The results suggest that the squint-beneficial conditions are operated by a local mechanism involving contraction of the orbicularis and increase in reflex blinking, whereas those that do not benefit from squint do not engage the orbicularis and decrease blink, possibly through central inhibition of spontaneous blinking. The EMG response is a sensitive objective measure for the squint-beneficial conditions. However, for the non-squint-beneficial conditions, blink rate may be a more sensitive objective measure, although EMG with longer trial durations should be tested.
LCSs differently affected blink rate, subjective dry eye symptoms, and visual discrimination speed. Those with wetting agents led to significantly fewer eye blinks while affording better ocular comfort for contact lens wearers, compared to that without. LCSs with wetting agents also resulted in better visual performance compared to wearing daily disposable contact lenses. These presumably are because of improved tear film quality.
A schema based view of addition development is compared with Siegler's latest strategy-choice model, which includes an addition goal sketch (a basic understanding of "the goals and causal relations" of addition; Siegler & Crowley, 1994, p. 196). This metacognitive component in the latter model is presumed to develop as a child practices a basic counting based procedure for calculating sums and to subsequently affect strategy choice by identifying correct and incorrect procedures. A study of 20 kindergartners was undertaken to examine key assumptions of this model. Participants were individually interviewed to determine their own procedure use and their ability to evaluate correct and incorrect procedures. The results did not support a central prediction of the strategy-choice model-that children who possess a goal sketch should recognize as correct a relatively advanced (counting-on) procedure they themselves do not use. These results are consistent with the schema based view that accurately evaluating or learning such advanced procedures requires a qualitative leap in conceptual development. Theoretical, methodological, and instructional implications include a case for a simulation that models assimilation (a cognitive process underlying developmental readiness and conceptual development), a conceptually based taxonomy of addition development, and a nuanced instructional theory of addition (i.e., one that goes beyond the direct instruction vs. discovery learning debate).When and how do children construct the conceptual understanding necessary to evaluate and adopt new counting based procedures for determining sums? Once children construct a basic understanding of the purpose (goals) and nature (causal relations) of addition, does this goal sketch empower them to comprehend, assess, and learn any new counting based procedure, even relatively sophisticated or advanced procedures they themselves have never used? In instructional terms, is direct instruction (modeling by, e.g., a parent, early childhood teacher, older sibling, or television character) sufficient for learning all such procedures or accelerating addition development? Or, does a goal sketch enable children to assimilate, judge, and internalize basic procedures but not more advanced procedures that require a deeper conceptual understanding? That is, must educators take into account developmental readiness when teaching addition procedures and focus on promoting the conceptual underpinnings of more advanced procedures? The main purpose of this study is to address these theoretical and practical questions.Researchers generally agree that children use increasingly sophisticated and abstract counting based procedures to determine sums (e.g.
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