Week 4. Perception PDF - University of Nicosia

MED 104-Medical Psychology Perception Dr Stelios Georgiades, AFBP’sS, C.Psychol, Associate Professor of Clinical Psychology  Resting and Action Potentials In earlier lessons i...

MED 104-Medical Psychology Perception Dr Stelios Georgiades, AFBP’sS, C.Psychol, Associate Professor of Clinical Psychology  Resting and Action Potentials In earlier lessons it was shown how shapes and colors are seen, how sounds are heard and how we smell and taste the world's chemicals. Our senses however, mean little without our brain's ability to organize and translate that data into meaningful perceptions. Without perception our mother's face would have been just a combination of shapes; without the ability to interpret scent we wouldn’t be able to differentiate the smell of a rose from that of a burning toast.  Resting Perception is theand Action Potentials process that allows us to give meaning to the information provided by our senses and by extent experience the world around us. Its what makes life understandable, but also it means that sometimes what you see is not actually what you get. Therefore in defining perception we may say that … “Perception is our most prominent action control device” (Chartrand and Aarts (2007), p.59)  Resting and Action Potentials The brain does all the work of perception, The eyes, the ears and all the other senses are just feeding raw data; important but not actually what we see and experience. What we see is the realm of the mind not the eye.  Resting and Action Potentials Illusion is the effect of misinterpreting data. There are three types of illusion that one needs to understand: 1. Geometric illusion 2. Ambiguous figures. 3. Fictitious Percepts.  Resting and Action Potentials Geometric illusion: this is when the image displayed appears distorted. Example: The Ponzo illusion in which the top line looks longer than the bottom line even though they are the exact same length.  Resting and Action Potentials Ambiguous figures. This is when an image can be seen in more than one way. The Necker Cube  Resting and Action Potentials The Dress Test:  Resting and Action Potentials What kind of bird do you see right now?  Resting and Action Potentials What kind of bird do you see right now? A Duck?  Resting and Action Potentials What kind of an animal/mammal do you see right now?  Resting and Action Potentials What kind of an animal/mammal you see right now? A Burney?  Resting and Action Potentials What do you see a duck or a bunny?  Resting and Action Potentials In reality both images can be seen. However, the brain tends to perceive first the image related to whichever cue hears first or whichever image is more familiar to. By mentioning the words bird or mammal influences the expectations and by extend one sees what one wants to see.  Resting and Action Potentials Expectations are just one factor in the perceptual set. The psychological factors that determine how one perceives his her environment sometimes seeing is believing. But perceptual set theory teaches us that believing is also seeing not only the image but also the context in which the image is presented.  Resting and Action Potentials Can you see the bunny?  Resting and Action Potentials In western cultures Easter eggs and bunnies go together. Therefore any decision about what we see is also influenced by cultural norms and beliefs. Therefore, culture seems to play an important role in our perception.  Resting and Action Potentials (c) Fictitious. Seeing something which is not actually there. Example Visual Constancies: Resting and ActionThey allow us to see Potentials things as remaining the same even though their physical characteristics are constantly changing. (a) Shape constancy: The ability to perceive the shape of an object as constant even if it appears to change through movement. For example we know an open door is still rectangular in shape even though from where we view it is distorted through perspective to color constancy. (b) This is the ability to perceive the color of an object as constant even if it appears to change with changes in lighting for example  Resting and Action Potentials üAs it has been indicated our perceptual sense as much as our perceptions are affected by context and expectations, culture, previous experience as well it is influenced by our emotions and motivations. üAn individual’s perceptual sets leads to reasonable conclusions but sets can also be misleading.  Resting and Action Potentials Gestalt Rules: Form Perception: Figure-ground relationship it's how we organize and simplify whatever scene we're looking at into the main objects or figures and the surroundings or ground that they stand out against. Resting and Action Potentials Resting and Action Potentials Similar principle apply to non-visual fields as well. The cocktail party effect.  Resting and Action Potentials Our minds deals with all of the stimuli we are bombarded by transforming it into something coherent by following the Gestalt rules of Grouping. Similarity Continuity Connectedness  Resting and Action Potentials Grouping:  Resting and Action Potentials Similarity: The principle of similarity states that things which share visual characteristics such as shape, size, color, texture, value or orientation will be seen as belonging together. Continuity: Resting and Action Potentials The tendency of people tend to organize visual elements into unified wholes.  Resting and Action Potentials Connectedness:  Resting and Action Potentials Depth perception refers to the ability of our eyes and brain to add a third dimension or depth to everything we see. Depth cues are things that allow us to add this third dimension. These are: 1. Linear perspective. 2. Two heights in plane. 3. Relative Size. 4. Superimposition/Overlap. 5. Texture gradients  Resting and Action Potentials 1. Linear perspective: Parallel lines appear to converge. Come together at a distant point.  Resting and Action Potentials 2. Two heights in plane: If an image is higher to the eye it is often seen as being further away than objects to the lower.  Resting and Action Potentials 3. Relative Size: When we expect things to be the same size and they are not we interpret this as meaning that they are further away.  Resting and Action Potentials 4. Superimposition/Overlap. When we can't see the whole of an object we assume that there is something in front of it allowing us to interpret it as further away.  Resting and Action Potentials 5. Texture gradients: where we can see the details of objects that are close but the detail fades the further away it is.  Resting and Action Potentials The Constructivists Theory: This theory says that we construct our perception of the world based not only on what we see in front of us but also on our past experiences. This supports the idea of top-down processing. This is when perception mainly has to do with what we expect to see. The notion of perceiving something based on expectation is called perceptual set.  Resting and Action Potentials There are two things that demonstrate perceptual set in processing: 1. Expectations (reading jumbled up words and sentences). 2.Motivations (TV example) Resting and Action Potentials  Resting and Action Potentials The main criticisms of this theory is that if perception is based on personal experiences then, (a) Why do we perceive things the same way? (b) If perception requires experience, then how do we explain a newborn baby's ability to perceive the world? (c) The effects of illusions goes against the constructivist theory. For example if we use our experiences to build perception then why do we fall for the same illusions time and time again?. The Nativists Theory: Resting and Action Potentials The nativists theory states that perception is a result of bottom-up processing. This means that perception is immediate or direct. We perceive the world as it is seen in front of us. It is not based on expectations or misinterpretation. The role of the mind is simply to analyze the information coming in through our eyes. Example: If you're looking at a tennis court you know where the ball or player is immediately just by looking. This explains how we perceive what's going on around us so quickly and why we see things in the same way. We have all evolved the same and therefore perceive the world in a similar way. Resting and Action Potentials Resting and Action Potentialsjy Constructivists vs Nativists Theories? Top-Down Processing Or Bottom-Up Processing