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Myers’ PSYCHOLOGY. Chapter 6 Perception. What is Perception?. Plato – we perceive objects through our senses with our mind Construct the outside world inside our heads Detect physical energy (bottom-up) and then encode it into neural signals – this is SENSATION
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Myers’ PSYCHOLOGY Chapter 6 Perception
What is Perception? • Plato – we perceive objects through our senses with our mind • Construct the outside world inside our heads • Detect physical energy (bottom-up) and then encode it into neural signals – this is SENSATION • We must then select, organize and interpret (top-down) our sensations – this is PERCEPTION
Perception • Perceptions come at us all the time • The circles to the right can be organized into several different images • Our minds switch back and forth • Our attention is selective
Selective Attention • Selective Attention • Awareness is like the beam of a flashlight – only shines one certain areas at one time • In truth – we have a very limited aspect • 11 billion bits of info at a time and we can process 40 of them
Cocktail Party Effect • You have the ability to attend to only one voice among many • We are aware of other people and conversations but we cannot pay attention to them. • Our attention is divided
Multitasking? • Is there is a such thing as multi-tasking? • Do you think we can truly multi-tasking? • Let’s Listen: • For your reference: • http://www.npr.org/player/v2/mediaPlayer.html?action=1&t=1&islist=false&id=95256794&m=95304837 • Let’s test it!
“The Myth of Multitasking” • Follow the directions from the video using sheet that I have handed you • Write down how many seconds you are at off to the side when you finish each step • 3 consequences • Take longer • Mistakes increase • Stress increases • Thoughts???? True??? • http://davecrenshaw.com/multitasking-example/
Conclusions • Our attention is divided • We cannot do 2 things at once • Switching gears costs time and results in mistakes • Inattentional blindness – failing to see an object when our attention is directed elsewhere
Other Similar Phenomena • Change blindness • Change deafness • Choice blindness • Choice-blindness blindness • See page 239 in book for more explanation of these
Perceptual Illusions • Illusions help us understand how we organize stimuli into meaningful perceptions • Have fascinated scientists for a long time
Visual Capture • Vision is our predominate sense • When it competes with other senses – it wins!
Perceptual Organization: Gestalt • To go from sensation to perception we must organize the information that we have received. • How do we organize that information • Group of German scientists studied this • Gestalt is German word for “form” or “whole” • We organize information by integrating them into meaningful wholes
Taking a Look Backwards • Parts are 8 blue circles and white lines • When we view them together we see the cube • This is gestalt theory
Steps Needed to Form Perception • 1. Figures and Ground – perceive an object as distinct from its surroundings • 2. Grouping – Stimuli have to be grouped together based on basic features • Grouping Principles • proximity--group nearby figures together • similarity--group figures that are similar • continuity--perceive continuous patterns • closure--fill in gaps • connectedness--spots, lines, and areas are seen as unit when connected • mjfgskljmg
Perceptual Organization: Closure • Gestalt grouping principles are at work here.
Perceptual Organization: Grouping Principles • Gestalt grouping principles are at work here. • Doghouse is NOT complete, but we perceive that it is • Closure and continuity
Perceptual Organization: Depth Perception • Depth Perception • ability to see objects in three dimensions • allows us to judge distance • We see 2D and our minds transform it to 3D • Binocular cues (that help us perceive depth) • Retinal disparity • Convergence
Binocular Cues: Retinal Disparity and Convergence • Eyes are 2.5 inches apart • Retina receives 2 slightly different images • Brain compares the difference between them – aka retinal disparity • 3D filmmakers exaggerate the retinal disparity by manipulating cameras • Convergence is a neuromuscular cue caused by the way our eyes turn in when we view objects near us • Brain notes angles of convergence and the more inward strain the closer the object is
Monocular Cues • Monocular cues – available to each eye separately • relative size • Further away = smaller • interposition • If one object blocks another we perceive it as closer • relative clarity • hazy object seen as more distant • texture • coarse --> close • fine --> distant
Monocular Cues 2 • Relative Height - higher = farther • We pour less liquid into a tall, skinny glass than a short, fat glass • We assume the tall glass holds more • St. Louis Arch explained by this? • Relative motion – as we move, objects that are stable appear to move • Looking at a car window • Linear Perspective – Parallel lines appear to converge with distance (railroad tracks) • Light and shadow • Closer objects reflect more light • Dimmer one seems further away
Perceptual Constancy • We must first perceive objects as having a distinct form, location and motion • Then…we must recognize the object without being deceived by changes in shape, size, brightness, and color • Perceptual constancy allows us to do this • Allows us to see an object is unchanging despite changing stimuli • Top-down process • Identify things despite angle, distance, and illumination • Information reaching your eyes has been sent to your brain where neurons work together to extract the essential features that are then compared with stored images and identified
Perceptual Constancy • Shape and Size Constancies • Even when the shape of an object seems to change we perceive the original form of the familiar object • Open door – no matter what angle we view it from – we know it is a door • Car – no matter the distance we are from it, we know its relative size • Size-Distance Relationship • Moon looks larger on the horizon than high in the sky • We can be lead astray (i.e. moon illusion)
Perceptual Constancy • Light Constancy • We perceive objects as having a constant lightness even when illumination varies • Relative luminance – the amount of light an object reflects relative to its surroundings • Squares A and B are identical in color, but B is received as lighter • Our visual system computes brightness and color relative to surroundings and context
Perceptual Organization and Other Senses • Applies to other senses • Why a ticking clock turns into a pattern • Unfamiliar language we have trouble hearing when one word turns to another and think that they just talk too fast • But we organize things to make sense • THEDOGATEMEAT • What do you see? • The dog ate meat? • The do gate me at • We go with what makes sense based on what we know
And the Debate Comes Again • Is perception nature or nurture? • Do we learn to perceive? • So…how important is experience and how much does it shape our perceptual interpretations?
Sensory Deprivation and Restored Vision • If you are born blind and knew the difference between two items because of touch, when your vision was restored as an adult would you be able to see the difference between the 2 objects? • Studies suggest that there is a period for normal sensory and perceptual development • Nurture seems to sculpt what nature has endowed
Perceptual Adaptation • Perceptual adaptation is what makes the world seem normal again when sensory input changes • After getting new glass, one may feel disoriented for a few days, but then it adjusts within a few days
Perceptual Set • Experiences, assumptions, and expectations give us a perceptual set • Mental predisposition • Once we have formed the wrong idea – we have trouble seeing the reality
Schemas • Through experience we form concepts, or schemas • We use our schemas to interpret and organize unfamiliar information • When we face ambiguous moving objects in the sky, we use schemas to help us “process” it • Different people have different schemas • It’s a bird! It’s a plane! It’s Superman! • Facial recognition attuned to expressive eyes and mouths (see Madonna pic on pg 259)
Context Effects • A given stimuli may trigger radically different perceptions partly due to differing schemas, but also because of immediate context. • Our minds can work backwards in time to allow a later stimuli to determine how we receive and earlier one • Top down influences perception as much as bottom up does.
Emotional Contexts • Emotional contexts also color our social perception • If a team has a history of aggressive play, then referees who are told before will give more penalties than normal. • Experience helps construct perception • So…nature or nurture? Both?
Perception and the Human Factor • Human Factors Psychology • explores how people and machines interact • explores how machine and physical environments can be adapted to human behaviors
Is There Extrasensory Perception? • Extrasensory Perception • controversial claim that perception can occur apart from sensory input • telepathy • clairvoyance • precognition • Parapsychology • the study of paranormal phenomena • ESP • Psychokinesis (mind over matter – levitating a table)
