THINKING
concepts are like piaget's idea of schemas
prototypes: best mental image or example of category.
heuristics: rule of them allows to make judgement and solve problems efficiently. shortcut, prone to errors.
fixation: inability to see problems form new perspective.
LANGUAGE AND THOUGHT
phonemes: smallest distinct sound unit in language. ex. syllables
morphemes: smallest unit that carries meanings. ex. suffix
INTELLIGENCE
...
Sunday, April 20, 2014
Perception
process of organizing and interpreting information, enabling us to recognize meaningful objects and events.
geslalt philosophy: whole is greater than the sum of its parts.
figure ground relationship: organization of visual field into objects (figures) that stand out from their surrounding (ground).
grouping: perceptual tendency to organize stimuli into groups that we understand. based on proximity, similarity, continuity, and connection.
depth perception: ability to see objects in 3D although the image that strike the retina are 2D allows to judge distance.
binocular cues - retinal disparity: a binocular cue for seeing depth.
closer an object comes to you the greater the disparity is between two image.
monocular cues:
interposition: if something is blocking our view, we perceive it as closer.
relative size: if we know that two objects are similar in size, the one that looks smaller is farther away.
relative clarity: we assume hazy objects are farther away.
texture gradient: the coaser it looks the closer it is.
relative height: things higher in our field of vision, they look farther away.
relative motion: things that are closer appear to move more quickly.
liner perspective: parallel lines seem to converge with distance.
light and shadow: dimmer objects appear farther away because they reflect less light.
motion perception: we perceive motion incredible well/ we judge mostly by the size of the object.
phi phenomenon: allusion of movement created when two or more adjacent lights blink on and off in succession.
perceptual consistency: perceiving objects as unchanging even as illumination and retinal images changes.
geslalt philosophy: whole is greater than the sum of its parts.
figure ground relationship: organization of visual field into objects (figures) that stand out from their surrounding (ground).
grouping: perceptual tendency to organize stimuli into groups that we understand. based on proximity, similarity, continuity, and connection.
depth perception: ability to see objects in 3D although the image that strike the retina are 2D allows to judge distance.
binocular cues - retinal disparity: a binocular cue for seeing depth.
closer an object comes to you the greater the disparity is between two image.
monocular cues:
interposition: if something is blocking our view, we perceive it as closer.
relative size: if we know that two objects are similar in size, the one that looks smaller is farther away.
relative clarity: we assume hazy objects are farther away.
texture gradient: the coaser it looks the closer it is.
relative height: things higher in our field of vision, they look farther away.
relative motion: things that are closer appear to move more quickly.
liner perspective: parallel lines seem to converge with distance.
light and shadow: dimmer objects appear farther away because they reflect less light.
motion perception: we perceive motion incredible well/ we judge mostly by the size of the object.
phi phenomenon: allusion of movement created when two or more adjacent lights blink on and off in succession.
perceptual consistency: perceiving objects as unchanging even as illumination and retinal images changes.
Sensation
sensation: your window to the world.
perception: interpreting what comes in your window.
sensation: process by which sensory receptors and nervous system receive stimulus from the environment.
bottom-up vs. top-down processing:
bottom-up: begins with sense receptors and works to the brain integration of the sensory information. (thalamus responses)
top-down: into processing guided by higher level mental process.
absolute threshold: minimum stimulation to detect a stimulus 50% of the time.
difference threshold: minimum difference that a person can detect between 2 stimuli. known as just noticeable difference.
weber's law: idea that to perceive a difference between two stimuli, they must differ by a constant percentage; not a constant amount.
signal detection theory: predicts how we detect a stimuli amid other stimuli. assumes that we do not have absolute threshold, we detect stuff based on experience and motivation.
sensory adaption: decreased responsiveness to stimuli due to constant stimulation.
selective attention: focusing of conscious awareness on a particular stimuli.
cocktail party phenomenon: describes ability to focus one's listening attention on a single talker among a mixture of conversations and background noise, ignoring other conversations. form of selective attention.
vision: most dominating sense. visual capture.
phase 1: gathering light
short waves = higher frequency (bluish color, higher pitched sounds)
long waves = low frequency (reddish wave, low-pitched sounds)
height of wave gives it's intensity (brightness)
length of waves gives it's hue (color)
ROY G BIV
long waves = more red
short waves = more violet
transduction: transforming signals into neural impulses. information goes from senses to thalamus, then various areas in brain.
conversion of one form of energy to another.
stimulus energies to neural impulses.
ex. light energy to vision
chemical to taste and smell. sound waves to sound.
color vision 2 major theory:
young-helmholtz trichromatic (3 color) theory: 3 types of cones.
opponent-process theory: the sensory receptors come in pairs
hearing: we hear sound waves
height of waves gives us amplitude of the sound.
frequency of waves gives the pitch of sound.
transduction in ear: sounds waves hit ear drum then anvil. then hammer. then stirrup then oral window. everything is vibrating. then cochlea vibrates which lined with mucus called basilar membrane and has hair cells.
when hair cells vibrate they turn vibrations into neural impulses which are called organ of corti. sent to the thalamus.
place theory: different hairs vibrate in the cochlea when there are different pitches.
so some hairs vibrate when they hear high pitches and others when they hear low pitches.
frequency theory: all hair vibrate, but at different speeds.
deafness:
conduction deafness: something goes wrong with sound and vibration or the way to cochlea. you can place the bones or get a hearing aid.
nerves (sensorineural) deafness: hair cells in cochlea get damage. loud noises can cause this type of deafness. no way to replace the hair. cochlea implants is possible.
smell and taste:
sensory interaction: principle that one sense may induce another.
taste: we have bumps on our tongue called papillae. taste buds are located on papillae (they are actually all over mouth)
sweet, salty, sour, bitter, hot&spicy
umami: flavorful, meaty, savory taste.
touch: receptors located in our skin. gate control theory of pain.
gate control theory of pain: spinal cord contains neurological gate that blocks pain signals or allows them to pass on to the brain.
vestibular sense: tells us where our body oriented in space. our sense of balance.
kinesthetic sense: tells us where our body parts are. receptors are located in muscles and joints.
perception: interpreting what comes in your window.
sensation: process by which sensory receptors and nervous system receive stimulus from the environment.
bottom-up vs. top-down processing:
bottom-up: begins with sense receptors and works to the brain integration of the sensory information. (thalamus responses)
top-down: into processing guided by higher level mental process.
absolute threshold: minimum stimulation to detect a stimulus 50% of the time.
difference threshold: minimum difference that a person can detect between 2 stimuli. known as just noticeable difference.
weber's law: idea that to perceive a difference between two stimuli, they must differ by a constant percentage; not a constant amount.
signal detection theory: predicts how we detect a stimuli amid other stimuli. assumes that we do not have absolute threshold, we detect stuff based on experience and motivation.
sensory adaption: decreased responsiveness to stimuli due to constant stimulation.
selective attention: focusing of conscious awareness on a particular stimuli.
cocktail party phenomenon: describes ability to focus one's listening attention on a single talker among a mixture of conversations and background noise, ignoring other conversations. form of selective attention.
vision: most dominating sense. visual capture.
phase 1: gathering light
short waves = higher frequency (bluish color, higher pitched sounds)
long waves = low frequency (reddish wave, low-pitched sounds)
height of wave gives it's intensity (brightness)
length of waves gives it's hue (color)
ROY G BIV
long waves = more red
short waves = more violet
transduction: transforming signals into neural impulses. information goes from senses to thalamus, then various areas in brain.
conversion of one form of energy to another.
stimulus energies to neural impulses.
ex. light energy to vision
chemical to taste and smell. sound waves to sound.
color vision 2 major theory:
young-helmholtz trichromatic (3 color) theory: 3 types of cones.
- red
- blue
- green
opponent-process theory: the sensory receptors come in pairs
- red/green
- yellow/blue
- black/white
hearing: we hear sound waves
height of waves gives us amplitude of the sound.
frequency of waves gives the pitch of sound.
transduction in ear: sounds waves hit ear drum then anvil. then hammer. then stirrup then oral window. everything is vibrating. then cochlea vibrates which lined with mucus called basilar membrane and has hair cells.
when hair cells vibrate they turn vibrations into neural impulses which are called organ of corti. sent to the thalamus.
place theory: different hairs vibrate in the cochlea when there are different pitches.
so some hairs vibrate when they hear high pitches and others when they hear low pitches.
frequency theory: all hair vibrate, but at different speeds.
deafness:
conduction deafness: something goes wrong with sound and vibration or the way to cochlea. you can place the bones or get a hearing aid.
nerves (sensorineural) deafness: hair cells in cochlea get damage. loud noises can cause this type of deafness. no way to replace the hair. cochlea implants is possible.
smell and taste:
sensory interaction: principle that one sense may induce another.
taste: we have bumps on our tongue called papillae. taste buds are located on papillae (they are actually all over mouth)
sweet, salty, sour, bitter, hot&spicy
umami: flavorful, meaty, savory taste.
touch: receptors located in our skin. gate control theory of pain.
gate control theory of pain: spinal cord contains neurological gate that blocks pain signals or allows them to pass on to the brain.
vestibular sense: tells us where our body oriented in space. our sense of balance.
kinesthetic sense: tells us where our body parts are. receptors are located in muscles and joints.
Sunday, April 6, 2014
Developmental Psychology
the study of you from womb to tomb. .
study how we change psychically, socially, cognitively, & morally over our life tim.
nature v.s nurture:
nature: way you were born
nurture: way you are raised
psychical development: psychical change over time.
prenatal development: conception begins with drop of egg and sperm. sperm seeks out the egg and attempts to penetrate the egg surface.
once the sperm penetrates egg and have fertilized egg called zygote: first stage of prenatal development. last about 2 weeks and consist of rapid cell division.
zygote: less than 1/2 of zygotes survive 1st 2 weeks.
about 10 days after conception, the zygote will attach itself to the uterine wall.
the outer part of the zygote becomes the placenta ( which filled with nutrients)
2 weeks after, zygot develops into embryo.
6 weeks and heart begins to beat and organs begin to develop.
fetus: 9 weeks. fetus by about 6th month, stomach and other organs have formed enought to survive outside of mother.
at this time the baby can hear ( and recognize) sources and respond to light.
teratogene: chemical agents that harm the prenatal enhiko.
reflex: inborn automatic responses.
rooting: baby's tendency when touched on the cheeck to open the mouth and search for the nipple.
puberty: period of several maturation, during which a person becomes capable of reproducing.
primary sexual characteristics: body structure that have reproducing possibility. penis, testis, vagina, ovaries
secondary sexual characteristics: non-reproducive sexual characteristics. ex. widening of hips, deepen voice, breast developments, and body hair.
landmarks for puberty: menarche for girls/ first ejaculation for boys ( spermarche)
adulthood: physical peak. then goes downhill.
physical milestone: menopause
death: elizabeth kubler:
stranger anxiety: instant encounter stranger and experience anxiety.
seperation anxiety - child is seperated from their parents.
attachment: harry harlon and his monkey. shows that monkeys need touch to form attachment.
critical period: the optimal period shortly after birth when an organism's exposure to certain stimuli or experiences produce proper development.
those who are deprived of touch have trouble forming attachment when they are older.
types of attachment:
trust vs. mistrust: ( ages 0-2 years)
can baby trust the world to fulfill its needs?
trust or mistrust they develop.
atonomy vs. shame and doubt: (1-3 years)
in which ask who am i? and what group do i fit in with?
intimacy vs. isolation (early adulthood)
have to balance work and relationship.
what are my priorities?
generationity vs. stagnation: ( 40-50)
look back on life. was my life meaningful or do i have regrets?
cognitive development: though that kids were stupid version of adults. jean piaget. kids learn differently than adults.
schema: children view the world through schema ( as do adults for the most part)
schema are way we interpret the world around us. it is basically what you picture in your head when you think of everything.
assimilation: incorporating new experiences into existing schema.
accommodation: changing an existing schema to adopt to new information.
stages of cognitive development:
concrete operational stage: can demonstrate concept of conservation. learn to think logically.
formal operational stage: abstract reasoning, manipulate objects in mind with out seeing them. hypothesis testing, trial and error, metacognition, not every adult gets to this stage.
types of intelligence:
crystallized intelligence:
pre-conventional morality: based on rewards and punishments. if rewarded, okay. punished, act must be wrong.
conventional morality: look at morality based on how others see you. if peers/society, thinks it is from then so do you.
post -conventional morality - board on self-defined ethical principle your own personal set of ethnics.
study how we change psychically, socially, cognitively, & morally over our life tim.
nature v.s nurture:
nature: way you were born
nurture: way you are raised
psychical development: psychical change over time.
prenatal development: conception begins with drop of egg and sperm. sperm seeks out the egg and attempts to penetrate the egg surface.
once the sperm penetrates egg and have fertilized egg called zygote: first stage of prenatal development. last about 2 weeks and consist of rapid cell division.
zygote: less than 1/2 of zygotes survive 1st 2 weeks.
about 10 days after conception, the zygote will attach itself to the uterine wall.
the outer part of the zygote becomes the placenta ( which filled with nutrients)
2 weeks after, zygot develops into embryo.
6 weeks and heart begins to beat and organs begin to develop.
fetus: 9 weeks. fetus by about 6th month, stomach and other organs have formed enought to survive outside of mother.
at this time the baby can hear ( and recognize) sources and respond to light.
teratogene: chemical agents that harm the prenatal enhiko.
- alcohol ( FAS)
- other std can harm baby ex. HIV
reflex: inborn automatic responses.
rooting: baby's tendency when touched on the cheeck to open the mouth and search for the nipple.
- sucking
- grasping
- moro
- babinski
puberty: period of several maturation, during which a person becomes capable of reproducing.
primary sexual characteristics: body structure that have reproducing possibility. penis, testis, vagina, ovaries
secondary sexual characteristics: non-reproducive sexual characteristics. ex. widening of hips, deepen voice, breast developments, and body hair.
landmarks for puberty: menarche for girls/ first ejaculation for boys ( spermarche)
adulthood: physical peak. then goes downhill.
physical milestone: menopause
death: elizabeth kubler:
- denial
- anger
- bargaining
- depression
- acceptance
stranger anxiety: instant encounter stranger and experience anxiety.
seperation anxiety - child is seperated from their parents.
attachment: harry harlon and his monkey. shows that monkeys need touch to form attachment.
critical period: the optimal period shortly after birth when an organism's exposure to certain stimuli or experiences produce proper development.
those who are deprived of touch have trouble forming attachment when they are older.
types of attachment:
- secure
- avoidant
- anxious/ambivilant
- authoritarian (parents)
- permissive (kids)
- authoritative ( both)
trust vs. mistrust: ( ages 0-2 years)
can baby trust the world to fulfill its needs?
trust or mistrust they develop.
atonomy vs. shame and doubt: (1-3 years)
- toddlers begin to control bodies (toilet)
- temper tantrums; big word is "NO"
- can learn control or they doubt themselves.
- "NO" to why?
- wants to understand world and ask
- are they good or bad.
- school begins
- we are 1st time evaluated by formal system
- successful or failure?
- can lead to us feeling bad about ourselves for the rest of our lives...inferiority complex.
in which ask who am i? and what group do i fit in with?
intimacy vs. isolation (early adulthood)
have to balance work and relationship.
what are my priorities?
generationity vs. stagnation: ( 40-50)
- is everything going as planned?
- am i happy with what i created?
- mid-life crisis
look back on life. was my life meaningful or do i have regrets?
cognitive development: though that kids were stupid version of adults. jean piaget. kids learn differently than adults.
schema: children view the world through schema ( as do adults for the most part)
schema are way we interpret the world around us. it is basically what you picture in your head when you think of everything.
assimilation: incorporating new experiences into existing schema.
accommodation: changing an existing schema to adopt to new information.
stages of cognitive development:
- sensorimotor: experience world though senses.
- do no have object permanance.
- 0-2
- have object permanence
- begins to use language to represent ideas and objects
- egocentric: cannot look at world thought anyone's eyes but their own.
- 2-7
concrete operational stage: can demonstrate concept of conservation. learn to think logically.
formal operational stage: abstract reasoning, manipulate objects in mind with out seeing them. hypothesis testing, trial and error, metacognition, not every adult gets to this stage.
types of intelligence:
crystallized intelligence:
- accumulated knowledge
- increase with age
- sbility to solve problems quickly and think abstractly
- peaks in 20;'s and decrease over time.
pre-conventional morality: based on rewards and punishments. if rewarded, okay. punished, act must be wrong.
conventional morality: look at morality based on how others see you. if peers/society, thinks it is from then so do you.
post -conventional morality - board on self-defined ethical principle your own personal set of ethnics.
Endocrine System
endocrine system: system of glands that secrete hormones. similar to nervous system, except hormones work a lot slower than neurotransmitters.
pituitary gland - secretes many different hormoes, some of which affect other glands. controlled by hypothalamus.
thyroid - affects metabolism, among other things.
parathryroid - helps regulate the level of calcium in the blood.
adrenal - inner part called medulla, helps trigger the "fight or flight" response.
pancreas - regulates level of sugar in blood.
ovary - secretes female sex hormones
testis - secretes male sex hormones.
pituitary gland - secretes many different hormoes, some of which affect other glands. controlled by hypothalamus.
thyroid - affects metabolism, among other things.
parathryroid - helps regulate the level of calcium in the blood.
adrenal - inner part called medulla, helps trigger the "fight or flight" response.
pancreas - regulates level of sugar in blood.
ovary - secretes female sex hormones
testis - secretes male sex hormones.
Biology Psychology 3/6/14
nervous system - starts with an individual never cell called a neuron.
parts of a neuron:
cell body - center and support cell life.
dendrites - transmits message to cells (other cells/recieve)
axon - passage messages away from cell body to other parts.
myelin sheath - covers the axon and helps speed up neural impluses.
terminal branches of the axon - forms junctions with other cells.
neurotransmitters - chemicals help inn the terminal buttons that travel through synapse.
synapse - a structure that permits a neuron to pass a chemical or electrical signal to other cell.
how does a neuron fire?
resting potential - slightly negative charge reach the threshold when enough neurotransmitters reach dendrites.
it is an electrochemical process.
the all-or-none response.
acetylcholine (ACH)
inter neuron (relay neuron): takes messages from sensory neuron to the other parts of the brain or to the motor neuron.
motor(efferent neuron): takes info from brain to the rest of the body.
central nervous system - brain and spinal cord.
peripheral nervous system - all nerves that are not encased by bone. everything but brain and spine.
divided into 2, somatic and autonomic.
somatic nervous system - controls voluntary muscles movement. uses motor/efferent neurons.
autonomic nervous system - controls automatic functions of the body. divided into 2 categories sympathetic and parasympathetic.
sympathetic nervous system - fight or flight response, automatically accelerates heart rate, breathing, dilated pupils, slows down digestion.
parasympathetic nervous system - automatically slows the body down after stressful event. heart rate and breathing slows down, pupils constrict and digestion speeds up.
reflex - normally, sensory (afferent) neurons take into up through spine to brain. some reactions occur when sensory neurons reach touch the spinal cord.
lesions - cutting into the brain and looking for change. less invasive way to study brain.
brain structure - brain divided into 3 parts. hindbrain, midbrain, and forebrain.
hindbrain:
medulla oblongata - heart rate , breathing, and blood pressure.
pon - connects hindbrain, midbrain, and forebrain together. involved in facial expression.
cerebellum - located in the back of the head. means "little brain"
mid brain: coodinates simple movements with sensory information. contains reticular formation: arousal and ability to focus attention.
thalamus: in fore brain, receives sensory information and sends them to appropriate areas of the forebrain like a switchboard.
limbic system: emotional control center of brain made of hypothalamus, amygdala, and hippocamppus.
hypoothalamus: pea sized. but plays big role. body temp., hunger, thirst, and sexual arousal (libido)
hippcampus & amygdala:
hippocampus - memory processing
amygdala - vital for our basic emotions.
cerebral cortex: top layer of our brain. wrinkles called fissures. fissures increase surface area of brain. laid out about the sized of a large pizza.
hemispheres : divided into left and right. contra lateral controlled - left controls right of body and vice versa.
brain lateralization
lefties are btter at spatial and creative task
righties are better at logic
splt brain patients: corpus callosum attaches the two hemispheres of cerebral cortex. when removed you have split brain.
cerebral cortex contains 4 lobes
motor cortex: sends sinals to body controlling muscle movements.
brocas's area: responsible for controlling muscles that produce speech.
damage to area is called broca's aphasia: unable to make movements to talk.
motor cortex: left hemisphere control right side.
parietal lobe: contains sensory cortex. receives incoming touch sensations from rest of the body.
most of parietal love are made up of association areas.
assocaition areas: any area not associated with recieving sensory information or coordinatinng muscles movements.
occipital lobe: deals with vision. contains visual cortex. interprets message from our eyes into images we can understand.
temperal lobe: source sensed by our ears. contains wernicke's area: interprets written and spoken speech.
wernicke's aphasia: unable to understand langauge: the syntax and grammar jumbled.
parts of a neuron:
cell body - center and support cell life.
dendrites - transmits message to cells (other cells/recieve)
axon - passage messages away from cell body to other parts.
myelin sheath - covers the axon and helps speed up neural impluses.
terminal branches of the axon - forms junctions with other cells.
neurotransmitters - chemicals help inn the terminal buttons that travel through synapse.
synapse - a structure that permits a neuron to pass a chemical or electrical signal to other cell.
how does a neuron fire?
resting potential - slightly negative charge reach the threshold when enough neurotransmitters reach dendrites.
it is an electrochemical process.
- electrical inside the neuron
- chem. outside the neuron ( in the synapse in the form of a neurotransmitter)
the all-or-none response.
- idea that either the neuron fires or doesn't. no part way firing.
acetylcholine (ACH)
- deals with motor movements and memory
- lack of ACH has been linked to Alzheimer's disease.
- deals with motor movement and alertness
- lack linked to parkinson's disease
- too much linked with schizophrenia
- mood control
- lack linked with clinical depression
- pain control
- many of our most addictive drugs deal with endorphins
- agonist: make neurons fire
- antagonist: stop neural firing
inter neuron (relay neuron): takes messages from sensory neuron to the other parts of the brain or to the motor neuron.
motor(efferent neuron): takes info from brain to the rest of the body.
central nervous system - brain and spinal cord.
peripheral nervous system - all nerves that are not encased by bone. everything but brain and spine.
divided into 2, somatic and autonomic.
somatic nervous system - controls voluntary muscles movement. uses motor/efferent neurons.
autonomic nervous system - controls automatic functions of the body. divided into 2 categories sympathetic and parasympathetic.
sympathetic nervous system - fight or flight response, automatically accelerates heart rate, breathing, dilated pupils, slows down digestion.
parasympathetic nervous system - automatically slows the body down after stressful event. heart rate and breathing slows down, pupils constrict and digestion speeds up.
reflex - normally, sensory (afferent) neurons take into up through spine to brain. some reactions occur when sensory neurons reach touch the spinal cord.
lesions - cutting into the brain and looking for change. less invasive way to study brain.
brain structure - brain divided into 3 parts. hindbrain, midbrain, and forebrain.
hindbrain:
medulla oblongata - heart rate , breathing, and blood pressure.
pon - connects hindbrain, midbrain, and forebrain together. involved in facial expression.
cerebellum - located in the back of the head. means "little brain"
mid brain: coodinates simple movements with sensory information. contains reticular formation: arousal and ability to focus attention.
thalamus: in fore brain, receives sensory information and sends them to appropriate areas of the forebrain like a switchboard.
limbic system: emotional control center of brain made of hypothalamus, amygdala, and hippocamppus.
hypoothalamus: pea sized. but plays big role. body temp., hunger, thirst, and sexual arousal (libido)
hippcampus & amygdala:
hippocampus - memory processing
amygdala - vital for our basic emotions.
cerebral cortex: top layer of our brain. wrinkles called fissures. fissures increase surface area of brain. laid out about the sized of a large pizza.
hemispheres : divided into left and right. contra lateral controlled - left controls right of body and vice versa.
brain lateralization
lefties are btter at spatial and creative task
righties are better at logic
splt brain patients: corpus callosum attaches the two hemispheres of cerebral cortex. when removed you have split brain.
cerebral cortex contains 4 lobes
- frontal
- temperal
- occipital
- parietal
motor cortex: sends sinals to body controlling muscle movements.
brocas's area: responsible for controlling muscles that produce speech.
damage to area is called broca's aphasia: unable to make movements to talk.
motor cortex: left hemisphere control right side.
parietal lobe: contains sensory cortex. receives incoming touch sensations from rest of the body.
most of parietal love are made up of association areas.
assocaition areas: any area not associated with recieving sensory information or coordinatinng muscles movements.
occipital lobe: deals with vision. contains visual cortex. interprets message from our eyes into images we can understand.
temperal lobe: source sensed by our ears. contains wernicke's area: interprets written and spoken speech.
wernicke's aphasia: unable to understand langauge: the syntax and grammar jumbled.
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