Academic journal article Attention, Perception and Psychophysics

Rapid Scene Perception with Tragic Consequences: Observers Miss Perceiving Vulnerable Road Users, Especially in Crowded Traffic Scenes

Academic journal article Attention, Perception and Psychophysics

Rapid Scene Perception with Tragic Consequences: Observers Miss Perceiving Vulnerable Road Users, Especially in Crowded Traffic Scenes

Article excerpt

Published online: 14 March 2015

# The Psychonomic Society, Inc. 2015

Abstract How does scene complexity influence the detection of expected and appropriate objects within the scene? Traffic research has indicated that vulnerable road users (VRUs: pedestrians, bicyclists, and motorcyclists) are sometimes not perceived, despite being expected. Models of scene perception emphasize competition for limited neural resources in early perception, predicting that an object can be missed during quick glances because other objects win the competition to be individuated and consciously perceived. We used pictures of traffic scenes and manipulated complexity by inserting or removing vehicles near a to-be-detected VRU (crowding). The observers' sole task was to detect a VRU in the laterally presented pictures. Strong bias effects occurred, especially when the VRU was crowded by other nearby vehicles: Observers failed to detect the VRU (high miss rates), while making relatively few false alarm errors. Miss rates were as high as 65% for pedestrians. The results indicated that scene context can interfere with the perception of expected objects when scene complexity is high. Because urbanization has greatly increased scene complexity, these results have important implications for public safety.

Keywords Scene perception .Objectrecognition . Attention . Traffic crashes

A central domain for perceptual science is the perception of everyday scenes and the objects within them. Research to date has established that the meaning of novel but typical scenes can be perceived remarkably quickly (e.g., Greene & Oliva, 2009; Kirchner & Thorpe, 2006;Potter,1976) and can facilitate the perception of scene-congruent objects (e.g., Biederman, 1981; Boyce, Pollatsek, & Rayner, 1989;Davenport & Potter, 2004). However, a different relation between scene context and objects has been observed in research on the perception of traffic scenes and crashes. For many years, traffic researchers have documented that drivers sometimes fail to consciously perceive vulnerable road users (VRUs-pedestrians, bicyclists, and motorcyclists), with tragic consequences (e.g., Ernst, 2011; Forman, Watchko, & Seguí-Gómez, 2011; Frumkin, 2002; Wulf, Hancock, & Rahimi, 1989). In lab situations in which the explicit task is VRU detection, such misperceptions are misses to expected target categories (e.g., Borowsky, Oron-Gilad, Meir, & Parmet, 2012; Gershon & Shinar, 2013; Pinto, Cavallo, & Saint-Pierre, 2014). We suggest that this is an effect of scene complexity during rapid scene perception, stemming from limitations in the ability of early vision to individuate multiple objects (e.g., Franconeri, Alvarez, & Cavanagh, 2013;Sanocki,1991;Xu&Chun,2009).

Complex scene perception theory

Computational studies of scene perception reveal its high complexity (e.g., Granlund, 1999; Tsotsos, 1990, 2001). Complexity is high because stimulus information is locally ambiguous: Any given subarea of a scene (e.g., a receptive field or larger localized region) almost always has many interpretations in terms of possible objects and regions. Combining possibilities across a scene causes combinatorial explosion. Processing, time, and structural constraints are necessary to disambiguate the scene information by reducing possible interpretations (Tsotsos, 1990; see also, e.g., Witkin & Tenenbaum, 1983).

Complexity is especially problematic in early vision, when the scene is parsed into meaningful objects and surfaces. Neurocomputational resources must be allocated wisely, and this involves favoring a few regions. The consequence is significant perceptual limitations and, in particular, a limitation on perceiving multiple objects during the early stages of scene perception (e.g., Franconeri et al., 2013;Sanocki,1991;Xu& Chun, 2009). Thus, early vision can be viewed as a competition between candidate regions for individuation as an object (e. …

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