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Please be aware that this is a student-generated wiki designed for review for my students' AP exams. Come in, look around, and enjoy yourself...just be aware of the nature of this wiki. Even though most everything is correct, I advise caution before citing this as an authoritative source.

Sensation

Sensing the World: Basic Principles
Sensation: The process by which our sensory receptors and nervous system receive and represent stimulus from our environment (Myers).
  • Sensory systems enable organisms to obtain needed information, such as humans' ability to easily detect the sound of an infant crying (Myers).
    • keeps us from being overwhelmed by the abundant sensory inputs we are always receiving
    • sensation and perception work together into one continuous process
    • Sensation focuses on how our mind interprets what our senses detect
  • Psychophysics- a study of relationships between the physical characteristics of stimuli such as their intensity and our psychological experience of them (Myers 194).
    • Our awareness of faint stimuli such as smelling a scent from across the room or feeling a rain drop fall on our head, illustrates our absolute thresholds.
    • detection of a stimulus depends on many factors such as arousal, surrounding and expectation (Myers).
    • Absolute threshold for each of the senses is determined when we pinpoint a stimulus 50% of the time. To test your absolute threshold for sounds, a hearing specialist would expose each of your ears to varying sound levels. For each pitch the hearing test defines where half the time you correctly detect the sound and half the time you do not (for each of these senses that 50-50 point defines your absolute threshold) (Myers).
    • Experiments reveal that we can process some information from stimuli too weak to recognize. But the restricted conditions under which this occurs would not enable unscrupulous opportunists to exploit us with subliminal message (Myers).
    • For example, our ability to see a candle's flame miles away when the environment is pitch black.
    • To survive and thrive, an organism must have difference thresholds low enough to detect minute changes in important stimuli. In humans, a difference threshold increases in proportion to the size of the stimulus- a principle known as Weber's law (Myers).
    • Animals have a similar threshold in that they adapted to hear what they needed to hear. Manatees heard what was needed in order to survive, this didn't include the low-pitch sounds of boats (Myers 194).
  • Signal detection Theory: predicting how and when we will notice a presence of faint stimuli. The theory takes into account that there are four possible outcomes on each trial in a detection experiment: hit, miss, false alarm, correct rejection (see below) . It also considers "account response bias, moods, feelings, and decision making strategies that can affect the likelihood of making a given response" (The Princeton Review). Assumes that there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivations, and level of fatigue (194).
  • Ex: Exhausted parents of a newborn will notice the faintest whimper from the cradle, while failing to notice louder, unimportant sounds. Responsiveness also increases in a horror-filled wartime situation, where the failure to detect an intruder may mean death (Myers).
  • Our ears are at their most sensitive when it comes to pitches in the same range as human speech, so sounds like a mosquito's buzz next to our ear would be detected while a bat's pitch would not be heard as well (Myers).
  • Perception: the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events (Myers). Failures of perception may occur anywhere between sensory detection and perceptual interpretation. ex)The eyes of a person born with cataracts may be unable to detect light (Myers).
  • Another example is after losing a temporal lobe area essential to recognizing faces patient "E.H." suffers from a condition called prosopagnosia. This means that although she can accurately report the features of a face (sensation) she is unable to recognize it (perception). (Meyers 193).
  • Bottom-Up Processing - Analysis that begins with the sense receptors and works up to the brain's integration of sensory information (Myers).
  • Top-Down Processing - Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations. (Myers)
  • Difference Threshold- (also known as just noticeable difference or JND) the difference threshold is the minimum difference a person can detect between any 2 stimuli half the time. We experience the difference threshold as a just noticeable difference (Myers 197).

  • Ex: By adding 10 grams to a 100 gram weight we would be able to feel the difference in the weight. However, if we added 10 grams to a 100 kilogram weight we wouldn't feel the difference in the weight because the threshold increased (Myers 197).
    • It is a rough approximation
    • Works well for non extreme sensory stimuli, and it parallels some of our life experiences (Myers).
    • According to Myers, for the average person to perceive their differences, two lights must differ in intensity by 8 percent. Two objects must differ in weight by 2 percent. And two tones must differ in frequency by only 0.3 percent (Teghtsoonian 1971).
    • greater the magnitude of the stimulus, the larger the differences must be to be noticed (Talamo).
    • Weber's law: The principle that to be perceived as different, two stimuli must differ by a constant minimum percentage rather then a constant amount (Meyers 197).
    • Important benefit by enabling us to focus on informative changes in our environment without being distracted by uninformative constant stimulation of our surroundings (Myers).
    • Fundamental lesson: We perceive the world not exactly as it is, but as it is useful for us to perceive it (Myers).
    • For example, you jump into a pool, and you notice its freezing cold, but as you continue to swim around you accommodate to it and next thing you know, you don't even feel the cold (Myers).
    • "All the senses receive sensory stimulation, transform it into neural information, and deliver that information to the brain" (Myers).
      • For example, when people are responsible for monitoring patients in intensive care (Myers).
    • People's vigilance to a task generally fades after around thirty minutes.
    • Four possible outcomes on each trial (Talamo).
      • hit- the signal was present, and the participant reported sensing it
      • miss- the signal was present, but the participant did not sense it
      • false alarm- the signal was absent, but the participant reported sensing it
      • correct rejection- the signal was absent, and the participant did not report seeing it
    • imagine going to a blood bank and giving blood, you will get a bandage wrapped around your vein which blood was drawn out of. At first you will notice the bandages and gauses wrapped around, but after a while you will forget about them and go about your day not noticing them.
Receptor Process
  • Receptor cells- designed to detect specific types of energy. (Princeton Review)
  • There are different receptors: temperature, pressure, body position, visual receptors, sight, smell, touch, chemical, pain, and hearing and more.
  • Receptive field- are from which our receptor cells receive input. (Princeton Review)
  • Transduction- the receptors convert the input, or stimulus, into neural impulses, which are sent to the brain. (Princeton Review) All incoming information from the senses, excluding smell, travel to the sensory neurons of the thalamus, since this is considered the sensory processing center (The Princeton Review).
    • ex) When a human sees a flower they look and see the different colors; a bee on the other hand would look at the flower and see colors based off of ultraviolet waves showing it where the pollen landing fields where they can obtain their nutrients (Myers 198).
  • Contralateral shift- occurs, in which much of the sensory input from one side of the body travels to the opposite side of the brain (Princeton Review).
  • Sensory Coding- the process by which receptors convey such a range of information to the brain ( Talamo)
  • Sensory Adaptation-diminishing sensitivity to an unchanging stimulus (Myers 198).
    • While sensory adaptation reduces our sensitivity, it makes it so we can focus our senses on the important stimuli going on around us instead of being overwhelmed by everything else. We are able to more readily notice the changes in our environment (Myers).
    • "Focuses our attention on informative changes in stimulation by diminishing our sensitivity to constant or routine odors, sounds, and touches" (Myers 199).
  • ex) When stepping into a cold air-conditioned classroom, one may feel very cold. However, as time passes, one will eventually become conditioned to the temperature and not notice how cold it actually is.
  • ex: When you enter your own home you do not notice the smell, but if you go to someone else's home you notice the smell at first, but after being there for a while, you no longer notice the smell of their house. (Meyers)

Subliminal Stimulation
  • Subliminal - Below ones absolute threshold for conscious awareness. (Myers) Although subliminally presented stimuli can subtly influence people, experiments discount attempts at subliminal advertising and self improvement.(myers)
Absolute Threshold- The smallest intensity of a stimulus in order for that stimulus to then be detected. (example: when you burn your hand you do not immediately feel the heat at first)(Psychology Glossary)
    • Psychologists usually measure absolute threshold by recording the stimulation needed for us to pinpoint its appearance fifty percent of the time (Myers).
  • Subliminal messages have no effect beyond that of a placebo- an effect of ones belief in them (Myers).
  • The consensus among research psychologists is that subliminal messages can not produce a powerful, enduring effect on one's behavior; and that lab research shows little effect beyond a subtle loss on thinking."For example, priming thirsty people with a subliminal word may, for a brief period of time, make a thirst-quenching beverage advertisement seem more persuasive" (Jansen).

Vision
"Each sense receives stimulation, transduces it into neural signals, and sends these neural messages to the brain. we have glimpse how this happens with vision" (Myers 211)
  • Visual impulses travel to the brain through the ocular nerve, which is the second cranial nerve.
  • Transduction - transforming of stimulus energies into neural impulses (Myers)
-Your eyes receive light energy and manage an amazing feat: They transduce (transform) the energy into neural messages that the brain the
processes into what you consciously see. (Meyers 199)
  • Wavelength - the distance from the peak of one wave (light or sound) to the peak of the next (the horizontal distance) (Myers)
    • Determines color (or formally known as hue) and sounds (or more specifically, the frequency)
    • Shorter wavelengths have a high frequency and are seen as a bluish color.
    • Longer waves have a low frequency and are seen in a reddish color.
  • Amplitude: the maximum extent of a vibration or oscillation, measured from the position of equilibrium. (the vertical distance from the lowest point to the highest point of a wave)
    .
    • Determines intensity or brightness of the color, while also determining the loudness of a sound
  • Hue - dimension of color determined by wavelength of lights (Myers)
  • Intensity- the amount of energy in a light or sound wave,which perceive as brightness or loudness,as determined by the waves amplitude[Myers].
  • Color Constancy - Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
  1. If the context in which an object is viewed changes, the perceived color of the object changes. (Myers)
- The color of the object depends on the object that the light wave hits and whether it is reflected, absorbed, or transmitted
  • When all of the light waves are absorbed, there are no light being reflected. As a result, the color black can be seen
  • solid objects reflect light
  • a transparent object will transmit light through them
    • For example, if you were to hold a glass filled with cranberry juice and a piece of white paper next to each other, the light will transmit the cranberry juice's color (red) on the piece of white paper
The Eye
What we see through our eyes is not color but pulses of electromagnetic energy, that our vision senses as color. (Myers)
  • Cornea- protects the eye and blends light to provide focus (Myers)
  • Pupil- the adjustable opening in the center of the eye through which light enters.[Myers]
  • Iris-a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.[Myers]
-"The iris adjusts light intake by dilating and constricting in response to light intensity and even to inner emotions.(Myers)
- The uniqueness of every iris enables iris scanning machines to confirm someone's identity (Myers 201)
  • Lens- the transparent structure behind the pupil that changes shape to help focus images on the retina. [Myers]
    • The image cast upon the retina is upside down. Research psychologists have discovered that while the image is projected upside down, the millions of receptor cells convert light energy into neural impulses, which are carried to and constructed by the brain as an upright image.
    • Accommodation- the process by which the eye's lens changes shape to focus near or far objects on the retina. (Myers)
  • Retina- the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information. (Myers)
    • The signals from the rods and cones are transferred through the optic nerve, which is composed of the axon of ganglion cells. The point at which the optical nerves cross-over is known as the optic chiasm.
      • Information processed by the ganglion cells is used to identify corners and edges. The ganglion cells use the comparison between brighter and darker areas int he visual field to identify these corners and edges. [1]
      • Information from the retinas travels to the corresponding visual cortices in the brain. If enough rod and cones are send out electrical impulses, the bipolar cells are also stimulated. If enough bipolar cells send out electrical impulses, then the next set of cells the ganglion cells of the optic nerve are activated.
      • The neural impulse travels from the optic nerve to the lateral geniculate nucleus, which is a part of the thalamus.
      • From this part of the thalamus, the neural impulses are sent to the occipital lobes, where the visual cortices are. Neural impulses sent from the left portion of the retina in each eye are processed in the left visual cortex. The impulses sent from the right portion of the retina in each eye are processed in the right visual cortex. [2]
      • "Natural philosophers" eventually included research psychologists who discovered that the retina doesn't read the image as a whole. Rather, its millions of receptor cells convert light energy into neural impulses. These impulses are sent to the brain and constructed there into a perceived, upright-seeming image (Meyers 201).
  • Acuity-the sharpness of vision, "which can be affected by small distortions in the shape of the eye". (Myers), there are a total of 3 basic kinds of Acuity
    • 1. Normal acuity, the normal extent to which humans can see
    • 2. Nearsightedness-condition in which nearby objects are seen more clearly than distant objects because distant objects in front of retina(Myers)
      According to Myers "glasses, contact lenses or LASIK surgery can reshape the cornea" and correct the problem of nearsightedness.While LASIK surgery is an option to help improve vision, it has its limits, and is not a perfect surgical procedure. Many times, it can only help those with milder myopia (nearsightedness), and for many with extreme myopia, LASIK surgery may create more hindrance than assistance, including dry eyes, a usual aftereffect of the surgery.
    • People with nearsighted vision see that more distant images are focused in front of the retina, then when they actually hit the retina the rays are spread out and blurry.
    • Ex. Star is looking at a cup that is in front of her which is clear, but when she sees another cup from a farther distance she views it as blurry.
    • 3. Farsightedness is a condition where faraway objects are seen more clearly than near objects because the image of near objects being focused behind retina. (Myers) The opposite of nearsightedness. Here, the light rays from nearby objects reach the retina before they have produced a focused image. (Meyers 202)
    • In children, the eye's ability to accommodate usually makes up for this problem, so they rarely need glasses - but they may suffer eyestrain from overusing their eye muscles, and some get headaches. (Meyers 202)
    • Individuals that are only mildly farsighted often do not discover their condition until middle age, when the lens loses its ability to change shape rapidly. (Myers 202)
    • People with farsighted vision see the light rays from nearby objects are focused behind the retina which causes nearby images to become blurry.
  • Rods-retinal receptors that detect black, white, and gray (Meyers).
  • They are responsible for visions of low light levels and have low spatial acuity.
  • Myers notes that some nocturnal animals have retinas that are made up with a majority of rods.
  • Cones-receptor cells that are concentrated near the center of the retina, that function in well lit conditions. the cones detect fine detail and give rise to color sensations. Red, blue, and green are the primary colors.(Myers) Unlike rods, many cones have their own bipolar cells to help relay their individual messages to the cortex, which devotes a large amount if its area to impulses from the fovea. This preserves the cones' precise information, making them better able to detect fine detail. (Myers 203)
  • Rods remain sensitive in dim light because several rods will funnel their faint energy from dim light onto a single bipolar cell. (Myers 203)
  • Optic Nerve-the nerve that carries neural impulses from the eye to the brain. (Myers)
  • Blind Spot-the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there. (Myers)
    • Each of your eyes has a small blind spot in the back of the retina where the optic nerve attaches (VSP).
    • In everyday vision, the blind spot does not impair your vision since your eyes are moving and one eye is able to catch what the other eye may miss. (Myers)
  • Accommodation- the process by which the eye's lens changes shape to focus near or far objects on the retina (Myers)
  • Fovea- the central focal point in the retina, around which the eye's cones cluster. (Myers)
    • Fovea only contains cones and no rods (Myers).
  • Blindsight- phenomenon that due to having lost a portion of their brain's visual cortex to surgery or stroke, people may experience blindness in part of their field of vision. (Myers)
  • Feature detector: Located in the visual cortex of the brain are nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.
    • Our neuron systems come together to form our perceptions. Each individual system performs a very simple task, but once they all merge, our complex form of perception is formed. One cell will pass on information to another cell and so on until the goal is met (Myers).
    ...Unlike most computers, which do step-by-step serial processing, our brains engage in parallel processing. That means we can do several things at once. We construct our perceptions by integrating the work of different visual teams, working in parallel. (Myers 206)
  • Color deficient people are not actually "colorblind". They just lack functioning red or green sensitive cones (Myers). So they might mix up the two or even see one or the other as brown.
    • The brain divides a visual scene into sub-dimensions such as color, depth, movement, and form and works on each aspect simultaneously.(Myers)
    • These sub-dimensions of viewing something were found by doing studies on brain-damaged patients.
  • Trichomatic Theory(Young-Helmholtz trichromatic theory): A theory created by Young and Helmholtz which says we have "3 different retinal color receptors." (red, green, blue) (Myers)
    According to Young and Helmholtz, the three color receptors can mix to form any of the colors in the visible spectrum. 3 colors, when mixed, created a white color, instead of black like regular paint color
    Example: The color yellow would be interpreted using the red and green color receptors.
    • People who are said to be "colorblind" are not actually "colorblind". Their vision is dichromatic which excludes red or green sensitive functioning cones. This is why they have difficulty distinguishing between red and green. (Myers) An example of this
    • is we don't have "receptors that are sensitive to yellow", but when "green and red cones are stimulated we see yellow". (Myers)
    • These colors would be opposite on the color wheel, so if red is on then green is off; if green is on then red is off; if blue is on yellow is off; if black is on white is off; etc.
    • After leaving the receptor cells, visual information is analyzed in terms of the opponent colors red and green, blue and yellow, and black and white (Myers 210)
  • Color Constancy: this term means that even when the lighting changes we still perceive two colors taste same. For instance, one would know that two gray sweaters are the same color even is one of the sweaters is under the shade and the other is under the sun.
  • Wavelength-the distance from the peak of one light or sound wave to the peak of the next (Myers 201)
-Research shows that any image, such as a face, can be broken down into patterns of changing light intensity that can be described mathematically (Myers).
Hearing
  • Frequency- the number of complete wavelegths that pass a point in a given time (Myers) Short wavelengths = high frequency (high-pitched sounds), while long wavelengths = low frequency (low-pitched sounds). (Myers)
  • Pitch- a tone's highness or lowness; depends on frequency (Myers)
  • Decibels- unit of measure for sound energy (Myers) Prolonged exposure above 85 decibels produces hearing loss. (Myers)
    • Examples of Decibels:
    • 1. Jet Plane at 500 feet = 110 Decibels (Myers)
    • 2. Street Corner with bustling commotion = 80 Decibels (Myers)
    • 3. Regular Conversation = 60 Decibels (Myers)
    • 4. Whisper = 20 Decibels (Myers)
    • 5. Rock Concerts = 120 Decibels
    • 6. Snoring = 85 Decibels
    • Sitting in front of the speakers at a rock concert can expose you to 120+ decibels, which is enough to begin to damage hearing in only 7 and a half minutes (Dodd-Murphy).
  • We transform sound waves into nerve impulses that our brain interprets by using our ouer ear to funnel sound waves to the eardrum. The bones then amplify and relay the eardrum's vibrations through the cochlea (Myers).
  • Audition - the sense of hearing (Myers)
  • Conduction Hearing Loss- Hearing loss caused by damage to the ear drum or the bones of the middle ear a problem in the mechanical system that conducts sound waves to the cochlea. (Myers)
  • Sensorineural Hearing Loss- Hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called never deafness (Myers). This is caused by periods of long exposure to loud noise.
  • Nerve Hearing Loss - hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve. (Myers)
  • Each inner ear hair cell has 50 to 60 cilia that produce an electric signal in response to sound (Myers).
-Deaf people generally lack high reading ability but visual compensation helps explain why many are visually skilled engineers, architects, and mathematicians. The brain tends to reorganize itself and expand on areas that are highly used while the ones that are not being used slowly deteriorate.
How to locate sound:
  • When a sound occurs, wave lengths are set off and will hit one ear sooner than the other, therefore exposing the location of the sound.
  • Our sensory auditory system can detect minute differences. The J.N.D. in the direction from two sounds corresponds to a time difference of 0.000027. (Myers). Eventhough this J.N.D. is so minute our brain is still able to predict the correct location
  • Hearing losses may be linked to prolonged exposure to loud noise and by diseases and age-related disorders
  • The Ear
    • middle ear- the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window (myers)
    • inner ear- the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs; transduce sound energy into neural impulses.(Myers)
    • cochlea- a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses. (Myers)
    • place theory- links the pitch we hear with the place where the cochlea's membrane is stimulated (Myers)
    • frequency theory- the rate (or frequency) of nerve impulses traveling up the auditory nerve matched the frequency of a tone, thus enabling us to sense its pitch. (Myers)3
  • Place and frequency theory combine to explain intermediate pitches (Myers)
  • volley principle: neural cells alternate firing in rapid succession to achieve a combined frequency of 1000 times per sound (Myers)
  • The outer ear funnels sound waves to the eardrum. The bones in the middle ear amplifies and relay the eardrum's vibrations through the oval window into the fluid-filled cochlea. (Myers)
  • The resulting pressure changes in the cochlea fluid cause the basilar membrane to ripple, bending the hair cells on the surface. Hair cell movements trigger impulses at the bases of the nerve cells, whose fibers converge to form the auditory nerve. (Myers)
  • By means of this mechanical chain of events, sound waves cause the hair cells of the inner ear to send neural messages up to the temporal lobe's auditory cortex (Meyers 213).
  • Auditory nerve - This bundle of fibers carries nerve impulses from the inner ear to the brain. (Myers)
  • The stimulus energy for hearing is the sound waves of compressed and expanded air that are created by vibrating objects. (Myers)

Hearing Loss and Deaf Culture
  • Conduction hearing loss - hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea, according to Myers.
- Digital hearing aids improve hearing by amplifying vibrations for frequencies in which one's hearing is weakest and also by compressing sound (Myers 216)
  • Conduction hearing loss might happen if you puncture your eardrum or if the tiny bones in the middle ear stop vibrating; thus it has lost its ability to vibrate (Myers).
  • Sensorineural hearing loss (nerve deafness) - hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness, according to Myers.
  • Sensorineural Hearing Loss maybe caused by a disease but mostly by biological changes caused by aging, and by often(daily exposure) loud sounds and noises
  • The only way to restore hearing for people with nerve deafness is by a sort of bionic ear "a cochlear implant".
  • Cochlear implant translates sounds into electrical signals that wired into the cochlea's nerves, convey some information about sound to the brain, according to myers
  • People with hearing loss often experience the sound of silence: phantom sounds- a ringing-in-the-ears sensation know as tinnitus. (Myers)
  • Like with other senses, those that have weak or no hearing at all have other senses that are above average and more sensitive.
  • Older people tends to hear low frequencies well but suffer hearing loss for high frequencies. This high frequency loss results from nerve degeneration near the beginning of the basilar membrane (Myers).

Touch
  • The Gate Control Theory was presented by psychologist Ronald Melzack and biologist Patrick Wall, no theory, including this one has been able to explain all the findings and studies involving pain. This shows that complex nature of pain and the truly complicated nature of the brain.
  • Gate-control theory: the theory that the spinal cord contains a neurological "gate" that blocks pain signals of allows them to pass on to the brain. The "gate" is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain. For example, when a person rubs their sore feet to reduce pain sensations, this stimulates the spinal chords large fibers and closing the pain "gate" (Myers 221)
  • The spinal cord, uses small nerve fibers to feel pain, and large nerve fibers are used to conduct our sensory signals. Large-fiber activity closes the pain gate, turning pain off. A way to treat chronic pain is to stimulate "gate-closing" activity in the large neural fibers (Myers 221).
  • the skin's basic four sensations are: pressure, warmth, cold, and pain
    • pressure is the body's most accurate and sensitive sensation for touch, really hot and really cold can sometimes mold together in our brains
  • pain is the way your body tells you something has gone wrong.(Myers)
    • Because pain is a phenomenon of the conscious brain, athletes sometimes endure serious injuries while focusing their attention outside their bodies. (Myers)
  • touch is the most important sense we have.
  • Involuntary responses can protect us by allowing us to react to things before we actually realize what has happened. If a person touches a hot stove, they will jerk their hand back before they actually feel the pain.
Other skin sensations are variations of the basic four:
  • Stroking adjacent pressure spots creates a tickle.(Myers)
  • Repeated gentle stroking ofa pain spot creates an itching sensation(Myers)
  • Touching adjacent cold and pressure spots triggers a sense of wetness, which you can experience by touching dry, cold metal(Myers)
  • Stimulating nearby cold and warmth spots produces a feeling of "hot." Cold spot respond either to very low or very high temperatures. We sense hot when a stimulus activates both warmth and cold spots.(Myers)
  • There is no simple relationship between what we feel at a given spot and the type of nerve ending found there (Myers).
  • Some 7 in 10 amputees’ may feel pain or movement in their non-existent limbs due to the fact that pain is not only of the senses of the region we feel it, but of the brain as well (Myers).
  • Phantom limb sensations are non-existent limbs that indicate pain, the brain can misinterpret the spontaneous central nervous system activity that occurs in the absence of normal sensory input.
Ex. Amputee may try to lift cup with phantom hand, or step off a bed onto a phantom limb (Myers).
Ex. A person who may have had their arm amputated, might feel an itchy sensation on their elbow.

Taste
  • Sensory Interaction- The principal that one sense may influence another, as when the smell of food influences its taste (Myers)
    • This concept proves that the senses are not completely separated signals, but rather are mixed up in a sense when they arrive at the brain and are interpreted (Myers 225)
    • To savor the flavor of foods the aroma is breathed in. Without the sense of smell the taste of foods can often be indistinguishable from other foods. This is why those who lose their sense of smell often believe they lose their sense of taste as well.
  • taste's sensations are sweet, sour, salty, bitter and umami.
    • each sensation of taste is concentrated on an area of the tongue, with sweet at the front. These sensation decline with age though as taste buds die.
    • umami is the "savory" taste
  • umami is is best experienced as a flavor enhancer monosodium glutamate ,or the "meaty" taste (Myers)
  • If from one side of your tongue you lose the ability to taste, you most likely won't notice because the other side will become super sensitive We also perceive taste coming from the whole tongue. (Myers)
  • We can neither taste nor smell most nutrients (fat, protein, starch, and food vitamins). (Myers)
  • people without tongues can still taste-through receptors in the back and roof of the mouth. (Myers)
  • According to Myers Taste buds are receptors for taste they are unevenly distributed. They reproduce themselves every week or two but decrease with aging, smoking and the use of alcohol
  • Even if you lose taste on one side of your tongue, the rest of your tongue will become super-sensitive to taste so most people wouldn't notice. This is because humans perceive taste from as coming from the whole tongue, not parts because our brain doesn't localize taste well (Myers, 224)
  • our emotional responses to taste are hard-wired. If you give a sweet to a baby or a adult their faces will react in a similar manner .(Myers)
  • taste allows humans to determine what foods are good or bad and also provides motivation to keep eating since food is satisfying to our taste buds at times.
Smell
Like taste, smell is a chemical sense. We smell something when molecules of a substance carried in the air reach a tiny cluster of 5 million receptor cells at the top of each nasal cavity. Because we are taking in molecules, we are, in a sense, inhaling a part of whatever it is that we smell (Myers 225).
  • Smell, also known as, the first cranial nerve (CNI) carries the sensory information for the sense of smell.
    • instantly alert the brain through their axon fibers. (Myers)
    • smell is actually the strongest sense that evokes memory
  • Precisely how the olfactory receptors work, is still a mystery, according to Myers.
  • Sniffing swirls air up to the receptors, enhancing the aroma. The receptor cells send messages to the brain's olfactory bulb
  • The Olfactory system has no parallel to the retina, which detects myriad colors with sensory cells dedicated to red, green,or blue.(Myers)
  • Olfactory receptors recognize odors individually. (Myers)
  • Receptor cells send messages to the brain's olfactory bulb, and then onward to the temporal lobe's primary cell cortex and to the parts of the limbic system involved in memory and emotion (Myers 225). The nerve cells going from the olfactory bulb to the brain go through the hippocampus and amygdala, which are related to memory and emotions. The hippocampus and amygdala make up the limbic system. Specific smells are therefore associated with memory retrieval. [3]
  • Seeing, hearing, touching, tasting, and smelling are not totally separated channels. Rather, they are blended to receive sensory input (Myers).
  • The sense of smell peaks in the early 20s, however declines after that (Myers 226)
  • Anosmia- experienced by those who are unable to smell (Meyers 227)
  • Smell plays a huge roll in how we taste, for instance when you eat something super hot try plugging your nose first it will decrease the the level of hotness you taste to a decent degree. Which can also explain why our mouth waters when we smell food cooking, just the sheer smell of food is enough to make anyone run to the kitchen.
  • According to laboratory studies, people have the capacity to recognize long-forgotten odors and memories with which they are associated (Myers 227).

Body Position and Movement
The ability for our body to be able to sense exactly where our body movements and positions are, our sixth sense. This is very helpful when we need to eat, stand up, or reach out and touch someone. (Myers)
  • Kinesthesis- the system for knowing our body's position and individual movement.
    • Vision and kinesthesis interact. For those who are not able to sense the position of their limbs vision is a necessary sense for them so they can learn to walk by visually focusing on their limbs. Even for those who do not have a problem with sensing their body position, vision still interacts with kinesthesis. For example, if you stand with your right heel in front of your left toes, it'd be easy. But if you close your eyes you will probably wobbly (Myers).
    • Controlled by the semicircular canals (three tiny, fluid filled tubes in the ear) and vestibular sacs (the two sacs in the ear), which are substances that move when the head rotates or tilts (Myers).

  • Vestibular Sense: the sense of body movement and position, including sense of balance.
    • Movement affects the vestibular sense by stimulating hairlike receptors in the semicircular canals and vestibular sacs (Myers).
    • The receptors in the semicircular canals and vestibular sacs send messages to the cerebellum enabling us to sense our body position and maintain balance--the vestibular sense (Myers).
    • millions of position and motion sensors are all over our body in the muscles, tendons, and joints.(Myers)
    • Example: The ability to balance a large object on one's head.

Sensation Vs Perception
~> Absolute Threshold is a measured point to which a sound or sensation is noticed, a movement sound or smell will go unnoticed if it does not reach the point
  • Sensation refers to the bottom up process by which the physical sensory system receives and represents stimuli.(Myers)
  • Perception refers to the mental process of organizing and interpreting the sensory input.(Myers)
  • Sensory and Perceptual processes work together to help us sort out the complex images in gestalts, to integrate pieces of information into meaningful wholes.
  • sensory adaptation is when a certain sensation sound or smell becomes so common it soon goes unnoticed like the feeling of the chair one sits in or the sound of of the a/c or the smell of your own house
  • REST- Stands for Restricted Environmental Stimulation Therapy, and is used when trying to reduce stress and unwanted behaviors by putting a patient into a bath in a dark room (also called a sensory deprivation tank, or an REST tank) to lower stimulation

  1. ^ Myers, David G. Myers' Psychology for AP. Seventh ed. New York, NY: Worth, 2004. Print.
  2. ^ McEntarffer, Robert, and Allyson Weseley. Barron's AP Psychology. Fifth ed. Hauppauge, NY: Barron's Educational Series, 2012. Print.
  3. ^ McEntarffer, Robert, and Allyson Weseley. Barron's AP Psychology. Fifth ed. Hauppauge, NY: Barron's Educational Series, 2012. Print.