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This study investigated the effect of different organizations of landmark-location pairings as fine-space information on wayfinding behavior and spatial knowledge on a total of 90 participants: 30 second graders, 30 sixth graders, and 30 adults. All participants had to find their way to a goal in a virtual environment with either randomized or categorical landmarks, or without any landmarks. Thereafter, they had to find the shortest way from the start position to the goal in two consecutive trials (wayfinding performance), and they had to solve a number of spatial knowledge tasks. The results showed that independent of their categorical function, the existence of landmarks influenced the wayfinding performance of adults and children in the same way. Whereas the presence of landmarks had no effect on spatial survey knowledge, landmark knowledge itself was influenced by the categorical function of the landmarks presented. Moreover, second graders showed limited achievement compared to adults independent of the existence of landmarks. The main results implicate firstly that children at school age indeed are able to use landmark-location pairings as fine-space information like adults during learning an unknown environmental space, and secondly that a dissociation between wayfinding behavior and spatial knowledge might exist.

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The relative DNA levels of different developmental stages ofBabesia bigemina andB. canis were measured by cytophotometry using the fluorochrome Hoechst 33258 as a staining dye. The DNA measurements provided direct proof of sexual reproduction, i.e., fusion of gametes resulting in the formation of zygotes followed by a meiotic division. BothBabesia species are considered to be typical members of the genusBabesia; however, the DNA measurements revealed important differences in the life cycle of these parasites, indicating thatBabesia species are not characterized by a life cycle, which is specific for this genus.