 Sensation  Detection of external stimuli  Response to the stimuli  Transmission of the response to the brain  Perception  Processing, organizing and interpreting sensory signals  Internal representation of the stimulus

 Stimulus  Sensation  Sensory receptors in the eye detect the stimulus

 Sensory Coding  Stimulus is transduced (translated into chemical & electrical signals that are sent to the brain)  Perception  The brain processes the neural signals and constructs a representation of the green light – a signal to go

The 5 Senses

 Stimuli  Molecules on the tongue  Receptors  Cells in taste buds on the tongue  Pathways to the brain  Portions of facial, glossopharyngeal, and vagus nerves

 Stimuli  Molecules on mucus membranes in the nose  Receptors  Sensitive ends of olfactory neurons  Pathways  Olfactory nerves

 Stimuli  Pressure on the skin  Receptor  Sensitive ends of touch neurons in skin  Pathway  Cranial nerves for touch above the neck, spinal nerves for touch elsewhere

 Stimuli  Sound waves  Receptors  Pressure-sensitive hair cells in the cochlea of the inner ear  Pathways  Auditory nerve

 Stimuli  Light waves  Receptor  Light sensitive rods and cones in the retina of the eye  Pathway  Optic nerve

Sensory organs constantly acquire information from the environment

 The minimum intensity of stimulation that must occur before you experience a sensation  Approximate Absolute Sensory Threshold  Taste – 1 tsp. of sugar in 2 gallons of water  Smell – 1 droplet of perfume in a standard size room  Touch – a fly’s wing falling on your cheek  Hearing – the tick of a clock at 20ft in quiet conditions  Vision – a candle flame seen at 30 miles on a dark, clear night

 The just noticeable difference between 2 stimuli  Minimum amount of change required for a person to detect a difference  Example:  If you’re reading a book and watching TV, a commercial comes on that is louder than the show – you look up and notice something has changed  The DT is the minimum change in volume required to detect a difference

 Detecting a stimulus requires making a judgment about its presence or absence  The detection of a faint stimulus requires a judgment  Example  A hearing test  Person wears headphones and is told to raise their hand when they hear the tone in that ear

 A decrease in sensitivity to a constant level of stimulation  Example  You are studying and your neighbor starts mowing their lawn  After a few minutes the noise seems to blend in or fade into the background

 The 2 nd sense to vision  Sound waves – pattern of changes in air pressure  Amplitude – loudness  Frequency – pitch

 Sound waves arrive at the outer ear  Travel down the auditory canal to the eardrum  Then to the middle ear  Sound waves make the eardrum vibrate  Vibrations transfer to 3 tiny bones  Hammer  Anvil  Stirrup  Then to the auditory nerve

 Most important source of knowledge  Does a place look safe or dangerous?  Does a person look friendly or hostile?

cornea  Light first passes through the cornea (transparent outer layer) lens  Cornea focuses incoming light, which enters the lens retina  Forms an image on the retina (thin inner surface of the back of the eyeball)  THE RETINA IS THE ONLY VISIBLE PART OF THE BRAIN OUTSIDE THE SKULL!  Pupil – dark circle at the center  Contracts – gets smaller  Dilates – gets larger

 Iris – eye color  Behind the iris, muscles change the shape of the lens  Lens – focuses images through accomodation

 Rods  Respond to extremely low levels of light  Used primarily in night vision  Cones  Respond in bright levels of light  Used for seeing color and detail

 Determined by wavelength  An object appears to be a particular color because of the wavelength it reflects  Color is always a product of our visual system; there is no color in the physical world!

ROYGBIVROYGBIV

 3 different types of cones that are sensitive to different wavelengths  1. Short (blue-violet)  2. Medium (yellow-green)  3. Long (red-orange)

 Some colors seem to be opposites  Stare at a red image – see a green afterimage  Stare at a green image – see a red afterimage  Stare at a blue image – see a yellow afterimage  Stare at a yellow image – see a blue afterimage

 Hue  Distinctive characteristics of a color  Ex. – blue, light blue, navy blue, turquoise  Saturation  Color’s purity, vividness  Ex. – lime green, fluorescent yellow  Brightness  Perceived intensity  Two of the same exact colors can be perceived differently in different light

 Brain regulates the experience of pain  Producing it  Suppressing it  Depends on biological, psychological, and cultural factors

 For a person to experience pain:  Pain receptors must be activated  A neural gate in the spinal cord must allow the signals through to the brain  Eventually, the “gate” closes and no more pain signals reach the brain

 Illusions are tools used by psychologists to determine how the brain understands information

“Organized whole”

 Binocular  Both eyes  Monocular  Each eye separately  1. Accommodation – change in the shape of the lens that varies with distance (1 eye)  2. Convergence – the way the eyes rotate inward and outward with changes in distance (2 eyes)  3. Binocular disparity – difference between the images provided by each eye 

 3 Principles  1. The figure is more “thinglike” and more memorable than the ground  2. The figure is seen as being in front of the ground  3. The ground is seen as unformed material and seems to extend behind the figure

 Occulsion  A near object blocks an object that is farther away  Relative Size  Far-off objects project a smaller retinal image than close objects  Linear perspective  Parallel lines appear to converge in the distance  Texture gradient  Shows depth or looks dense  Position relative to the horizon  Objects below the horizon that appear higher in the visual field are perceived as being farther away

 Different kinds of movement:  A figure moving against a stationary background  Objects at rest against a moving background  Objects moving at different speeds in relation to each other  Observer’s own movements in relation to his/her surroundings  Induced movement  perception of movement of an object that is not moving

 Which line appears longer?

Which of the two horizontal lines on the track appear longer?

The cubes seem to shift and another side seems closer to you. Then it shifts back again

Designed by E.G. Boring Ambiguous figure Young girl/old woman

 Albert Ames  Appears to be a normal room  Actually shaped so the left corner is almost twice as far from the viewer as the right corner  The viewer perceives the nearer person as being much larger than the other, although both are exactly the same height