Sensory Perception Blog

By: Jess Chou, Purva Dave, Emily Joyce, and Katie Leite

The Laws of Perceptual Organization are gestalt principles that suggest how the brain prefers to group stimulus elements together to form a percept

1. Closure: If an image is incomplete, we tend to fill in the gaps to complete them. For example, instead of seeing random lines, we see a human stick figure. 

2. Continuity: This principle states that we perceive smooth, continuous patterns rather than discontinuous ones. For example, instead of seeing the left line of berries branching off, we still see it as a smooth continuous flow from the rest of the berries.

3. Similarity: Our brains group together figures that are similar to each instead of different groups. For example, instead of seeing this picture as individual lines with one circle among triangles, we see a zigzag of circles surrounded by triangles.

4. Proximity: We group nearby figures together. An example of this would be a keyboard. Our brains group together the number pad, the arrow keys, the top row of function buttons, etc. 

5. Figure-Ground Perception: This refers to the organization of the visual field into objects that stand out from their surroundings as a background. For example, depending on whether you perceive the white or black as the background, you will either see faces or a vase.

6. Perception of Movement: Our brains perceive objects getting smaller as retreating and objects getting bigger as approaching. For example, when driving in a car, seeing a traffic light getting bigger causes us to believe that we are approaching the traffic light. 

• Stroboscopic motion: We perceive continuous movement when watching a rapid series of slightly varying images. For example, when looking through a flip book of drawings that only have small changes, we see one continuous moving picture

7. Phi Phenomenon: This refers to an illusion of apparent movement, caused by flashing lights in a sequence. We see a single light moving back and forth between two lights that are blinking on and off. 

8. Reversible Figures: A stimulus pattern in which figure-ground organization can be reversed. You may either perceive A closer to you or B closer.

Depth Perception: 


9. Monocular Cues: Information about depth that relies on input of one eye; includes relative size, light, and shadow, interposition, relative motion, and atmospheric perspective.

Relative size: These two cups are the same size, but since the one the right looks smaller, we think that it is farther away. 

Relative clarity: The blurry berries are perceived as farther away.

10. Monocular Cues (cont.): 

• interposition: If one object partially blocks view of another, it appears to be closer
• texture gradient: gradual change from course, distinct texture to fine, indistinct texture=increasing distance
• linear perspective: parallel lines appear to converge with distance; the more they converge, the greater their perceived distance

11. Binocular Cue: Information taken in by both eyes that aids in depth perception. Includes:

• convergence: come together from different directions and meet

• retinal disparity: left eye and right eye view slightly different images

Perceptual Constancies: Perceiving objects as unchanging, such as consistent lightness, color, shape, or size, even as illumination and retinal images change.

12. Size constancy: objects closer to our eyes will produce bigger images on our retinas but we take distance into account with size estimations. Although the people in the background of the photo below look small, we still perceive them as about the same size as the two girls since we take distance into account.

13. Brightness constancy: we perceive objects as being a constant color even when light reflection changes.
Ex.) Brick wall always looks "brick red", even as daylight fades and reflection color turns gray. In the images below, the wall still looks orangish/red even thought the bottom picture's lighting is darker. 

14. Shape Constancy: objects viewed from different angles will produce different shapes on our retinas, although we know the object's shape remains constant.
Ex.)  When we look at a cup from above, we see circles. However, we still perceive the cup as a cylindrical shape because our brain keeps its shape constant.

15. Visual Illusions:

          1) This illusion has closure because in actuality the legs of the elephant are not completely drawn in, causing our brains to extend the drawing and fit in what we expect to be there. This also exemplifies interposition, because one leg of the elephant may seem to be closer to you than another due to the way that it is drawn, which is another cause of our brains seeing more legs than there really are.



http://www.scientificpsychic.com/graphics/elephant.jpg

          2) In this illusion, you see the two lines that meet at a point and the two circles, but this can also be interpreted as being two parallel lines that go off into the distance, and because the definition of parallel lines states that they never meet, our brains do not want to realize that they are in fact meeting. This is an example of convergence.


http://www.greenwych.ca/moonillu.htm



          3) In this illusion, you can see both a man playing an instrument and the face of a young woman. Seeing both of these pictures is possible due to figure-ground perception. Depending on which way you see the picture, whether you choose to focus on the background or the foreground, you can see different images because it  is necessary to block one out in order to see the other.



http://allpsych.com/wp-content/uploads/2014/08/clinton.jpg