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Thomas F. Shipley, Mandy J. Maguire, Jonathan Brumberg; Segmentation of event paths. Journal of Vision 2004;4(8):562. doi: 10.1167/4.8.562.
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© ARVO (1962-2015); The Authors (2016-present)
Humans perceptually segment events, but models that predict where events will be segmented are limited. Developing a detailed model may be hard because of the overlapping quality of events (i.e., one can smile and walk at the same time, but the endpoint of each event can be different). However, some aspects of events appear to be universally represented in the world's languages. For example, path, the trajectory of an object's movement, is one of the most universally encoded event features. Although it is generally encoded in the prepositions of English (e.g., up), in other languages it is encoded in the verbs (e.g., descendere). Linguistic universals may represent basic levels of event perception. Here we consider how one of these, path, might be parsed. Because the spatiotemporal projection of paths to an observation point is similar to the spatial projection of objects, we tested the hypothesis that path segmentation and object segmentation would be based on similar image properties, such as discontinuities in orientation. To test this, one group of subjects segmented line drawn objects into parts, and a second group indicated the event segments of a dot moving along paths defined by the line drawings. Overall, the perceived locations of object and event boundaries were similar, with path segmentation more variable than object segmentation. The locations of object boundaries were well predicted by Singh and Hoffman's (2001) geometric models of segmentation. The critical finding was that a model of object segmentation also predicted the points of segmentation along event paths. The results suggest that it should be possible to develop a quantitative model of segmentation for events, or at least their paths. Models of event segmentation and recognition may require addressing the various aspects of an event in different ways. Consideration of how languages represent events appears to be a useful starting place for this endeavor.
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