Perception PowerPoint PDF

Perception Dr. Amira Ali Alshowkan How many animals can you see?  Outlines Definition of terms Perceptual processes Factors affecting perception Principle of perceptual organization (Gestalt theory) Disturbance of perception ...

Perception Dr. Amira Ali Alshowkan How many animals can you see?  Outlines Definition of terms Perceptual processes Factors affecting perception Principle of perceptual organization (Gestalt theory) Disturbance of perception  Definitions Sensation: is the process by which our senses gather information and send it to the brain Perception: process of selecting, organizing, interpreting raw sensory data into useful mental representations of the world.  Definitions Absolute Threshold: is the point where something becomes noticeable to our senses. It is the softest sound we can hear or the slights touch we can feel.  Definitions Difference Threshold: is the amount of change needed for us to recognize that a change has occurred. This change is referred to as the Just Noticeable Difference.  How sensation occurs 1. Eye, ears, skin, nose and tongue are contain receptor cells receive and process sensory information from the environment. 2. Sensory receptors (five senses) convert the stimulus into neural impulses which are sent to the brain. 3. Different people can have widely varying sensory thresholds. Thresholds can change within a person over time and as a function of hormone status, e.g. Olfactory sensitivity during pregnancy. How sensation occurs  Perceptual Process I. Selection of stimuli: is the process of filtering information received by our sense. The selecting of the stimuli is done thought our five senses. II. Organization: involves collecting the information into some pattern. The stimuli must be organized so as to assign some meaning. III. Interpretation: involves understanding the pattern. After selection and organization, the stimuli have to interpret in order to make a sensible meaning. It is a judgmental process. The individual may use his/her past experience add or delete information bring his/her own subject feeling opinion, and emotion in interpreting. Factors affecting perception  Principles of perceptual organization (gestalt theory) The German word (Gestalt) roughly translates to “whole, configuration, or pattern”. The gestalt psychologist’s sincerely believed that the whole is greater than the sum of its parts. They theorized that in order to interpret what we receive through our senses; we attempt to organize this information into certain groups. This allows us to interpret the information completely without unneeded repetition. There are 5 principle in the perceptual organization  5 principles of the perceptual organization 1. Figure and ground 2. Gestalt principles of grouping 3. Perceptual constancy 4. Depth perception 5. Ambiguous phenomenon  1. Figure and ground Not only does perception involve organization and grouping, it also involves distinguishing an object form its surroundings Notice that once you perceive an object, the area around that object becomes the background. For example, when you look at your computer monitor, the wall behind it becomes the background. The object, or figure, is closer to you, and the background, or ground, is farther away.  2. Gestalt principles of grouping Gestalt psychologists sincerely believed that the whole is greater than the sum of its parts. In order to interpret what we receive through our senses, gestalt psychologists theorized that we attempt to organize this information into certain groups. The gestalt principles of grouping include four types: a) Similarity b) Proximity c) Continuity, and d) Closure  Gestalt principles a. law of similarity Similar items will be perceived in groups The law of similarity leads us to link together parts of the visual field that are similar in color, lightness, texture, shape, or any other quality. That is why, in the following illustration, we perceive rows of objects instead of columns or other arrangements.  Gestalt principles b. law of proximity Elements close to one another in space or time will be perceived as group. The groups we see are 1 + 2 = as one group 3 + 4 = as another group  Gestalt principles c. law of contiunity A string of items will project the probable location of the next item. The law of continuity leads us to A to O and O to D are two lines. see a line as continuing in a Similarly, C to O and O to B are two lines. particular direction, rather than The principle of continuity predicts the preference for continuous figures. We making an abrupt turn. perceive the figure as two crossed lines instead of 4 lines meeting at the centre.  Gestalt principles d. law of closure Parts of a figure that are not presented will be filled in the perceptual system. According to the law of closure, we prefer complete forms to incomplete forms. In the drawing, we mentally close the gaps and perceive a picture of a duck. This tendency allows us to perceive whole objects from incomplete tend imperfect forms.  3. Perceptual constancy Refers to our ability to see things differently without having to reinterpret the object’s properties. There are typically three constancies including; size, shape, and brightness.  4. Depth perception Is the ability to see the world in three dimensions- height, width, and depth. Depth perception allows you to estimate your distance between an object and the distance between that object and other one. Without depth perception, you would be unable to drive a car or ride a bicycle, or simply navigate around a room. The world would be look like a flat surface.  5. Ambiguous phenomenon Is a drawings in which the figure and ground can be reversed. You may see two dark faces that point toward one another. Although such illustrations may fool our visual systems, people are rarely confused about what they see. In the real world, vases don’t change into faces as we look at them. Instead, our perception are remarkable stable.  Disturbance of perception A. Illusion B. Hallucination  A. Illusion Illusion: are sensory stimuli that are misinterpreted. It is an incorrect perception caused by a distortion of visual sensations. I. Visual Illusion: occur when your perceptual experience of a stimulus is substantially different from the actual stimulus you are viewing. Rabbit–duck illusion II. Muller-Lyer Illusion: is a visual illusion in which a line with inward pointing arrowheads is seen as longer than an equal line with outward pointing arrowheads.  B. Hallucination An imaginary sensation- such as seeing, hearing or smelling something does not exist in the external world. People perceive objects or events that have no external reality. I. Visual Agnosia: people with visual agnosia have normal sensations of what is in front of them, but they cannot recognize what they see. II. Prosopagnosia: Severely impaired ability to recognize human faces.