Eye Spy
You enter a dark movie theater. Which photoreceptors become especially important, and why?
Rods - they are more sensitive in low light
Explain the Gestalt principle of closure and give an example.
We perceive incomplete shapes or patterns as complete by mentally filling in missing information.
Example - seeing a circle even when parts of its outline are missing
monocular - gets information from one eye
binocular - needs information from both eyes
Explain the difference between pitch and loudness. Which property of a sound wave represents each?
Pitch depends on frequency
loudness is related to amplitude
What are the scientific names for taste and smell? Explain the difference.
taste - gustation: detects chemicals dissolved in saliva through taste receptor cells
smell - olfaction: detects airborne chemical molecules through olfactory receptors in the nasal cavity
You're reading a book and then look up at something across the room. What happens to the shape of your lens, and what is this process called?
The lens flattens to focus on distant objects - accommodation
In signal detection theory, what is the difference between a hit, a miss, a false alarm, and a correct rejection?
Hit: Detecting a stimulus that is present.
Miss: Failing to detect a stimulus that is present.
False alarm: Reporting a stimulus when none is present.
Correct rejection: Correctly identifying that no stimulus is present.
Explain relative size. How does it help us perceive depth?
Relative size is a monocular depth cue. When two objects are assumed to be similar in actual size, the one that appears smaller is perceived as farther away.
How are sound waves transduced into neural signals? Name the cells that do it.
Vibrations move fluid in the cochlea and bend the cilia on hair cells, which fire the auditory nerve
What are tastants, and what are the five basic tastes?
Tastants are chemical substances that activate taste receptors.
sweet, sour, salty, bitter, and umami
What is transduction, and how does it occur in the eye?
In vision, photoreceptors (rods and cones) in the retina convert light energy into electrical signals, which are then transmitted through the visual system for processing by the brain.
Name and explain two Gestalt principles of perceptual organization other than closure
Similarity: Grouping objects that look alike.
Proximity: Grouping objects that are physically close together.
Good continuation: Perceiving lines or patterns as continuing smoothly.
Figure-ground: Distinguishing an object from its background.
Explain linear perspective and give an example of how it helps us perceive depth.
Linear perspective is a monocular depth cue in which parallel lines appear to converge as they extend into the distance.
Ex: railroad tracks appear to come together at the horizon
Explain place theory of pitch perception. Where along the basilar membrane are high- and low-pitched sounds detected?
Place theory proposes that pitch is determined by where (location) the basilar membrane vibrates most strongly.
High-pitched sounds: near the base of the cochlea.
Low-pitched sounds: near the apex (tip) of the cochlea.
Name and explain the two types of olfaction
Orthonasal olfaction: Detecting odors/chemicals that enter through the nostrils when we sniff or breathe.
Retronasal olfaction: detecting odor molecules/chemicals that travel from the mouth to the nasal cavity while eating, contributing to our perception of flavor.
What causes the blind spot in each eye, and why don't we normally notice it?
The blind spot is where the optic nerve exits the retina, so there are no photoreceptors to detect light.
We typically don't notice it because the brain fills in the missing information, and the other eye provides overlapping visual input
Explain trichromatic theory of color vision. How does this theory explain our ability to perceive different colors?
We have three types of cones that are most sensitive to different ranges of wavelengths (short, medium, and long). Different patterns of activation across these cones allow us to perceive different colors.
What is retinal disparity, and how does the brain use it to perceive depth?
Retinal disparity is a binocular depth cue.
Because our eyes are positioned slightly apart, each receives a slightly different image. The brain compares these images to estimate depth and distance.
Explain frequency coding theory of pitch. For which sounds does it work, and why can't it explain higher pitches?
Auditory neurons fire in time with the sound wave, so the firing rate matches the frequency.
It only works for very low frequencies - a single neuron can't fire fast enough to match higher ones.
Describe the difference between A-delta and C fibers in how they transmit pain signals.
A-delta fibers: Myelinated, transmit fast, immediate, sharp pain, initiates action (touching a hot stove)
C fibers: Unmyelinated, transmit slower, duller, aching or burning pain
If an object appears in your left visual field, which hemisphere of the brain initially processes that visual information? Explain why.
The right hemisphere.
Information from the left visual field of both eyes is routed to the right hemisphere through the visual pathways
Explain opponent-process theory of color vision. How does this theory account for negative afterimages?
Color is processed through opposing channels (red–green, blue–yellow, and black–white). Prolonged exposure to one color alters the balance of activity in an opponent channel, producing an afterimage of the opposing color.
What is convergence, and how does it help us perceive depth? Explain how our eyes respond differently when looking at nearby versus distant objects.
Convergence is a binocular depth cue in which the eyes turn inward to focus on an object. Our eyes converge (look towards each other) more when looking at nearby objects and less when looking at distant objects. The brain uses this information to judge distance.
Explain volley theory. What problem does it solve, and for which frequencies?
Groups of cilia are staggered and fire in alternation (volleys), so together they match the wave's frequency even though no single neuron can keep up. It covers very high frequencies.
Explain gate control theory of pain. Why might rubbing your elbow after hitting it help reduce the pain?
Gate control theory proposes that pain signals can be modulated (turned up or down) in the spinal cord.
Rubbing the injured area activates touch-sensitive nerve fibers, which can inhibit the transmission of pain signals to the brain.