What is the difference between sensation and perception?
Sensation is what happens when our sensory modalities (vision, hearing, taste, etc.) are activated.
Perception is how we understand these senses.
Stimuli from the outside world are converted into neural impulses to be processed by our brains through what process?
What two processes stop you from feeling your shirt press against the hairs on your arms all day?
sensory adaptation: when the hairs on our arms are constantly being pressed, we simply stop responding to the feeling of pressure
sensory habituation: the pressure on our hairs stops being novel, so there is no reason for us to continue paying attention to it
If you are zoning out in class and your teacher suddenly uses a swear word, you will snap back to attention. What is the phenomenon called that is responsible for this?
The cocktail party phenomenon/effect involuntarily focuses our attention on something salient, like hearing our name in a roomful of people, or hearing a teacher curse.
What are the "energy senses" and why are they called that?
These senses convert stimuli into energy, like light, sound waves, and pressure.
What are the "chemical senses" and why are they called that?
These senses take stimuli and convert them into chemical signals to be processed.
What is a human's dominant sense?
What are the factors in seeing a bright light or a blue sky versus a black jacket?
Light intensity will affect how bright an object appears, and color or hue is affected by the light wavelength in the visual color spectrum an object reflects. Objects that appear black actually absorb all colors, while objects that are white reflect all light wavelengths. The blue sky absorbs all colors but blue, which it reflects.
The cornea is the protective covering of the eye, where light first enters and is focused.
The black part in the middle of the eye, the pupil acts like the shutter of a camera, and is controlled by the iris.
The iris is the colored disc surrounding the pupil that changes its dilation, allowing more or less light in.
The lens focuses light entering through the pupil (called accommodation), then flips and inverts the image and projects it onto the retina.
The upside-down and inverted image is projected onto the retina, where neurons are activated to interpret the image via transduction. The retina has several layers of cells involved in transduction.
What are the parts of the retina?
rods and cones
lateral geniculate nucleus (LGN)
When the sun sets and everything in the dark around you looks bluish, are your rods or your cones activated?
Rods are activated. Rods react to light, rather than color, with the exception of blue, which explains why we can only see shades of blue in the dark. Cones are activated by other colors.
The fovea is an indentation in the retina. It is the eye's fixation point, or the part of the eye uses when attending to detail, and has the greatest concentration of cones in the eye.
Why do we have a "blind spot"?
The area where the optic nerve leaves the retina has no photoreceptors (rods or cones).
The optic nerve is comprised of axons from what?
What is the lateral geniculate nucleus (LGN)?
It is the visual part of the thalamus that receives information from the optic nerve.
Information from the left side of the retinas go to the left side of the brain, and information from the right side of the retinas go to the right side of the brain. Where does the information get routed to each side?
Since the optic chiasm, where this information intersects, is shaped like an X, an easy way to remember this is to remember that "chi" is the letter X in Greek.
After visual impulses are processed in the thalamus, where do they end up?
Vision is ultimately processed by the occipital lobe.
There are five feature detectors in vision, labeled V1 through V5. Who won the Nobel Prize for their discovery?
David Hubel and Torsten Wiesel
In the context of vision, what does each of the five feature detectors do?
V1. mental image formation and imagination
V2. illusory contours
V4. color analysis and pattern recognition
V5. motion and direction
What is the trichromatic theory?
It is the theory that the cones in our retinas perceive blue, green, and red, and are activated in combination to create a perception of all the colors in the visual spectrum.
When you look at the sun for a while and then look away, why is there a dark spot in your vision for a period of time?
This is called an afterimage. Afterimages of red are green, and afterimages of blue are yellow and vice-versa. The opponent-process theory states that when you look at something of one color, you inhibit its color pair, which you see when you look away.
Why would the opponent-process theory help explain color blindness?
The opponent process theory hypothesizes that the retina has its sensory receptors arranged in color pairs, and if a person is missing a specific pair, he will be unable to perceive either of those colors.
What characteristics of a sound wave determine what we actually hear?
The amplitude of a soundwave determines the loudness of a sound (decibels).
The frequency of a soundwave determines the pitch of a sound (hertz).
The pinna is the flap of skin outside the ear that helps capture and focus sound.
The eardrum or tympanic membrane concentrates sound energy, vibrating when sound from the ear canal hits it.
Ossicles are three tiny bones in the middle ear that connect the eardrum to the oval window.
- hammer (malleus)
- anvil (incus)
- stirrup (stapes)