Do we really need to know a theory for the Ames room?

[lolbox]

People on this site have been saying we need to know the apparent distance theory for the ames room however all the questions I've encountered in practise exams have been along the lines of

'State how the Ames room is constructed in terms of its shape and the position of the peephole to create an illusion'

Thoughts? Comments? were you actually taught a theory on the Ames room by your teacher?

I know my class was just told the basics
- trapezoid room, designed to look rectangular
- lack of binocular cues due to peephole
- careful positioning of objects
- one side is double the distance from the viewer then the other side

[Transcendent]

Some practice exams have asked to define the apparent distance theory.

You should also know that shape constancy is maintained over size constancy.

[Visionz]

I was taught the apparent distance theory.

Most questions ask how the shape of the room contributes to the illusion though.

[littlebecc]

Visionz, how would you answer that?
Would you just talk about the shape of the ames room? Would it be like : the back wall is actually slanted away from the observer, the far left corner is double the distance of the right corner from the peephole, thus, as the people swap sides of the room, when looking through a peephole, the person sees the people in the room appear to shrink or grow??

[Visionz]

The ames room is trapezoidal in shape with one back corner much higher and further back than the other corner. For the illusion to work it must be viewed through a peephole, which means the powerful binocular depth cues are unable to be used. Because we cannot use binocular cues both back corners produce the same visual angle, we perceive them as being the same distance from the us and thus the room as being rectangular. When a person walks from the closer corner to the more distant corner they seemingly shrink. This is because they produce a smaller visual angle as they move further into the distance. The ames room illusion demonstrates our tendency to maintain shape constancy over size constancy.

[littlebecc]

what does the 'visual angle' bit mean

[The Detective]

does visual angle increase as objects get closer?

[lolbox]

Some practice exams have asked to define the apparent distance theory.

You should also know that shape constancy is maintained over size constancy.

yea was also taught that, forgot it add it in the thread description

[Visionz]

does visual angle increase as objects get closer?

yep. the same object, further away, will have a smaller visual angle than it does up close. An object 100m away that has the same visual angle as an object 25m away will be perceived as larger.


Visual Angle is when you draw a line from the top of the object to the bottom of the retina and a line from the bottom of the object to the top of the retina.