I'm a NOMIS Foundation Fellow at Columbia University at the Italian Academy for Advanced Studies, and an affiliate of Niko Kriegeskorte's Visual Inference Lab at the Zuckerman Mind Brain Behavior Institute. My work focuses on:
1. Developing a New Theory of Visual Experience,
2. Illustrating its Significance through 5 New Visual Illusions, and
3. Linking this Theory to Early Visual Processing in the Brain.
I am also leading a Generative Adversarial Collaboration on the Primary Visual Cortex (V1) and was the lead organizer of a Royal Society Scientific Meeting and Volume on New Approaches to 3D Vision.
I'm extremely grateful to the NOMIS Foundation for supporting my work, as well as the Presidential Scholars in Society and Neuroscience and the Italian Academy for Advanced Studies at Columbia University.
In my book The Perception and Cognition of Visual Space (Palgrave, 2017), and in two articles, I develop a new low-level theory of visual experience:
The Hollow Face Illusion is often appealed to as evidence that visual experience is the visual system's "inference" ("best guess") about what is out there in the world, since a hollow mask is percieved as inverted in depth.
However, in two illusions I question whether percieved depth is really inverted:
I show that if you add physical objects into the hollow of the Hollow Face Illusion - space that physically exists, but which is "impossible" according to the illusion - the illusion still persists (as evidenced by illusory motion), but you still see the true (non-inverted) depth ordering of the objects and mask in stereo depth.
LINTON MORPHING FACE ILLUSION
I show that if you add balls to the tip of the nose and the cheek, and morph back and forth from a receding to a protruding mask, the change in the ordinal depth of the balls (inverting back and forth) is apparent.
If the Un-Hollow Face Illusion suggests that 3D Shape is governed solely by stereo vision, then the next question is how the visual system extracts 3D shape from disparity. Traditionally, it is thought that retinal disparities are "scaled" to transform them from retinal to world coordinates.
However, I argue there is no "depth constancy" (scaling into world coordinates):
Traditional accounts ask participants to make evaluative depth judgments. I simplify the question by testing which of two conditions appears to move rigidly in depth (with angular size controlled): a stimulus moving in depth with contant physical separation, or a stimulus moving in depth with contant disparity?
As you see below, the answer is "constant disparity" (right), suggesting that percieved stereo depth is simply a function of disparities on the retina.
We know that increasing the separation between the eyes makes scenes seem miniature. Traditionally, this has been explained as due to "vergence" (eye rotation) making objects seems smaller and closer.
However, I argue that it instead rests on a purely cognitive association between accentuated stereo depth (from horizontal disparities) and closer distances given disparities fall off with distance squared:
I replicate the effect in VR (Condition 1), but show it disappears as soon as we control for changes in horizontal disparities (Condition 2).
Switching between the two conditions we see a startling effect: the "scale" of the scene changes, even though all that has changed is the geometry of the scene, not the apparent distance of the scene itself.
Size constancy is thought to change the percieved angular size of objects in images, for instance the apparent size of the cars in this image:
(c) Alex Blouin / Reddit
However, I argue that size constancy does not affect perceived angular size:
If we add frames to the cars, the cars appear more distorted than the frames, which is inconsistent with size constancy affecting perceived angular size.
Color constancy is thought to affect the percieved color of objects, so that the disk in this illusion by Akiyoshi Kitaoka (based on Anderson & Winawer, 2005) is perceived differently as yellow or blue:
(c) Akiyoshi Kitaoka
However, I argue that color constancy does not affect perceptual appearance:
I show that if we switch back and forth between the two interpretations of the disks, our judgement of the disk's color ("yellow" or "blue") changes without the disk's perceptual appearance changing.