s+p exam 4 pt 6!

what are illusions?

They’re not a breakdown of perceptual systems→ visual systems is working exactly how it should, but illusions are in very specific and dcontrived situations (the system is working in a very specific situation under very specific conditions)

what are the 3 percieved distance illusions?

1. panzo illusion

2. moon illusion

3. shepard’s table illusion

panzo illusion:

• a type of percieved distance illusion

• the top horizontal line looks longer than the bottom one (but they’re the exact same length). It is a misperception of distance– the top line is perceived to be further away. The two diagonal lines add to the strength of the illusion (when the diagonal lines are removed, the horizontal lines look like they’re the same length now). When we see the diagonal lines, we assume they’re parallel and think they converge in the distance.

moon illusion:

type of percieved distance illusion

• when the moon is near the horizon, it looks bigger, or does the moon look really small when it’s all the way up in the sky? Compared to a mountain or a building, the moon should look huge (and it does). Why: because we don’t know how high up the moon is we think it’s closer than it actually is and so it has to be smaller since we can’t perceive the actual distance. From a view point on the earth, the solid line is the true path of the earth as it moves ip in the sky, but if we mispercieve the path of the moon as being more shallow than it actually is, then it’s the opposite of the ponzo illusion, so since we’re perceiving it to be closer than it actually is, it has to be smaller because we can’t perceive the actual distance. This is the oldest illusion known to mankind 

shepards table illusion

type of percieved distance illusuon

the table tops are the exact same size and shape (they don’t look like it, but they are) why we’re seeing this: on the left (longer and thinner) is like looking at the table from the head of the table, on the right is like looking at it on the broad side of the table (where I sit at the dining room table)

what are contrast illusions

where we are contrasting between figure and ground (contrasting between different parts of the same picture)

what are the two contrast illusions?

• ebbinghaus illusion

• lightness contrast illusuion

ebbinghaus illusion

• type of contrast illusion

• contrasting looking at the center circle with the circles around it (when small circles surround the middle circle, it looks bigger, when big circles surround the center circle, it looks smaller (when in reality the center circles from both pics are the same size)

light contrast illusion

type of contrast illusion

•  in both A and B you’re comparing the two lighter grey areas (the bottom one of A looks like it’s darker than the top one) in B al;l; 7 of the greys are th exact same, but they don’t look like it. This can be explained by lateral inhibition: the grey in the black box is percieved as lighter than the grey in the white box– when you have a lot of stimulation around ioti, you’re going to be inhibiting the center more and it’s going to be perceived as darker (a lighter (brighter) surround is going to cause more inhibition, so it’s going to be perceived as darker)