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Concept Learning in Preschool Children: Effects of a Short-Term Logo Experience

The ability of kindergarten children to solve rule-learning problems following five weeks of LOGO computer experience was compared with that of children not having such experience. Fifteen children were randomly assigned either to a LOGO experience condition or a wait-list control condition. A single-keystroke LOGO was gradually introduced to the children in the LOGO condition. All children were subsequently tested on affirmative and conjunctive rule-learning tasks. Children receiving LOGO instruction had a significantly higher proportion of correct responses on two problem-solving tasks than children in the control condition (p < .05). Frequencies of subjects correctly solving each problem revealed no statistically significant differences between conditions (ps > .10). The kindergarten children adapted easily to the use of the computer and the single-keystroke LOGO. Suggestions for future research are presented.

Dynamical simulations of fractional giant Shapiro steps

We have numerically simulated 2D arrays of resistively shunted Josephson junctions in the presence of commensurate magnetic fields and alternating and direct currents. Fractional giant Shapiro steps appear in the simulated current-voltage characteristics at values determined by the external magnetic field, in agreement with recent experimental measurements. We summarize previous results that confirm the model of vortex motion previously proposed by Benz, et al. , and present further results at low frequencies that indicate the possibility of subharmonic fractional steps.