AP psychology Unit 4

Difference Threshold (Just-Noticeable Difference)

1) Smallest amount of change needed in a stimulus before we detect a change 2) Computed by Weber's Law

Trichromatic Theory

1) A theory of color vision 2) Also called Young-Helmholtz Theory 3) Hypothesizes that we have three types of cones in the retina that detect the primary colors of light: red,blue, and green 4) These cones are activated in different combinations to produce all the colors of the visual spectrum 5) Even though this theory has some research support and makes sense intuitively, it cannot explain such visual phenomena as afterimages and color blindness 6) Most researchers agree that color vision is explained by a combination of the Trichromatic and Opponent-Process theories

Opponent-Process Theory

1) A theory of color vision 2) States that sensory receptors are arranged in the retina come in pairs: red/green, yellow/blue, and black/white 3) If one sensor is stimulated, is pair is inhibited from firing. This theory explains the concept of afterimage 4) If you stare at the color red for a while, you fatigue the sensors for red. Then when you switch your gaze and look at a blank page, the opponent pair of red will fire, and you will see a green afterimage 5) The Opponent-Theory explains afterimage and color blindness

Sensory Adaption

1) Decreasing responsiveness to stimuli due to constant stimulation EX: we eventually stop perceiving a persistent scent in a room

Gestalt Rules

1) Developed by a group of researchers from the early 20th century who described the principles of how we perceive a group of objects 2) Based on an observation that we normally perceive images as a group, not as isolated elements 3) This process is believed to be innate and inevitable

Sensation

1) Sensation occurs when one of our senses is activated by something in our environment 2) Occurs before the process of perception (The brain interpreting these sensations)

Vision

1) Dominant sense in human beings. Sighted people use vision to gather info about their environment more than any other sense 2) The process of vision involves several steps: - Light is reflected off objects - Reflected light coming from the object enters the eye through the cornea and pupil, and is focused by the lens, and is projected on the retina where specialized neurons are activated by the different wavelengths of light - Transduction occurs when light activates the special neurons in the retina and sends impulses along the optic nerve to the occipital lobe of the brain - Visual cortex receives the impulses from the retina, which are feature detectors for vertical lines, curves, motion, among others. What we perceive visually is a combination of these features

Lens

1) Focuses light that enters the pupil 2) Curved and flexible in order to focus the light 3) As the light passes through the lens, the image is flipped upside down and inverted 4) The focused, inverted image projects onto the retina

Kinesthetic Sense

1) Gives us feedback about specific position and orientation of specific body parts 2) Receptors on our muscles send info to our brain about our limbs 3) This info, along with visual feedback, lets us keep track of our body

Cocktail-party Phenomenon

1) If you're talking with a friend and someone across the room says your name, your attention will probably involuntarily switch across the room 2) An example of selective attention

Fovea

1) Indentation at the center of the retina where cones are concentrated 2) When light is focused onto your fovea, you see it in color 3) Your peripheral vision, especially at the extremes, relies on rods and is mostly in black and white 4) Foveal vision, focusing light on the fovea, results in the sharpest and clearest visual perception

Color Blindness

1) Individuals with dichromatic color blindness cannot see wither red/green shades or blue/yellow shades 2) Those who have monochromatic color blindness can only see shades of gray

Retina

1) Like a screen in the back of your eye 2) As the light passes through the lens, the image is flipped upside down and projected on the retina 3) Special neurons in the retina are activated by light and send impulses along the optic nerve to the occipital lobe of the brain

Occipital Lobe

1) Location of the visual cortex 2) Part of the brain that processes visual sensations 3) Receives impulses via the optic nerve 4) The optic nerve is divided into two parts. Impulses from the left side of each retina go to the left hemisphere of the brain, and those from the right side of each retina go to the right side of the brain

Smell (Olfaction)

1) Molecules of substances rise into the air and are drawn into our nose 2) The molecules settle in the mucous membrane at the top of each nostril and are absorbed by receptor cells located there 3) As many as 100 different types of smell receptors may exist. These receptor cells are linked to the olfactory bulb, which gathers the messages from the olfactory receptor cells and sends the info to the brain---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Weber's Law

1) Named after psychophysicist Ernst Weber 2) Describes the different thresholds for different senses 3) States that the more intense a stimulus is, the more it will need to change before we notice a difference

Optic Nerve

1) Nerve leading from the retina that carries impulses to the occipital lobe of the brain 2) The optic nerve s divided into two parts. Impulses from the left side of each retina go to the let hemisphere of the brain, and those from the right side of each retina go to the right side of the brain

Taste (Gustation)

1) Nerves involved in chemical senses respond to chemicals rather than energy 2) Taste buds absorb chemicals fro the food we eat 3)Taste buds are located on papillae and on some parts on the inside of the cheeks and the roof of the mouth 4) Humans sense sweet, salty, sour, umami, and bitter 5)The flavor of food is a combination of taste and smell

Size Constancy

1) Object closer to our eyes will produce bigger images on our retina but we take distance into account in our estimations of size. 2) We keep a constant size in mind for an object and know that it does not grow on size as it moves closer or farther away

Nerve Deafness

1) Occurs when hair cells in the cochlea have been damaged ( Often by loud noise) 2) In conduction deafness - when something goes wrong with the system of conducting sound to the cochlea 3) Difficult to treat since no method has been found to regenerate hair cells

Pupil

1) Opening in the center of the eye 2) Similar to the shutter of a camera 3) Muscles that control the pupil (the iris) open it to let more light in and also make it smaller to let less light in

Perceptual Set

1) Our experience creates a mental representation of how we expect the world to be. (Schemata). This influences how we perceive the world 2) Schemata can create a perceptual set (Perceiving something in a certain way. EX: you might perceive a cloud to look like a heart around valentines day)

Sensory Habituation (Perpetual Adaption)

1) Our perception of sensations is partially determined by how focused we are on them EX: no longer hearing traffic from the nearby freeway after having lived in a place for years

Vestibular Sense

1) Our vestibular sense tells us about how our body os oriented in space. Three semicircular canals in the inner ear give the brain feedback about body orientation 2) When the position of your head changes, the fluid moves in the canals, causing sensors in the canals to move 3) The movement of these hair cells activate neurons, and their impulses go to the brain EX: our vestibular sense helps up figure out which way is up or down when doing a flip

Feature Detectors

1) Perception researchers Hubel and Weisel discovered that groups of neurons in the visual cortex respond to different types of visual images 2) Visual cortex has feature detectors for vertical lines, curves, and motion, among others. What we perceive visually is a combination of these features

Cornea

1) Protective covering on the front of the eye 2) Helps focuses the light

Absolute Threshold

1) Smallest amount of stimulus we can perceive (The minimal amount of stimulus we can detect 50% of the time) EX: the absolute threshold of vision is the smallest amount of light we can detect, which is about a single candle about 30 miles away on a perfectly dark night

Rods and Cones

1) Special neurons in the retina that are activated by light 2) Cones are activated by color 3) Rods respond to black and white

Subliminal Messages

1) Stimuli below our absolute threshold 2) No research supports the claim that subliminal messages affect our behaviors in overt ways

Perception

1) The brain's interpretation of sensory messages 2) Occurs after the process of sensation 3) The process of understanding and interpreting sensations

Cochlea

1) The process of transduction occurs in the cochlea 2) Shaped like a snail's shell and filled with fluid. As sound waves move, hair cells move and neurons are activated by the movement of the hair cells 3) Neural messages are sent to the auditory cortex in the temporal lobe

Chemical Senses

1) The senses of taste and smell 2) These senses work by gathering chemicals

Energy Senses

1) The senses of vision, hearing and touch 2) These senses gather energy in the form of light, sound waves and pressure, respectively

Transduction

1) The translation of incoming stimuli into neural signals 2) Neural impulses from the senses travel first to the thalamus and then into different cortices of the brain 3) The sense of smell is the one exception to this rule

Pitch Theories

1) Theories that explain how we hear different pitches or tones 2) Place theory explains that the hair cells in the cochlea respond to different frequencies of sound based on where they are located in the cochlea

Bipolar Cells and Ganglion Cells

1) These cells make up different layers in the retina 2) In the retina, light activates rod and cone cells 3) Rods and cones send signals to the next layer of cells in the retina - bipolar cells. 4) Bipolar cells send signals to the next level of cells in the retina - ganglion cells 5) Ganglion cells send signals to the brain through the optic nerve

Brightness constancy

1) We perceive objects as being a constant color eve as the light reflecting off the object changes EX: we perceive a brick wall as brick red even as the daylight fades and the actual color reflected from the wall turns gray

Shape Constancy

1) When objects viewed from different angles create a different image on our retinas but we still know the shape of the object remains constant. EX: When we look at coffee mugs from different angles, the top might not appear circular but we know it is due to shape constancy

Top-Down Processing

1) When we use top-down processing, we perceive by filling in gaps in what we sense 2) Occurs when you have background knowledge to fill in gaps in what you perceive 3) Our experiences creates schemata (mental representations of how we expect the world to be) which influences how we perceive the world 4) Schemata can create a perceptual set

Touch

1) activated when our skin is touched, pierced, or feels a change in temperature 2) Some nerve endings in the skin respond to touch while others respond to temperature 3) Brain interprets the amount of indentation ( temperature change or intensity of touch) 4) We sense placement of touch by the place of our body when nerve endings fire 5) Nerve endings are more concentrated in different parts of our body ( Such as when we want to feel something we use our fingers instead of our elbows because our fingertips have a high nerve concentration) 6) Pain warns us of potential danger

Constancy

1) every object we see changes minutely from moment to moment due to our changing angle of vision, variations in light, and so on 2) our ability to maintain a constant perception of an object despite these changes 3) There are several different types of constancy: size constancy, shape constancy, and brightness constancy

Signal Detection Theory

1) investigate the effects of the distractions and inferences we perceive while experiencing the world 2) Takes into account hoe motivated we are to detect certain stimuli and what we expect to perceive. These f0 actors together are called response criteria 3) By using factors like response criteria, this theory tries to explain the different perceptual mistakes we make EX: not seeing a stop sign, or thinking you see your friend in the distance but it is really a stranger

Bottom-up Processing (Feature Analysis)

1) opposite of top-down processing 2) instead of using our experiences to perceive and object, we use only the features of the object to build a complete perception 3) We start our perception at the bottom with individual characteristics of the image and put all those characteristics together into our final perception. (Our mind builds the picture from the bottom up using basic characteristics)

Blind Spot

1)The spot on the retina where the optic nerve leaves the retina and there are no rods or cones 2) We cannot detect objects in our blind spot, but our brains and the movement of our eyes accommodate for the blind spot, so we usually don't notice it

Visible Light

Color is perceived due to a combination of different factors 1) light intensity - how much energy the light contains determines how bright the object appears. 2) Light wavelength - The length of the light waves determines the particular hue we see. We see different wavelengths within the visible light spectrum as different colors

Hearing

There are several steps to hearing: 1) Sound waves travel through the air and are collected by the ear 2) Vibrations enter the ear and vibrates the eardrum, which connects with three bones in the middle ear: The hammer (malleus), the anvil (incus), and the stirrup (stapes) 3) Vibration is transferred to the oval window (similar to the eardrum) 4) Oval window is connected to the cochlea where transduction occurs and neural messages are sent to the auditory cortex in the temporal lobe

Sound Waves

Vibrations in the air that have amplitude and frequency (Amplitude - height of wave & determines loudness of the sound) (Frequency - length of the wave & determines pitch)