Sensation and Perception Flashcards
Sensation and Perception
> testing sensory-motor or conceptual decision making tasks
>use reaction time tests (less invasive)
Why study sensation & perception?
> everything you know entered through senses
consciousness is largely result of what see, hear, taste, touch, and smell
this is earliest part of psych (early believed in Tabula Rasa)
*Transduction
> converting environmental stimulus into nerve impulses
>sensory receptors convert environmental energy into nerve impulses (then to brain)
The Eye
> humans are primarily visual
retina- 3D cup at back, does transduction
fovea- dent in back
Photoreceptors
> convert light into nerve impulses
>ex. rods & cones (which are modified neurons)
Cones
>contributes to perception of color >refines image, acuity >in/around fovea (back,center) >less common than rods >need bright light
Rods
> sensitive to dim light (night vision)
can NOT perceive color
not a lot of acuity
outside of fovea and at edges
*Doctrine of Specific Nerve Energies
> quality of experience determined by sensory receptor stimulated and where info goes
Nerve Impulses
> AKA “action potential”
action potentials are all same
ex. rods/cones also respond to touch
Young-Helmholtz Trichromatic Theory
> suspected there are 3 diff types of cones (r,g,b)
>wave length- blue:short, green:middle, red:long
Opponent-Process Theory (Hering)
> three sub-processes choose one color to fire
>sub-processes made of opposing pairs (red-green, blue-yellow, back-white)
The Ishihara Test
> Red-Green color blindness (can still see yellow-disproves Trichromatic Theory)
most are only color deficient, can’t perceive certain combos
ex. Fish firing rate (thalamus changes firing rate to display color)
Negative Color Afterimages
> selectively fatigue black, yellow, green cones
>white slide allows r,w,b fully operational
Correct Eye Theory?
> both correct (how perceive/process color)
Eye: Trichromatic Theory
Brain: Opponent-Process Theory
Nystagmus
> eye almost vibrates, moves rapidly
muscles cause eye shifts
keeps image moving so rod/cones don’t fatigue
Stabilized Images
> pictures fixed on retina
no permanent damage
rods/cones fatigue and break circuit (parts of visual disappears)
cell assemblies/neural circuits formed w/experience
Cataract
> clouding of lens
can be surgically removed (take out lens)
surgery restores sight, but brain lacks neural circuitry (kids had trouble differentiating between circle/triangle)
changing angle would throw off brain
*Feature Detection
> cells in visual cortex respond to specific features
>plant electrobe in cortex to test activity in animals
*Feature Detectors
> edge detectors
complex cells
hyper complex cells
Edge Detectors
> simple cells, respond to lines w/certain orientations
Receptive Fields
> can be found in other places
>ex. groups of rods and cones in retina
Complex Cells
> more selective cells
>responds to particularly oriented lines, motion, color, and combos
Hyper Complex Cells
> perceives attributes, length, width, and simple shapes/contours
Inhibitory Connections
> prohibit signals from sending
Excitatory Connections
> when fires, also fires neighbor
Motion Aftereffects
> fatigue selected motion detectors
brain interprets higher firing rate of others as firing
implode look from spinning spiral
Perception
> Perception = Sensation + Experience
ex. Foreign langue speaker displays sensation without experiential knowledge
ex. Inverting goggles (Stratton)
First motion sickness, day 8 could respond, brain didn’t adapt permanently
Perceptual Adaptation
> visual ability to adjust to displaced visual field
Kinesthesis
> sense of body position/movements
>helps to understand what is happening visually
Visual Deprivation
> active cat vs. passive cat w/same visual experience
active cat- normal visual development
pass. cat- couldn’t understand surroundings (feature detectors didn’t develop properly)
visual parts of brain need kinesthetic parts
Sensory Deprivation
> kittens raised without hz lines, couldn’t understand hz lines
could eventually recover if put in normal environment
Cataract Removal (Restored Vision)
> innate vs. learned abilities
can: fixate, scan, follow objects, discriminate colors, and brightness (learned)
cannot: name objects by sight, make perceptual judgements
innate: basic sensory abilities, learned: complex perceptual processing
Depth Perception
> innate, but enhanced by learning
Visual Cliff
> modified table: 72% go away from glass, 8% go on glass
newborn heart rate spikes when face down on glass
retina 2D image -> brain 3D image
baby farm animals stay on decorated side
learning/practice improves depth perception
*Top Down Process
> stuff stored in head from previous experiences
knowledge, beliefs, expectations, memories
ex. LSU game outcome changed judge’s sentences
*Bottom Up Process
> sensory input from sensors go to brain
>info from feature detectors
Perception
> constructed from top-down to bottom-up
>ex. scream at KI vs. scream in violent area
Expectations vs. Perception
> prone to errors since combining top/bottom
>people see what they want to (top/down effect perception)
Eyewitness Identification
> can do real world experiences to test accuracy
ex. draw pennies
not as accurate as they think
False Convictions and DNA
>300+ DNA exonerations in US >Average age 27 yrs. >Average prison time: 9 yrs >Some on death row >#1 cause of false convictions (mistaken eye witness)
Simultaneous Presentation of Suspects
> all brought out at once in line-up
Sequential Presentation
> brings people out one at a time
less likely to guess
ex. TMC experiment found 3x more accurate
DOJ recommends sequential
Binocular Clues
> AKA “disparity” (difference between left/right eye perspective)
feedback from seeing objects closer than 20 ft.
Monocular Clues
Relative Size
> AKA “pictoral”
can use only one eye to determine distance
perceive based on SIZE
big = close, small = far
Monocular Clues
Interposition
> perceive based on OVERLAP of objects
>front = close, back = far
Monocular Clues
Relative Height
> perceive based on HEIGHT of objects in frame
> higher = far, lower = close
Monocular Clues
Relative Motion
> nearby objects move past
far objects move with
ex. Riding in vehicle
Monocular Clues
Linear Perspective
> parallel lines appear to converge in distance
Monocular Clues (Lights/Shadows)
> light “comes from above” object
shadows are lower than object
ex. Table mixes up these concepts (doesn’t match experiences, looks artificial)
Size-Distance Relationship
> ex. distance monster appears bigger due to distance cues
>ex. traffic lights (bigger than expected, since seen far way)
Ittleson’s Experiment of Familiar Size
> manipulated size of common objects
>people thought objects were in different planes/depths
Ames Room
> people of same height stand in two corners of room
>look different heights (demonstrates size-distance illusion)
Escher
> deliberately messed w/depth cones in art
>illustrated non-possible outcomes
Sp = K (Sr x Dp)
> Perception Size = K (retina size x perceived distance)
Image Size on Retina
> large: closer
small: farther
ex. “fixed” size of bird image (greater distance = larger illusion)
