Cognitive Psychology - Essay Example

?Analyse and evaluate the role played by top-down factors in both visual and auditory misperceptions. Please refer to relevant empirical evidence in your answer. Top-down factors are considered very important in the cognitive psychology of perception. Top-down theories suggest that what is already in the mind (what people are thinking) greatly influence the way that something is perceived to that individual. This is part of a theory known as constructivism, which suggests that cognition is what shapes the world (Eysenck & Keane, 2005). These factors play an important role in recognition, as what is already known about an object is allows us to understand who are friends and relations are from what we already know, as well as where we live and a whole other set of amazing abilities. Of course, it is always possible that what is known can greatly influence the way something is perceived to such an extent that it becomes a misperception. Visual and auditory misperceptions have been studied widely in the literature, as they illustrate not only how something can be misperceived due to top-down factors but can shed some light on how perception relies on these factors also. A variety of empirical evidence will be used to evaluate the role that these top-down factors have in perception, focusing mainly on visual and auditory misperceptions. One of the most widely studied examples of the way that top-down factors have a role in misperceptions are illusions. Optical illusions are often used as fun examples of how the mind can trick us, but they also have a huge role in cognitive psychology. Illusions are good because they show how the mind follows certain rules and places certain constraints on perception, and how top-down factors cause the brain to have a bias towards perceiving certain things (Eysenck & Keane, 2005). In everyday life, these are usually correct and can help us to identify objects that have never been perceived before accurately and simply. Without these rules, there would be no perception in the sense we understand today. However, when these rules are applied in a different sense to that which they would usually be employed misperception or illusion results. Misperceptions can be found within all sensory systems, although visual and auditory are the most researched and understood. Sometimes, a healthy individual can briefly mistake one object that is known for another. The research by Summerfield, Egner, Mangels & Hirsch (2006) investigates the reaction of the brain during these occasions using functional magnetic resonance imaging to understand the neuroscience behind this. The interesting part of this research is that Summerfield et al (2006) manipulated images of houses and faces to such an extent that they could be realistically mistaken for the other. This may seem ridiculous, as houses and faces are two very different structures that could not easily be mistaken for each other in reality. This is an example of a top-down factor; we think that it would be impossible to mistake a house for a face (or vice versa) because of the rules and regulations put in place in the way that objects are perceived. However, this research showed that at a certain level of degradation, this misperception can easily occur. This misperception occurs even in psychologically normal patients. Top-down factors associate some areas of the image with a house or a face and the medio-frontal and right parietal regions of the brain make assumptions based upon what is already known and help the individual perceive. Faces themselves are also victim to visual misperception. Research by Leopold, Rhodes, Muller and Jeffery (2005) has shown that top-down factors can lead to perceived identity and expression. In this case, what is known about individuals that are familiar is applied to individuals that are not, and thus misperceptions occur. The brain here is suggesting that someone with similar visual appearance to an individual must be that individual. Again, this is an example of the rules placed on perception by the brain, and how what is already known is applied to something that is not known. Facial expressions are also a cause of misperceptions. Research by Diekhof et al (2011) used the example of suggesting that a fearful facial expression would be seen during the course of the experiment. Using this knowledge, the participants associated the actual images of faces shown with fear and thus there was a significant amount of misperceptions that previously were considered to be so. The research also showed that suggesting that a mildly fearful face will be shown makes extremely fearful faces appear less so. Another famous example of a visual misperception concerns antigravity hills. Antigravity hills are places where a car in neutral appears to move uphill on a sloping road. These, as suggested by the name, were previously attributed to anomalies in the rules of gravity, but a study by Bressan, Garlaschelli and Barracano (2003) shows that these are visual misperceptions. These were tested in the study by using tabletop representations of the same phenomenon. These are unusual because it would seem that there would be no top-down explanation of why the car would be perceived to go upwards, as this is not what would usually be expected in the same situation. The Mystery Spot is another example of visual misperceptions based on top-down factors. The Mystery Spot is a location in California which is a popular tourist attraction because in this location, the height of individuals is greatly distorted. The work by Shimamura & Prinzmetal (1999) has shown that this occurs because it causes a misperception of true horizontal and true vertical axes. Perception of height is commonly assumed to be created by the brain in relation to other objects surrounding the individual (Eysenck & Keane, 2005) and as such any distortion in the surrounding objects or the cardinal axes will affect how height is perceived. Top-down factors are implicated because height is something that is known to the individual, and this knowledge is used to attribute height (or lack of it) to other individuals, even in situations where we do not know the height of the surrounding object. This phenomenon is also shown in photographs. A photograph is essentially a replica of what is seen in reality (Eysenck & Keane, 2005) captured and made still. What we already know about the world is applied to photographs, in that we do not assume that because the photograph is 7”x5” the person in the photograph is only 7” tall. This phenomenon has been widely studied. For example, Weintraub (1979) showed that individuals can correctly identify the height of the individual to within 4” by use of the photograph. Misperception occurs when the usual top-down factors associated with this knowledge are absent, and the height of the individual on the photograph (or indeed on the screen) is assumed to be the real height. Top-down factors also play a role in the development of this ability, although the factors involved in understanding the concept of photographs is thought to develop quite early (Binnie, 2002). Other forms of visual art also show evidence of visual misperceptions, or perhaps the artist is manipulating the perception system to create these misperceptions. The work of artist James Turrell was studied by Beveridge (2000), and it was suggested that colours are not the absolute primary qualities that they are thought to be. The works of Turrell were a good example of how top-down factors can affect the way that we view artwork and colour. From what we already know, we have some idea of how colour should be and how it relates to other things around it. When colour is manipulated, such as when it is applied to something that we do not typically associate with this colour (blue grass, a yellow sky) our perception system fills in the gaps. Similarly, when blue is placed next to green both colours become more similar to each other, sometimes to the extent that they are indistinguishable from each other. Again, the rules and regulations placed by our brain have dictated the way that we see colour and artwork. Until now, the focus has been on visual misperceptions. However, as previously mentioned all other senses are liable to misperception and the auditory system is another prominent example of how top-down factors mediate this. Aphasia, for example, is the inability of an individual to correctly perceive (or use) speech and phonetics. Research on this phenomenon, such as that by Blumstein (1994) has not only shown that speech perception and speech use are located in the same area of the brain (the language hemisphere) but also that top-down factors can affect the auditory perception of speech. From what we already know, the brain commonly fills in the gaps left by the auditory sensory system, of which there are usually many. Blumstein (1994) discussed the thought that aphasia is a deficit in the brains ability to fill these gaps, or a deficit in the knowledge already obtained that leads to the inability to correctly perceive speech and phonetic sounds. Davies (1991) explores this further with a study into the way in which the brain fills in the gaps with knowledge. Using recordings of speech from individuals who cannot be heard clearly, Davies (1991) asked participants to record what they heard on the tape. The astounding result was that a significant amount of people heard very similar things, and many of these heard exactly the same speech. In this case, it is evident that not only do top-down factors play a role in auditory perception, but there are very similar top-down factors present in some people. The interesting part of this research was that the perception was in fact a misperception, and the individuals heard speaking did not actually say what the majority of participants heard. This shows that auditory misperception is very common and can be seen in normal individuals, not just those suffering from aphasia or similar. Combining the two factors, auditory and visual, it can be possible to perceive speed, and top-down factors mediate the combination of the two to help provide an individual with a perception of speed that matches already observed speed (Eysenck & Keane, 2005). Sound is important in speed because it changes dependant on the location of the individual (the Doppler Effect, for example, shows that objects approaching an observer have a higher frequency than those leaving. Information like this can help the brain to process things like speed). Visual perception is also important because images also change with speed. An individual in a car, for example, perceives speed differently to an individual watching the car from the outside. Using examples of this that the brain already knows, perceptions and misperceptions about the speed of an object can be made. Again, this is usually done by comparison with other objects which have a known speed or are stationary. In conclusion, there is a lot of evidence that shows that top-down factors are very important in visual and auditory misperceptions. Visual misperceptions occur in all realms, even to psychologically normal people, and these are all based on the fact that the brain makes certain assumptions about the way things visually appear. Auditory hallucinations occur in much the same way, because the brain has some knowledge already about the nature of these things and can apply this in certain ways to fill in the gaps. Misperception occurs when what is real is different from what is perceived, and this is commonly because of these top-down factors having a role in suggesting what is real. The wide range of empirical evidence on this topic shows just how common these misperceptions are. They also suggest how perception itself works, because some of the constrictions of the cognitive system can be deduced from what generally appears in place of what is real, as with optical illusions. The future holds some interesting options for the study of misperception, and the use of functional magnetic resonance imaging has already played an important role in deducing which areas of the brain are important in these misperceptions. With this new research and the past research discussed here, it will be possible to further evaluate the role that these factors have in perception and misperception. References Beveridge, P. (2000). Color Perception and the Art of James Turrell. Leonardo, 33(4), 305-313. Blumstein, S. E. (1994). Impairments of Speech Production and Speech Perception in Aphasia. Philosophical Transactions: Biological Sciences, 346(1315), 29-36. Bressan, P., Garlaschelli, L., & Barracano, M. (2003). Antigravity hills are visual illusions. Psychological Science (Wiley-Blackwell), 14(5), 441. doi:10.1111/1467-9280.02451 Collerton, D., Perry, E., & McKeith, I. (2005). Why People See Things That Are Not There: A Novel Perception and Attention Deficit Model for Recurrent Complex Visual Hallucinations. Behavioral and Brain Sciences, 28(06), 737-757. doi:10.1017/S0140525X05000130 Davies, M. (1991). Individualism and Perceptual Content. Mind, New Series, 100(4), 461-484. Diekhof, E. K., Kipshagen, H. E., Falkai, P., Dechent, P., Baudewig, J., & Gruber, O. (2011). The power of imagination -- How anticipatory mental imagery alters perceptual processing of fearful facial expressions. NeuroImage, 54(2), 1703-1714. doi:16/j.neuroimage.2010.08.034 Eysenck, M. W., & Keane, M. T. (2005). Cognitive psychology: a student’s handbook. Psychology Press. Kolmel, H. W. (1993). Visual illusions and hallucinations. Bailliere’s Clinical Neurology, 2(2), 243-264. Shimamura, A. P., & Prinzmetal, W. (1999). The Mystery Spot Illusion and Its Relation to Other Visual Illusions. Psychological Science, 10(6), 501-507. Summerfield, C. (2005). Mistaking a House for a Face: Neural Correlates of Misperception in Healthy Humans. Cerebral Cortex, 16(4), 500-508. doi:10.1093/cercor/bhi129 Weintraub, D. (1979). Review: Perceptual Phenomena. Science, New Series, 204(4400), 1402. Read More