Essay Example on Whether the perception is what directs Cognition









Psychologist have always been divided on whether perception is what directs cognition or if it is constructed by cognition In the first case this approach can be considered and classified as data driven since it is only constructed by the stimulus received from the environment and is not influenced by internal goals expectations or memories It is defined as bottom up processing In the second case perception is driven not only by the external stimuli but also by one s previous memories and knowledge and this is defined as top down processing Therefore what can be said is that one of the main focus of multiple researches about perception was to find whether the process is to be defined as top down or bottom up Many psychologists stated that the two occurs simultaneously and that it is not possible for one to exist without the other however multiple experiments have been conducted and we have yet to find a definite answer to the question if there is one This essay will explore through different experiments the possibility that perceptions are more likely to be constructed through top down processing This controversy was especially discussed by the British psychologist Richard Langton Gregory 1970 who proposed the top down theory According to Gregory we are actively constructing our perception of reality and in this process our past experiences play a major role In 1970 he stated that since about 90 of the information that we perceive through the eyes doesn't reach our brain the latter has to guess what a person sees 

This process involves the making of a lot of different hypothesis to try to understand what has been presented to our sense organs Therefore our perceptions of the world are hypothesis based on our prior knowledge and not only on sensory inputs However it is important to keep in mind that our perception is naturally flawed because the stimulus that our organs receive by the environment are often ambiguous Therefore it is necessary for people to use their previously acquired knowledge to be able to decode the external information and successfully act in all the different situations The first experiment that will be taken in consideration is the Necker cube When asked to stare at the intersections of the cube people see how the orientation can suddenly change or flip The switch can be caused by focusing on different parts of the cube Gregory stated that this object appears to flip between orientations because the brain creates two different but convincing hypothesis and therefore it is not capable to choose between the two However when the perception changes there is no actual change of the input received by the environment therefore the change of appearance cannot be associated with bottom up processing It must be set by the prevailing perceptual hypothesis of what is near and what is far In the experiment the participants were shown the cube very briefly so that they would not experience a reversal 

They were then asked to imagine the cube No subject ever reported a reversal while imagining the cube but the latter had only one form based on prior knowledge As the consequence of the lack of incoming stimuli the percept was frozen The second experiment that will be presented is the one of the Hollow Mask Illusion where Highly unlikely objects tend to be mistaken for likely objects The mask is an optical illusion in which the perception of a concave mask of a face appears as a normal convex face Wikipedia It is believed that humans have special regions of the brain which are dedicated to processing faces and we know from experience that faces are convex Therefore our brain processes the image in a way that makes sense to us and matches our expectations and this tendency is so strong that can override the 3D depth information provided by our stereoscopic vision Even when we are aware that we are looking at the concave reverse side we can t stop ourselves from perceiving it as a convex face With this experiment it can be confirmed that it is needed for us to interpret and filter the stimuli and information that we receive from our environment and it also shows how conceptual and perceptual knowledge are largely separate A third experiment that can be taken in consideration is about speech perception One flaw of bottom up processing is that it does allow people to perceive the stimuli quickly but it is not able to give them a meaning Therefore top down processing is needed to make sense of what we are perceiving Warren and Warren studied the perceptual organization of heard speech and the correction of the listener s errors and acoustic ambiguities demonstrating that phonemic restoration effect is a top down process In the experiment firstly the sentence 

The state governors met with their respective legislatures convening in the capital city was recorded Then the first s in legislatures was cut out of the tape Secondly the recorded sound of a cough of the same duration was inserted into the tape to replace the deleted segment When this modified sentence was played to listeners nineteen out of the twenty people that were asked to listen to the tape heard no missing sound Therefore even if the sound wasn't present in the tape people still restored it In a bottom up process this could never happen because that kind of processing allows you to only recognize the sounds that are actually present However on a top down account the participants believed to have heard the full word even if they did not This was because they managed to extract information from the sound and the meaning of the sentence When people get enough information to start building a possible representation of what they are hearing they will look for more evidence to support their idea

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