We investigated the importance and efficiency of active and passive exploration on the recognition of objects in a variety of virtual environments (VEs). In this study, 54 participants were randomly allocated into one of active and passive navigation conditions. Active navigation was performed by allowing participants to self-pace and control their own navigation, but passive navigation was conducted by forced navigation. After navigating VEs, participants were asked to recognize the objects that had been in the VEs. Active navigation condition had a significantly higher percentage of hit responses (t (52) = 4.000, p < 0.01), and a significantly lower percentage of miss responses (t (52) = -3.763, p < 0.01) in object recognition than the passive condition. These results suggest that active navigation plays an important role in spatial cognition as well as providing an explanation for the efficiency of learning in a 3D-based program.

Abstract:Frequent heavy rainfalls during the East Asian summer monsoon drastically increase water flow and chemical loadings to surface waters. A solid understanding of hydroclimatic controls on watershed biogeochemical processes is crucial for water quality control during the monsoon period. We investigated spatio-temporal variations in the concentrations and spectroscopic properties of dissolved organic matter (DOM) and the concentrations of trace metals in Hwangryong River, Korea, during a summer period from the relatively dry month of June through the following months with heavy rainfall. DOM and its spectroscopic properties differed spatially along the river, and also depended on storm and flow characteristics around each sampling time. At a headwater stream draining a forested watershed, the concentrations (measured as dissolved organic carbon (DOC)), aromaticity (measured as specific UV absorbance at 254 nm), and fulvic acid-and protein-like fluorescence of DOM were higher in stormflow than in baseflow waters. DOC concentrations and fluorescence intensities increased along the downstream rural and urban sites, in which DOC and fluorescence were not higher in stormflow waters, except for the 'first flush' at the urban site. The response of DOM in reservoir waters to monsoon rainfalls differed from that of stream and river waters, as illustrated by storm-induced increases in DOM aromaticity and fulvic-like fluorescence, and no significant changes in protein-like fluorescence. The results suggest that surface water DOM and its spectroscopic properties differentially respond to changes in hydroclimatic conditions, depending on watershed characteristics and the influence of anthropogenic organic matter loadings. DOC concentrations and intensities of spectroscopic parameters were positively correlated with some of the measured trace metals (As, Co, and Fe). Further research will be needed to obtain a better understanding of climate effects on the interaction between DOM and trace metals.

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A video see-through head mounted display (HMD) has a different viewing point than does the real eye, resulting in visual displacement (VD). VD deteriorates visuomotor performance due to sensory conflict. Previous work has investigated this deterioration and human adaptation by comparing fixed VD and real eye conditions. In this study we go a step further to investigate whether any differences in visuomotor and adaptation trends exist across 16 distinct VD conditions. The performance tasks studied were of two types: foot placement and finger touch. In contrast to our initial prediction, the results showed equal task performance levels and adaptation within about 5 minutes regardless of VD conditions. We found that human adaptation covered a variety of VDs -up to 55 mm in the X, Y direction; up to 125mm in the Z direction; and up to 140mm of interocular distance (IOD). In addition, we found that partial adaptation gave participants the interesting experience of a sense of body structure distortion for a few minutes.

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