Flashcards in 6A: Sensing the environment Deck (79)
What is a threshold?
The minimum amount of stimulus required to cause an action potential
What is the absolute threshold?
The minimum intensity of a stimulus that one can detect
What is the difference threshold?
The minimum difference in intensity between two stimuli that one can detect; also known as the just noticeable difference
What does Webers Law indicate?
There is a constant ratio between the change in stimulus to produce a difference threshold and the magnitude of the original stimulus;
What is Weber's constant/fraction?
1/5 or 2%
What is Signal Detection Theory?
It states that nonsensory factors can influence thresholds; it focuses on changes in our perception of the same stimuli depending on psychological and environmental context;
The ability to discern between stimuli and noise
What are the parts of a signal detection experiment?
Consists of catch trials (where stimuli is present) and noise trials (where stimuli are absent)
What are the outcomes of a signal detection experiment?
HIT = signal present and detected
MISS = signal present and not detected
FALSE ALARM = single absent and detected
CORRECT NEGATIVE/REJECTION = single absent and not detected
What is sensory adaptation?
It is the ability of our bodies to become accustomed to a stimulus after repeated application of the stimulus; both the physiological and psychological component get decreased
What does sensory adaptation allow us to do?
It allows us to differentiate meaningful information from the background; unable to feel clothing after getting dressed
What do sensory receptors do?
They respond to stimuli and trigger electrical signals
What are sensory pathways?
Sensory pathways are nerve endings or sensory cells that receive stimuli and carry the information through sensory ganglia and arrive at the CNS
What are Ganglia?
Ganglia are found outside of the CNS and they are group of neuron cell bodies
What are Projection Areas?
Projection areas are portions of the brain that analyze the sensory input
What are the major sensory receptors?
Hair cells, Photoreceptors, Thermoreceptors, Mechanoreceptors, Osmoreceptors, Nocireceptors, Olfactory receptors, Chemoreceptors
What do Hair cells detect?
Movement of fluid in the inner ear
What are simple receptors?
Neurons with free nerve endings
What are complex neural receptors?
Nerve endings that are enclosed in connective tissue capsules
What are special senses receptors
These are neurons that release neurotransmitter onto sensory neurons that initiate action potentials
Which lobe of the brain is devoted to vision?
How does the eye receive nutrients?
Choroidal and retinal vessels
What is the duplicity theory of vision?
This theory posits that the retina contains two kinds of photoreceptors which are specialized for light and dark detection
What is the function of Rods? What kind of pigment(s) do they contain?
It functions in reduced illumination and allow for sensation of light and dark; they have a low sensitivity to detail; pigment = rhodopsin
What is the function of Cones? What kind of pigment(s) do they contain? How does the Fovea relate to cones?
It functions in color detection and sensing of fine detail; contain S, M and L pigments; Fovea only has cones so its important in visual acuity and sensitivity to daylight vision
What is the function of amacrine & horizontal cells?
They receive input from many of the retinal cells before it is passed onto the ganglion cells; they focus the slight differences between the visual information in each cell increases the perception of stimuli
What are the two muscles of the iris and what do they do?
Dilator pupillae = opens the pupil under sympathetic stimulation
Constrictor pupillae = constricts pupil under parasympathetic stimulation
What is the Choroid and what is its function?
It is a continuous structure of the iris along with the ciliary body; it produces aqueous humor and washes the anterior chamber of the eye
Where is the lens of the eye located and what is its function?
It's located behind the iris and controls the refraction of entering light
What is the function of the ciliary muscle (part of the ciliary body)?
It contracts under parasympathetic stimulation to change the shape of the lens (known as accommodation)