Top-Down And Bottom-Up Approach In Visual Perception

Explain and discuss bottom-up and top-down processes in the context of visual perception. 

Principle of perception and two-way theory flow of knowledge

Perception is a principle as to how exactly humans perceive the knowledge or information of the people or objects that surrounds humans with the help of their senses and as to how this information is processed that it allows humans to interact with the nature and the environment that surrounds us (Lu, Hua, Huang, Zhou, & Dosher, 2010). In our surrounding environment, huge number of sensory information exists which humans easily sense but humans tend to intake only a small amount of information at a time.  Perception of some of the objects automatically handles actions which can be made towards the object (Coello, 2005). The purpose of this essay is to do the general principle research and to know about a two way theory flow of the knowledge with the help of Top-Down and Bottom-Up Approach. The theorists involved in this approach are Gibson and Gregory (Richards, 1976). There are direct and indirect theses which are stated by Gibson and are based on the visual perception and both are compared and also contrasted.

Bottom-Up approach is the data driven process in which the data is always influenced by the senses and then is driven for whatever is perceived by the brain of the humans (Orquin, Bagger, & Loose, 2013). Huitt proposed that this theory has a basis of believing that humans gain the world’s understanding in the way directly by analyzing input of the senses (Lutz & Huitt, 2003).

 Information that is stored in the memory of the humans about the surroundings that are based on the factors related to the human brain like eagerness is known as the top-down approach and it is known as an indirect processing of visual perception. The space that lies between the objects perception in the theory always depends upon the shapes against the usual background and also on the impression of the surface behind the other. 

Bottom-up approach always uses the aspect of the recognition which depends on the knowledge of the stimuli which drives to the memory of the brain from senses of humans. Gibson had believed that genetics and biology are dependent on each other for human senses for reacting over stimuli and humans require no prior knowledge of the environment but should just have this theory of processing information which is not done cognitively but neutrally (Conner, Egeth, & Yantis, 2004).

During the World War II, Gibson formed a film for training the fighter plane pilots who were having trouble in the taking off and the landing the planes. He named the available information as optical flow pattern also known as OFP. Gibson also advice that the light bounces off the various surfaces with many dissimilar gradients which create designs with help of the perception of eyes. Light is then extended over period of time and space which is known as optical array. Knowledge which is worked upon by the optic array consists of 3 forms: affordance, optical flow designs and gradients (Khuziakhmetov & Porchesku, 2016).

Top-Down approach as indirect processing of visual perception

One of the Gibson’s notions is affordance which links perceptions and the actions both in opposite inclination and one can say that the perception does not depend on the action. Connection is actually between environment and the one who perceives it (Fajen, Riley, & Turvey, 2008).

Draper about affordance stated that it may be a sound weird to the humans who feel that the perception is a measurement of the quality of the objects as affordance is not the quality of the object but it is a relation in between perceiver and the object (Gaver, 1991). When humans measure the object in a careful way with the scale, humans are already using their perception that they have with the relationship of the ruler with the object for deriving a complete property.

By usage of the OFP, Gibson was able to share with the pilots the information of the speed and the altitude.  Giving directions will also be a part of the information as to where the pilots were going to land. He also argued that optic illusions do occur when inadequate information is available in optic array and that he could not see the distinction in between the sensation and the perception (Lee, 2005). Hence, he suggested that perception in the end is always a direct process which involves both senses and perception.

Top-down processing approach starts from the bottom, passes on to the stimulus for proceeding at the higher cognitive phase. Stimulus is used in the direct way for forming of the pattern of light and if it gives the observer hints of the surroundings and the relationship. This approach is in contrast to what Gregory’s indirect approach of top-down processing which used the state of cognition as the point of starting and then goes to the bottom in order to pass the visual data on prior information of the environment (Larrison, 2000). 

This approach was also founded by Gregory. He stated that experience which is relevant and old knowledge always plays a significant role in the visual perception as the usage of that past knowledge will help in perceiving object which exists in current scenario (McLeod, 2008). Hence, the theory of top-down approach is indirect process that takes the leap way beyond of what is being perceived.

Illusions that are visual, support with an active but indirect approach with which humans use old experiences. Several time though, the perceptual area of the brain misunderstand the information which is received and it creates the discrepancy in between the cues and that is what explains Gregory’s optical illusion.

Bottom-Up approach as a data-driven process

Gregory suggested that illusion actually fall into the four categories. The first is based on Top-down approach, second one is based on bottom-up, third is when the mechanisms are misused and they do not fall in any of the two approaches and are also known as Side-ways rules (Gregory, 1997). The fourth one is dependent on the psychological states like fatigue in very specific cells.

Muller and Ponzo illusions are explained by using Side-ways rules and sometimes by psychological mechanisms too. Muller-Iyer happens due to the size consistency scaling and perception of depth. He stated that in this way humans can interpret two dimensional data which causes illusion.   

Daniels stated that the arrows that are pointing outwards represent the right angels which are formed in the room or the ceiling. Inward arrows can be taken as the outer corners of the structure.  Sometimes the designs are the same which the retina of the eyes see but our brain with the use of the size consistency and do the scaling up of one of the images so that it appears longer or broader. Ponzo effect is also a similar effect (Gulan & Pavle, 2013).

Cardwell in 1996 also stated the same thing. That using the past experiences and the information with the indirect approach helps in giving the clues as to how the human brain makes our difference in the visual images. Differences in the individual and the culture might affect the past knowledge as everyone has different experiences which are based on the perception a human brain makes. Hence, the incoming information differs all the time because it will always depend on the surroundings or the perception that human brain has made already and this phenomena is known to be as schemas.

Both top-down and bottom-up together helps in recognizing the world of perceptions. Both of them work together many times. For example: when quality of stimuli or the writing on the white paper is very difficult to read, the top-down approach adjusts the readings by completing the gaps on the places where the words are not well perceived. These gaps can always be filled because of the redundancy of the world which provides the clues of what is going on. Humans can create clues about making out the depth and the distance recognition is also easy. Top-down compensates for the ambiguous stimuli too. For example: Rearranging a sentence structure so that it has some meaning in it and it can be recognized. 

Gibson's theory of affordance, OFP, and optical array

Both the approaches, top-down and bottom-up plays a very significant role in the visual perception. They contrast when it comes to the direct and indirect theories but then also they adjust themselves when a task which is visually tough occurs. Both of them give the details and explanation as to how visual illusion happens with the help of the processing of the information of visual perception (DeWit, Kamp, & Withagen, 2015). Top-down theory states that past knowledge or learning is important for the process. Practically, every visual perception process which humans face in their daily lives involves the usage of both the theories and there always have been a huge allowance in the field of visual perception and also in the cognitive psychology. As there is a quote by Gross and Harris that:

“Perception is just not the task but it contributes in many different ways in the daily life. Few of them might be difficult as compared to the others and also it might seem that a few of them can be completed directly while others might need sophisticated internal information and hence that is better described as indirect approach (Intaite, Noreika, Šoli?nas, & Falter, 2013). This essay involves the comparison and the contrasting of the top-down and the bottom-up approach in the context of the visual perception. 

References

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Richards, R. (1976). James Gibson's Theory of Perception. Philosophy and Phenomenological Research , 37 (2), 218-233.