Sensation & Perception
Sensation – transduction of mechanical energy into neural energy (bottom-up)
Vision
Transduction in the retina
cornea – pupil (iris controls opening) – lens – retina (rods & cones) –
bipolar cells – ganglion cells – optic nerve
fovea – point of central focus (highest concentration of cones)
Blind spot
Lateral geniculate nucleus (LGN) – region in thalamus for vision
Hubel & Wiesel – feature detectors
Theories of color vision
Young-Helmholtz trichromatic theory – blue, red, green detectors
Opponent-process theory – afterimages (red/green, yellow/blue,
black/white)
Hearing
Amplitude (height – loudness), frequency (pitch)
Pinna – auditory canal – eardrum (tympanic membrane) – ossicles – oval window
– cochlea (transduction)
Cochlea – hairs connect to organ of Corti – then to auditory nerve
Place theory – hairs react to certain frequencies in a certain place
Frequency theory – hairs fire at different rates to match frequency
Conduction hearing loss vs. sensorineural hearing loss
Touch
Gate-control theory of pain
Endorphins
Chemical senses: taste, smell
Taste buds on papillae (sweet, salty, sour, bitter)
Receptors in nose – directly to olfactory bulb – limbic system – bypasses thalamus
Vestibular (balance – semicircular canals) & kinesthetic (body position, orientation)
Perception – analysis and interpretation of sensation (top-down)
Absolute threshold – minimal stimulus for detection 50% of the time
subliminal – below absolute
Difference threshold (JND)
Weber’s law – difference vary in proportion to intensity of stimulus
Theories of perception
Signal detection theory (depends on state of perceiver)
Perceptual set (approach to perceptual task – influenced by schemata)
Rules of visual perception
Figure-ground
Gestalt rules
proximity
continuity
similarity
closure
Constancies
size
shape
brightness
Depth perception
visual cliff – crawlers have perception of depth
Binocular cues (both eyes)
binocular (or retinal) disparity
convergence
Monocular cues (can perceive as well with one eye as with two)
Linear perspective
Texture gradient
Relative size
Shadowing
Interposition
Illusions
Muller-Lyer (lines with arrows) – culture affects perception
phi phenomenon (blinking lights appear to travel)
stroboscopic movement (flip books, cartoons)