The behaviour of juvenile fishes is critical in establishing the link between recruitment and subsequent adult populations. If juvenile fishes move, they can respond to variation in local conditions ...before adult home ranges are established. Alternatively, if juveniles establish fixed home ranges at settlement, their decisions may determine future population densities at small spatial scales. Field observations and translocations revealed that juvenile rabbitfishes (
Siganus
corallinus
and
S
.
doliatus
) have small home ranges and strong homing abilities (covering 6 m in 1 h or 36 m within 24 h). Only four of 22 individuals failed to return; all were transferred up-current, suggesting that olfaction is important in homing. Small home ranges and strong homing tendencies in juvenile herbivores suggest that decisions made by recruits will impact the spatial extent of both adult fishes and the functional roles they play within ecosystems.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Displacement studies have clearly shown that experienced avian migrants are able to perform true navigation, i.e., they can find the correct direction leading to a target destination from unfamiliar ...sites. The sensory mechanisms of true navigation remain poorly understood, though some remarkable progress has been made in the last 10–15 years. There are two primary hypotheses explaining the sensory nature of navigation: (1) a magnetic map hypothesis proposes that birds use parameters of the geomagnetic field that are predictably distributed on the globe. As for the sensory nature of this hypothesis, it has been assumed by some researchers that the magnetic receptor cells reside in the upper beak (the so-called “beak organ”), and transmit information via the trigeminal nerve to the brain; (2) an olfactory map hypothesis assumes that birds can smell their position by taking advantage of odours distributed in the atmosphere. There are a growing number of studies supporting both of the hypotheses mentioned though in different avian model species. In this review, an attempt is made to provide an overview of the evidence for different navigational cues proposed thus far, with the main focus on the recent studies addressing the magnetic and olfactory navigation hypotheses. Also, a list of key open questions, together with possible experimental approaches, is proposed.
Spatial knowledge about the environment often helps people accomplish their navigation and wayfinding tasks more efficiently. Off-the-shelf mobile navigation applications often focus on guiding ...people to go between two locations, ignoring the importance of learning spatial knowledge. Drawing on theories and findings from the area of learning spatial knowledge, we investigated how the background reference frames (RF) and navigational cues can be combined in navigation applications to help people acquire better spatial (route and survey) knowledge. We conducted two user studies, where participants used our custom-designed applications to navigate in an indoor location. We found that having more navigational cues in a navigation application does not always assist users in acquiring better spatial knowledge; rather, these cues can be distracting in some specific setups. Users can acquire better spatial knowledge only when the navigational cues complement each other in the interface design. We discussed the implications of designing navigation interfaces that can assist users in learning spatial knowledge by combining navigational elements in a complimentary way.
It is thought that young homing pigeons are able to use information acquired en route for their initial homeward orientation. However, the cues involved and mechanisms utilised are under discussion. ...Blocking light-dependent route-specific information during the first leg of an outward journey detour, together with analysis of pigeons that were raised under different loft conditions, allowed us to correctly evaluate the functioning of this mechanism and, more generally, the navigational map of birds. Pigeons from the same stock were raised and kept in two different lofts. The birds in the experimental groups were transported to the release sites via detours, and light-dependent information was denied during the first half of the outward journey (no compass information was available). Control birds were transported by the most direct route and had access to all available information. In general, the results showed that the low-loft birds preferred to use magnetic compass cues, whereas the high-loft birds preferred to use navigational map cues to collect information of the first part of the outward journey. The impairments observed in the homing performances of the experimental groups highlight the reliability of information collected inside the map area. Relevant to an understanding of the route-reversal mechanism was the evidence that this mechanism is able to function in the absence of compass information (birds raised in a wind-exposed loft show a detour effect). In systems where directional information could be provided by multiple sources, processing and extracting accurate course trajectories through a common mechanism may prove more efficient and reliable.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In haptic environments, it is especially demanding to design realistic interaction paradigms and provide global navigational cues. In this paper, we present a methodology that can replace and/or ...augment realistic haptic environments and is inspired by the psychological basis of haptics. The system employs haptic cueing to convey information about shape, size, texture, and material of the object through user-determined cues. The key conceptual framework that guides this approach is that humans have haptical memory of an object, and sparse data about the object features presented through cues can invoke spatial concepts that reveal the identity of the object. Secondly, the system represents an object's surface as a 2D raised surface map in the virtual environment. Since the haptic modality is specialized to perceive surface properties, surface rendering mimics the real environment and presents veridical sensations about the surface. We compare this methodology to conventional rendering of haptic objects where the object is sensed in its entirety through a haptic interface. The paper further studies usability of realistic haptic rendering in 1) egocentric and exocentric reference frames, and 2) with tactile and/or force feedback. Initial results indicate that tactile cueing in combination with realistic rendering of surfaces with force feedback in an egocentric reference frame leads to the most efficient perception
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