Ch. 2: Sensation and Perception Flashcards
defn: sensation vs. perception
sensation = transduction = taking the physical, electromagnetic, auditory, and other information from our internal and external environment and converting this info into electrical signals in the nervous system = a raw signal
- performed by receptors in. the peripheral nervous system, which forward the stimuli to the central nervous system in the form of action potentials and neurotransmitters
perception = processing this information within the CNS in order to make sense of the info’s significance = includes both the external sensory experience and the internal activities of the brain and spinal cord
- helps make us make sense of the world
defn: sensory receptors
neurons that respond to stimuli by triggering electrical signals that carry information to the CNS
defn: psychophysics
the relationship between the physical nature of stimuli and the sensations and perceptions these stimuli evoke
defn: ganglia
collections of neuron cell bodies found outside the CNS
defn: projetion areas
further analyze sensory input after stimuli are transduced into electrical signals
func: photoreceptors
respond to electromagnetic waves in the visible spectrum (sight)
func: mechanoreceptors
respond to pressure or movement (hair cells respond to movement of fluid in the inner ear)
movement, vibration, hearing, rotational and linear acceleration
func: nociceptors
respond to painful or noxious stimuli
somatosensation
func: thermoreceptor
respond to changes in temperature
thermosensation
func: osmoreceptors
respond to osmolarity of the blood (water homeostasis)
func: olfactory receptors
respond to volatile compounds
smell
func: taste receptors
respond to dissolved compounds
taste
defn: threshold
the minimum amount of a stimulus that renders a difference in perception
defn: absolute threshold
the minimum of stimulus energy that is needed to activate a sensory system (how bright, loud, or intense a stimulus must be before it is sensed)
a threshold of sensation, not perception
defn: threshold of conscious perception
the level of intensity that a stimulus must pass in order to be consciously perceived by the brain
defn: subliminal perception
information that is received by the CNS but does not cross the threshold of conscious perception
what is the difference between absolute threshold and the threshold for conscious perception?
a stimulus below the absolute threshold will not be transduced and never reaches the CNS
a stimulus below the threshold of conscious perception arrives at the CNS, but does not reach the higher order brain regions that control attention and consciousness
defn: difference threshold (just noticeable difference)
the minimum change in magnitude required for an observer to perceive that two stimuli are diferent
defn: discrimination testing
participant is presented with a stimulus
stimulus is varied slightly and researchers ask the participant to report whether they perceive a change
the difference continues to be increased until the participant reports they notice the change, and this interval is recorded as the just noticeable difference
defn: Weber’s law
difference thresholds are proprotional and must be computed as percentages
defn: signal detection theory
how internal (psychological) and external (environmental) factors influence threshold of sensation and perception
defn: noise trials vs. catch trials
noise trials = trials in which the signal is presented
catch trials = trials in which the signal is not presented
after each trial, the subject is asked to indicate whether or not a signal was presented
defn: hit vs. miss vs. false alarm vs. correct negative
HIT = a trial in which the signal is presented and the subject correctly perceives the signal
MISS = a trial in which the subject fails to perceive the presented signal
FALSE ALARM = a trial in which the subject indicates perceving the signal, even though the signal was not presented
CORRECT NEGATIVE = a trial in which the subject correctly identifies that no signal was presented
defn: adaptation
our ability to detect a stimulus can change over time through this
can have a physiological (sensory) component and a psychological (perceptual) component
one way in which the mind and body try to focus attention on only the most relevant stimuli
Defn and func: sclera
Thick structural layer of the eye that covers the eye (this is the white of the eye)
Defn and func: choroidal vessels
Blood vessel intermingling complex between the sclera and the retina
What are the two sets of blood vessels that supply the eye with nutrients?
Choroidal vessels and retinal vessels
Defn and func: retina
Innermost layer of the eye (at the back of the eye); contains the actual photoreceptors that transduce light into electrical info for the brain
like a screen made of neural elements and blood vessels
considered to be part of the CNS
Defn and func: cornea
Clear, domed window at front of the eye
Gathers and focuses incoming light
What are the two divisions of the front of the eye and where are they located in relation to the iris?
Anterior chamber: in front of the iris
Posterior chamber: between the iris and the lens
Defn and components (and their functions): iris
Iris: colored part of the eye
Composed of 2 muscles: dilator pupillae (opens pupil under sympathetic)
constrictor pupillae (constricts pupil under parasympathetic)
Defn and func: choroid
Vascular layer of connective tissue that is continues with the iris
Provides nourishment and surrounds retina
Func: ciliary body
Produces the aqueous humor that bathes the front of the eye
Cont. with the iris
Func: canal of Schlemm
Where the aqueous humor drains
Loc and func: lens
Lies behind the iris
helps control refraction of incoming light
Func: ciliary muscle
Part of the ciliary body, under parasymp. control
When it contracts, it pulls the suspensory ligaments and changes the shape of the lens to focus on an image as distance varies
What is the process that the ciliary muscle executes called?
Accommodation (ciliary muscle contracts, pulling the suspensory ligaments, and changing the shape of the lens to focus on an image as distance varies)
Defn and loc: vitreous humor
Transparent gel that supports the retina
lies behind the lens
Defn: duplexity/duplicity theory of vision
The retina contains 2 kinds of photoreceptors: light-and-dark detection AND color detection
Mnemonic: cones v. rods
Cones are for Color
Rods function best in Roduced light
Func: Cones
Used for color vision and to sense fine details
Most effective in bright light
Types of cones
S: short (blue)
M: medium (green)
L: long (Red)
Cones are named for the wavelengths of light they best absorb
Func: Rods
Rods are highly sensitive to photos, easier to stimulate than cones so they work best in low light
Can be stimulated by light of any color, but only allow sensation of light and dark (not good for fine details –> rods are spread over a large area of the retina)
Defn and func: rhodopsin
The pigment type that all rods contain
Is part of why rods are so sensitive
Loc and defn: macula
the central section of the retina
high concentration of cones
Defn and loc and func: fovea
Contains only cones
The centermost region of the macula
most functional in normal daylight vision bc high concentration of cones
Defn: optic disc
A region of the retina where the optic nerve exits the eye
Devoid of photoreceptors –> so there is a blind spot