Ch 2- Sensation and Perception Flashcards
What is sensation?
“more appropriately aligns with transduction, which is the conversion of physical, electromagnetic, auditory, and other information from our internal and external environment to electrical signals in the nervous system. ”
“Sensation can therefore be thought of as a raw signal, which is unfiltered and unprocessed until it enters the central nervous system.”
What is perception? How does it differ from sensation?
Perception refers to the processing of the raw signal (sensation) to make sense of its significance”
“Perception thus helps us make sense of the world.”
What are sensory receptors?
They are neurons that respond to stimuli and trigger electrical signals.”
“Sensory receptors may encode multiple aspects of a stimulus. For example, photoreceptors respond to light and can encode not only the brightness of the light, but also its color and shape.”
“ In each case, different types of receptors—generally nerve endings or specific sensory cells—receive the stimulus, and transmit the data to the central nervous system through
sensory ganglia.
“Ganglia are collections of neuron cell bodies found outside the central nervous system”
Are then sent to projection areas of the brain (analyze sensory input)
What are photoreceptors?
Repsond to electromagnetic waves in the visible spectrum
What is a threshold when it relates to psychology?
“the minimum amount of a stimulus that renders a difference in perception”
Its a good example of the psychological element of perception
“ There are three main types of thresholds: the absolute threshold, the threshold of conscious perception, and the difference threshold.”
What is the absolute threshold?
“the minimum of stimulus energy that is needed to activate a sensory system.”
“Sounds of extremely low intensity may still cause slight vibrations in the sensory receptors of the inner ear, but these may not be significant enough to be converted to an action potential through transduction.”
“how bright, loud, or intense a stimulus must be before it is sensed.
What is the difference between absolute threshold and threshold for conscious perception?
a stimulus below the absolute threshold will not be transduced, and thus never reaches the central nervous system. A stimulus below the threshold of conscious perception arrives at the central nervous system, but does not reach the higher-order brain regions that control attention and consciousness.”
What is the threshold of conscious perception
“It is possible for sensory systems to send signals to the central nervous system, but a person may still not perceive them. This may be because the stimulus is too subtle to demand our attention, or may last for too brief of a duration for the brain to fully process the information.So its the minimum intensity needed to be perceived
What is the difference threshold or just-noticeable difference (jnd)”
“ refers to the minimum difference in magnitude between two stimuli before one can perceive this difference.”
“it is far more important to focus on the ratio between the change in stimulus and its original value, rather than the actual difference between the frequencies”
What is Webers law
“states that there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus.”
“If we’ve calculated the jnd as 0.68 percent for sound frequency, then an individual would be expected to be able to discriminate between sounds at 1000 Hz and 1006.8 Hz (6.8 Hz = 0.68% of 1000 Hz), but not between 1000 Hz and 1003 Hz (3 Hz = 0.3% of 1000 Hz). Weber’s law appears to be accurate for all sensory modalities, except at the extremely high and low ends of each range.
What is the signal detection theory?
“ocuses on the changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context.This is because Perception of stimuli can also be affected by nonsensory factors, such as experiences (memory), motives, and expectations.”
What is response bias?
“refers to the tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors”
In a basic signal detection experiment, A significant proportion of misses or false alarms gives an indication of response bias in the subject.”
“ A basic signal detection experiment consists of many trials; during each trial, a stimulus (signal) may or may not be presented. Trials in which the signal is presented are called ____, those which signal is not presented is called ______
Catch Trials, Noise Trials
“hits, in which the subject correctly perceives the signal; misses, in which the subject fails to perceive a given signal; false alarms, in which the subject seems to perceive a signal when none was given, and correct negatives, in which the subject correctly identifies that no signal was given.”
What is adaptation?
Detection of a stimulus changing over time
“Adaptation can have both a physiological (sensory) component and a psychological (perceptual) component”
“The innermost layer of the eye is the _____, which contains the actual photoreceptors that transduce light into electrical information the brain can process.”
Retina
“The eye is supplied with nutrients by what two sets of blood vessels:”
“the choroidal vessels, a complex intermingling of blood vessels between the sclera and the retina, and the retinal vessels. ”
Where is the anterior and posterior chamber of the eye located
Anterior: Front of the iris
Posterior: Between Iris and lens
“The iris, which is the colored part of the eye, is composed of what two muscles”
“the dilator pupillae, which opens the pupil under sympathetic stimulation; and the constrictor pupillae, which constricts the pupil under parasympathetic stimulation.”
What structures of the eye are continueous with the choroid?
The iris and the ciliary body
Ciliary body “ produces the aqueous humor that bathes the front part of the eye before draining into the canal of Schlemm”
“The ____ lies right behind the iris and helps control the refraction of the incoming light. ”
Lens
“Contraction of the ciliary muscle, a component of the ciliary body, is under parasympathetic control
“Contraction of the ciliary muscle, a component of the ciliary body, is under what control
parasympathetic control
“ As the muscle contracts, it pulls on the suspensory ligaments and changes the shape of the lens, a phenomenon known as accommodation.”
As the ciliary muscle contracts, it pulls on the suspensory ligaments and changes the shape of the lens, a phenomenon known as
accommodation.”
What is the function of the retina?
“Its function is to convert incoming photons of light to electrical signals.”
“It is actually considered part of the central nervous system and develops as an outgrowth of brain tissue.”
“The duplexity or duplicity theory of vision”
“states that the retina contains two kinds of photoreceptors: those specialized for light-and-dark detection, and those specialized for color detection.”
Whats the difference between cones and words
“Cones are for color vision. Rods function best in “roduced” light.”
Cones are used for color vision and to sense fine details. Cones are most effective in bright light and come in three forms, which are named for the wavelengths of light they best absorb”
“In reduced illumination, rods are more functional and only allow sensation of light and dark because they all contain a single pigment called rhodopsin. Rods have low sensitivity to details and are not involved in color vision, but permit night vision.”
What are the 3 types of cones?
S,M,L
The cones are named for the wavelengths at which they have highest light absorption: short (S, also called blue), medium (M, green), and long (L, red)”
Where in the eye has the highest concentration of cones?
Macula
“in fact, its centermost point, called the fovea, contains only cones.”
“As one moves further away from the fovea, the concentration of rods increases while the concentration of cones decreases.”
“ Therefore, visual acuity is best at the fovea, and the fovea is most sensitive in normal daylight vision. ”
“Bipolar cells synapse with _____, which group together to form the optic nerve.”
Ganglion Cells
“Because there are many, many more receptors than ganglion cells, each ganglion cell has to represent the combined activity of many rods and cones”
“As the number of receptors that converge through the bipolar neurons onto one ganglion cell increases, the resolution decreases.”
“As the number of receptors that converge through the bipolar neurons onto one ganglion cell increases, the resolution
decreases
“On average, the number of cones converging onto an individual ganglion cell is smaller than for rods. Therefore, color vision has a greater sensitivity to fine detail than black-and-white vision does.”
What are Amacrine and Horizontal cells in the eye?
receive input from multiple retinal cells in the same area before the information is passed on to ganglion cells.
They can thereby accentuate slight differences between the visual information in each bipolar cell. These cells are important for edge detection, as they increase our perception of contrasts.”
Visual Pathway refers to what 2 components
“both the physical anatomical connections between the eyes and the brain and the flow of visual information along these connections”
Each eye’s right visual field projects onto the left half of each eye’s retina and each eye’s left visual field projects onto the right half of each eye’s retina.
“As the signal travels through the optic nerves toward the brain, the first significant event occurs at the ___ ___
optic chiasm
“Because the temporal fibers (which carry the nasal visual field) do not cross in the chiasm, this reorganization means that all fibers corresponding to the left visual field from both eyes project into the ______ side of the brain, and all fibers corresponding to the right visual field from both eyes project into the _____ side of the brain”
Right; Left
“These reorganized pathways are called optic tracts once they leave the optic chiasm.”
In the visual pathway, after the optic chasm, the info goes to _______ then to ______
“the lateral geniculate nucleus (LGN) of the thalamus”
Then to Visual Cortex in the occipital Lobe
“There are also inputs into the superior colliculus (midbrain), which controls some responses to visual stimuli and reflexive eye movements.”
What is parallel processing?
“the ability to simultaneously analyze and combine information regarding color, shape, and motion. Then, these features can be compared to our memories to determine what is being viewed.
For example, most people can recognize a moving car very easily from a distance because they are familiar with the usual motions and shapes of cars.”
What is feature detection
A neuroscience concept in which our visual pathways contain cells specialized in detection of either color, shape, or motion.”
Color: Cones
Shape: Parvocellular Cells (High color spatial resolution but low temporal solution)
Motion: Magnocellular Cells
The feature detection concept of shape is detected by what cells
“parvocellular cells, which have very high color spatial resolution; that is, they permit us to see very fine detail when thoroughly examining an object. However, parvocellular cells can only work with stationary or slow-moving objects because they have very low temporal resolution.”
(Unlike magnocellular cells that detect motion that have high temporal resolution)
The feature detection concept of motion is detected by what cells
“Motion is detected by magnocellular cells because they have very high temporal resolution. However, magnocellular cells have low spatial resolution, so much of the rich detail of an object can no longer be seen once it is motion. Magnocellular cells therefore provide a blurry but moving image of an object”
The ear is responsible what what 2 types of senses?
Hearing and Kinesthetic Senses (Rotational/Linear Acceleration)
“A sound wave first reaches the cartilaginous outside part of the ear, called the ”
pinna or auricle.
“The main function of the pinna is to channel sound waves into the external auditory canal, which directs the sound waves to the tympanic membrane (eardrum)”
What determines the rate at which the tympanic membrane vibrates?
The frequency of the sound wave
it moves back and forth at a high rate for high-frequency sounds and more slowly for low-frequency sounds.”
“Louder sounds have greater intensity, which corresponds to an increased amplitude of this vibration.”
What divides the outer and middle ear?
Tympanic Membrane
Where are the 3 ossicles of the ear found?
Middle ear
“The middle ear is connected to the nasal cavity via the Eustachian tube, which helps equalize pressure between the middle ear and the environment.”
Which ossicle is affixed to the tympanic membrane?
Malleus (hammer)
“The baseplate of the stapes rests in the _____ ______ of the cochlea, which is the entrance to the inner ear.”
Oval Window
