Last Updated 5/21/13
current science presentation
Sight, hearing, taste, touch, smell. We believe what our senses tell us about the world, but most of all we trust our eyes. Out of all the organs, our brains are extraordinarily powerful and processors of the world around us, which has been crucial to our evolution.
Color:
Take colour. Why do we need to see in colour? Try to find the predator that's about to jump out at you. If it takes you more than a second, you are dead.
Take colour. Why do we need to see in colour? Try to find the predator that's about to jump out at you. If it takes you more than a second, you are dead.
Why is it so easy this time? The reason is because the image shows the surfaces according to the quality of light they reflect (not just their intensity). In other words, your brain has a lot more information to go on in making its decisions.
Brightness:
Below we have two physically identical squares. Not surprisingly, they also look the same. Explaining vision would be easy if all we had to do is see the image that falls onto the back of the eye (called the retinal image). But we don't. In fact we never see what our eyes see. That's because the eyes have very little to do with what we see. This is good news: an image of the world is very different from the world itself.
For instance, the retinal image has only two dimensions, whereas the world of course has three. The retinal image is upside-down, but we see the world right side up. So what happens if I change the context surrounding the squares, and leave the squares the same?
Brightness:
Below we have two physically identical squares. Not surprisingly, they also look the same. Explaining vision would be easy if all we had to do is see the image that falls onto the back of the eye (called the retinal image). But we don't. In fact we never see what our eyes see. That's because the eyes have very little to do with what we see. This is good news: an image of the world is very different from the world itself.
For instance, the retinal image has only two dimensions, whereas the world of course has three. The retinal image is upside-down, but we see the world right side up. So what happens if I change the context surrounding the squares, and leave the squares the same?
All we've done is put them on different backgrounds. As a result, the small square on the dark background looks lighter than the one on the light background.
Cube:
What can we infer about the lighting conditions that cause this to happen?
The information in the image strongly suggests that the dark brown tile on the top now means a poorly reflective surface under bright light, whereas the bright orange one at the side means a highly reflective surface in shadow.
Cube:
What can we infer about the lighting conditions that cause this to happen?
The information in the image strongly suggests that the dark brown tile on the top now means a poorly reflective surface under bright light, whereas the bright orange one at the side means a highly reflective surface in shadow.
Table:
What's true for seeing colour is also true for seeing form and shape?
The one of the left seems a lot longer and thinner than the one on the right. What if I tell you that the red table is simply the green table on its side, in other words that the dimensions of the two tabletops are identical.
What's true for seeing colour is also true for seeing form and shape?
The one of the left seems a lot longer and thinner than the one on the right. What if I tell you that the red table is simply the green table on its side, in other words that the dimensions of the two tabletops are identical.
It is actually true. The length of the red table is the same as the width of the green table and vice versa.
So why do they look so different? Because your brain takes the image on the retina and creates what it sees according to what the information would have meant in the brain's past experience of interacting with the world. In this case the angles suggest depth and perspective and the brain believes the green table is longer than it is while the red table appears squarer.
The beautiful thing about illusions is they make us realize things are never what they seem, and that our experiences of the world shape our understanding of it.
So why do they look so different? Because your brain takes the image on the retina and creates what it sees according to what the information would have meant in the brain's past experience of interacting with the world. In this case the angles suggest depth and perspective and the brain believes the green table is longer than it is while the red table appears squarer.
The beautiful thing about illusions is they make us realize things are never what they seem, and that our experiences of the world shape our understanding of it.