How does sensation related to perception

For example - one of the most well known Gestalt principles is the Phi Phenomenon, which is the illusion of movement from presenting stimuli in rapid succession. When you see a cartoon or running Christmas lights, you see movement although none actually exists because of this principle.

When we look at an object, we see that object figure and the background ground on which it sits. For example, when I see a picture of a friend, I see my friends face figure and the beautiful Sears brand backdrop behind my friend ground. However, the idea of "good form" is a little vague and subjective. Most psychologists think good form is what ever is easiest or most simple.

There are simply 3 elements from my keyboard next to each other, but it is "easy" to organize the elements into a shape that we are familiar with. Objects that are close to each other in physical space are often perceived as belonging together.

As you probably guessed, this one states that objects that are similar are perceived as going together. Dots in a smooth curve appear to go together more than jagged angles. This principle really gets at just how lazy humans are when it comes to perception. For example, when you see geese flying south for the winter, they often appear to be in a "V" shape. For example, the picture of two faces looking toward each other that is also a vase.

I am sure most every Introductory Psychology book has this example. You know the artist, Escher who draws the pictures like Pain is an unpleasant yet important function for survival: warning system but not all pain is needed for survival. There are two different pathways to the brain on which pain can travel - information brought from free nerve endings in the skin to the brain via two different systems:.

For example - child birth: Lamaze method falsely leads us to believe it won't be painful. Maybe if we know it will be bad we can adequately prepare to handle it. For example - study manipulated moods of subjects then asked them to complete questionnaires of pain perception. Those in negative mood group reported significantly more pain than other subjects. So, it can be opened to allow pain through or closed to prevent pain from being perceived.

The Gate - actually a neural network controlled by the brain. Located in an area of the spinal cord called the Substansia Gelatinosa. There are two types of nerve fibers in this area:. So - when pain occurs it is because the large fibers are off and the small are on, opening the gate. Since the gate is controlled by the brain, he factors discussed earlier expectations, mood, personality influence the functioning of the gate. May explain acupuncture, acupressure, pain tolerance during last two weeks of pregnancy, etc.

BUT- endorphins may work with the gate control theory - maybe pain is perceived, endorphins are released, so the brain no longer needs the signals and closes the gate. Often person feels phantom moving in perfect coordination with the rest of the body - some report a missing arm extending outward at a 90 degree angle so they turn sideways when going through a doorway.

Still, the foot feels as though it is part of the body. Go to Phantom Limb Pages - includes case studies. Signals follow the same pathways the brain as when the appendage existed. As an example, imagine yourself in a very dark movie theater. If an audience member were to receive a text message on her cell phone which caused her screen to light up, chances are that many people would notice the change in illumination in the theater. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice.

The cell phone brightness does not change, but its ability to be detected as a change in illumination varies dramatically between the two contexts. Webers Law : Each of the various senses has its own constant ratios determining difference thresholds.

Webers ideas about difference thresholds influenced concepts of signal detection theory which state that our abilities to detect a stimulus depends on sensory factors like the intensity of the stimulus, or the presences of other stimuli being processed as well as our psychological state you are sleepy because you stayed up studying the previous night. Human factors engineers who design control consoles for planes and cars use signal detection theory all the time in order to asses situations pilots or drivers may experience such as difficulty in seeing and interpreting controls on extremely bright days.

While our sensory receptors are constantly collecting information from the environment, it is ultimately how we interpret that information that affects how we interact with the world. Perception refers to the way sensory information is organized, interpreted, and consciously experienced. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built from sensory input, stimuli from the environment.

On the other hand, how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts related to the stimuli we are experiencing. This is called top-down processing. One way to think of this concept is that sensation is a physical process, whereas perception is psychological.

When we see our professor speaking in the front of the room, we sense the visual and auditory signals coming from them and we perceive that they are giving a lecture about our psychology class. Although our perceptions are built from sensations, not all sensations result in perception. This is known as sensory adaptation. Imagine entering a classroom with an old analog clock. Upon first entering the room, you can hear the ticking of the clock; as you begin to engage in conversation with classmates or listen to your professor greet the class, you are no longer aware of the ticking.

The clock is still ticking, and that information is still affecting sensory receptors of the auditory system. The fact that you no longer perceive the sound demonstrates sensory adaptation and shows that while closely associated, sensation and perception are different.

Additionally, when you walk into a dark movie theater after being outside on a bright day you will notice it is initially extremely difficult to see. If you are wondering why it takes so long to adapt to darkness, in order to change the sensitivity of rods and cones, they must first undergo a complex chemical change associated with protein molecules which does not happen immediately. Now that you have adapted to the darkens of the theater, you have survived marathon watching the entire Lord of the Rings series, and you are emerging from the theater a seemly short ten hours after entering the theater, you may experience the process of light adaptation, barring it is still light outside.

During light adaptation, the pupils constrict to reduce the amount of light flooding onto the retina and sensitivity to light is reduced for both rods and cones which takes usually less than 10 minutes Ludel, So why is the process of raising sensitivity to light to adapt to darkness more complex than lowering sensitivity to adapt to light? Caruso has suggested that a more gradual process is involved in darkness adaptation due to humans tendency over the course of evolution to slowly adjust to darkness as the sun sets over the horizon.

There is another factor that affects sensation and perception: attention. Attention plays a significant role in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask what song had just finished playing, you would probably be unable to answer that question. One of the most interesting demonstrations of how important attention is in determining our perception of the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris In this study, participants watched a video of people dressed in black and white passing basketballs.

Participants were asked to count the number of times the team in white passed the ball. During the video, a person dressed in a black gorilla costume walks among the two teams.

You would think that someone would notice the gorilla, right? Because participants were so focused on the number of times the white team was passing the ball, they completely tuned out other visual information. Failure to notice something that is completely visible because of a lack of attention is called inattentional blindness. More recent work evaluated inattention blindness related to cellphone use. Participants were not aware that while they walked through the square a unicycling clown would ride right in front of them.

Information from each visual field is sent to the opposite side of the brain at the optic chiasm. Visual information then moves through a number of brain sites before reaching the occipital lobe, where it is processed.

Two theories explain colour perception. The trichromatic theory asserts that three distinct cone groups are tuned to slightly different wavelengths of light, and it is the combination of activity across these cone types that results in our perception of all the colours we see. The opponent-process theory of colour vision asserts that colour is processed in opponent pairs and accounts for the interesting phenomenon of a negative afterimage.

We perceive depth through a combination of monocular and binocular depth cues. Sound waves are funnelled into the auditory canal and cause vibrations of the eardrum; these vibrations move the ossicles. As the ossicles move, the stapes presses against the oval window of the cochlea, which causes fluid inside the cochlea to move. As a result, hair cells embedded in the basilar membrane become enlarged, which sends neural impulses to the brain via the auditory nerve.

Pitch perception and sound localization are important aspects of hearing. Our ability to perceive pitch relies on both the firing rate of the hair cells in the basilar membrane as well as their location within the membrane.