Sensation and Perception (2) Flashcards
Sensation
conversion of physical, electromagnetic, auditory, and other info from the internal and external environment into electrical signals in the nervous system.
Perception
processing of sensory information to make sense of its significance.
Photoreceptors
responds to electromagnetic waves in the visible spectrum (vision)
Nociceptors
responds to painful or noxious stimuli (somatosensory)
Olfactory receptors
responds to volatile compounds (smell)
Taste receptors
respond to dissolved compound (taste)
Threshold
the minimum stimulus that causes a change in signal transduction
Absolute threshold
minimum of stimulus energy that is needed to activate a sensory system.
The threshold of conscious perception
minimum of stimulus energy that will create a signal large enough in size and long enough in duration to be brought in awareness.
difference threshold or just-noticeable difference (jnd)
the minimum difference in magnitude between two stimuli before one can perceive this difference.
jnd for sound frequency is more accurately quantified as 0.68%.
Weber’s Law
states that there is a constant ratio between the changes in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus.
Signal detection Theory
focuses on the changes in our perception of the same stimuli depending on both internal and external context.
Cornea (eye)
gathers and focuses incoming light
pupil
allows passage of light from anterior to posterior chamber
Iris
- Dilator pupillae
- Constrictor pupillae
Iris: controls the size of the pupil
Dilator pupillae –> opens the pupil under sympathetic
Constrictor pupillae –> constricts pupil under parasympathetic.
Cilary body
produces aqueous humor; accommodation of the lens
Lens
refracts the incoming light to focus it on the retina
Retina
detects images
Sclera
provides structural support.
Cones and Rods
Cones –> color vision
Rods –> contains a single pigment called rhodopsin permits for night vision.
Mnemonic:
Cones for COLOR
Rods for RAAT
Optic nerve
rods and cones are connected with bipolar cells, bipolar cells synapse with ganglion cells, which group together to form Optic nerve.
Visual Pathway
Cornea –> pupil –> vitreous humor –> retina (rods + cones to bipolar cells to ganglion cells) –> optic nerve –> optic chasm –> optic tract –> LGN (lateral geniculate nucleus in thalamus) –> radiation through parietal and temporal lobe –> visual cortex in occipital lobe
Parallel Processing
Ability to simultaneously analyze and combine information regarding color, shape, and motion.
Parvocellular cells
cells that detect shapes, very high color spatial resolution.
only work with stationary or slow-moving objects.
Magnocellular cells
cells that detect motion, because it has a high temporal resolution.
Tymphanic membrane ( eardrum)
vibrates as sound waves enter the ear. Also divides outer and inner ear.
Ossicles (middle ear)
consists of malleus (hammer), incus (anvil), and stapes (stirrup).
Bony labyrinth
contains the cochlea, vestibule, and semicircular
canals
These structures contain endolymph.
Endolymph
found in the membranous labyrinth
Perilymph
found in bony labyrinth.
transmits vibrations from the outside world and cushions the inner ear structures.
Cochlea: spiral-shaped divided into 3 parts called scalae
middle scalae: houses hearing apparatus called the organ of Corti, rests on the basilar membrane.
The organ of Corti consists of hair cells which bathe in endolymph.
Stereocilia
long tufts on the surface of hair cells. As vibration reaches to the basilar membrane, stereocilia go back and forth. This motion opens ion channels, causing receptor potential.
Auditiory Pathway
pinna –> external auditory canal –> tympanic membrane –> malleus –> incus –> stapes –> oval window –> perilymph of cochlea –> basilar membrane –> hair cells –> vestibulocochlear nerve –> brain stem –> MGN of thalamus –> auditory cortex (temporal).
Vestibule
a portion of the bony labyrinth, contains utricle and saccule.
Utricle and Saccule–> sensitive to linear acceleration, part of balancing apparatus determine orientation in 3D. contained modified hair cells covered with otolithus.
Semicircular canals
sensitive to rotational acceleration. They arranged perpendicular to each other. Hair cells are located in the ampulla. When the head rotates, the endolymph in the semicircular canal resists motion, bending the hair cells, sending signals to the brain.
Place Theory
states that the location of hair cells on the basilar membrane determines the perception pitch when that hair cell is vibrated.
High-frequency pitch cause vibration close to oval window
Low-frequency pitch cause vibration away to oval window
Pacinian corpuscles
respond to deep pressure and vibration
Meissner corpuscles
respond to light touch
Merkel cells
respond to deep pressure and texture
Ruffini cells
respond to stretch
free nerve ending
respond to pain and temperature
Physiological zero
normal temp of the skin to which objects are compared to determine if they feel warm or cold
Gate theory of pain
states that pain sensation is reduced when other somatosensory signals are present.
Bottom-up processing
recognition of objects by parallel processing and feature detection. slower but less prone to mistake.
Top-down processing
recognition of objects by memories and expectations. Faster but more prone to mistakes.
Perceptual organization
refers to our synthesis of stimuli to make sense of the world including the integration of depth, motion, form, and constancy.
