timothy
brady

Visual perception and recognition are problems of induction - problems where we are given ambiguous input and must decide which of many possible interpretations to take. In middle-level vision, this is typically referred to as the problem of perceptual organization: how we take the bits and pieces of visual information that are available in the retinal image and structure them into larger units like objects.

In this talk I will present data on perceptual organization across different spatial frequencies - how the blurry, low spatial frequency of an image and the fine, high spatial frequency details in that image interact to form our eventual percept. Our visual system is thought to break down images by spatial frequency early on in the visual pathway, so examining perceptual organization across spatial frequencies should allow us to get a better idea of the types of integration the visual system has to deal with as it builds a representation of the world.

To examine this process of integration across spatial scales, we will use hybrid images made up of different images at different spatial frequencies. In the first part of the talk, I will discuss basic properties of integration across spatial scale: how the amount of information from each of the images affects the way we see the hybrid, and how this interacts with our contrast sensitivity function. In the second part I will present data on the effects of top-down knowledge on our organization of images across spatial frequencies, and will suggest that our visual system is designed to integrate across spatial frequencies in a way that provides us with the most accurate interpretation of the world as we move through it.