Perception as Gateway to the world

The purpose of perception is to inform us about properties of the environment that are important for our survival. The ability to perceive is the ability to use all our senses, and if not all then some of them at least.

  The perceptual process is a sequence of steps that animals go through by recognition of the stimulus, and action regard to the stimulus if necessary.  In the environment, there are a lot of stimulus but we may just focus on few .Transduction occurs after it. In the nervous system, transduction occurs when the environmental energy is transformed into the electrical energy. After the electrical signals have been sent, then these signals in the receptors send new signals in cells called neurons. After perception is taken into account, two other perceptual behaviors have to occur. These two perceptual behaviors are called recognition and action. The main channels that process these signals are through the brain.

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  Much of the research that is done to see how perception works is through studying the cerebral cortex.This cortex covers the surface of the brain and contains the brain’s machinery for creating perception. Other functions such as language, memory and thinking are also processed in this area.  A basic function of this area is modular organization. Modular organization is how senses are organized into primary receiving areas. The primary receiving area for vision is in the occipital lobe.

  The area for hearing is located in the part of the temporal lobe. The area for skin senses such as touch, temperature, and pain is located in the parietal lobe. These lobes are just broad areas where the signals are send, but there are more specific areas within these lobes were everything is processed.     Neuroimaging techniques are used to check what senses activate what parts of the brain. Another main area that is deeply involved with the senses is the lateral geniculate nucleus.There are maps of body parts on the lateral geniculate nucleus and striate cortex.  For example, for the sense of touch, there is a map of the body on the brain in which touching a place activates a specific places of the somatosensory cortex in the parietal lobe. Vision and touch seem to be the obvious ways to perceive objects.

If they are not available then the hearing and chemical senses have  a stronger impact on the brain. For vision the path ways are the parts of the eye, the neurons carrying the signals, and the different areas in which they are sent.  Touch involves all of the body and the receptors in them.  Hearing requires parts of the ear.

There are specialized neurons for each of the senses. Groups of neurons have different ways of sending signals.  Taste involves the receptors of the tongue, and the three different nerves that the signals are send on to the brain.

Smell involves the receptors of the nose that are destroyed on a weekly basis and new are grown.  According to research , there might be a sixth sense described called temperature.B. Information processed in the computer and the brainComputer and the human brain have different ways of gathering their information.  The computer’s hardware is made from the human though. What a computer is programmed to do is what it will perform. Human mind gathers information by its senses.  Aristotle distinguished only about five senses.

There might be six senses if temperature is taken into account. The bottle neck effect states that amount of information being processed is limited at the same time. This done so there is not so information loss.  Then the filter selects what type of information is taken in, but the computer will only filter what the person has programmed it to. The human mind chooses itself what is needed.  The brain itself has some sensory modalities.

These channels can be called the olfactory perception, somatosensory perception, auditory perception, and visual perception.The olfactory perception is the basic sensory system. The most important of these channels seems to be the visual perception. Vision provides us with a variety of information. We might take this perception for granted. The camera of the computer might be compared to the vision system of the human. Cognitive psychology studies how we think.

This topic is very complicated and detailed.  Knowledge counts as a part of perception. The mind must take in more than what is show on the retina. The meaning of the objects and our knowledge of characteristics of the environment are filtered also. A computer might lack the ability of perceptual intelligence. There are different ways of seeing a certain object.

  Different human minds process different information.  According to cognitive psychology however, the ways the computer processes information is basically through the keyboard, camera, microphone, modem, etc. Why would computers have trouble perceiving objects then? First, objects are seen from different view points in the human mind and not in the computer. Second, objects need to be separated.  Is it possible for a computer to distinguish a tiger hiding in the bushes? These process is used for survival, but how would we program that into a computer? It might be difficult to distinguish which objects starts where and ends where.

Third, determining the shapes of partially hidden objects is difficult.The human mind may guess what the object is. Gestalt psychology explains this quite well through its principles. The mind finds ways to simplify objects.  Lastly, computers may not be able to distinguish from what effect is caused from light and illumination. Changes in lightness and dark are caused by how much light reflects. Things get more complex due to the different shapes in the world and the reflection of light on them.

Behavior and thinking in the mind based on a network of information processing. Sensation and perception is the starting point  for the human mind to analyze something. The network to attention, memory and thinking is stimulated afterwards. In conclusion, there are many similar ways that a computer might process information like the human mind. New questions like how can computers perceive strike as more of a challenging question for researchers.

2. Illusions as Key to RealityA. Added value of color and two leading theories of color visionColor is one of the most obvious qualities in our environment. Achromatic colors are such as white, black or gray. When some wavelengths are reflected more than others then those colors are called chromatic colors. How the experience of color represented by signals in the nervous system has been a question to many researchers. There have been two different approaches to theories of color vision.

First, the Trichromatic theory of color vision was introduced by Thomas Young and Herman von Helmholtz during their experiments of color matching. The theory states that color vision depends on the activity of three different receptor mechanisms.  In these color matching experiments, observers were asked to adjust the amount of three different wavelengths of light mixed together until it matched the color of a certain single wavelength.

The pigments in these cones can absorb up to certain amount of wavelength. These different type of pigments have different sequences of groups of amino acids that make up the opsin molecules. The differences in the opsin’s amino acids are what causes the different pigments to have different absorptions.  The short and middle wavelength cones have only about 44 percent of their amino acids in common which results in similar absorptions. Their peaks only have short distance separation.  These three type of cones were named L, M, and S. They respond best to light around 560 nm, 530 nm, and 420 nm.

Researchers questioned if all three receptor mechanisms were necessary for color vision. It can be possible just with two receptors but not with one alone. One pigment would not provide enough information of telling the difference between one wavelength from another. For some people that are missing some cones, they have a color deficiency. Monochromats have no functioning cones. They usually are called color blind.

They see shades of white, gray and black. Dichromats experience some color. The trichromat needs all three wavelengths to match any wavelength.

Color deficiency occurs from receptor problems but can also from problems in the cortex. Although the Trichromatic theory gave a lot of information there was still some questions left. Ewald Hering proposed the opponent-process theory of color vision which states that the color vision caused by opposing responses was generated by the blue, yellow, green and red fields. His observations stated that viewing a red field generates a green afterimage, viewing a green field generates a red afterimage, and so it continues analogous results occur for the other colors.  He concluded that red and green are paired as are the other two colors.The negative responses are caused by the buildup of chemicals in the retina. This part of his theory did not prove out correct.

  After the techniques made to measure responses of neurons in the retina and lateral geniculate nucleus were made, the theory by Hering was more accepted. Researchers began to find opponent neurons in the retina and lateral geniculate nucleus that show an excitatory response to light from one end of the spectrum but with a inhibitory response to light from the other end. The experience of color vision is shaped by physiological mechanisms in the receptors and in the opponent neurons. The three different kind of cone receptors show that we need a minimum of three wavelengths to match any wavelength in the spectrum.  The opponent cells are responsible for perceptual experiences. For signals to reach the brain, the receptors must respond to different patterns of wavelength which then neurons integrate to signals.

  Even though these two theories exist, the question of how color is represented in the cortex is not fully answered.B. Basic concepts of visual informationThe three major divisions of the visual system are the eye, the lateral geniculate nucleus in the thalamus, and the striate cortex in the occipital lobe. These all work together to get the picture.

Creation of depth perception is based on binocular disparity. The difference in the images on the two eyes is determined and then this difference is transformed into the perception of the depth. This perception that results from the information given by binocular disparity is stereopsis.  Our eyes have oculomotor and monocular depth cues.

The oculomotor cues are for convergence and accommodation for the inward movement of the eyes. These cues are effective for near by objects. The monocular cues are effective for one eye. The can pick up the relative height differences, size, linear perspectives, texture gradients, and even motion.The perception created in our minds can also help us perceive movement. There can be real movement, apparent movement, induced, and the aftereffect.  The aftereffect is when the person sees illusions.

  Such movements as things rotating seem to be moving inward can be known as illusions.  Perception researchers have studied object perception at different levels.Wilhelm Wundt established the approach to psychology called structuralism. This stimulated the founding of Gestalt psychology.  Wertheimer questioned Wundt’s observations.  He and other members introduced some basic principles such as that the whole is different from the sum of its parts. These principles together made up the laws of perceptual organization. These are a series of rules that specify how we organize small parts into wholes.

Pragnanz if translated into English means “ good figure”.  This is the central law of Gestalt psychology which states that every pattern is seen in such a way that the resulting structure is seen simple as possible. Geometric shapes placed together can be seen as a specific object to a specific person rather than seen separately.

Similar things will be tried to be grouped together which leads to the law of good similarity. Grouping can be done to the similarity of lightness.  The light objects form one group and the dark objects form another group.  Points that are connected result in a some smooth lines are seemed to be belonging together as described by law of good continuation.

For example, if going to a oil refinery , we might see each pipe continuing smoothly. Each law translates into another law. Things that are near to each other seemed to be grouped together which is stated in the law of proximity. In our mind we like to make everything simple and whole.These principles we see are applied to our daily lives.

Buildings are structured in ways that the lines are softly continuing and giving the building a square or rectangular type of shape Halls and concert rooms are designed as such to be pleasing to the eye which means simple to the mind of the viewer. The law of closure states that we tend to view objects as in complete shapes as in wholes. Seeing two small tables together we might want to imagine as one whole table or seeing an incomplete circle. These principles are heuristics. Small elements become perceptually grouped to form larger objects. In the environment, not only a single object is seen but many different objects are.

The ability to perceptually separate the objects is perceptual segregation. There might be some neurons that provide the  physiological way of looking a the Gestalt principles.  Some neurons might fire to a particular pattern, a similarity of orientation, and good continuation.

  There are many approaches to object perception and Gestalt laws are a few of them.3. The Chemical SensesA. Odor sourceThere are receptors that serve taste and smell are constantly exposed to chemicals.

  They go through neurogenesis which is they only have a 5 to 7 week living period. Humans are capable of detecting small differences in odor intensity. The chemical senses serve as guards to identify which substances the body needs and should consume. They also detect which things may be harmful and that should be rejected.

Smelling an odor triggers memories and can create different emotional reactions. Humans have a less keen olfactory system since we do not rely on it as much as animals do. Animals use olfaction to orient themselves in the area, to mark territory,  and guide them to specific places or other animals.

How is an odor sensed and localized? Well first there is a region named the olfactory mucosa that is located in the nasal cavity and it is where transduction occurs.    The olfactory receptor neuron is where transduction that is the process of transformation of chemicals to electrical signals occurs.The actual olfactory receptors are found on the ends of ORNs. Odorants stimulate the Ors and then become attached to olfactory binding proteins.

A opening of ion channels is triggered. There are about 1,000 different kinds of ORNs with about 10,000 of each type The axons reach the olfactory bulb and synapse to the glomeruli. Each glomerulus’s collects information from receptors that respond to the same type of odorants.

  The glomeruli seem to function like the visual cortex in responding to similar forms of objects. The destinations of these signals goes to primary olfactory cortex, orbitofrontal cortex, and amygdala. Localizing an order is not only include the chemical senses working but the other senses as well. It may be difficult to recognize some odors, but the brain needs to get trained into recognizing these odors.The brain needs to differentiate all the aromas of the environment to separate that one particular aroma the person is looking for. How does the brain recognize what odorant molecules are entering the nose? Researchers are looking at the chemical basis of these molecules to see how neurons respond to them in the brain. For the mind to recognize the molecule, the memory needs to retain its information. The information from the cavity to the amygdala travels to hypothalamus, cortex, and hippocampus.

These brain parts play roles in motor control and many other things. The person can sniff particles in the air and start walking in that direction through control of those brain parts.  The hypothalamus receives a large amount of information which can be used for accepting food or rejecting it. Due to the amount of these receptors that gather the information, the brain can recognize up to 10,000 different odorants and animals can recognize even more.

There is still some information that is unknown to researchers on how specifically what type of patterns the brain recognizes. We can recognize and find the different odorants in a single room. There can be coffee brewing and cigarette smoke, but we can differentiate which smell belongs to which substance.

To conclude, trying to locate a specific odor is a function of different parts of the brain along with the olfaction system. The odor stimulates the receptors in the nasal cavity which carry the signals to glomeruli and different parts of the brain such as the hypothalamus. The memory plays a role in recognizing what the odor is and then motor control comes in to locate the area. There are different neurons that are specialized for each of the senses. These neuron’s axons synapse together to send all information that is needed. B.

Quality of tasteThe process of tasting begins with the tongue. The tongue has four different structures called papillae. There are the filiform papillae that cover the entire surface of the tongue. The fungi form papillae are found on the sides and on the tip. The foliate papillae are also in the same areas.

Most of these papillae contain taste buds. A taste bud itself has many taste cells and taste pores. The electrical signals from the tongue are generated in three pathways to the brain. First, the chorda tympani nerve conducts the signals from the front and sides of the tongues. Then the gloss pharyngeal nerve takes the signals from the back of the tongue. Signals from the taste receptors travel through the vagus nerve. These nerves make a connection in the brain stem in the nucleus of the solitary tract and in areas of the frontal . Different senses affect each other.

Color affects taste and smell. A color that is consistent with the substance’s odor can be a way of identification of that odor. It provides information on how the signals of what that odor is likely to be. All signals synapse in the brain.

One sense provides information about another, and brain activity itself helps to understand the senses. There are four qualities of taste: bitterness, sourness, sweetness, and saltiness. To taste the quality of saltiness, that certain found has a amount of sodium in it. Sourness is symbolized by more hydrogen ions in the substance. Sweetness is symbolized by the opposite of it. There might be a fifth quality of taste which describes meat.  Taste preference is usually described in these four qualities but there have been differences in people.

To check the genetic effects in taste, people’s ability to taste the bitter substance PTC was tested. People who could taste the PTC were classified as tasters and who could not were called non tasters. Some people are more sensitive to taste of bitterness. The quality of taste is described through the perception of flavor. Before we taste anything, we get the smell of it, and then the flavor of it.

Flavor is a mixture of smelling and tasting that is experienced. Taste and smell affect each other. A person that has lot the sense of smell finds no stimulation on the tongue.

Many people confuse taste with flavor. Does the quality of taste exist without smell?  People who have lost their ability to smell usually find things tasteless. In the orbit frontal cortex, the responses of taste and smell are combined. This is the center for detecting the flavor and getting the perceptual representation of the food.

The orbit frontal cortex is also the area where input is received from all other senses. Vision, taste, olfaction, and touch send input into this area.  The neurons in this area respond to hunger.    To conclude,  the quality of taste can not be separated from smell. Flavor greatly influences what we eat. Color affects taste and smell.

Color of the food is also used for survival. How something smells influences if we are going to eat it or not. The neurons act like the other neurons for the other senses in the same way. Many of the signals use similar pathways to reach the brain or a certain area. A taste of substance has to do with the chemicals in it. An area that is common to all senses is the orbit frontal cortex which also controls the motor actions we do. This is how the brain signals for the hand to grab that cup of coffee and drink it after we smell the aroma of it.

4. Individual Effector SystemA. Eye movement systemMany people believe vision to be the most important sense since the information that it provides is numerous. For us to view objects, the eyes must observe them. The movement of the eyes causes the image to shift on the retina. There are different type of eye movements.

The type of eye movements include saccadic, smooth pursuit, vestibular-ocular,  vergence, nystagmus, miniature and compensatory. A saccade is a fast type of movement for the head, eye ,or the other parts of an animal’s body.  The eyes move around to check the area and they make a map of the scene to send to the brain. The central part of the retina, the fovea, has a high concentration of photoreceptor cells. They have also rod cells which are good for motion detection.

The part of the eye that is responsible for the high resolution is the fovea. The eyes move together rapidly in the same direction. It is like in a pattern. The saccade eye movement is different from other eye movements by its speed of analyzing the scene.

Pursuit movement is when the eyes  follow a moving object around. This is less accurate than the vestibular-ocular reflex since it requires the brain to process incoming visual information and  then it provides feedback.  An example for this movement is if the eyes watch a car go by while waiting for the bus. The vestibular-ocular reflex (VOR) is a reflex eye movement .

It stabilizes the images on the retina during the head movement . The image is stabilized by  an eye movement going in the direction opposite to head which keeps the image on the center of the visual field. If the head moves to the left, then the eyes will move to the right. This eye movement is very important. People’s whose vestibular-ocular reflex is impaired can not read since they can not stabilize the image. This reflex can still be active even if there is no visual input. Another movement which causes eyes to be in opposite directions is vergence.

In this, the eyes are in opposite directions to each other.This is a  simultaneous movement of both eyes in opposite directions . This movement is used for binocular vision. The eyes have to converge to look at the same object. To look at an object that is closer the eyes have to rotate towards each other which is known as convergence.

When the eyes look at the same object that is farther away then the eyes rotate away from each other which is known as divergence. Eyes automatically accommodate and have vergence movements. Like the saccade movement there is another rapid eye movement known as nystagmus.  The difference is that the eyes move together quickly in one way and then slowly in the other direction.  There are different phases of this movement. These phases are downbeat nystagmus, upbeat nystagmus, seesaw nystagmus, periodic alternating nystagmus, and pendular nystagmus. There are similar alterations of periodic eye movements in saccade eye movements as well.

They are saccadic oscillations.  The nystagmus movement can be described as  a vestibular-ocular movement with a saccade movement after it.The movements so far described are basically rapid except for the movement that needs to stabilize the image. The miniature movements include the tremor and micro saccades.

These movements are not fast. They are large and slow.  The compensatory movements can be slow as well to keep the image , the eyes follow it. The compensatory movements follow the pursuit movements. While waiting for the bus, the eyes might see a car go by and when the head needs to be shifted to keep the image on the eyes then the eye movement is made. These movements differ from saccade movements. The saccade movements is a way of gathering visual information quickly while the other movements have different duties.  In conclusion, for an eye to maintain an image , it must go through different eye movements.

These eye movements include the saccades, miniature, smooth pursuit, compensatory, vergence, nystagmus, and vestibular-ocular.B. Auditory PerceptionThe ability to hear can be of a great use when we can not see a certain object. Hearing can provide signals in which where we might know there is a problem such as hearing a fire alarm. Hearing provides a way of communication between people. Usually when one sense lacks the other gets stronger. Sound has two different meanings.

Sound can mean a physical stimulus or it can mean a perceptual response.  A sound stimulus occurs if there are vibrations. These vibrations cause pressure changes in air.  The pattern of these pressure changes is called a sound wave. The qualities of the sound we usually hear are the pitch and loudness. Sound waves can be studied by the amplitude and frequency.  The difference in pressure between high and low waves is the amplitude. How many waves there are is the frequency.

There is a range  of hearing for humans. We can hear between 20 hertz and 20,000 hertz.Our eyes are sensitive to the wavelengths and the same way our ears are sensitive to certain frequencies. Before we can hear, the sound stimulus must be delivered to the receptors, the pressure changes must be traduced into electrical signals, and what the electrical signals are composed of what must be processed. The processing of the electrical signals means analyzing the qualities of sound source which are pitch, loudness, timbre, and location. Sound waves first pass through the outer ear , then the middle ear which constitute  of the three smallest bones in the human body, and to the inner ear that has the liquid filled cochlea. Within the cochlea is the organ of Corti which has the hair cells. When the cilia bends is when transduction occurs.

Binaural cues are used for sound localization. Spectral cues are used for  locating a sound’s elevation. Sound at long distance can be analyzed by its sound level, frequency, and reflection.There are regions in the brain that are specialized for all the senses. Vision has a certain cortex that the signals are send to and so does hearing.  The auditory cortex is used for localization and other auditory functions. The temporal lobe is dominated with the auditory information. The thalamus is another region where information is sent, but the auditory cortex is where most of the signals are sent.

That is where most of the information is gathered. As the other senses get damaged so can hearing.  Hearing can become impaired for the following reasons : the stimulus can not be delivered to the receptors, there is damage done to receptors, there is damage to the transmission system, and if there is damage to the auditory cortex. There are different disorders and hearing losses. Presbycusis is the most common form of a sensor neural hearing loss. It seems to occur with increase of age like byopia occurs for the eye. Studying the different regions of the brain provide information for building devices that can aid restore the same processes of the senses.

            Researchers can study what frequencies people hear through a graphical representation.An audiogram or audibility function is a graphical representation on how people perceive different sounds. The frequencies are laid out by a logarithmic scale. The hearing thresholds are in dBSPL to dBHL.  SPL is the sound pressure, dB is for decibel , and HL is hearing level.

Normal hearing on the graph is represented by  being between -10dBHL and 15dBHL. What is out of these decibels can be where the hearing loss occurs. To conclude,  hearing is one of the senses. There are regions of the brain that are specialized for this sense.

Hearing can provide information that vision may not provide at that moment. All the senses are sensitive to damage. There have been different techniques to study the damage of auditory system. The audibility function was developed to see how people perceive different sounds. At different levels, we can classify what range can we hear a waterfall.

Hearing loss can be studied through what ranges an average person hears. Different devices can be made by studying the ranges . The audibility function gives more specific information.