Master Quiz guide

1. You notice that, when driving at night, green traffic lights appear unusually bright compared to red lights. This effect seems to disappears in full daylight. Which physiological mechanism best explains this phenomenon?

Rod receptors are becoming dominant and have peak sensitivity around 500 nm, making green wavelengths appear relatively brighter

A patient suffers an injury that damages their lens but leaves the cornea completely intact and functional. You explain that, even though the cornea provides 80% of the eye's focusing power, the patient will still have severely blurred vision without the lens. Why is the lens critical for clear vision despite providing only 20% of total focusing power?

Without the lens's adjustable focusing, light from objects at different distances would cause overlapping images on the retina

Cats are effective nocturnal hunters, partly due to a reflective layer behind their retina called the tapetum lucidum. This extra-retinal lining causes their eyes to appear to 'glow' when light shines on them at night. Based on principles of phototransduction and visual sensitivity, how does the tapetum lucidum enhance a cat's vision in low-light conditions?

It bounces light that passed through the retina back throughout the eyeball, giving photoreceptors more chances to absorb light

Eve is trying to observe a very faint star that is barely visible. They know that looking slightly to the side of the star (using their peripheral vision) makes it easier to see compared to looking directly at it. Additionally, Eve notices that the star appears reddish when looking directly at the star through a telescope during the day. However, the star looks almost colorless when using their superior, peripheral vision at night. Which combination of factors best explains both observations?

Rods provide higher sensitivity for detecting dim light, but rods cannot differentiate colors, making the star appear colorless

Hubel and Wiesel discovered that some cortical neurons respond best to oriented bars but only when the bar moves across the receptive field in a specific direction. A researcher finds such a neuron that fires vigorously to a vertical bar moving leftward. When the same vertical bar moves rightward, the neuron doesn't respond. What type of cell is this most likely to be, and what does this reveal about cortical processing?

A complex cell, demonstrating that V1 neurons can integrate both form (orientation) and motion information beyond what retinal ganglion cells provide

Farad, a visual neuroscientist presents a small spot of light to different locations across a monkey's retina while recording from a simple cortical cell. The cell responds strongly when the spot illuminates a narrow vertical strip of the retina, but shows no response when spots illuminate regions on either side of this strip. If Farad now presents a horizontal bar across the entire receptive field, how will this cell respond compared to presenting an optimal vertical bar?

Weaker or no response compared to vertical bar, because the horizontal bar simultaneously stimulates both excitatory and inhibitory regions arranged side-by-

Michael Burnham uses fMRI to map retinotopic organization in human V1. She presents a small visual stimulus at two locations: one 2 degrees from the fovea and another 20 degrees into the periphery. Both stimuli are the same physical size and activate the same number of photoreceptors. Based on cortical magnification, what pattern of cortical activation would she observe

Larger cortical activation for the smaller (2deg) stimulus, because foveal representation is magnified in cortex even though receptor numbers are equal

A researcher is mapping the receptive field of a simple cell in cat visual cortex by presenting oriented bars at different angles. The cell fires 50 action potentials per second to a bar oriented at 0 degrees (vertical), 30 spikes/sec at +10 degrees (tilted 10 degrees clockwise from vertical), and 0 spikes/sec at +90 degrees (horizontal). Based on the nature of simple cell tuning curves, approximately how many spikes per second would this cell fire to a bar oriented at -10 degrees (tilted 10 degrees counterclockwise from vertical)?

Approximately 30 spikes/sec, because orientation tuning curves are typically symmetric around the preferred orientation

Hubel and Wiesel discovered neurons in visual cortex that respond best to bars or edges of specific lengths, showing reduced firing when the stimulus extends beyond an optimal length. James records from such a neuron and finds it responds with 40 spikes per second to a 2-degree vertical line moving upward, 25 spikes/sec to a 4-degree vertical line moving upward, but only 10 spikes/sec to an 8-degree vertical line moving upward. When he presents a stationary vertical line of any length, the neuron barely responds. What type of cortical cell is this, and what visual features is it encoding

A hypercomplex cell that integrates information about orientation, movement direction, and stimulus length, responding optimally to corners or lines of specific lengths

Anantya is exploring her interest in color perception and presents lights of different wavelengths to a participant with normal, trichromatic, vision. The participant - accurately - reports seeing blue at 450 nm, green at 520 nm, and red at 650 nm. When she presents a wavelength of 1000-nm, what does the participant see?

The participant reports seeing no light at all because 1000 nm is outside the visible spectrum

Nathan is a vision scientist who creates a diagram showing photoreceptor density across the human retina. The diagram shows that cone density is highest at the fovea and decreases toward the periphery, while rod density is zero at the fovea, peaks at about 20 degrees from the fovea, and then decreases toward the far periphery. His research assistant asks: 'Why would evolution create a blind spot for rods right at the fovea where we look directly at things?' Nathan’s response includes:

Rods are absent from the fovea because the fovea is specialized for high-acuity color vision in bright light; in bright light rods would be saturated and nonfunctional anyway

Research on the Himba people of Namibia shows they can rapidly distinguish between subtly different shades of green that English speakers find difficult, but have more difficulty distinguishing blue from green. What linguistic feature best explains their superior discrimination among green shades?

The Himba language has multiple distinct words for different categories of green, which sharpens perceptual discrimination within those categories

In Suchow and Alvarez's motion-induced color blindness demonstration, observers report that the colors of moving dots appear to fade away or disappear, even though the dots remain physically colored. What does this phenomenon demonstrate about motion and color?

Motion processing can interfere with or suppress color perception when the visual system is tracking moving objects

Odors seem to have unique and reliable activation maps within the olfactory bulb. This specific pattern of activation is:

Lost when information is sent to higher order regions (e.g., Piriform cortex and OFC)

In a blind taste test, participants rate the same odor as more pleasant when told it is “vanilla” than when told it is “cleaning fluid.” What does this suggest about olfactory processing?

Higher-level knowledge and labeling can shape perceptual experience

Some individuals lose their sense of proprioception due to illness or injury, and as a result, report that their limbs feel “disconnected” or that they slowly drift without awareness. For example, they may knock over an object out of view or reach for an object and entirely miss it. What best explains this perceptual deficit?

Without proprioceptive feedback, the brain cannot monitor limb position

Imagine you're eating a strawberry candy while holding your nose. You can still tell it’s sweet, but it doesn’t taste like “strawberry” anymore. What does this reveal about how the brain constructs flavor?

Flavor perception depends heavily on olfactory input, which is blocked during nose

pinching

Two different odors can activate overlapping sets of olfactory receptors, yet still produce distinct percepts. What theory of olfactory coding best explains this phenomenon?

Population coding: the identity of a smell is derived from a distributed pattern of

activation

Infants who have recently learned to crawl often show good spatial judgment — for instance, avoiding drop-offs or ledges. Yet, when these same infants begin walking, they may suddenly fail at the same spatial tasks. What does this tell us about the relationship between motor skill and spatial understanding?

Each new motor posture seems to require a new mapping between vision and action

When the sensory input could be interpreted in more than one way, the visual system doesn’t experience both possibilities — it “commits” to just one. According to Helmholtz’s Unconscious Inference, what drives this choice?

The brain selects the interpretation that is most likely given past experience

Two completely different 3D scenes can cast the exact same 2D image onto the retina, yet we normally experience only one stable interpretation of the external world. What challenge does this create for the visual system during perception?

The visual system must infer which of several possible 3D worlds produced the 2D

retinal image

You and a friend are on a hike and stop to view a mountain very far in the distance. Your friend claims that they can tell exactly how far away a mountain is “because each eye gets a slightly different view of it.” You suspect they’re misunderstanding depth cues, but what exactly is wrong with their reasoning?

At such large viewing distances, each eye receives nearly the same image, so binocular disparity provides almost no useful depth information

Suppose you recognize a fire hydrant from behind a fence, even though only part of it is visible and you’ve never seen it from that angle before. According to RBC, what makes recognition possible in this situation?

Geons and their arrangement remain detectable even from unfamiliar or novel viewpoints

While blindfolded, Jordan is handed an unfamiliar object. Within seconds, they identify it as a stapler by lifting, rotating, and tapping it against the table. Why is active touch typically more accurate for object identification than passive touch?

Active touch engages movement and exploratory procedures, generating additional information about texture, contour, and weight.

Stimulation of a small patch on the wrist and the same sized patch on the lips produces very different neural responses in the brain. What principle underlies this difference in cortical representation?

Cortical magnification in primary somatosensory cortex (S1)

When learning about the tongue’s anatomy, a common misconception is that all visible structures on the tongue are involved in taste. In reality some tongue structures serve different purposes. Based on what we know about the distribution and function of papillae, which of the following statements is most accurate?

Some papillae (e.g filiform) do not contain any taste buds

In the “Cyberball” experiment, participants are excluded from a virtual ball-tossing game. What does this reveal about the neural basis of social pain?

Social exclusion activates many of the same brain regions (e.g., anterior cingulate cortex) as physical pain

Even with your eyes closed, you can often tell whether you're standing, lying down, or hanging upside down. This awareness arises from:

Integration of vestibular, proprioceptive, and gravitational cues

In an “oddball” paradigm using Electroencephalography (EEG), standard stimuli are played repeatedly, interspersed with rare, deviant stimuli (these might be different in color, size, tone, etc.). How would we expect the P3 (aka P300) to look when you correctly identify the deviant as lasting “longer” in time compared to when you fall for the illusion and incorrectly identify the deviant as “longer”?

Oddball stimuli elicit larger P3 amplitudes than standard stimuli, meaning that the amplitude should be highest when you fall for the illusion

When participants cross their fingers and move a pen between them without visual feedback, they often feel as if there are two pens. What causes this illusion?

Stimulating the outside of the fingers simulates a real-world situation where only two objects could cause the stimulation

What is a primary mechanism by which people reduce pain using the

strategy of distraction?

Engaging cognitive control regions (e.g., ACC) can dampen pain signals in lower brain structures

When a face is presented upside down, viewers often fail to notice grotesque alterations like inverted eyes and mouth — a phenomenon known as the Face Inversion Effect (aka Thatcher Illusion). What best explains this effect?

A disruption of holistic processing which makes configural anomalies harder to detect and which occurs regardless of egocentric orientation

During cognitive reappraisal—when individuals reinterpret a painful experience in a more neutral or positive light—which brain region is primarily responsible for modulating pain in this situation?

VLPFC — engages downstream brain regions (e.g., amygdala, ACC) to reduce pain

When a single flash is accompanied by two auditory beeps, observers often report seeing two flashes. This is an example of what type of temporal processing?

Postdictive integration, where later inputs alters the percept of an earlier event.

We saw that using a mirror box can lead to substantive pain relief in amputees. Why might a mirror box alleviate pain in amputees?

Visual feedback of an intact limb can help re-map somatosensory representations and reduce mismatch signals

After getting a cut on your finger, nociceptors begin to send signals to the brain which are initially processed by the Dorsal Root Ganglion. Select the answer which best describes the remainder of the journey to the brain.

Signals travel via the spinothalamic tract and are processed in thalamus before going to somatosensory cortex

During a free-fall experiment, participants report that time seems to slow down as they drop. What does this reveal about time perception under extreme stress?

The subjective expansion of time reflects retrospective reconstruction, not an actual increase in perceptual acuity

The semicircular canals of the vestibular system are primarily responsible for sensing:

Head rotation via fluid motion in curved canals

A moving object and a flashed static object are briefly aligned on the screen. Yet, observers reliably report the moving object as being further along its trajectory. What does the flash-lag illusion suggest about how the brain handles perception and motion?

The brain uses postdiction to compensate for neural delays in how long it takes to perceive moving vs static objects

Deep within the inner ear, the cochlea is responsible for the initial processing and disambiguation of frequencies from the complex mesh of sounds we hear in our environment. One of the key features of this organ is:

That it is tonotopically mapped

Sound, as a physical stimulus is best described as:

The compression and rarefaction of molecules in the air, water, etc.