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Sensation and Perception (Object recognition (Gestalt Principle (Proximity…

- - - - Distal stimuli - ex. campfire
      - Proximal stimuli - photons that reach the eye and heat
    - - Ganglia are collections of neuron cell bodies found outside the CNS
      - Project areas - where the sensory input is further analyzed
    - - Photoreceptors - respond to electromagnetic waves in visible spectrum
      - Hair cells - respond to movement of fluid in inner ear structure
      - Nocireceptors - respond to pain
      - Thermoreceptors - respond to change in temp
      - Osmoreceptors - respond to osmolarity of blood
      - Olfactory receptor - smell - respond to volatile compounds
      - Taste receptors - respond to dissolved compounds
  - - - Threshold of converting a stimuli into action potental - sensation threshold
    - - Threshold of perceiving an already sensed stimuli
        
        Discrimination testing - increase the difference between two things until the difference is perceived
    - - Just noticable difference (jnd) -min diff in magnitude between two stimuli before one can perceive this difference
        
        Weber's law
        
        the ratio of the difference that can be perceived over the original amout -- the law says this ratio is accurate for all sensory modalities except in extremely high or low ends of each range
  - - - The tendency of subjects to systematically resond to a stimulus in a particular way duue to nonsensory factors
    - - Catch trial - a signal is presented
      - Noise trial - a signal is not presented
      - 4 possible outcome (hit, miss, false alarm, correct negative)
- - - - Covers most of the exposed portion of the eye (the white of the eye) - it is a think structural layer
      - Does not cover Cornea
    - - Choroidal vessels
        
        f: Complex intermingling of blood vessels between the sclera and the retina
      - Retinal vessels
    - - inner most layer of the eye - F: contains the actual photoreceptors that tranduce light into electrical information the brain can process
      - screen with neural elements and blood vessels
      - considered a part of the CNS - it dvelops as a outgrowth of brain tissue.
      - Duplexity or duplicity theory of vision
        
        retina contains two kinds of photoreceptors - one to specialize in detecting light and dark - the other specialized for color detection
      - 6 million cones and 120 million rods
        
        cones - F: used for color vision and to sense fine details - most effective in bright light
        
        three forms depending on the wavelength they best absorb
        
        S - short - blue
        
        M - medium - green
        
        L - long - red
        
        Rods - F: more functional and allow sensation of light and dark - permit night vision
        
        rhodspin - pigment that allows for dark and light
      - Central section - macula
        
        centermost point - fovea - only cones
        
        the concentration of cones lower as we get further away from the center and more rods as we get furhter away
    - - F: gathers and focuses the incoming light
    - - Dilutor pupillae
        
        F: muscle that opens under sumpathetic stimulation
      - Constructor pupillae
        
        F: constricts the pupil under parasympathetic stimulation
      - Iris is continous with the choroid
    - - F: produces the aqueous humor that bathes the front part of the eye before draining into the canal of Schlemm
      - Ciliary muscle
        
        Contraction is under parasypathetic control
        
        when muscle contracts it pulls on thhe supensory ligaments and changes the shape of the lense - accomodation
    - - lies right behind the Iris
      - F: controls the refraction of the incoming light
    - - bipolar, ganglion, horizontal and amacrine cells
        
        bipolar - highlight gradients between adjacents rods aor cones
        
        bipolar cells synapse ith ganglion cells
        
        ganglion cells group together to form optic nerve
        
        the cells are in front of the cones and rods - the signals are moving towards the front of the eye.
        
        the more cones or rods go into a ganglion - the less resolution there is
        
        with cones, less cones go into a ganglion - more color resolution compared to black and white
        
        amacrine and horizontal cells - receive input from multiple retinal cells in the same area before the information is passed on to the ganglion cell
        
        accentuate slight differences between the visual info in each bipolar cell
        
        important for edge detection
  - - - info goes to
        
        lateral geniculate nucleau of the thalamus
        
        through radiation in temporal and parietal lobe to the visual cortex in the occipital lope
        
        superior colliculus - controls some responses to the visual stimuli and reflexive eye movements
  - - - ability to simultanously analyze and combine infor regarding color, shape and motion - these features are compared to memories to determine what is being viewed.
      - not only a psychological model - in neurosceince - this is called feature detection
      - Color - cones responsible for color vision
      - Shape - parvocellular cells - low temporal resolution, high spatial resolution.
      - Motion - magnocellular cells - high temporal resolution, low spatial resolution
- - - - sits within a bony labyrinth
        
        cochlea
        
        Scalae
        
        Organ of Corti
        
        The main hearing apparatus
        
        Rests on basilar membrane
        
        Composed of thousands of hair cells bathed in endolymph
        
        tectorial membrane
        
        on top of organ of Corti and it is relatively immobile
        
        The movement of hair is transmitted into an electrical signal which is carried to the CNS via the auditory (vestibulocochlear) nerve
        
        Two other scalae
        
        filled with perilymph
        
        Continous with the round and oval window of cochlea
        
        The sound enters the cochlea via the oval window
        
        causes vibration in the perilymph
        
        1 more item...
        
        The round window is covered with a membrane and it allows the perlilymph (which is a fluid and basically incompressible) to move within the cochlea.
        
        vestibule
        
        Refers to portion of the bony labyrinth that contains the utricle and the saccule
        
        The utricle and saccule are sensitive to linear acceleartion - used as part of the balancing apparatus to determine one's orientation in three dimensional space.
        
        The utricle and saccule are covered with modified hair cells that are covered in otolith. As the body accelerates, otolith with resist that motion - this bends and stimulates the underlying hair cells which send signal to brain.
        
        semicircular canals
        
        sensistive to rotational acceleration
        
        Three semi-circular canal
        
        All arrange perpendicularly and they end in a swelling called ampulla
        
        Ampulla is where all the hair cells located
        
        When the head rotates, the endolymph in the canals resists the motion and moves the hair cells under it -- then a signal is sent to the brain
      - these structures are continous with each other
      - They are filled with membranous labyrinth
        
        bathed potassium rich fluid called endolymph
      - perilymph
        
        suspends the membranous labyrinth in the bony labyrinth
        
        transmits vibrations from the outside world and cushions the inner ear structure
    - - F: houses the ossicles - the three smallest bones in the body
        
        F: transmit and amplify the vibrations from tympanic membrane to the inner ear
        
        malleus (hammer)
        
        affixed to the eardrum and it acts on the incus
        
        Stapes (stirrup)
        
        base plate of stapes rests in the oval window of cochlea and this is the entrace to the inner ear
        
        Incus (anvil)
        
        it acts on the stapes
        
        Eustachian tube
        
        connects the middle ear to the nasal cavity
        
        helps equalize pressure between the middle ear and the environment
    - - Pinna or auricle
        
        F: channel sound waves into the external auditory canal which directs the sound waves to the tympanic membrane (eardrum)
        
        Eardrum's rate of movement depends on the frequency of the sound wave and loud sounds lead to increased amplitute of the eardrum
  - - - swaying opens the ion channels
        
        causes receptior potential
    - - these are involved in amplifying the incoming sound
    - - Location of the hair cell on the basilar membrane determines the perception of the pitch when it is vibrated
        
        the hair cells located closer to the oval window detect high-freq pitches
        
        hair cells located further from the oval window detect higher frequency pitches
        
        The basical membrane is tonotopically organized
  - - - brainstem (Most)
        
        ascends to the medial geniculate nucleus (MGN) of the thalamus
        
        auditory cortex in the temporal lobe for sound processing
      - superior olive
        
        localizes the sound
      - inferior colliculus
        
        involved in startle reflex and helps keep the eyes fixed on a point while the head is turned (vestibulo-ocular reflex)
- - - - monocular cues
        
        relative size of the object, partial obscuring of one object by another, the convergence of parallel lines at a distance, position of an object in the visual field and lighting and shadowing
      - binocular cues
        
        slight difference in images projected on the two retinas, the angle between the two eyes to bring an object into focus
  - - - elements close to one another tend to be perceived as a unit (if dots are arranged in a triangle shape we seem them as a triangular formation rather than dots)
    - - objects that are similar tend to be grouped together
    - - elements that appear to follow in the same pathway tend to be grouped together - we like to perceive flow and not abrupt changes
    - - perceiving contours - shapes that are not actually present in the stimulus
    - - perceptual organization will always as regular, simple and symmetirc as possible
    - - when a space is enclosed byy a contour it tends to be perceived as ac omplete figure
- - - - Effects animal's social, foaging and sexual behaviour - debatable what effects it has on humans
    - - inhaled through nasal passage
        
        contact olfactory nerves in the olfactory epithelium
        
        receptor cells are activated sending signal to olfactory bulb
        
        the signals are relayed via the olfactory tract to the higher regions of the brain (including the limbic system)
  - - - Individual interplay between taste and smell -affected by non chemical stimuli like texture and mood
    - - Saltiness - reaction to alkali metal, triggered by sodium in table salt
      - Sourness is a reaction to acid such as lemon juice or vinegar
      - Sweet, bitter, savoury flavours are also triggered by specific molecules binding to receptors
  - - - Pacinian corpuscles 0 respond to deep pressure and vibration
      - Meissner corpuscles: respond to light touch
      - Merkle cells: respond to deep pressure and texture
      - Ruffini endings - respond to stretch
      - Free nerve endings - respond to pain and temperature
    - - minimum distance necessary between two points of stimulation on the skin such that two different stimuli are felt
      - depends on the density of the nerves in a particular skin area
    - - Temp is judge in reference to the physiological zero or the normal temperature of the skin (btwn 86 and 97 degree F)- cold means temp is lower than PZ, warm means temp is higher than PZ
    - - Nociceptors - variety of sensory receptors
      - Thresholds vary from one person to the other
      - Gate theory of pain
        
        special gating mechanism can turn pain signals on and off - affecting whether ot not to perceive pain
        
        the spinal cord is able to prefeentially forward the signal from other touch modalities (pressure, temperature) to the brain - reducing the sensation of pain
        
        Ex. rubbing after we bump out knee against a surface
  - - - Ability to tell one's body in space
      - The ability to tell where your hand is in space even when your eyes are closed