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Vertical attention bias (VAB) is the tendency to prioritize object tops and scene bottoms. Though the pattern may seem paradoxical, it aligns with progressive ecological theory, which views perceptual and cognitive biases as functional adaptations shaped by reliable, behaviorally relevant, environmental regularities. These adaptations guide attention toward meaningful spatial locations and support efficient interaction. VAB was first demonstrated using a triptych similarity-judgment paradigm. Participants compared a central target image to flanking images sharing the same top or same bottom. Results generally support VAB effects across objects and scenes for polygon-like figures but not for artificial scenes. Robust effects were exhibited, however, when using ecologically valid stimuli, showing a top-salience bias for object images and bottom-salience bias for scene images. These findings suggest vertical interactive-feature imbalance drives a generic downward vantage tendency that focuses attention on personal action space and body-level affordances. Study 1 investigated the developmental timeline of VAB by comparing 4- to 7-year-old children with adults. Results revealed common VAB effects despite age and body size differences. This confirmed that early in development, the perceptual system is largely tuned to the environmental structure within individual action space. Study 2 investigated the role of image orientation and presented the same triptych stimuli in upright and inverted orientation. Results showed that VAB effects reversed with inversion, with participant choices favoring comparison images with the original object tops and scene bottoms and this preference flipped along with the inverted image. This supports that the typical vertical feature imbalance in real-world stimuli drives a generic downward vantage tendency. Study 3 extended investigation of VAB to dynamic naturalistic contexts. Participants wore head-mounted eye-tracking glasses while performing eight common everyday activities within their home environment. Across tasks, participants consistently exhibited a significant downward orientation in head pitch and overall gaze angles, while eye angles consistently remained aligned with head angle. This generalizes VAB effects to real-world behavior and integrates it with past findings for an attentional center bias. Collectively, these studies support VAB is a functional adaptation that directs attention to locations of reliable interactive aspects of the environment within personal action space.