Attention and automation: New perspectives on mental underload and performance

There is considerable evidence in the ergonomics literature that automation can significantly reduce operator mental workload. Furthermore, reducing mental workload is not necessarily a good thing, particularly in cases where the level is already manageable. This raises the issue of mental underload, which can be at least as detrimental to performance as overload. However, although it is widely recognized that mental underload is detrimental to performance, there are very few attempts to explain why this may be the case. It is argued in this paper that, until the need for a human operator is completely eliminated, automation has psychological implications relevant in both theoretical and applied domains. The present paper reviews theories of attention, as well as the literature on mental workload and automation, to synthesize a new explanation for the effects of mental underload on performance. Malleable attentional resources theory proposes that attentional capacity shrinks to accommodate reductions in mental workload, and that this shrinkage is responsible for the underload effect. The theory is discussed with respect to the applied implications for ergonomics research

THE THERMAL-PHOTOPERIOD REQUIREMENT FOR FLORAL BUD GROWTH

Temperature and photoperiod effects on floral bud growth rates, between detection of a primordium with a dissecting microscope and an open flower, need to be quantified for plant growth and yield models. Plants of several crop and weed species were grown in controlled environment chambers at several daylengths. Degree-day values for bud growth were determined; bud growth rates were much slower under long days in long day sensitive plants. The node at which the first floral bud appeared and total nodes at first flower were also recorded. The soybean strains most sensitive to photopreiod initiated floral buds in a reasonable length of time (50 days, 29/19℃ day/night temperatures), but their floral buds had not opened by the end of the experiment (over 125 days) and it seemed likely they never would. Large floral buds were produced on such plants, but these plants were too large to prevent shading in the growth cabinet

THE THERMAL-PHOTOPERIOD REQUIREMENT FOR FLORAL BUD GROWTH

Temperature and photoperiod effects on floral bud growth rates, between detection of a primordium with a dissecting microscope and an open flower, need to be quantified for plant growth and yield models. Plants of several crop and weed species were grown in controlled environment chambers at several daylengths. Degree-day values for bud growth were determined; bud growth rates were much slower under long days in long day sensitive plants. The node at which the first floral bud appeared and total nodes at first flower were also recorded. The soybean strains most sensitive to photopreiod initiated floral buds in a reasonable length of time (50 days, 29/19℃ day/night temperatures), but their floral buds had not opened by the end of the experiment (over 125 days) and it seemed likely they never would. Large floral buds were produced on such plants, but these plants were too large to prevent shading in the growth cabinet

THE GROWTH AND DEVELOPMENT OF HIPPEASTRUM IN RESPONSE TO TEMPERATURE AND CO_2

Flowering time of Hippeastrum can be controlled by applying specific thermal regime to large sized bulbs. Due to high-energy costs, the aim of this study was to examine the possibility to reduce soil heating and keep high bulb growth rate by increasing the CO_2 concentration. Two sets of experiments were carried out in a controlled greenhouse at the North-Western Israeli Negev Desert. In both experiments, bulbs of different initial sizes were grown under two levels of CO_2 concentrations (ambient, 350ppm and elevated, 1000ppm) combined with different minimum soil temperature regimes. In the first experiment three temperature regimes (16℃, 22℃ and 24℃) were tested, while in the second experiment only one minimum soil temperature regime (22℃) was investigated. In both experiments, raising CO_2 concentration from the ambient level to elevated one, or increasing soil temperature resulted in a higher bulb growth rate. Temperatures, CO_2 concentration and initial bulb size significantly influenced the final diameter of the bulbs. A significant difference in final bulb diameter was obtained only between the 16℃ treatment and the 22℃ and 24℃ treatments, but not between the two high temperatures tested. The area of the largest leaf was significantly affected only by the soil temperature treatments. No effect of CO_2 concentration on leaf area development was detected. The number of leaves, however, was affected by the CO_2 but not by the temperatures. Bulbs grown under elevated CO_2 had a higher flowering rate compared to ambient CO_2. This was effective both in shortening the period of time from replanting until flowering and by the significant high number of flowers compared to the ambient CO_2 conditions

THE GROWTH AND DEVELOPMENT OF HIPPEASTRUM IN RESPONSE TO TEMPERATURE AND CO_2

Flowering time of Hippeastrum can be controlled by applying specific thermal regime to large sized bulbs. Due to high-energy costs, the aim of this study was to examine the possibility to reduce soil heating and keep high bulb growth rate by increasing the CO_2 concentration. Two sets of experiments were carried out in a controlled greenhouse at the North-Western Israeli Negev Desert. In both experiments, bulbs of different initial sizes were grown under two levels of CO_2 concentrations (ambient, 350ppm and elevated, 1000ppm) combined with different minimum soil temperature regimes. In the first experiment three temperature regimes (16℃, 22℃ and 24℃) were tested, while in the second experiment only one minimum soil temperature regime (22℃) was investigated. In both experiments, raising CO_2 concentration from the ambient level to elevated one, or increasing soil temperature resulted in a higher bulb growth rate. Temperatures, CO_2 concentration and initial bulb size significantly influenced the final diameter of the bulbs. A significant difference in final bulb diameter was obtained only between the 16℃ treatment and the 22℃ and 24℃ treatments, but not between the two high temperatures tested. The area of the largest leaf was significantly affected only by the soil temperature treatments. No effect of CO_2 concentration on leaf area development was detected. The number of leaves, however, was affected by the CO_2 but not by the temperatures. Bulbs grown under elevated CO_2 had a higher flowering rate compared to ambient CO_2. This was effective both in shortening the period of time from replanting until flowering and by the significant high number of flowers compared to the ambient CO_2 conditions