Review Session 3

Sensation- activation of our senses Perception- understanding these

sensations Transduction- information

received by our sensory organs is transformed into neural impulses

Travel through the thalamus (except for smell) to different areas of the brain

Sensory adaptation- decreasing responsiveness to a stimuli due to constant stimulation

Sensory habituation- our perception is partially due to how focused we are on them

Cocktail party phenomenon- when someone says our name across a room, we will switch our attention involuntarily

Step 1- Gathering Light - Light is reflected off objects and gathered by the eye.• Visual light is only a small part

of the electromagnetic spectrum; color we perceive depends on: Wavelength- determines the hue we

see Amplitude- determines the

brightness of the color• Objects appear a color because

they reflect that color of light.

Step 2: Within the Eye- Light coming from an object enters the eye• First goes through the cornea, a protective

covering that also helps focus• Then goes through the pupil which opens

(dilates) to let light in. The iris (muscles) controls this opening

• Through the process of accommodation, light is focused by the lens and the image is flipped upside down and inverted

• The focused image projects on the retina at the back of the eye

Step 3: Transduction- the translation of stimuli into neural signals, specifically when light activates neurons in the retina• 1st Layer- directly activated by light

Cones- respond to color, concentrated in the fovea (center of the retina)

Rods- outnumber cones, respond to black and white, reason for peripheral vision

• 2nd Layer- activated by rods and cones firing Ganglion cells- their axons make up the optic nerve- thalamus- occipital lobe (visual cortex)

Step 4- In the Brain• Visual cortex in the brain receives the

impulses from the retina• Impulses activate feature detectors-

specific groups of neurons that respond to different types of visual images (vertical lines, curves, motion, etc.)

Stimulus

Cell’s responses

Trichromatic Theory- we have three types of cones in the retina that detect the colors blue, red, and green. • These cones are activated in different combinations to

produce all colors of the visual spectrum.• Can’t explain afterimages or color blindness

Opponent-Process Theory- sensory receptors arranges in the retina come in pairs: red/green pairs, yellow/blue pairs, and black/white pairs. • If one sensor is stimulated, its pair is inhibited from

firing. If you stare at the color red for awhile, you fatigue the sensors for red.

• People with color blindness are missing one pair Most researchers agree in a combination of both

Sounds create vibrating sound waves that are collected by our ears

Vibrations go through transduction and neural impulses are sent to the brain

Amplitude- the height of the wave, determines the loudness of a sound, measured in decibels

Frequency- the l---e----n----g----t----h of the wave, determines pitch, measured in megahertz

How do we hear different tones?

Conduction Hearing Loss• hearing loss caused by damage to the

mechanical system that conducts sound waves to the cochlea

Nerve Hearing Loss• hearing loss caused by damage to the

cochlea’s receptor cells or to the auditory nerve, usually by loud noise, more difficult to treat

Exact relationship between nerve endings is not understood

Skin Sensations• Pressure

only skin sensation with identifiable receptors• Warmth• Cold• Pain

Gate Control Theory• Some pain messages have higher priority

than others• When a higher priority message is sent, the

“gate” swings open for it and swings shut for a low priority message

• Scratching an itch: the gate swings open for high intensity chemicals

• Endorphins (inside morphine in the brain) control pain and can also swing the gate shut

Chemicals from the food we eat are absorbed by taste buds on the tongue, located on the papillae (bumps on tongue)• Also located on some parts of the cheek and roof

of the mouth Four tastes: sweet,

salty, sour, and bitter People differ: more

densely packed taste buds, more intense taste

Flavor: taste + smell

Molecules of substances rise into the air , are drawn into the nose, and settle into the mucus membranes at the top of each nostril and are absorbed by receptor cells- as many as 100 different types exist

Linked to the olfactory bulb, which gathers and send the information to the brain

Connects at the amygdala and then to the hippocampus instead of through the thalamus

Sense of how our body is oriented in space

Three semicircular canals in the ear are filled with liquid; when the position of your head changes, sensors in the canals move

Nausea and dizziness- agitated canals

Gives feedback about the orientation and position of specific body parts

Receptors in the muscles and joints send info that combined with visual feedback, lets us keep track of our body

Absolute threshold- the smallest amount of a stimulus that we can detect 50% of the time• Ex) candle flame 30 miles away on a dark

night, one drop of perfume in a three room house, etc.

Subliminal- stimuli below our absolute threshold• No scientific evidence that it can change

behavior

Difference threshold (just noticeable difference- JND)- the smallest amount of change needed in a stimulus before we can notice a change

Weber’s Law- the change needed is proportional to the original intensity of the stimulus

The more intense the stimulus, the more it will need to change before we detect a change

Investigates the effects of the distractions and interference we experience while perceiving the world• What will we perceive among competing stimuli• Take motivation and

expectations into account- response criteria

• False positive- when we think we perceive a stimulus that is not there

• False negative- not perceiving a stimulus that is present

We perceive by filling in the gaps in what we sense by using background knowledge• Schemata- mental representations on

how we expect the world to be• Perceptual set- a predisposition to

perceive the world in a certain way Backmasking

Aka Feature Analysis- using the features of the object itself to create a complete perception• Happens very automatically• Takes longer than top-down but is more

accurate

Figure and Ground- organization of the visual field into objects (figures) that stand out from their surroundings (ground)

We normally perceive images as groups, not isolated elements

Ability to maintain a constant perception of an object despite changes• Size constancy• Shape constancy• Brightness constancy

Sometimes out brains perceive objects to be moving when they are not• Stroboscopic effect (movies, flip books)-

images in a series of pictures presented at a certain speed

• Phi phenomenon- series of light bulbs turned on and off at a particular rate

• Autokinetic effect- a spot of light is projected steadily onto the same place of a wall in a dark room

Depend on experience- crawling- Visual Cliff Experiment (Eleanor Gibson)

Monocular Cues•relative size smaller image is more distant

•interposition closer object blocks distant object

•relative clarityhazy object seen as more distant

•texture coarse --> closefine --> distant

Binocular cues• retinal disparity

images from the two eyes differ closer the object, the larger the disparity

• convergence neuromuscular cue two eyes move inward for near objects

1) Which of the following is NOT an example of a monocular visual depth perception cue?• Texture gradient• Motion parallax• Interposition• Opponent process• Relative size

2) The cochlea is responsible for• Protecting the surface of the eye• Transmitting vibrations received by the eardrum to the hammer,

anvil, and stirrup• Transforming vibrations into neural signals• Coordinating impulses from the rods and cones in the retina• Sending messages to the brain about orientation of the head and

body

3) In a perception research lab, you are asked to describe the shape of the top of a box as the box is slowly rotated. What concept are the researchers most likely investigating?• feature detectors in the retina• Feature detectors in the occipital lobe• Placement of rods and cones in the retina• Binocular depth cues• Shape constancy

4) The blind spot in our eye results from• The lack of receptors at the spot where the optic nerve connects to the

retina• The shadow the pupil makes on the retina• Competing processing between the visual cortices in the left and right

hemispheres• Floating debris in the space between the lens and the retina• Retinal damage from bright light

5) Smell and taste are called _______ because _______.• Energy senses; they send impulses to the brain in the form of

electric energy• Chemical senses; they detect chemicals in what we taste and smell• Flavors senses; smell and taste combine to create flavor• Chemical senses; they send impulses to the brain in the form of

chemicals• Memory senses; they both have powerful connections to memory

6) Weber’s law determines• Absolute threshold• Focal length of the eye• Level of subliminal messages• Amplitude of sound waves• Just-noticeable difference

7)Color blindness and color afterimages are best explained by what theory of color vision?• Trichromatic theory• Visible hue theory• Opponent-process theory• Dichromatic theory• Binocular disparity theory

8) You are shown a picture of your grandfather's face, but the eyes and mouth are blocked our. You still recognize it as a picture of your grandfather. What type of processing best explains this example of perception?• Bottom-up processing• Signal detection theory• Top-down processing• Opponent-process theory• Gestalt replacement theory