Topic 6A Flashcards
Weber’s Law
states that the difference threshold is proportional to the magnitude of the stimulus, where ΔI is the difference in threshold and I represent the initial stimulus; suggests that the just noticeable difference is a constant proportion of the original stimulus
signal detection theory
the detection of a stimulus depends on both the intensity of the stimulus and the physical/ psychological state of the individual. Basically, we notice things based on how strong they are and on how much we’re paying attention.
presbyopia
image focuses behind the retina; similar in a sense to hyperopia which is caused by an eyeball that is too short
Myopia
nearsightedness = eyeball is elongated and the image focus falls in front of the retina, so images in the distance are blurry but images nearby are clear
Rods
are strongly photosensitive and are located in the outer edges of the retina. They detect dim light and are used primarily for peripheral and nighttime vision.
Cones
weakly photosensitive and are located near the center of the retina. They respond to bright light, and their primary role is in daytime, color vision.
fovea
region in the center back of the eye that is responsible for acute vision. It has a high density of cones.
In humans, _____ far outnumber ____ in the fovea.
In humans, cones far outnumber rods in the fovea.
magnocellular (big cell) pathway
carries information about form, movement, depth, and differences in brightness
parvocellular (small cell) pathway
carries information on color and fine detail
Parallel processing
the use of multiple pathways to convey information about the same stimulus.
Feature detection
Once visual information reaches the visual cortex via parallel pathways, it is analyzed by feature detection. There are cells in the visual cortex of the brain that optimally respond to particular aspects of visual stimuli. These cells provide information concerning the most basic features of objects, which are integrated to produce a perception of the object as a whole.
Hearing
transduction of sound waves into a neural signal that relies on the structures of the ear
External ear
auricle/outer ear = visible structure of hearing The C-shaped curves of the auricle direct sound waves towards the ear canal, which enters into the skull through the external auditory meatus of the temporal bone. At the end of the auditory canal (external acoustic meatus) is the tympanic membrane (ear drum), which vibrates with the movement of air in sound waves.
Along the length of the auditory canal are ceruminous glands that contribute to the production of cerumen (earwax) which helps protect the tympanic membrane.
Middle ear
ossicles
Malleus (hammer)
- Incus (anvil)
- Stapes (stirrup)
‣ The malleus is attached to the tympanic membrane and articulates with the incus, which articulates with the stapes. The stapes is then attached to the inner ear at the oval window where the sound waves will be transferred to the inner ear
Internal ear
The inner ear is entirely enclosed within the temporal bone.
It has three separate regions:
- The cochlea: responsible for hearing
- The vestibule
- Semicircular canals: responsible for balance and equilibrium
Oval window
the connection b/t the middle & inner ear; it’s a membranous area at the entrance of the snailshaped cochlea. The vibrations transmitted through the ossicles pass into the cochlea by way of the oval window.
cochlea
composed of 3 chambers separated from one other by membranes.
◦ The scala vestibuli (upper chamber) and the scala tympani (lower chamber) extend the length of the cochlea and are continuous with a connection at the helicotrema
◦ The cochlear duct is the third, middle chamber positioned between the scala vestibuli and scala tympani.
◦ As the oval window is pushed in by sound waves vibrating from the ossicles, fluid within this tube is pushed along its length and the round window at its other end bulges out as a result of that movement.
Organ of Corti
a spiral organ that is the organ for hearing and contains the sensory receptors. It’s located throughout the cochlear duct.
◦ It’s composed of a lower basilar membrane against the scala tympani and an upper tectorial membrane within the cochlear duct
2 types of equilibrium:
Static (gravitational) equilibrium = involves the movement of the head w/ respect to gravity
◦ Dynamic (rotational) equilibrium = involves acceleration of the head in rotation, horizontal, and vertical movements
interaural level differences
refers to the fact that a sound coming from the right side of your body is more intense at your right ear than at your left ear because of the attenuation of the sound wave as it passes through your head
interaural timing differences
refers to the small difference in the time at which a given sound wave arrives at each ear. Certain brain areas monitor these differences to construct where along a horizontal axis a sound originates.
Temporal theory of pitch perception
asserts that frequency is coded by the activity level of a sensory neuron. This would mean that a given hair cell would fire action potentials related to the frequency of the sound wave.
place theory of pitch perception
suggests that different portions of the basilar membrane are sensitive to sounds of different frequencies. More specifically, the base of the basilar membrane responds best to high frequencies and the tip of the basilar membrane responds best to low frequencies. Therefore, hair cells that are in the base portion would be labeled as highpitch receptors, while those in the tip of basilar membrane would be labeled as low-pitch receptors.
inner hair cells
the primary auditory receptors and exist in a single row, numbering approximately 3,500.
stereocilia
from inner hair cells extend into small dimples on the tectorial membrane’s lower surface.
outer hair cells
are arranged in three or four rows. They number approximately 12,000, and they function to fine tune incoming sound waves
Merkel’s disks
ound in the upper layers of skin. They are densely distributed in the fingertips and lips. They are slowadapting, unencapsulated nerve endings, which respond to light touch
Meissner’s corpuscles
found primarily in the glabrous skin on the fingertips and eyelids. They respond to fine touch and pressure, but they also respond to low-frequency vibration or flutter.
Ruffini endings
aka bulbous corpuscles; they’re located deeper in the dermis, near the base. They are slow-adapting, encapsulated mechanoreceptors that detect skin stretch and deformations within joints.
Pacinian corpuscle
they’re located deep in the dermis are rapidly-adapting mechanoreceptors that sense deep, transient (not prolonged) pressure, and high-frequency vibration. Pacinian receptors detect pressure and vibration by being compressed, which stimulates their internal dendrites.
Proprioception
sense of the position of parts of our body and force being generated during movement.
Golgi tendon organs
they are proprioceptive sensory receptor organs that are located at the insertion of skeletal muscle fibers into the tendons of skeletal muscle.
Describe the tastants
A salty tastant (containing NaCl) provides the sodium ions (Na+) that enter the taste neurons, exciting them directly.
- Sour tastants are acids which belong to the thermoreceptor protein family. Binding of an acid or other sour-tasting molecule triggers a change in the ion channel which increases hydrogen ion (H+) concentrations in the taste neurons; thus, depolarizing them.
- Sweet, bitter, and umami tastants require a G-protein-coupled receptor.
- These tastants bind to their respective receptors, thereby exciting the specialized neurons associated with them.
Olfactory transduction
a series of events in which odor molecules are detected by olfactory receptors. These chemical signals are transformed into electrical signals and sent to the brain, where they are perceived as smells.
Kinesthesia
awareness of the position and movement of the parts of the body using sensory organs (proprioceptors), in joints and muscles. It is a critical component in muscle memory and hand-eye coordination.
Bottom-up processing
perceptions are built from sensory input. In bottom-up processing, sensory receptors pick up signals for the brain to integrate and processs.
Ie- stubbing your toe on a chair, the pain receptors detect pain and send this information to the brain where it is processed.
top-down processing
how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts
An example of this is if you see the chair you have stubbed your toe on before and you avoid it to make sure it does not happen again.
◦ In top-down processing, there is always bias of environmental factors on a personal perception of the stimulus = context effect. Where cognitive psychology of a person’s environment affects their stimulus processing.
Gestalt laws of grouping
set of principles in psychology first proposed by Gestalt psychologists to explain how humans naturally perceive stimuli as organized patterns and objects. Gestalt psychology says that our brain groups elements together whenever possible instead of keeping them as separate elements.
law of proximity
posits that when we perceive a collection of objects, we will perceptually group objects that are physically close to each other. This allows for the grouping together of elements into larger sets and reduces the need to process a larger number of smaller stimuli. For this reason, people tend to see clusters of dots on a page instead of a large number of individual dots. The brain groups together the elements instead of processing a large number of smaller stimuli, allowing us to understand and conceptualize information more quickly.
Law of Similarity
tates that people will perceive similar elements will be perceptually grouped. This allows us to distinguish between adjacent and overlapping objects based on their visual texture and resemblance.
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Figure-Ground Law
posits that a visual field can be separated into two distinct regions: the figures (prominent objects) and the ground (the objects that recede into the background. Many optical illusions play on this perceptual tendency
Law of Closure
explains that our perception will complete incomplete objects.
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Law of Continuity
explains that lines are seen as following the smoothest path.
