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Visual Environment (visual + environment)
Selected AbstractsEyes and vision in Arion rufus and Deroceras agreste (Mollusca; Gastropoda; Pulmonata): What role does photoreception play in the orientation of these terrestrial slugs?ACTA ZOOLOGICA, Issue 2 2009Marina V. Zieger Abstract This paper deals with the orientational behaviour in the two terrestrial slugs Arion rufus and Deroceras agreste. It presents anatomical details of their eyes and provides an appraisal of the eyes' optical system. In both species the retinae contain two principal types of cell: photoreceptive and pigmented supportive cells. While only the eye of A. rufus apparently contains neurosecretory neurones, that of D. agreste is the only one equipped with a small additional retina with its own separate lens. Lens shapes vary between ovoid (A. rufus) and spherical (D. agreste). Our results demonstrate that the camera-type eyes in A. rufus and D. agreste have optical systems that do not allow the production of a sharp image on the retina. The slugs demonstrate negative visually mediated phototactic behaviour, but no polarization sensitivity. Only one aspect of the visual environment, namely the overall distribution of light and dark, seems to be important for these slugs. As the main role of the slugs' photoreceptors is to monitor environmental brightness and to assist the animal in orientating towards dark places, we conclude that these slugs do not need to perceive sharp images. [source] The brain weights body-based cues higher than vision when estimating walked distancesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2010Jennifer L. Campos Abstract Optic flow is the stream of retinal information generated when an observer's body, head or eyes move relative to their environment, and it plays a defining role in many influential theories of active perception. Traditionally, studies of optic flow have used artificially generated flow in the absence of the body-based cues typically coincident with self-motion (e.g. proprioceptive, efference copy, and vestibular). While optic flow alone can be used to judge the direction, speed and magnitude of self-motion, little is known about the precise extent to which it is used during natural locomotor behaviours such as walking. In this study, walked distances were estimated in an open outdoor environment. This study employed two novel complementary techniques to dissociate the contributions of optic flow from body-based cues when estimating distance travelled in a flat, open, outdoor environment void of distinct proximal visual landmarks. First, lenses were used to magnify or minify the visual environment. Second, two walked distances were presented in succession and were either the same or different in magnitude; vision was either present or absent in each. A computational model was developed based on the results of both experiments. Highly convergent cue-weighting values were observed, indicating that the brain consistently weighted body-based cues about twice as high as optic flow, the combination of the two cues being additive. The current experiments represent some of the first to isolate and quantify the contributions of optic flow during natural human locomotor behaviour. [source] Effect of spatial inhibition on saccade trajectory depends on location-based mechanismsJAPANESE PSYCHOLOGICAL RESEARCH, Issue 1 2009HIROYUKI SOGO Abstract:, Saccade trajectory often curves away from a previously attended, inhibited location. A recent study of curved saccades showed that an inhibitory effect prevents ineffective reexamination during serial visual search. The time course of this effect differs from that of a similar inhibitory effect, known as inhibition of return (IOR). In the present study, we examined whether this saccade-related inhibitory effect can operate in an object-based manner (similar to IOR). Using a spatial cueing paradigm, we demonstrated that if a cue is presented on a placeholder that is then shifted from its original location, the saccade trajectory curves away from the original (cued) location (Experiment 1), yet the IOR effect is observed on the cued placeholder (Experiment 2). The inhibitory mechanism that causes curved saccades appears to operate in a location-based manner, whereas the mechanism underlying IOR appears to operate in an object-based manner. We propose that these inhibitory mechanisms work in a complementary fashion to guide eye movements efficiently under conditions of a dynamic visual environment. [source] Early elementary students' development of astronomy concepts in the planetariumJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 2 2009Julia D. Plummer Abstract The National Science Education Standards [National Research Council (1996) National science education standards. Washington, DC: National Academy Press] recommend that students understand the apparent patterns of motion of the sun, moon and stars by the end of early elementary school. However, little information exists on students' ability to learn these concepts. This study examines the change in students' understanding of apparent celestial motion after attending a planetarium program using kinesthetic learning techniques. Pre- and post-interviews were conducted with participants from seven classes of first and second grade students (N,=,63). Students showed significant improvement in knowledge of all areas of apparent celestial motion covered by the planetarium program. This suggests that students in early elementary school are capable of learning the accurate description of apparent celestial motion. The results also demonstrate the value of both kinesthetic learning techniques and the rich visual environment of the planetarium for improved understanding of celestial motion. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 46: 192,209, 2009 [source] INVESTIGATING MATERIAL DECAY OF HISTORIC BUILDINGS USING VISUAL ANALYTICS WITH MULTI-TEMPORAL INFRARED THERMOGRAPHIC DATAARCHAEOMETRY, Issue 3 2010MARIA DANESE This paper shows how visual analytics methodology can be used to facilitate interpretation of multi-temporal thermographic imagery for the purpose of restoration of cultural heritage. We explore thermographic data in a visual environment from the unifying spatio-temporal perspective in an attempt to identify spatial and spatio-temporal patterns that could provide information about the structure and the level of decay of the material, and the presence of other physical phenomena in the wall. The approach is tested on a thermographic dataset captured on the façade of a Romanesque building from the 13th century,the Cathedral in Matera (Italy). [source] Symposium on the visual environment, its descriptors and consequences for human endeavourCOLOR RESEARCH & APPLICATION, Issue 6 2002J. SchandaArticle first published online: 23 OCT 200 No abstract is available for this article. [source] Isolating endogenous visuo-spatial attentional effects using the novel visual-evoked spread spectrum analysis (VESPA) techniqueEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2007Edmund C. Lalor Abstract In natural visual environments, we use attention to select between relevant and irrelevant stimuli that are presented simultaneously. Our attention to objects in our visual field is largely controlled endogenously, but is also affected exogenously through the influence of novel stimuli and events. The study of endogenous and exogenous attention as separate mechanisms has been possible in behavioral and functional imaging studies, where multiple stimuli can be presented continuously and simultaneously. It has also been possible in electroencephalogram studies using the steady-state visual-evoked potential (SSVEP); however, it has not been possible in conventional event-related potential (ERP) studies, which are hampered by the need to present suddenly onsetting stimuli in isolation. This is unfortunate as the ERP technique allows for the analysis of human physiology with much greater temporal resolution than functional magnetic resonance imaging or the SSVEP. While ERP studies of endogenous attention have been widely reported, these experiments have a serious limitation in that the suddenly onsetting stimuli, used to elicit the ERP, inevitably have an exogenous, attention-grabbing effect. Recently we have shown that it is possible to derive separate event-related responses to concurrent, continuously presented stimuli using the VESPA (visual-evoked spread spectrum analysis) technique. In this study we employed an experimental paradigm based on this method, in which two pairs of diagonally opposite, non-contiguous disc-segment stimuli were presented, one pair to be ignored and the other to be attended. VESPA responses derived for each pair showed a strong modulation at 90,100 ms (during the visual P1 component), demonstrating the utility of the method for isolating endogenous visuo-spatial attention effects. [source] | ||||||||||