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Frederick Turner and Ernst Pöppel (1983) proposed that lines of metrical poetry tend to measure three seconds or less when performed aloud, and that the metrical line is fitted to a three second "auditory present" in the brain. In this paper I show that there are faults both in their original argument, and in the claims which underlie it. I present new data, based on the measurement of line durations in publicly available recorded performances of 54 metrical poems; in this corpus, lines of performed metrical verse are often longer than three seconds: 59% of the 1155 lines are longer than 3 seconds, 40% longer than 3.5 seconds and 26% longer than 4 seconds. On the basis of weaknesses in the original paper, and the new data presented here, I propose, against Turner and Pöppel, that there is no evidence that lines of verse are constrained by a time-limited psychological capacity.
A majority of the plant species that are introduced into new ranges either do not become established, or become naturalized yet do not attain high densities and are thus considered ecologically and economically unproblematic. The factors that limit these relatively “benign” species are not well studied. The biotic resistance hypothesis predicts that herbivores, pathogens and competition reduce growth and reproduction of individual plants and so suppress population growth of non-native species. We explored the effect of insect herbivory and surrounding vegetation on growth and fitness of the non-native biennial plant Verbascum thapsus (common mullein) in Colorado, USA. Mullein is widespread in its introduced North American range, yet is infrequently considered a management concern because populations are often ephemeral and restricted to disturbed sites. To evaluate the impact of insect herbivores on mullein performance, we reduced herbivory using an insecticide treatment and compared sprayed plants to those exposed to ambient levels of herbivory. Reducing herbivory increased survival from rosette to reproduction by 7%, from 70–77%. Of plants that survived, reducing herbivory increased plant area in the first year and plant height, the length of the reproductive spike, and seed set during the second year. Reducing herbivory also had a marked effect on plant fitness, increasing seed set by 50%, from about 48,000 seeds per plant under ambient herbivory to about 98,000 per plant under reduced herbivory. Our findings also highlight that the relationship between herbivory and performance is complex. Among plants exposed to ambient herbivory, we observed a positive relationship between damage and performance, suggesting that, as predicted by the plant vigor hypothesis, insect herbivores choose the largest plants for feeding when their choice is not restricted by insecticide treatment. In contrast to the strong effects of experimentally reduced herbivory, we found that cover of other plants surrounding our focal plants explained relatively little variation in performance outcomes. Overall, we found that herbivore-induced impacts on individual plant performance and seed set are substantial, and thus may help prevent this naturalized species from becoming dominant in undisturbed recipient communities.