If we were to lose our perception of depth, we might indeed fall off of the cliff: even if we could sense the change of color we might mistakenly believe that the ground and the depths below were on the same plane. Auditory illusions have similar effects and can cause people to distort reality. One of the most notable examples of auditory illusions causing a distortion of reality is the ventriloquist who "throws" his or her voice. Attention and concentration are also essential aspects of sensation and perception. Human beings are usually bombarded by a barrage of sensory data and must consciously or unconsciously filter out extraneous information. Although our senses are exposed to a multitude of material, much of the sensory data remains outside of our conscious awareness. For example, we tune out conversations in a crowded restaurant in order to listen to our dining partner, or we tune out the radio when we want to study. Our failure to perceive everything works in our favor, as we would become exhausted and confused if we perceived everything that we sensed at any given moment. However, in some cases our attention fails us: as when our mind wanders in class or when we are engaged in conversation. Occasionally our attention shifts, and sometimes the brain senses danger before we perceive it. For instance, if we are watching television and someone tries to break into the house, we would probably perceive the sound. On the other hand, if we knew that children were playing in the other room, we would probably ignore any extraneous noises. Furthermore, concentration enables...

For instance, we choose to pay attention to the television in lieu of listening to a conversation in the next room.
Animals and human beings sense and perceive the world differently, and comparing different species can draw attention to the nuances of sensation and perception. For example, dogs can hear sounds that human beings cannot; their ears sense sound waves beyond the threshold of human perception. A dog's sense of smell is likewise more powerful than that of human beings. Nocturnal animals can sense objects in darkness, and in some cases can see objects in the infra-red visual spectrum.

If we could not perceive, our lives would be far more dangerous and far less interesting. Our sense organs deliver information to the outside world to our brain. The rods and cones in our eyes process waves of light, and the ocular bones react to sound waves. Similarly, our taste buds react to the chemicals present in the food we eat. From our sense organs, our brain can process the sensory data, transforming the raw information into meaningful perceptions. Thus, the rods and cones in the eye send information along the ocular nerve into the brain, where the information is transformed into neural data that is processed in the visual cortex of the brain. From here, our perceptive processes kick in, leading to cognitive interpretations.

Works Cited

Bach, Michael (2005). "55 Optical Illusions & Visual Phenomena." Online at http://www.michaelbach.de/ot/.