Sensation and Perception Flashcards
Sensation
intake of sensory information; conversion of physical, auditory, etc information into electrical signals for nervous system
Perception
processing of sensory information to make sense of its significance
Sensory Receptors
neurons that respond to stimuli and trigger electrical stimuli
Ganglia
collections of neuron cell bodies found outside the central nervous system
Name 7 sensory receptors
Photoreceptors - respond to electromagnetic waves in the visible spectrum
Hair cells - respond to movement of fluid in the inner ear structures
Nocireceptors - respond to painful or noxious stimuli
Thermoreceptors - respond to changes in temperature
Osmoreceptors - respond to the osmolarity of the blood
Olfactory receptors - respond to volatile compounds
Taste receptors - respond to dissolved compounds
Threshold
the minimum amount of stimulus that renders a difference in perception
Absolute Threshold
minimum of stimulus energy that is needed to activate a sensory system
Subliminal Perception
Perception of a stimulus below a given threshold. The stimulus arrives at the CNS but does not get to higher order brain regions that control attention and consciousness
Discrimination testing
having a participants shown two stimulus and record when they can tell a difference between the two in order record human perceptive ability
Difference threshold
aka “just-noticeable difference (jnd)” minimum difference in magnitude between two stimuli before one can perceive this difference
Weber’s Law
there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus
Signal Detection Theory
perception of stimuli is affected by nonsensory factors, such as experiences, motives and expectations, evaluates changes in perception based on internal and external factors
Response bias
the tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors
Adaptation
a change in our detection of a stimulus over time
What is the pathway for stimulus to reach conscious perception?
Sensory receptor —> afferent neuron —> sensory ganglion —> spinal cord —> brain (projection areas)
What is the sclera?
the white of the eye that covers most the exposed portion of the eye except the cornea, provides structural support
What supplies the eye with blood?
the choroidal vessels - complex intermingling of blood vessels between sclera and retina and retinal vessels
What is the retina?
innermost layer of the eye which contains the actual photoreceptors that transduce light into electrical information the brain can process
What is the cornea?
a clear, domelike window in front of the eye which gathers and focuses incoming light
Describe the iris
The colored part of the eye, the iris, has two muscles. The dilator pupillae which opens under sympathetic stimulation and the constrictor pupillae which constricts under parasympathetic stimulation.
What does the lens do?
helps control the refraction of incoming light and found behind the iris
Describe the retina
located in the back of the eye, it’s like a screen of neural elements and blood vessels. It works to convert incoming photons of light into electrical signals
Describe the structure of the eye
Front to Back: cornea, anterior chamber, then the iris/pupil, posterior chamber, lens. The iris merges into the ciliary body/muscle which then merges into the choroid as you go around and to the back of the eye. The ciliary creates aqueous humor which is drained through the canal of schlemm.
What does the ciliary body do?
it produces aqueous humor that bathes the front part of the eye
How does accommodation work?
Accommodation is changing the shape of the lens due to light. This is accomplished by the ciliary muscle reacting to light via the parasympathetic system, the contraction pulls on suspensory ligaments and changes the shape of the lens.
What is the gel that supports the eye called?
the vitreous
What is the pathway light takes through the eye?
First it goes through the clear cornea which gathers the light and focuses it, next it will go through the pupil and into the lens which helps control the refraction of light, then the light goes through the gel of the eye (vitreous) to the retina in the back, which then coverts the light into neural signals, the retina is connected to bipolar cells then ganglion cells which then lead into the optic nerve
Duplicity Theory of Vision
states that the retina contain two kinds of photoreceptors: those specialized for light-and-dark detection and those specialized for color detection
Cones vs Rods
Cones - for color vision (6 million)
Rods - light and dark (120 million)
Both make up the retina
What are the fovea and macula?
The macula is the center section of the region which contains high concentration of cones and the fovea is the most center point of the retina and only contains cones
Why are amacrine and horizontal cells important?
They increase of perception of contracts through edge detection
What is parallel processing?
ability to simultaneously analyze and combine information regarding color, shape and motion
What kind of cells detect shape?
parvocellular cells (only work with stationary or slow moving objects)
What kind of cells detect motion?
magnocellular cells
What is the function of the pinna?
aka “auricle” - channel sound waves into the external auditory canal
What are the ossicles and their function?
malleus (hammer), incus (anvil), and stapes (stirrup). they act to transmit and amplify vibrations from the eardrum to the inner ear
What is the function of the Eustachian tube?
it helps equalize the pressure between the middle ear and the environment
Describe the cochlea
Spiral shaped organ which is divided into three parts called scalae
(1) Organ of Corti - middle scala which has the hearing apparatus, this rests of the basilar membrane
The other two scala are like sacs filled with perilymph through which vibrations are transmitted
What is the function of the vestibule?
to detect linear acceleration through the use of utricle and saccule
What is the function of the semicircular canals?
to detect rotational acceleration through the bending of hair cells via endolymph fluid moving
What is place theory?
states that the location of a hair cell on the basilar membrane determines the perception of pitch when that hair cell is vibrated. Highest frequency pitches cause vibrations of the membrane close to the oval window
List the auditory pathway from entering the ear to the brain
pinna –> external auditory canal —> tympanic membrane –> malleus –> incus —> stapes —> oval window —> perilymph in cochlea —> basilar membrane —> hair cells –> vestibulococholear nerve –> brainstem —> medial geniculate nucleus (MGN) of thalamus –> auditory cortex (temporal lobe)
What are smell receptors called?
olfactory chemoreceptors/nerves
List the olfactory pathway to the brain
odor molecule –> nasal passage —> olfactory nerves –> olfactory bulb —> olfactory tract —> limbic system
What is somatosensation?
the complex interplay between pressure, vibration, pain and temperature
Pacinian corpuscles
respond to deep pressure and vibration
Meissner corpuscles
respond to light touch
Merkel cells (discs)
respond to deep pressure and touch
Ruffini endings
respond to stretching
Free nerve endings
respond to pain and temperature
What is a two point threshold?
refers to the minimum distance necessary between two points of stimulation on the skin such that they points will be felt as two distinct stimuli
What is physiological zero?
the normal temperature of the skin. Objects feel “hot” or “cold” based on their deviation from this number
What is the gate theory of pain?
proposes that there is a special “gating” mechanism that can turn pain signals on or off, affecting whether or not we perceive pain.
What is proprioception?
aka “kinesthetic sense” refers to the ability to tell where one’s body is in space
What is bottom up processing?
“data driven” the brain takes individual sensory stimuli and combines them to get a big picture
What is top down processing?
“concept driven” allows the brain to recognize the whole object and then recognize the individual components based on expectations
What is perceptual organization?
the ability to use top and bottom down processing along with all other sensory clues to create a complete picture
What are monocular cues?
cues that can be interpreted with only one eye
(1) relative size of objects
(2) partial obscuring of one object by another
(3) convergence of parallel lines in the distance
(4) position of an object in the visual field
(5) lighting and shadowing
What are binocular cues?
cues that need both eyes to be interpreted
(1) slight differences in images projected on the two retinas
(2) angel required between the two eyes to bring an object into focus
What are some Gerstalt principles?
ways for the brain to infer missing parts of a picture when it is incomplete
(1) Law of proximity - elements that are close together tend to be perceived as a unit
(2) Law of similarity - objects that are similar tend to be grouped together
(3) Law of good continuation - elements that appear to follow in the same pathway tend to be grouped together, tendency to perceive continuous patterns rather than abrupt changes
(4) Subjective contours - perceiving shapes that are not actually there
(5) Law of closure - when a space is enclosed by a contour it tends to be perceived as a complete figure
Law of Pragnanz
states that perceptual organization will always be as regular, simple and symmetric as possible
