Wednesday, November 6, 2013

Perceptual Constancies - brightness constancy (Kessler)

Perceptual Constancies deal with humans being able to see familiar objects as having standard shape, size, color, or location regardless of changes in the angle of perspective, distance, or lighting. The subcategory: brightness constancy, is the ability to perceive objects as continuing to have the same brightness even though light may change their immediate sensory properties. This is due to our retina depending on surrounding objects to determine the brightness of others.

In the picture above, tile "A" and tile "B" are actually the same shade of grey. However, due to the surrounding tiles, our brain perceives them to be different shades.
http://www.skidmore.edu/~hfoley/images/Adelson1.jpg

Motion Perception (Kessler)

Motion perception is the ability to infer the speed or direction of an object given in a particular scene. The motions of our simulators are developed to reproduce the perception associated with the physical motion due to the space
 

In the picture above, it seems as if it is moving sort of and it seems to have depth. Even though this is a flat picture, our brain infers the orange circles to be moving due to their relative space and shaping in proximity to the other circles.
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPcSLRWRNdRiWGB73agphIinB47ANYztWcAVU7FVHCA6rhHh48zQBHbFO10i3EAaWTGAkj2kgnhNyc-eaJUt64ovpjF4DE9zP_Z08mbOE_uq0uVTugh7YZHzhT0jRcuIqRj_vlCwnbUnKi/s1600/425750_493456617363529_1795884434_n.jpg

Rules of Perceptual Organization - Closure (Kessler)

The Rules of Perceptual Organization state how people categorize and organize stimulus information into meaningful units to make sense of the stimuli. The subcategory of closure explains how items grouped together look like a whole. When familiar objects such as circles or squares have missing parts, our brain is still able to identify the shape and fill in the missing pieces.
 
In the picture above, our brain is able to recognize a triangle even though there are no established lines or boundaries defining it. This represents closure in the Rules of Perceptual Organization.
 

Tuesday, November 5, 2013

Proximity (Bechtel)

Proximity is when we group objects that are near to each other together. Instead of viewing a large array of figures as one group, we often separate them into several groups based on how close they are to other figures. It is how we naturally associate objects. 

This is an image of soldiers marching. We view them as rows of people instead of a group because of the way they are standing.

http://photos.cleveland.com/plain-dealer/2009/05/eye_on_the_world_tuesday_may_5_6.html

Similarity (Bechtel)

Similarity is when we group together similar objects. We group objects with similar size, color, shape, or other characteristics together because we view them as belonging together. 

For example, in this image we see columns of flowers of the same color, not rows of flowers of different colors. This is based on our tendency to group similar looking things together. 

http://crazy-frankenstein.com/beautiful-flower-garden-wallpapers-2.html

Continuity (Bechtel)

Continuity is when we perceive smooth, connected patterns rather than discontinuous patterns. We are more likely to view things as connected lines instead of separate lines. When it is unclear whether lines or objects are whole or disconnected, we typically assume that they are whole.

For example,in this image it looks like the letters PSU are continuous when in reality they are made up of people. Although we perceive it to be a whole object, it is actually discontinuous. 

Monocular Cues

Monocular cues are the set of depths we can perceive with just one eye.  One example of a monocular is linear convergence.  This is where a set of lines appears to converge at some point on the horizon.  A good example of this would be looking at a set of railroad tracks, although they do not converge it appears as if they do further on the tracks.

Another example of a monocular cue is occlusion.  When we see one object blocking another object, we assume it is closer in depth.  An example of this would be one box in front of another box.  In this case, we see the one box partially obstruct our view of the other box, therefore we determine that it is closer in distance.

Binocular Cues

Binocular cues are instances where we need to use both of our eyes to determine whether objects are close or far away.  In other words we use both of our eyes to judge depth perception. Too help explain this, think of making a shot in billiards.  You mill most likely be more accurate if you have both of your eyeballs open, allowing you to better perceive how far your ball is from the pocket therefore guaranteeing a more accurate shot.  This is due to the fact that binocular cues are more powerful than monocular cues, or instances where we use one eye to judge depth perception.  One of the major binocular cues is called binocular convergence.  To demonstrate this, take a pool cue and hold it at a reasonable distance from your face, then slowly bring it towards your face.  At some point your eyes will lose focus of the pool cue and strain to see it.  This is because your eye muscles were being strained by trying to rotate beyond their inward limit.



Shape Constancy (Plummer)

Sometimes referred to as Subjective Constancy, Shape Constancy is a lot like Size Constancy in many ways. The visual system will sometimes interpret items of identical dimensions as differing in size, based on their viewing angle. Below there is a photo of 3 identical doors. As a door opens, its visual angle decreases and it begins to appear different in shape.

Size Constancy (Plummer)

Size Constancy is the mind's proneness to percieve a particular familiar object as larger than another because of differences in distance. It is similar to depth perception. The visual system will often exploit regularities from the environment when it determines size and distance relationships, meaning that your mind will accept a clearly impossible size difference instead of noticing the environment. The photo below depicts two dogs of the same size, however it initially appears that the dog farthest from us is larger.
 

Figure-Ground Perception (Plummer)

Figure-Ground Perception is a term that is used to describe the way our minds interpret images in different sections. The main item we are seeing would be called the 'figure', and anything behind it -- in the background -- would be called the 'ground'. The following is one of the most famous examples of Figure-Ground Perception, it is an illusion called 'the Rubin Vase'. Dependent upon whether you're focusing in on the figure or the ground you will either see a vase or two faces, respectively.