Academic journal article Attention, Perception and Psychophysics

Saccade Latency Reveals Episodic Representation of Object Color

Academic journal article Attention, Perception and Psychophysics

Saccade Latency Reveals Episodic Representation of Object Color

Article excerpt

Published online: 14 May 2014

# Psychonomic Society, Inc. 2014

Abstract While previous studies suggest that identity, but not color, plays a role in episodic object representation, such studies have typically used tasks in which only identity is relevant, raising the possibility that the results reflect task demands, rather than the general principles that underlie object representation. In the present study, participants viewed a preview display containing one (Experiments 1 and 2) or two (Experiment 3) letters, then viewed a target display containing a single letter, in either the same or a different location. Participants executed an immediate saccade to fixate the target; saccade latency served as the dependent variable. In all experiments, saccade latencies were longer to fixate a target appearing in its previewed location, consistent with a bias to attend to new objects rather than to objects for which episodic representations are being maintained in visual working memory. The results of Experiment 3 further demonstrate, however, that changing target color eliminates these latency differences. The results suggest that color and identity are part of episodic representation even when not task relevant and that examining biases in saccade execution may be a useful approach to studying episodic representation.

Keywords Attention . Interactions with memory . Visual working memory . Eye movements . Cognitive

Fundamental to visual cognition is the formation of represen- tations of visual information following visual inspection of a scene. Such representations may focus on global scene prop- erties, such as the scene's gist (e.g., Potter, 1976)orlayout (e.g., Sanocki, 2003). In addition to these global scene properties, however, observers also form representations of the objects present within the scene (e.g., Hollingworth, 2006). The present study is focused on representations of specific object exemplars that are present in a particular loca- tion and time, often referred to as token (Henderson, 1994)or episodic representations. Such representations are thought to reside within visual working memory (e.g., Gajewski & Brockmole, 2006) and play an important role in many aspects of visual cognition.

Episodic representations appear to play a critical role in maintaining perceptual stability across change, while a dy- namic display is viewed (e.g., Kahneman, Treisman, & Gibbs, 1992) or while one's eyes are moved within a scene (e.g., Henderson & Siefert 2001;Irwin,1996). Irwin and his col- leagues (e.g., Irwin, 1996; Irwin & Andrews, 1996), for example, have argued that transsaccadic integration, which underlies the perception of stability across eye movements, is supported primarily by a limited set of episodic representations that are maintained across the saccade. Similarly, Kahneman and Treisman (1984)arguedthatepi- sodic representations support integration of object information within dynamic displays, when the information that can be derived from a particular object is constantly changing. Finally, episodic representations of objects may form the foundation for constructing representations of more complex scenes (e.g., Hollingworth, 2004), and so understanding such representations is fundamental to an understanding of visual representation in general. Among the most successful theories of object representation is the object file theory proposed by Kahneman and Treisman (1984), in which each attended object is represented by a "file" that integrates and maintains information about the object over time.

Episodic representations are thought to play a critical role in supporting perceptual continuity across change. According to object file theory, continuity depends on the outcome of a series of processing stages. When an object is first attended, an object file is constructed to represent that object. When a change occurs-whether because of a change within the scene or because of an eye movement-a correspondence process establishes links between the objects that are visible and the object files that are stored in memory. …

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