Sensation & Perception

• Q1 Sensation is …..

• Requires coordination between receptors, neural pathways, sensory processing in the brain

• Perception is ……

• Psychophysics is

Q2 - Processing

• Top-down…

• Bottom-up …

• Parallel/ serial ….

Thresholds

• Q3 Absolute threshold - the intensity level at which a stimulus can be. ….

• Subliminal stimulation …

• Priming …..

Signal detection theory – Q4

• Predicts ….

• Thresholds will …

• Tries to show why people respond …

• Q4 Difference threshold - the minimum change …

• This may vary depending on health, stress, etc• Weber’s Law

• Why can’t you buy 63 watt light bulbs?

Adaptation, habituation

• Q6 Sensory adaptation - decline in receptor activity …

• (it’s also true that your brain filters out sensory info you don’t need - reticular formation)

• Habituation - weakening of a …..

Parts of the eye – Q7• Cornea• Iris• Pupil• Lens• Retina• Rods - 120 million - edge - fewer bipolars• Cones - 6 million at fovea - indiv bipolars• Bipolar cells• Ganglion cells• Optic nerve --- blind spot

Transduction

• Q8 Transduction is …..

• The electromagnetic spectrum …

• Q9 - Frequency / amplitude – intensity/hue

Q10 - Near and Far

• Near-sightedness

• Far-sightedness

From the optic nerve to the brain

• Optic nerve

• Crossover -

• Sensory switch…..

• Visual ….

Visual fields

Optical chiasm - Q11

Color and detail - feature detection

• Only the cones respond to color• Low ratio of cones to bipolar increases

detail• Q12 -Feature detection - individual neurons

in visual cortex respond …

• Other neurons integrate features - face recognition

Low light

• Cones do not work in low light - no color vision

• Rods have higher ratio of rods to bipolar cells - aids in concentrating response to low light

Color vision

• Q13 - Young-Helmholtz trichromatic theory

• RGB ….

• Q14 - Color-blindness …

Q15

• Additive color mixing …

• Subtractive color mixing …

Opponent process theory – Q15

• See afterimage graphic

• Neuron pairs ……

• Some neurons turn on …..

• When you stare at a green image for a while …

Color constancy – Q16

• Why can you distinguish colors when wearing sunglasses?

A little physics - Q17

• Sound is waves of air striking our ears• Height of waves = amplitude = • Length of waves = frequency = • Complexity = • Decibel scale measures loudness• Log scale: 20 = 10 x 10 30 = 10 x20

30 = 100 x 10 WHY?

Parts of the ear

• Q18 See the diagram

Perceiving pitch - Q19

• Helmholtz’s place theory - different sound waves stimulate hair cells …

• This works for higher pitched sounds

Low pitched sounds – Q19

• Frequency theory says the entire basilar membrane…

• The brain interprets this as pitch.

• Works for low pitched sounds

Perceiving pitch

• Some combination of place and frequency theory works for all sounds

Locating sound – Q20

• Just as two eyes help us locate objects with our vision …

• Sounds strike each ear at different …

• Differences are extremely small

Hearing loss – Q21

• Sensorineural …

• Conduction hearing loss …

• Implants

Touch – Q22

• The four senses of touch …

• Are they distinct?

Pain – Q23

• Pain is ……

• Gate control theory says …

Taste – Q24

• The 5 tastes are ….

• Are there really 5 tastes?

• Other influences on what we taste …

Smell – Q25

• Smell is different …

• Processing smells ….

Body position – Q26

• Kinesthesis ….

• Vestibular sense …

• Vestibular sacs and semicircular canals contain fluid and hair cells that react when we move. Hair cells send message to brain

Review

• Light energy transduced in retina - rods, cones – sent to bipolar cells, ganglions to optic nerve to visual field crossover at optic chiasm to thalamus for more color processing to visual cortex for feature detection to temporal and frontal lobes for integration which is influenced by context, assumptions and expectations

Selective attention – Q27

• An animated Necker cube

• Cocktail party effect

• Inattentional blindness – http://viscog.beckman.illinois.edu/

flashmovie/15.php

Muller-Lyer

• Q28

Organization

• Q29 Gestalt principles of perception

• Gestalt therapy

Figure and ground

Grouping

• Proximity

• Similarity

• Continuity

Grouping

• Connectedness

• Closure

Depth perception

• Q30 Innate ability - Gibson & visual cliff

• http://www.vimeo.com/77934

• Q31 Binocular cues– Retinal …– Conver…

Depth perception

• Q32 Monocular cues– Relative size

– Interposition

– Relative clarity

Monocular cues

– Texture gradient

– Relative height

– Relative motion

– Light / shadow

Constancies & Other Stuff

• Q33 Phi phenomenon

• Q34 Size - distance relationship

• Size / shape constancy

• Lightness constancy

Set, expectancy

• Q35 – Perceptual set

• Context

• Expectancy

Your opinion

• Which of these American minority groups should be admired most? Choose one.

• Latino

• Native American

• African-American