Sensation and perception Flashcards
Define sensation.
The detection of external stimuli and the transmission of this information to the brain.
Define perception.
The interpretation of sensory signals.
What is the difference between bottom-up processing and top-down processing?
Bottom-up = perception based on physical features of the stimulus. Top-down = how knowledge, expectations, or experience shape perception
What is sensory coding?
Translating the physical properties of stimuli into patterns of neural impulses.
What is transduction?
The process by which sensory stimuli are converted to signals the brain can interpret.
How does neural firing differ when it comes to qualitative information and quantitative information?
Qualitative - firing in different combinations
Quantitative - firing in different rates
What is the absolute threshold? (!not activation)
The minimum intensity of stimulation that must occur before you experience a sensation.
What is the difference threshold?
The minimum amount of change that must occur for you to notice the difference between 2 stimuli.
-Just noticeable difference.
(!the more intense the stimulus, the larger the difference threshold)
Explain the idea behind the signal detection theory.
A theory of perception based on the idea that detection of a stimulus requires a judgement - it is not all-or-nothing process
- there are always competing stimuli
- outside (amplitude)
- inside (mood, attention, motivation, experience)
Explain sensory adaptation.
A decrease in sensitivity to a constant level of stimulation.
How is the perceptual phenomenon that enables you to “hear colors” or “see music”?
Synesthesia.
What are the stimuli, receptors and pathway to brain for vision?
Light waves, rods + cones, optic nerve.
What are the stimuli, receptors and pathway to brain for hearing?
Sound waves, hair cells, auditory nerve
What are the stimuli, receptors and pathway to brain for taste?
Molecules dissolved on the tongue, taste receptors in taste buds, cranial nerves (facial, glossopharyngeal, vagus nerves)
What are the stimuli, receptors and pathway to brain for smell?
Molecules dissolved on the membranes in nose, olfactory receptors, olfactory nerve.
What are the stimuli, receptors and pathway to brain for touch?
Pressure on the skin, sensitive ends of touch neurons in skin, cranial nerves - above neck + spinal nerves - the rest of the body.
Which part of eye contains rods and cones?
Retina.
What is the function of rods + cones?
Transduce light into neural signals.
Describe the function of rods.
Retinal cells that respond to low levels of light and result in black and white perception.
Describe the function of cones.
Retinal cells that respond to higher levels of light and result in color perception.
-3 types - determine how we see color
Which part of retina contains densely packed cones?
Fovea.
What is the function of lens in the eye?
Focuses light waves on retina.
- closer—thickens
- further—flattens
What is the function of ganglion cells in the eye?
Ganglion cells receive signals from rods + cones (receptors) and generate action potentials that are sent to the brain by the optic nerve.
(receptors do not have axons)
What is the optic chiasm?
A place where each optic nerve splits, and half of its fibers cross over to the other side.
Explain the theory that proposes that visual areas beyond the primary visual cortex form 2 parallel processing streams. (two pathways)
“What” and “Where” pathways.
Ventral stream = perception and recognition of objects (what)
Dorsal stream = spatial perception (where)
Which condition results from the damage of the ventral (“what”) stream?
Agnosia.
What does the trichromatic theory propose?
That color vision results from activity of three types of cones.
Name and explain the 5 Gestalt perceptual grouping rules.
Proximity - the closer 2 objects are next to each other, the more likely we are to group them together
Similarity - grouping figures according to how closely they resemble each other
Continuity - grouping together contours with the same orientation
Closure - completing figures that have gaps
Illusory contours - perceiving contours when they do not exist
Which part of the brain is responsible for recognizing faces and what is the medical term for face blindness?
Fusiform gyrus, prosopagnosia.
What is binocular disparity?
It is caused by the distance between 2 eyes. Brain uses the disparity to compute distances to nearby objects.
Stereoscopic vision:
The ability to determine an objects depth based on projection to each eye.
Explain the term convergence.
A cue to binocular depth perception. When a person views a nearby object, the eye muscles turn the eyes inward.
Explain object constancy.
Correctly perceiving objects as constant in their shape, size, color,… despite raw sensory data that could mislead perception.
Describe the process of perceiving sound.
Sound waves—-eardrum vibrates—-ossicles + oval window vibrate—-cochlea—-pressure waves in cochlea move the basilar membrane—stimulation of sensory receptors—-hair cells convert the pressure waves into signals that are sent to the brain via auditory nerve—-thalamus—-primary visual cortex
Temporal coding vs place coding:
Temporal coding - encoding low-frequency auditory stimuli, firing rates of hair cells match the frequency of the sound wave
Place
Temporal coding vs place coding:
Temporal coding - encoding low-frequency auditory stimuli, firing rates of hair cells match the frequency of the sound wave
Place coding - encoding high-frequency stimuli, frequency of the sound is encoded by the location of the hair cells along the basilar membrane.
Describe what are the taste buds.
Sensory organs in the mouth that contain the receptors for taste.
What is the olfactory epithelium?
A thin layer of tissue within the nasal cavity, that contains the receptors for smell.
What is the olfactory bulb?
The brain center for smell, located bellow the frontal lobes.
Describe the process of perceiving smell.
Odorants—nasal cavity—olfactory epithelium—olfactory receptors—olfactory bulb—olfactory nerve—areas of the cortex and amygdala
What is the difference between haptic sense and kinesthetic sense?
Haptic sense - the sense of touch (temperature, pressure, pain)
Kinesthetic sense - perception of the position in space and movements of our bodies and limbs
Anything that makes contact with our skin provides ____ stimulation.
tactile
How do the fast and slow nerve fibers for pain differ?
myelination/non-myelination of axons
Explain the Gate control theory.
Neural “gates” in the spinal cord allow signals through. Those gates can be closed when other information is being transmitted. (touch, distraction, mood,..)
