We conduct experiments comparing the performance of individuals and teams of four subjects in solving two rather different tasks. The first involves nonograms, logic puzzles that require a series of incremental steps to solve. The second task uses CRT-type questions, which require a single, specific insight. Contrary to the existing literature, team performance in both tasks is statistically indistinguishable from that of individuals when communication is costless. If a tiny message cost is imposed, team performance improves and becomes statistically better than that of individuals, although still worse than previous research on teams would have suggested. To the best of our knowledge, our study is the first to find that imposing friction on communication leads to more effective performance in teams. Message costs reduce the quantity of messages but increase the quality, specifically the mix of good and bad suggestions. The improved quality of communication with message costs allows teams to out-perform individuals. Our analysis suggests that organizations would do better by identifying an able individual to perform an intellective task rather than using teams; prediction exercises indicate that this will not harm, and will generally increase, performance relative to a team, and only requires the cost of paying one individual rather than many.

In this paper, we study the dynamics of the Newton maps for arbitrary polynomials. Let p be an arbitrary polynomial with at least three distinct roots, and f be its Newton map. It is shown that the boundary $\partial B$ of any immediate root basin B of f is locally connected. Moreover, $\partial B$ is a Jordan curve if and only if $\mathrm {deg}(f|_B)=2$ . This implies that the boundaries of all components of root basins, for the Newton maps for all polynomials, from the viewpoint of topology, are tame.

Participation in cognitively stimulating leisure activities such as crossword puzzles may delay onset of the memory decline in the preclinical stages of dementia, possibly via its effect on improving cognitive reserve. We followed 488 initially cognitively intact community residing individuals with clinical and cognitive assessments every 12–18 months in the Bronx Aging Study. We assessed the influence of crossword puzzle participation on the onset of accelerated memory decline as measured by the Buschke Selective Reminding Test in 101 individuals who developed incident dementia using a change point model. Crossword puzzle participation at baseline delayed onset of accelerated memory decline by 2.54 years. Inclusion of education or participation in other cognitively stimulating activities did not significantly add to the fit of the model beyond the effect of puzzles. Our findings show that late life crossword puzzle participation, independent of education, was associated with delayed onset of memory decline in persons who developed dementia. Given the wide availability and accessibility of crossword puzzles, their role in preventing cognitive decline should be validated in future clinical trials. (JINS, 2011, 17, 1006–1013)