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Visual Perception and illusion

VisualPerception and illusion

VisualPerception and illusion

Thereality about what the eyes see and how this compares with what theeye believes it has seen has been a subject of much controversy, andsubjected to numerous scientific researches over time. Thus, peoplesee color when there is none, perceive depth in environments wherethere is no spatial variation, sense motion where there is none, andsee size differences in objects that are factually identical in size(Humphries &amp Riddoch, 1987). This paper will explore the natureof visual perception and expose the underlying principles upon whichthe truth as the human brain knows it is constructed. It will attachrational concepts that make it necessary that eyes see what is notthere, and act according to the illusion so made to appear factual.In essence, this paper will show that visual perception is not true,but a concept entirely made of brain illusion.


Perceptionas a term can be taken to mean the manner by which informationpresented to the human brain by the environment through any channelincluding smell, sight, sound, touch and taste are processed andmeaning attached to it. The sensory inputs to be acted upon orprocessed by the brain are admitted through any of the sense organswith which all living things are equipped. The Science Daily, ascientific research database, defines perception as theinterpretation of stimuli presented from the environment through thevarious senses. Thus the literal perception is the representation ofthe stimuli as it really is which cognitive perception is the meaningthat arises of the stimuli so presented after it has undergoneintensive analysis and interpretation by the brain, the body’sorgan for intelligence, coordination, and logical interpretations(Bradley, 2014). Visual perception, therefore, is the interpretationof stimuli or sensory information incident upon the body’s visualsensory organ- the eye. Visual perception is processing ofinformation regarding an object through the nature of light wavesreflected by the object and incident upon the eye once light falls onit. The nature of information that ordinarily is available to thehuman brain as a result of sight includes information about the colorof the object seen, and its size- both the approximated real sizethat results after the brain adjusts the sensory input for spatial ordepth variations, and the apparent perceived size. The informationalso contains its shape, distance from eye, and all its associatedfeatures (Humphries &amp Riddoch, 1987).

Visualperception, however, seems to have a big disconnect in many instanceswith the factual reality as scientifically and logically established.Numerous research has been done in order to establish the cause ofthis disconnect, and what implications this might have on allgeneralizations made based upon human perception alone. Thiswidespread research is collaborated with other forms of illusionaryresearch in human psychology, developmental studies and business(Scholte.et.al, 2001). The fundamental underlying reality is that thebrain is the organ behind all information processing, and istherefore the organ that misinterprets the information that isfactually presented to it (Bradley, 2014). The rationale for thisalteration will be explained below.

Howthe Brain Works

Oneof the best theories that explain the brain function is the Gestalttheory which holds that the human brain does not see objects as thesum of the parts forming them, but sees them as being much more thanthe total of their parts (Mack, 2003). The foundation of this beliefis in the school of thought that the brain tries to attach meaning toeverything it sees, in order to avoid ambiguity. When a child isborn, its brain has to start processing information and makinglogical conclusions based on experience it gets. The human memory isempty, and starts to fill up upon birth. There is established anatural order of logic and reason intuitively developed within thehuman mind, that helps one organize information regarding things,occurrences, associations between things, actions and effects,information regarding self preservation- which is one basic instinctof humans upon birth, sexuality and the need for food, among otherthings. This extremely wide database of information is organized intoschemas. Schemes are groupings of related objects, concepts, causeand effect relations, expectations and all other dynamics ofhumanism. Thus, to enable easy processing and commitment to memory ofevery new sensory information the brain automatically scans itssystem of schemas and associates the new data with the most logicallyappropriate schema, thus allowing easy thought and reaction process,as well as memory processing. According to Gestalt psychology, thereare several ideas underlying brain-senses relationship (Bradley,2014).

Inaddition to the perceptual complexities of the brain, modernpsychology also focuses on selective vision, a property that ischaracterized by the brain directing the visual system to completelycut out vision of unwanted stimuli. Mack (2003) discusses thisconcept in the workInattentional Blindness: Looking Without Seein. Inthe article, he documents various experiments that illustrate howpeople may fail to see even conspicuous objects in the field of viewso long as they are not focused on them (inattentional blindness),and in other cases experience unconscious perception, the oppositeof inattentional blindness, where a person sees an object withoutconsciously focusing their attention on it. Neural imaging techniquesare currently being developed to try and understand the process ofattention synthesis, and what happens in the brain when one seeswithout looking, or looks without seeing (Scholte et al, 2001).

Emergence,which is the tendency for the brain to form various complex datatypes from simple perceived information, is one key Gestalt idea. Thebrain forms complex information from basic forms in the perceivedinformation, such as spheres when one sees a circle due to theautomatic reconstruction of depth by the brain. In addition, lightand shade, concepts normally associated with depth, prompt the brainto detect depth and automatically vary the distance of the perceivedobject to match its shadow patterns (Mack, 2003). To do this, thebrain draws from a wide bank of experience as stored in the memory.In the diagram below, the top shows an elephant, but closelyexamining the legs reveal inconsistencies that defy the mind’slogical expectation of elephant’s feet. There is an emergencepattern showing four feet, which on examination reveal more feet, andthen the brain concludes that the figure is inconsistent withreality. So strong is the emergence principle that examining theelephant after a while leads one to the same illusion.


Reificationis another key concept, in which the brain tries to fill in all gapsit perceives are missing from the sensory data in order to match atruth already in its memory. Thus, one is able to read a handwritingin which letters are mis-constructed or missing, so long as thereexists enough formal resemblance between it and a word in its schema.This concept, however, may also misdirect the brain to alter sensoryinformation to resemble something familiar, while the objectperceived is intentionally different from the one referred by thebrain. As an example, the illustration below is of a paragraph ofletters, symbols and numerals which individually would have norational meaning, but collectively are easy to construct into ameaningful grammatical sentence. This message shows how the humanbrain can fill in missing gaps in order to come up with a trustablereality that completes our expectations in line with the existingschema (Scholte.et.al, 2001). This aspect of the human brain alsomakes it possible to read out words with entire groups of lettersmissing, or to understand bad handwriting depending on the conceptabout which the writing was done.

(Freeoptical illusion, 2014)

Multi-stabilityis the tendency of the brain’s interpretation to rapidly shiftbetween multiple possibilities of perception in cases where ambiguousor conflict visual information is presented for analysis. Thus, thebrain might rapidly shift between seeing a negative image and apositive one, where the presented information may have implicationsof both a positive and a negative image. This is typical of images inblack and white color only. Focusing on one possibility with anactive mindset makes that perspective dominant, and the equallylikely alternative is overshadowed. Shifting one’s focus alsoshifts the dominant perception. For example, the image below canrepresent the figure of an elderly woman in a fur coat and a featheron the head, or a young woman with a necklace and thick hair.Focusing on one perception eliminates the other. In the second image,one may perceive two facial outlines against a black background or ablack vase against a white background. Focusing on one eliminates theother.


Invarianceis the concept that gives the brain continuity of aspects, even whenthey are hidden. Thus, an image of a man’s head showing the backdoes not confuse the mind into failing to recognize the image as thatof a man, or not rationally expecting that the man has a face withall facial features in the opposite side. Similarly, one is able toknow of the existence of formal features not actually seen in anobject by judging from comparison with similar objects previouslyseen.

Thus,in general, the brain attempts to save time, avoid ambiguity, upholdsimplicity and avoid danger by instinct. This general principle,while actually helping animals to live safe, efficient and easylives, also presents an immense danger in the form of sensory orvisual illusion, a reality which may have just as many benefits asshortcomings in real life. Law of Pragnatz- this law forms a basicgestalt principle of preferring simple, organized perception, whichthe brain associates with safety and efficiency. For instance, thetwo shapes below are entirely different, and may represent differentthings, yet the brain relates the figure in the left to the one onthe right, with which it is familiar and can safely conceptualize.The mind fragments to simpler, familiar ones.


Clousureis the basic brain’s way of forming simpler objects into a complexwhole, when there are no simpler logical expectations from theseforms. As an example, the brain sees a triangle with vertices loggedin circles, or a panda, in the right side diagram, even while theseare not implicitly in the sensory information.


Inother considerations, the brain tends to see objects closer togetheras related, just as it interprets objects parallel to each other (proximity and parallelism), while those far apart or skewing are notrelated. So also is the concept of color or directionality. In a poolwith many objects, those moving in the same direction are perceivedas being related, while those that are stationary or moving inopposite directions are seen to be unrelated. In addition, the braintends to focus on sensory stimuli conspicuous in a field of view, andinstinctively ignore the homogenous parts. In the figure below, theeye tends to focus on the red dot, and not on the much more blackones.


Apartfrom illusion generally caused by the brain’s interpretation ofsensory stimuli, there exists also numerous perceptual effects thatarise when the visual system is damaged. These effects similarly haveeffects on the way the brain judges the limited or misrepresentedstimuli.

UnilateralVision Neglect (UVN), for instance, is a perception disorder that isobserved in people whose parietal cortex has sustained lesions duringincidences of brain damage. In this condition, the person fails tosee objects positioned in the visual field which is opposite the sideof the brain opposite the lesion’s position. Rafal (1998) exploredthe causal and behavioral trends of UVN, giving the example of a UVNpatient who fails to eat food in the left side of the plate inresponse to a dominant lesion in the right brain hemisphere. Rafalnotes that both UVN and inattentional blindness share similarities inthat they both exhibit attention deficit. Work conducted by otherresearchers including Bradley (2014) and Zhil, Von C. &amp Mai(1983) has shed light on the concepts of the dynamics of vision,including IB and UVN, making the topic to be widely understood.However, information regarding the exact nature of selective vision,as well as its causal effects and the role the brain plays duringinattentional blindness and unconscious perception (UP), is stillincomplete. Thus further research and experimentation is beingconducted to gain a working insight into visual perception dynamics(Scholte.et.al, 2001).


Theforegoing discussion has revealed numerous mystical observationsregarding sight, and the brain’s interpretation of it. Thediscussion has revealed evidencing showing three disturbinglyrealistic aspects of the brain-sight interrelation. Firstly, evidenceexists to show that sometimes the eye fails to see what it is lookingat. Secondly, the eye sees without intending to see or sees andimmediately forgets that it saw. Thirdly, research andexperimentation has proofed that even when the eye sees and the brainregisters the object seen, the visual perception may still be marredby illusion, leading the observer to make wrong conclusions regardingfactual observations, in other words bending the truth. Emergence,which is the tendency for the brain to form various complex datatypes from simple perceived information, is one key Gestalt idea.

Farfrom this discussion, physics has already shown through rectilinearpropagation of light concept that the initial images formed at theeye’s retina is inverted, and that it takes analytical output forthe brain to change the image to appear upright. With all thesefacts, can it still be argued that the world as it appears to thehuman eye today is not entirely an illusion?

Thetruth is that the visual world as it is today is an illusion of thebrain, since it has been demonstrated that humans are not sure howmuch they see and miss out, and they also cannot be sure that anyobservation they make is factually correct. Human visual perceptionis a subjective phenomenon based on, among other factors, theirdevelopment environment and the associated schema, their expectationsregarding the subjective environment, their visual health conditions(as evidenced by the cases of UVN), and their specific attention tosight detail ( as evidenced by the cases of inattentional blindnessand unintended vision) . Attempting to justify the complex interplayof these variables in order to marry what the human eye sees and whatthe brain says it sees would be subjective, as evidence existssuggesting multiple possibilities none of which can be accuratelyasserted. While it is true and sufficient that the range of visiblephenomenon helps the human brain make judgments that basically helpthe human being realize the fundamental instinctive objectivesincluding survival, learning, safety and operational efficiency, itis nonetheless true to state that the visually perceived reality ashumans know it is based on perceptual illusion.


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