Perception Laws

Monocular Cues - Depth cues available to either eye alone

              Relative Height - When objects higher in our field of vision are perceived as farther away/longer,                                            and objects lower in our field of vision are perceived as closer/shorter

       

              Example:

The picture on the left shows the man to be farther away in the distance but still a relatively proportional size to the woman to his left. But in the picture on the right, because the man is lower in our field of vision, he seems to be much shorter and unproportional to his female counterpart. In actuality, when measured the two male figures are the same height, but due to relative height, they are perceived very differently. 

               Light and Shadow - The perception that "light always comes from above," objects that are                                               reflecting more light appear to be closer, and objects reflecting less light                                               appear to be farther away

              Example:

In this example, we notice several areas in the pictures with varying levels of lightness. The outer most area, the lightest, seems to be closest to us. While the inner portion, where it gets darker, seems to be deeper. The darkest portions seem to be the deepest and most far away from us; this is a result of light and shadow.

Motion Perception - Motion perception is the process of inferring the speed and direction of                                          objects that move in a visual scene given some visual input

             Example:

In this example to the left, two images are shown; one with the arm in front of the leg, and the other with the arm behind the leg. Due to motion perception, even though we did not see the arm move behind the leg, our brain processes and assumes the motion.

Perceptual Constancies

             Size Constancy - Our perception that things have a constant size even though distance and                                              their size in our retinal view may change

             Example:

In this example, the apple looks the same size or even larger than the mans head. Because of size constancy, our brains are able to know that our heads are much larger than an apple; even though our visual perception says otherwise.          






             Brightness Constancy - The assumption that things have constant lightness although the                                                             lightness could vary

             Example:

            

In the bottom two images, the floor is a constant brown color. But in the top two images, a shadow is cast onto the floor making the area where the shadow is cast appear a darker shade. Because of brightness constancy, we are able to retain the actual color information even though our visual perception is that its darker.












             Shape Constancy - Although shapes may change in our retinal view, we are still able to                                                       identify them because its the form of a familiar shape

             Example: Due to shape constancy, even though the orientation and angle change on the coin, we are able to tell it is still a coin.