PSY2012 Exam 2 Study Guide Chapter 4 Contrast sensation and perception Sensation Detection of physical energy by sense organs which then send information to the brain Perception Perception is the brain s interpretation of raw sensory inputs Explain the difference between bottom up and top down processing Bottom up Sensory detection encoding construction of whole from parts Have to use all of your senses and combine them together to create your perception Example Lines angles shapes colors etc Items events that grab our attention Top down Conceptually driven organization of information Knowing what a picture is suppose to look like and trying to find the pieces to put it together Involves experiences and expectations Items that we deliberately direct orient our attention to goal directed Reading words that are mixed up except for the first and last letter is top down processing This is because we know what the words are supposed to look like and we use past experiences to read them Distinguish between an absolute threshold and a just noticeable difference threshold Absolute Threshold Minimum stimulation needed to detect a particular stimulus 50 of the time Just noticeable difference threshold Just how different does something need to be for you to notice the difference o Example If you turn a light off you will notice it If you dim the light a little bit how much will you need to dim it until you notice it o Overall percentage change is important o Example In a dim room if you added a little light you would notice o In a light room if you added a little light you wouldn t notice Know how signal detection theory explains the likelihood of perceiving a stimulus Helps us understand how well we can detect a stimulus while there is a distraction Predicts how and when we detect the presence of a faint stimulus signal amid background stimulation noise Assumes that there is no single absolute threshold Detection depends partly on each person s experience expectations motivation and level of fatigue Explain the signal to noise ratio Signal is the stimulus Noise is everything else All of the other stimulus that you are not trying to focus on Weber s Law There is a constant minimum percentage difference that must be met for us to detect perceive something as different Weber Fraction k dI I o Change in difference difference Define sensory adaptation and explain why it is functional Activation is greatest when a stimulus is first detected In other words sensitivity diminishes as a consequence of constant stimulation We are most aware of a stimulus when it first occurs Then we adapt to the stimulation and don t notice it as much How does this benefit us Reduced sensitivity to constant sensory information frees us to focus on informative changes in our environment Define parallel processing and discuss its role in visual information processing Simultaneous processing of multiple information streams by the brain The brain engages in multiple subtasks at the same time Example Processing visual information The binding problem Making all of these perceptions into a single experience Define perceptual set and explain why the same stimulus can evoke different perceptions in different contexts i e context effects Perceptual sets occur when our expectations influence our perceptions A given stimulus may trigger different perceptions based on context Example Your expectation of how people behave is going to influence your perception of this person Context Effects A given stimulus may trigger different perceptions based on context Explain how perceptual constancies help us to organize our sensations into meaningful perceptions e g shape constancy size constancy You have to reconstruct the world from the distorted retinal image Perceiving objects as unchanging having consistent shape size and color even as illumination and retinal images change Allows us to flexibly navigate our world and rely on object recognition at the same time Example of Shape Constancy Whether a door is open or closed we always perceive it as a rectangle no matter what angle we look at it from Example of Size Constancy We perceive objects as the same size no matter how far away they are from us Describe Gestalt psychology s contribution to our understanding of perception and be able to explain the 6 Gestalt principles Our brains do more than register information about the world i e bottom up processing We perceive objects as wholes within their overall context 1 Closure Closure occurs when an object is incomplete or a space is not completely enclosed If enough of the shape is indicated people perceive the whole by filling in the missing information 2 Proximity Stimulus elements that are closed together tend to be perceived as a group 3 Similarity Similarity occurs when objects look similar to one another People often perceive them as a group or pattern 4 Continuity Stimuli tend to be grouped as to minimize change or discontinuity Continuation occurs when the eye is compelled to move through one object and continue to another object 5 Symmetry Regions bound by by symmetrical boarders tend to be perceived as coherent figures The idea that when we perceive objects we tend to perceive them as symmetrical shapes that form around their center When perceiving the configuration we see three pairs of symmetrical brackets as opposed to 6 individual brackets or two pairs and two singles This happens despite what is suggested by some of the brackets immediate proximity to each other 6 Figure ground The eye differentiates an object form its surrounding area a form silhouette or shape is naturally perceived as figure object while the surrounding area is perceived as ground background Describe the process behind our perception of motion the Phi phenomenon The brain perceives motion by comparing visual frames A rapid series of slightly varying images creates perception of motion The brain compares images of what is to what was Perceptions are governed by comparisons Chapter 6 Define learning and identify two major types of learning Learning a relatively permanent change in thought or behavior that results from experience Classical Conditioning pairing two things together to make an association of some sort Pavlov used dogs to study salivation and noticed that they showed a physiological response to cues associated with food o When is the timing of the stimulus to the response The stimulus comes first before the response o INVOLUNTARY reflexive
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