Sensation And Perception Flashcards
What are ganglia?
Collections of neuron cell bodies found outside the CNS
What are nociceptors?
Respond to painful or noxious stimuli
Absolute threshold:
Minimum of stimulus energy needed to activate sensory system
Threshold of conscious perception:
Stimulus arrives at CNS but does not reach higher order brain regions
Difference threshold/just-noticeable difference
Minimum difference in magnitude between two stimuli before one can perceive difference
Weber’s law as it relates to just-noticeable difference
Constant ratio between change in stimulus magnitude
For higher magnitude stimuli, the difference must be larger to produce the jnd
Signal detection theory
Effects of experiences, memory, motives, and expectations
Changes in our perception of the same stimuli depending on both internal and external context
Eye is supplied with nutrients by which vessels?
Choroid also and retinal
Position of lens?
Right behind iris to help control refraction of incoming light
Iris is continuous with:
The choroid
The retina:
Back of the eye; converts incoming photons of light to electrical signals
Cones used for
Colour vision and sense fine details; more effective in bright light
Rods used for
Sensation of light and dark; low sensitivity to details
Not involved in colour vision but permit night vision
Central section of the retina called the macula has a high concentration of
Cones
Blind spot
Where the optic nerve leaves the eye; no photoreceptors here
Amancrine and horizontal cells receive input from
Multiple retinal cells before passing information to ganglion
Help accentuate differences between visual information; increase perception of contrasts -> setting the edge
Explain the visual pathways:
Each eye’s R visual field projects to left retina; left projects to right
@optic chiasm, fibres from nasal half (L eye’s left visual field and R eye’s R visual field) cross over
All fibres corresponding to left visual field project to R brain, reorganised pathways called optic tracts
Parvocellular detects?
Shape
High colour spatial resolution, see fine detail thoroughly
Motion detected by what kind of optical cells?
Magnocellular
Provides blurry but moving image
Outer part of the ear called?
Pinna/auricle
Purpose of the eardrum/tympanic membrane:
Vibrates in phase with incoming sound; louder sounds have greater intensity, corresponding to an increased amplitude of this vibration
Name the 3 ossicles:
Malleus, incus, stapes
Help transmit and amplify
Inner ear contains:
Cochlea, vestibule, and semicircular canals
Filled with endolymph
Suspended by perilymph
Cochlea split into
Organ of corti consisting of thousands of hair cells bathed in endolymph
Sensitive to linear acceleration, orientation, balancing
Vestibule consisting of utricle and saccule
Sensitive to rotational acceleration
Semicircular canals
Lateral geniculate nucleus for
Medial geniculate nucleus for
Light/vision
Sound
Pacinian corpuscles respond to
Deep pressure and vibration
Meissner corpuscles respond to
Light touch
Merkel cells respond to
Deep pressure and texture
Ruffini endings respond to
Stretch
Bottom up (data driven) processing
Object recognition by parallel processing and feature detection
Top-down processing
Driven by memories and expectations that allow brain to recognise object first and then components
Gestalt principles: ways for brain to infer missing parts of picture
Law of proximity - perceived as a unit
Law of similarity - similar objects grouped together
Law of good continuation - follow same pathway rather than abrupt changes
Subjective contours - perceiving contours; shapes that are not actually present
Law of closure - space enclosed by contours tends to be perceived as complete figure
Law of pragnanz - perceptual organisation will always be regular, simple, and symmetric
