visual_perception

= = =__Visual Perception__=

This is arguable the best understood of all forms of perception that have been studied by researchers. The meaning of visual perception is basically to extract meaning through means of recognition and understanding from the light that penetrates our eyes. Visual perception allows us to recognize a room, our family, friends, a lamp, a TV show, etc... all done through the process of detecting colour, shapes and the edges of objects. The brain extracts and makes memories of past understandings associated with the ojbect you're viewing appear, so you can make sense of what you are seeing. Visual perception can be branched off into sub-groups that can be studies such as: 1.depth perception. 2. pattern recognition. 3. developmental aspects. A popular example is trying to determine which of the following two lines are longer:

=How People Perceive the World=

Richard Gregory, a leading theorist, researcher, and the creator of the constructivist account of visual perception, claims that the idea that we can construct our perception of the world from some of the sensory data falling on our senses is how we perceive images. This leads into the topic of perceptual constancy.

The idea of perceptual constancy is best explained with the use of an example. Say that you see a red car during the day, when sunlight is hitting it, and your photoreceptors in your eyes can clearly make out the colour 'red.' Later that night, when you see the car again, with some of the streetlights casting it in sort of a yellowish-glow, you still know that car is red, regardless of the shift in light to perpetuate the viewing of the colour red. Perceptual constancy is our "ability to perceive an object or scene in an unchanged fashion despite changing illumination, viewpoint and so forth affecting the information arrivig at our senses." (Benyon et. all, 111)

=The Horizontal-Vertical Illusion=

The diagram shows two intersecting lines. Which one is longer? It is impossible to determine which is longer... since they are both the same length. The vertical line seems longer due to the it seeming to be receding in depth. The argument goes that individuals who dewell in more enclosed environments, and who are not exposed to the view of a horizontal landscapt often, are more likelty to view the vertical line as being longer. Those that are exposed to horizontal landscapes more often are less susceptible to the horizontal-vertical illusion.

=The Stairs Illusion= Most people would describe the next image as what? A flight of stairs ascending, right? Well why can't they be descending, since stairs go both ways, do they not? Obviously! Yet it is our North American, Westernized concept attributed to our reading style of going left to right on a page that leads us towards the natural inclination of believing that those stairs are going up. If the stairs were flipped to face the opposite direction, what would you be more inclined to say?



=**The Lego-Block Illusion**= The lego block illusion again, starts to play with our idea of three dimensional perception.



=Conclusion=

When it comes to perception in terms of depth in relation to cultural factors, it is clear that such factors have a large influence on how groups of people learn to perceive objects.


 * Blind Spot Experiment**

The retina is the part of the eye covered with receptors that respond to light. A small portion of the retina where the optic nerve connects to the brain has no receptors. An image that falls on this region will not be seen. Close your right eye. With your left eye, look at the L below. Slowly move your head closer or further away from the screen while looking at the L. The R will disappear when your head is approximately 50 cm (20 in) from the screen. You can repeat the experiment with your right eye by looking at the R.



=Bibliography= 1. Benyon, David and Phil Turner and Susan Turner. "Designing Interactive Systems" Addison Wellesley: Essex, 2005. 2. Chandler, Daniel. "Visual Perception."  3. all images courtesy of  4. top image: <http://www.bartlettcommunications.com/images/stock/concepts/vision.jpg 5. Blind Spot Experiment http://www.nu.ac.za/undphil/collier/202/CSfiles/Perception%20puzzles,%20Visual%20Perception,%20Optical%20illusions%20and%20Paradoxes.html