Visual+Perception

Visual Perception



Two sets of arrows that exhibit the Müller-Lyer optical illusion. The set on the bottom shows that all the arrows are of the same length.

The Ames room is a trapezoidal shaped room with a peephole that only allows the observer to use one eye. Therefore only monocular depth cues can be used.

The apparent distance theory states that if 2 images are the same size on the retina but one is perceived as further away, then the one will be interpreted as larger.

Due to the trapezoidal shape of the Ames room one corner is twice as far away from the observer as the other. However both corners produce the same size retinal image. They are interpreted as being the same size as the lack of binocular depth cues does not allow the observer to perceive depth. Therefore the room is perceived as rectangular.

As a person walks from one side of the room to the other the image they produce on the retina gets bigger or smaller due to the change in distance. The observer interprets this change as shrinking or growing even though they know this is not possible.

Size constancy fails and shape constance is maintained.