Abstract
After an initial stage of local analysis within the retina and early visual pathways, the human visual system creates a structured representation of the visual scene by co-selecting image elements that are part of behaviorally relevant objects. The mechanisms underlying this perceptual organization process are only partially understood. We here investigate the time-course of perceptual grouping of two-dimensional image-regions by measuring the reaction times of human participants and report that it is associated with the gradual spread of object-based attention. Attention spreads fastest over large and homogeneous areas and is slowed down at locations that require small-scale processing. We find that the time-course of the object-based selection process is well explained by a 'growth-cone' model, which selects surface elements in an incremental, scale-dependent manner. We discuss how the visual cortical hierarchy can implement this scale-dependent spread of object-based attention, leveraging the different receptive field sizes in distinct cortical areas.
Highlights
Neurophysiological studies over the past 40 years have revealed that the neuronal representation of an object in low-level areas of the visual cortex consists of a set of simple features such as colors and edge orientations
High-speed object recognition presumably relies on feedforward processing, leveraging the hierarchy of features represented in the visual cortex
We examined the time-course of perceptual grouping in line drawings with a new task where subjects judged whether two cues were placed on the same object or two different objects (Figure 2a)
Summary
Neurophysiological studies over the past 40 years have revealed that the neuronal representation of an object in low-level areas of the visual cortex consists of a set of simple features such as colors and edge orientations. This is not how we perceive a visual scene. Such a rapid grouping process would be in line with studies demonstrating that object recognition can be extremely fast and pre-attentive (Thorpe et al, 1996; Moore and Egeth, 1997; Treisman, 1985). There exist conditions where perceptual grouping requires a slow and serial process (Roelfsema, 2006)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
