Sensation and Perception Flashcards
Define sensation
conversion, transduction, or physical, or electromagnetic, auditory and other information from the internal and external environment into signals in the nervous system
Define perception
processing of sensory information to make sense of its significance
Describe how a sensation is received
sensory neurons are associated with sensory ganglia which are collections of cell bodies outside of the CNS
these stimuli are transmitted to projection areas in the brain which analyze the input
Define a threshold and describe the different kinds of threshold
the minimum stimulus that causes a change in signal transduction
absolute threshold- minimum of stimulus energy that is needed to activate a system
threshold of conscious perception- minimum stimulus energy that will create a signal large enough and long enough in duration that it will be brought into awareness
difference threshold- min diff in magnitude between 2 stimuli that will allow someone to perceive the differences
Define webers law
the jnd for a stimulus is proportional to the magnitude of a stimulus and this proportion remains constant
Describe signal detection theory
effects of non sensory factors such as experiences, motives, and expectations on the perception of stimuli
Define sclera
thick structural layer that covers the eye
What is the blood supply to the eye?
choroid vessels and the retinal vessels
Describe the retina
is the innermost later and contains the photoreceptors including the rods and the cones
cones are used for color vision and rods are used for the sensation of light and dark due to rhodopsin
Define the macula
center portion of the retina that contains a high concentration of cones and includes the fovea
Describe what happens as you move farther or closer away from/to the fovea?
As you move towards the fovea, the concentration of cones increases and the visual acuity is at its best. The fovea is most sensitive in daylight situations
AS you move away, the concentration of rods increases and the concentration of cones decreases. there is more night vision but less acuity
Describe the blind spot that is present in the eye
occurs where the optic nerves leave the eye and there are no photoreceptors
Describe the path of light through the eye
passes first through the cornea where the light is gathered and focused then it foes through the anterior chamber, posterior chamber, and through the iris and to the lens which refracts the incoming light, then it goes into the retina to the rods and cones, and to the brain via the optic nerve where it is perceived by the brain
What are the various muscles that are involved in vision? Describe it in terms of sympathetic versus parasympathetic
Under sympathetic (fight or flight)
-the dilator pupillae which opens the pupil
Under parasympathetic stimulation
-the constrictor pupillae constricts the pupil and then the ciliary muscle is contracted which changes the shape of lens, which contracts the suspensory ligaments, which changes the shape of the lens, leading to accommodation
Describe how the signals from the rods and cones are able to get to the optic nerve? In terms of neurons
They connect to each other with bipolar cells which then synapse with ganglion cells, who cluster together to form the optic nerve
amacrine cells also receive input from retinal cells and pass on info the the ganglion cells (edge detection)
Describe the visual pathway in the brain, where do the right and left visual fields go?
the left visual fields go to the right side of the brain and the right goes to the left side of the brain
Where do the visual paths travel after going through the optic chiasm?
To the lateral geniculate nucleus in the thalamus, the visual cortex of the occipital lobe, or the superior colliculus
Define parallel processing
the ability to simultaneously analyze and combine information regarding color, shape, and motion which can then be compared to our memories
How are shapes identified in the visual system?
parvocellular cells which lead to spatial resolution
How is motion detected in regards to vision?
magnocellular cells because they have high temporal resolution
Describe the inner ear in regards to sensations that can be detected
The cochlea detects sounds
The utricle and saccule detects linear acceleration
and the semicircular canals detect rotational acceleration
Describe the auditory pathway
Travels from the cochlea to the vestibular nerve and then foes to the medial geniculate nucleus of the thalamus and then to the auditory cortex of the temporal lobe
Define somatosensation
the four touch modalities; pressure, vibration, pain, and temperature
Describe bottom up processing
recognition of objects by parallel processing and feature detection; slower but less mistakes
Describe top down processing
recognition of an object through memories and expectations, with little attention to detail; it is fast but accident prone
Define a Gestalt principle
the ability of the brain to infer missing parts of a picture and fill in the gaps basically
What are the 6 “laws” of the Gestalt principle?
- law of proximity; if they are close together they can be perceived as one unit
- law of similarity; similar objects are grouped together
- law of good continuation- elements that tend to follow the same pathway may be grouped together
- subjective contours- using the env or surroundings to infer the edges of something
- law of closure-brain completes a line
- law of pragnanz- perceptual organization will always be as symmetrical as possible
