embodiment of cognition, and, ultimately, to a grand theory of development--dynamic systems theory. Four central concepts emerged during her career: (1) a new emphasis on time; (2) the proposal that behavior is softly assembled from the interaction of multiple subsystems; (3) the embodiment of perception, action, and cognition; and (4) a new respect for individuality. Esther Thelen communicated these ideas to scientists and practitioners alike, so the ultimate benefactors of her work were children.     

The effects of computer-assisted instruction on number combination skill in at-risk first graders

The purpose of this pilot study was to assess the potential for computer-assisted instruction (CAI) to enhance number combination skill among children with concurrent risk for math disability and reading disability. A secondary purpose was to examine the effects of CAI on spelling. At-risk students were assigned randomly to math or spelling CAI, which they received in 50 sessions over 18 weeks. Acquisition and transfer effects were assessed. The results indicated that math CAI was effective in promoting addition but not subtraction number combination skill and that transfer to arithmetic story problems did not occur. Spelling CAI effects were reliable on acquisition and transfer spelling measures, with small to moderate effect sizes on transfer to reading measures. These results provide the basis for additional work with larger samples.     

Are They Watching? Visitors and Videos in Exhibitions

Abstract Data from the Women's Health summative evaluation video study prompted a comparison with similar data for other videos in exhibitions. Values for attraction power, holding time, and holding power were compiled in a database of 45 video titles. On average, 32 percent of the visitors are attracted to videos, and the average time spent watching is 137 seconds. An attraction power of more than 60 percent was exceptional. On average, people watched more than one‐third of the total length of videos, but less than one half. A holding power of more than .70 was exceptional. Once a video has attracted people's attention, it does not always hold it. Visitors are constantly tempted to move to another exhibit element, looking for what's next. One cannot assume that introductory videos will be watched thoroughly by the majority of visitors. This has implications for introductory videos that are expected to teach visitors concepts and vocabulary necessary to understand the rest of the exhibition or a main message that ties everything together. Using these data as a guideline, we can realistically gauge what levels of use are possible, and what levels of success, as measured by visitors' attention, can be anticipated.