I. Sensing the World: Some Basic Principles
-Sensation and Perception are one CONTINUOUS process
-Bottom-up vs Top-down processing
–Bottom-up: Beginning with sense receptors and working up to the brain
–Top-down: Beginning with higher level mental processes and constructing perceptions based on expectations
-Man on Horseback in Forest
-Bev Doolittle
-Let’s take another look…
-The Forest Has Eyes
-Bev Doolittle
-Man on Horse in Forest
-The Forest has Eyes
–Did a title difference change the way you viewed the painting?
-Frog- “bug detector”
-Male Silkworm- sensitivity to female scent
-Human- voice consonants and baby cry
A. Selective Attention
-A flashlight beam on an almost infinite canvas
-11,000,000 bits of information taken in every second
-Humans process about 40 of them
-That leaves 10,999,960 for your unconscious mind to work with
-Cocktail party effect (one voice among many)
i. Selective Attention and Accidents
-Texting and driving?
-Statistics show that even using a GPS greatly increases your risk for having an accident
ii. Selective Inattention
-Inattentional blindness
–While focusing on one task, we may miss some very important “stuff”
-Change blindness
–Most won’t notice a switch
-Change deafness (list of words)
-Pop-out phenomenon
-Some stimuli demand our attention, such as the one smiling face amidst a crowd of crying faces
B. Thresholds
-Visible and Audible spectrums
-Psychophysics-The study of relationships between the physical characteristics of stimuli (intensity of stimuli and our psychological experience of them)
i. Absolute Thresholds
-Candle at 30 miles
-Drop of perfume
-Minimum stimulation needed to detect a particular stimulus 50% of the time
-Absolute thresholds vary with age
ii. Signal Detection
-Signal Detection Theory-No absolute threshold
-Depends on a person’s experience, expectations, motivation, and alertness
-Ability to catch a faint signal diminishes after 30 minutes
iii. Subliminal Stimulation
-Can we sense stimuli below our absolute threshold?
-Priming-negative image flashes vs positive image flashes
-Follow up images and participant response
-MIND OVER MATTER
iv. Difference Thresholds
-Just noticeable difference
-1 lb added to 10 lbs
-1 lb added to 100 lbs
C. Sensory Adaptation
-The smelly room that no longer smells
-After constant exposure, our nerve cells fire less frequently
-T-Rex vision-The ever moving eye
-Fast-paced movies vs slow-paced ones
II. Vision
-The eye receives light energy
-This light is transduced or transformed into a neural message
-Our brain processes what we are actually seeing
A. The Stimulus Input: Light Energy
-We don’t see color, we see light in different frequencies
-Wavelength-Distance from peak to peak on waves
-Hue-Dimension of color that is determined by the wavelength of light
-Intensity-Brightness or loudness
B. The Eye
-Pupil
-Iris
-Lens
-Retina
-No singular image is projected on the back of the eye
-Millions of particles of light energy are transducted and reassembled by the brain
i. The Retina
-Rods-Detect black, white, and gray
-Cones-Detect color and well lighted areas
-Optic Nerve-Blind spot, no receptor cells
C. Visual Information Processing
-Retina’s Neural Layers
-Migrated brain tissue (not just a messenger)
-Encode and analyze
i. Feature Detection
-Much like frogs with “bug detector” cells, humans also have detector cells or centers
ii. Parallel Processing
-Color, Motion, Form, and Depth
-30% of the cortex required for facial recognition
D. Color Vision
-Is a tomato red?
-No. It is everything BUT red
-It reflects red
-Humans can discriminate between 7,000,000 different colors
-Trichromatic theory (R,G,B)
-Three different types of receptors
-Color deficiency
D. Color Vision (cont)
-Opponent process theory
-Red and Green
-Blue and Yellow
-Black and White
III. Hearing
-Vision in the major sense
-Audition is highly adaptive
-Difference threshold with human voices
A. The Stimulus Input: Sound Waves
-The movement of air molecules
-Air pressure changes perceived as sound
-Low frequency and low pitch
-High frequency and high pitch
B. The Ear
-Outer, Middle, and Inner Ear
-EardrumàThrough the Middle EaràOval Window VibratesàFluid RipplesàHairs VibrateàAuditory NerveàTo the Brain
-A very complex process
-Damage to the hairs in the ear
-Carpet example
i. Perceiving Loudness
-The number of activated hair cells, not from the intensity of the response
ii. Perceiving Pitch
-Combination of 2 theories
-Place Theory-Links the pitch we hear with the place where the cochlea’s membrane is stimulated
–Good for high pitches
-Frequency Theory-The rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone
–Volley principle
iii. Locating Sounds
-Stereophonic hearing (3-D)
-Sense of place
-Time lag between sounds reaching each ear
C. Hearing Loss and Deaf Culture
-Conduction Hearing Loss-mechanical damage
-Sensorineural Hearing Loss-damage to the cochlea’s receptor cells (nerve deafness)
-Cochlear Implant
IV. Other Senses
-Seeing and hearing have priority
-Touch
-Body position and movement
-Taste
-Smell
A. Touch
-Types of Touch
–Pressure
–Warmth
–Cold
–Pain
-Kinesthesis
-Vestibular Sense
B. Pain
i. Understanding Pain
-Bottom-up sensations
-Top-down processes
a. Biological Influences
-Not a simple neural cord running to a definable area in the brain
-Noriceptors (pressure, temperature, chemicals)
-Gate-Control Theory-Neurological gate within the spinal column (blocks or allows pain to pass)
-Phantom limbs
-The creation of pain
b. Psychological Influences
-Rubber hand illusion
-Perspiration and pain while bending the fingers
-Hand in cold water (60 seconds and 90 seconds)
-More net pain, but less at the end
c. Social-Cultural Influences
-Pain may be sympathetic
-Biopsychosocial
ii. Controlling Pain
-Physical methods
-Psychological methods
C. Taste
-Sweet, Sour, Salty, and Bitter
-Chemical sense
-Taste buds (200)
-Regenerate after a week or so
-Age and taste
i. Sensory Interaction
-Taste and smell
-A bad cold
-Hard of hearing with CC
-Synaesthesia-hearing sound may cause you to visualize color
-Seeing a number may evoke taste
D. Smell
-Chemical sense
-5 million receptor cells at the top of each nasal cavity
-An old sense, bypasses the switchboard (thalamus)
V. Perceptual Organization
-When given a random set of data or sensations we organize them into a Gestalt (“whole” or “form”)
-The whole may exceed the sum of its parts
A. Form Perception
-How do we recognize faces?
-What abilities does this “simple” task require?
i. Figure and Ground
-Distinctiveness from an objects surrounding
-Continually reversing
-More than one perception
ii. Grouping
-Must organize info into meaningful form
-We must “group” stimulus together to extract form
-Proximity-We group nearby figures together
-Similarity-We group similar figures together.
-Continuity-We perceive smooth continuous patterns rather than discontinuous
-Connectedness-We perceive each set of two dots and a line as a single unit
-We fill in the gaps to complete the whole object
B. Depth Perception
-Seeing in 3D helps us judge distance
-Each species displayed depth perception abilities by the time they were mobile
i. Binocular Cues
-Our retinas receive slightly different images
-Comparing images allows us to perceive depth
-Allows filmmakers to produce a 3D effect
ii. Monocular Cues
-Taller than it is wide?
-Equal distance
-Vertical images appear to be taller than horizontal-vertical illusion
-Relative Height-We perceive objects higher in our field of vision as farther away
-Relative Size-If we assume 2 objects are similar in size, most people perceive the one that casts the smaller retinal image as farther away
-Interposition-If one object partially blocks our view of another we perceive it as closer
-Linear Perspective-Parallel lines such as railroad tracks appear to converge in the distance
-Relative Motion-As we move, objects that are stable may appear to move.
-Light and Shadow-Shading produces a sense of depth consistent with our assumption that light comes from above
C. Motion Perception
-Without the ability to perceive motion, life would be very difficult
-Stroboscopic Movement-Animation
-Phi Phenomenon-Lights on marquee signs are not actually moving, but only switching on and off
D. Perceptual Constancy
-Perceiving objects as unchanging
-We can recognize and identify people regardless of distance, angle of view, and illumination
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