Review Session 3. Sensation- activation of our senses Perception- understanding these sensations ...
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Transcript of Review Session 3. Sensation- activation of our senses Perception- understanding these sensations ...
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