Midterm 1 Flashcards
(309 cards)
1
Q
What is Fechner’s Law?
A
Fechner’s Law states that subjective percept (P) is proportional to the logarithm of the ratio between the physical intensity of a stimulus (S) and the absolute threshold (S₀), with a modality-specific constant (k). The equation is P = k * log(S/S₀).
“The way we feel changes in intensity depends on how big the change is compared to what we started with.”
Instead of feeling changes directly, we experience them on a curve—big jumps matter more at lower levels, and small changes are harder to notice at higher levels.
2
Q
What is Plato’s Theory of Forms?
A
Plato’s Theory of Forms states that beyond the physical world lies a realm of perfect, immutable, and eternal “Forms” or “Ideas,” which are the true essence of all things. The physical objects we perceive are merely imperfect reflections of these ideal Forms.
3
Q
How does Aristotle’s view of form and matter differ from Plato’s?
A
Plato believed in the existence of Forms (Ideas) as separate, perfect entities that exist independently from the physical world. For example, the idea of a “circle” exists as a perfect Form, and any physical circle is just an imperfect copy of that ideal Form.
Aristotle, on the other hand, rejected the idea that Forms exist independently. He argued that form and matter always exist together—you can’t have one without the other.
In Aristotle’s view:
- Matter = the physical substance something is made of (e.g., wood, clay).
- Form = the structure or organization of that matter (e.g., a table, a statue).
4
Q
What is the main difference between rationalism and empiricism?
A
Rationalism asserts that knowledge is primarily gained through reason and logical thought, while empiricism argues that knowledge comes from sensory experience and observation.
5
Q
What is the difference between inductive and deductive reasoning?
A
- Inductive reasoning draws general conclusions from specific observations (e.g., “All swans seen so far are white, so all swans must be white”). The conclusion is probable but not certain.
- Deductive reasoning draws specific conclusions from general premises (e.g., “All mammals have lungs; a whale is a mammal; therefore, a whale has lungs”). The conclusion is necessarily true if the premises are true.
Deductive reasoning starts with a hypothesis or general rule and applies it to specific cases. If the premises are true, the conclusion must be true.
Inductive reasoning starts with observations and forms a general conclusion.
6
Q
Harvey Specter is cross-examining a witness. He starts with general premises: “All employees sign NDAs. You were an employee. Therefore, you signed an NDA.” What type of reasoning is he using?
A
Deductive reasoning. He starts with a general principle and applies it to a specific case.
7
Q
Shawn notices that every time Gus sneezes after eating from a specific food truck, it’s when they serve dishes containing peanuts. He concludes that Gus is allergic to peanuts. What type of reasoning is this?
A
Inductive reasoning. Shawn observes a pattern and makes a general conclusion based on specific experiences.
8
Q
Patrick Jane is solving a case and assumes that the killer must be someone who had access to the victim’s home. He then systematically eliminates suspects who didn’t have access. Which philosophical method is he using?
A
Rationalism. He relies on logical deduction rather than sensory experience to eliminate suspects.
9
Q
Michael Westen is tracking a target and notices that every time the man stops at a café, he sits at a table with a clear line of sight to the entrance. He concludes that the man is a paranoid ex-intelligence officer. What philosophical stance does this align with?
A
Empiricism. Michael is drawing conclusions based on sensory observation and past experiences.
10
Q
Abed argues that every TV show follows a predictable formula, and based on this, he predicts what will happen in a new show before seeing any episodes. Is he using rationalism or empiricism?
A
Rationalism. He is using logic and patterns rather than direct sensory experience to form conclusions.
11
Q
Rory is preparing for a debate and argues that a true democracy must allow free speech. She builds her argument using general principles rather than specific case studies. What method is she using?
A
Deductive reasoning. She is applying a general principle (free speech is necessary for democracy) to support her argument.
12
Q
Mike Ross remembers that in every contract dispute case he has studied, the side with more documented evidence usually wins. He predicts that his current case will follow the same pattern. What type of reasoning is this?
A
Inductive reasoning. He is making a general prediction based on specific past observations.
13
Q
Lisbon tells Jane that not everything is just logic—sometimes, experience and observation reveal the truth. If Jane argues that logical deduction is superior, whose view aligns with empiricism, and whose with rationalism?
A
- Lisbon aligns with empiricism (knowledge comes from experience).
- Jane aligns with rationalism (knowledge comes from logical deduction).
14
Q
Michael tells Fiona that he doubts everything he sees because deception is everywhere. He claims the only thing he can be sure of is that he is thinking. Which philosopher does this sound like?
A
This perspective closely aligns with the philosophy of René Descartes, who famously doubted all external reality, considering the possibility that a powerful demon could be deceiving him. However, he concluded that the very act of doubting proved his own existence, leading to his famous statement: “I think, therefore I am.”
15
Q
What is John Locke’s theory of simple and complex ideas?
A
Locke believed that sensory information enters the mind as “simple ideas” (e.g., “blue” or “triangular shape”). These simple ideas can then be combined to form “complex ideas” (e.g., “blue triangle”).
16
Q
How did Titchener’s introspection method differ from Locke’s approach?
A
Titchener attempted to go in the opposite direction, breaking down complex ideas into their simpler elements through introspection.
17
Q
What was David Hume’s view on causality?
A
David Hume’s view on causality is that we cannot logically prove that one event necessarily causes another. Instead, our belief in cause-and-effect relationships comes from habit and experience, not from logical certainty.
(e.g., the sun has always risen, so we expect it to rise again).
18
Q
What are Immanuel Kant’s a priori structures?
A
Kant believed that certain concepts, such as space, time, and causality, exist independently of sensory input and structure how we experience the world.
19
Q
What is the difference between noumenon and phenomenon in Kant’s philosophy?
A
The noumenon is the thing-in-itself, which exists independently of human perception, while the phenomenon is how we perceive that thing. According to Kant, we can only have direct knowledge of phenomena.
20
Q
What are some reasons philosophers believed the mind could not be studied scientifically?
A
- The mind has no measurable physical substance.
- Inner observations cannot be separated and recombined at will.
- The act of introspection changes the content of the mind.
21
Q
What was Ernst Heinrich Weber’s contribution to psychology?
A
Weber studied proprioception and the Just Noticeable Difference (JND), which refers to the smallest weight difference a person can perceive.
22
Q
How did Gustav Fechner’s personal experiences influence his work?
A
After suffering severe eye damage from sun-gazing experiments and experiencing what he saw as a miraculous recovery, Fechner became deeply spiritual and developed an obsession with the relationship between mind and matter.
23
Q
What is panpsychism, and how does it differ from dualism?
A
Panpsychism is the idea that everything material has a mental aspect, suggesting a unified reality with both physical and mental properties. This differs from dualism, which suggests that mind and matter can exist independently.
24
Q
Shawn and Gus are trying to solve a case. Shawn insists on breaking it down into simple elements, like noticing that a suspect always wears blue and has a specific walk. He argues that by combining these elements, they can understand the suspect’s full personality. Which philosopher does this align with?
A
John Locke. His idea of simple and complex ideas suggests that perception starts with basic sensory elements that combine into more complex thoughts.
25
Jeff tells the study group that just because they’ve had seven ridiculous adventures at Greendale, it doesn’t necessarily mean the next one will be ridiculous too. What philosopher’s view does this align with?
David Hume. He argued that cause-and-effect relationships are not logically necessary, but people believe in them due to habit.
26
Jane sees a man about to cross the street and predicts that he will hesitate before stepping off the curb. When Lisbon asks why, Jane explains that based on prior experience, people like him always do that. What concept is he relying on?
Hume’s idea of psychological habits—expecting an outcome based on repeated past experience.
27
Donna tells Harvey that even though they can measure every aspect of a legal case—facts, arguments, and precedents—there’s still an intangible element to persuasion that can’t be broken down into data. Which philosopher’s idea does this support?
Kant’s concept of a priori structures—certain concepts (like persuasion or causality) exist beyond raw sensory experience.
28
Michael Westen tells Sam that intelligence gathering isn’t just about recording facts—it’s about interpreting them within a structure of time, space, and cause-and-effect. Which philosopher does this align with?
Immanuel Kant. He argued that experience is shaped by a priori structures like space, time, and causality.
29
Rory argues with Paris that just because every Yale student they know has been competitive, it doesn’t necessarily mean all Yale students are. Which philosopher would support Rory’s argument?
David Hume. He believed that inferring necessary cause-and-effect relationships is flawed, even though humans naturally do it.
30
The study group debates whether Greendale’s chaos is real or just a product of how they perceive it. Abed argues that Greendale might have an objective reality (noumenon), but all they can ever know is how they perceive it (phenomenon). Who does this align with?
Immanuel Kant. He distinguished between noumenon (the thing-in-itself) and phenomenon (how it appears to us).
31
Gus insists that science can’t study the mind because just thinking about thinking changes what you’re thinking about. Which argument does this support?
The philosophical concern that introspection changes the content of the mind, making scientific study difficult.
32
Mike and Harvey are arguing about whether a negotiation can be analyzed scientifically. Harvey says negotiation is based on instinct, not cognitive processes. Mike argues that every case follows patterns that can be broken down into parts. Who aligns with which philosopher?
- Harvey aligns with those who doubted the mind could be studied scientifically.
- Mike aligns with Weber and Fechner, who sought to quantify perception and cognition.
33
Michael says that when training new spies, the most important thing is teaching them to notice small changes—like the weight of a gun in their hand—because small differences can be critical in the field. What psychological concept does this align with?
Weber’s Just Noticeable Difference (JND), which refers to the smallest perceivable difference in weight or intensity.
34
Jane believes that everything in the world, even inanimate objects, has both a physical and a mental aspect. He suggests that perception and behavior are influenced not only by observable factors but also by hidden mental properties present in all things. Which philosopher’s ideas does this reflect?
Fechner’s panpsychism—the idea that everything has both a material and mental aspect, influencing perception and behavior.
35
What is panpsychism, and how does it differ from dualism?
Panpsychism is the idea that everything material also has a mental aspect. Unlike dualism, which suggests mind and matter can exist separately, panpsychism proposes that reality has both material and mental aspects simultaneously.
36
What does Fechner’s Law describe?
Fechner’s Law describes the relationship between physical stimulus intensity and perceived sensation, using the formula:
p = k * log(S_0)
where p is subjective perception, S is stimulus intensity, S₀ is the absolute threshold, and k is a modality-specific factor.
37
What does a high Weber fraction indicate?
A high Weber fraction means low discriminability—it is harder to distinguish between two different intensities.
38
What does a high k value in Fechner’s function indicate?
A high k value means higher discriminability—it is easier to distinguish between different intensities.
39
What are the three main methods used to study sensation and perception?
1. Computational psychophysics (e.g., Fechner’s formula)
2. Physiological methods (tracing a stimulus through the central nervous system)
3. Behavioral experiments (observing responses to stimuli)
40
What are the three steps of sensation and perception?
1. Transduction – A physical stimulus interacts with sensory neurons, activating transducer proteins.
2. Transmission/modulation – Sensory signals enter the brain via cranial or spinal nerves.
3. Perception/modulation – Sensory information reaches association cortices for conscious interpretation.
41
What proteins are involved in temperature sensation?
- CMR proteins respond to cold temperatures.
- VR1 and VRL proteins respond to warm temperatures.
42
Michael Westen is teaching a recruit how to detect subtle environmental changes. He places two nearly identical objects in their hands and asks which one is slightly heavier. The recruit struggles. What psychological concept is at play?
Weber’s fraction—if the difference between the objects is below the Just Noticeable Difference (JND), the recruit will have trouble distinguishing them.
43
Shawn Spencer claims he can instantly tell the difference between two very similar shades of blue, but Gus says he’s exaggerating. If Shawn really has high discriminability for color, what does this imply about the k value in Fechner’s function?
A high k value, meaning Shawn has a greater ability to distinguish between different intensities of sensory stimuli.
44
Jane watches a suspect drink tea and later recalls that they grimaced slightly. He correctly deduces that the tea was too hot. What step of sensation and perception did Jane use?
Perception/modulation—the sensory input (hot tea) reached the association cortices, allowing the suspect to consciously experience heat and react.
45
Abed wants to test the study group’s ability to distinguish subtle sound differences. He plays two nearly identical tones, but only Shirley can tell them apart. What does this say about Shirley’s Weber fraction?
Shirley has a low Weber fraction, meaning she has high discriminability for auditory stimuli.
46
Luke hands Rory two different cups of coffee and asks which one is stronger. Rory immediately identifies the stronger one, but Kirk cannot tell the difference. What psychological principle explains this?
Rory has a lower Weber fraction for taste, meaning she has higher discriminability for coffee strength.
47
Harvey and Louis are arguing about how perception works. Harvey says that perception is purely a brain process and that the sensory pathways are just conduits for data. Louis insists that sensory proteins determine what we experience. Which process aligns with each of their views?
- Harvey aligns with perception/modulation—the idea that conscious interpretation happens in the brain’s association cortices.
- Louis aligns with transduction—the process where sensory proteins (e.g., CMR for cold, VR1 for heat) chemically react to stimuli.
48
Fiona is training to improve her ability to recognize small temperature differences in explosives. Over time, she becomes better at detecting slight heat variations. Which psychological concept does this demonstrate?
Increased discriminability—her k value in Fechner’s function has likely increased, meaning she perceives temperature differences more easily.
49
Shawn and Gus are competing to see who can tell when a stereo’s volume has increased. If Gus notices a small change before Shawn does, what does this mean about Gus’s sensory perception?
Gus has a lower Just Noticeable Difference (JND), meaning he can detect smaller changes in intensity than Shawn.
50
The study group is playing a game where they have to guess what they’re touching while blindfolded. Annie correctly identifies a textured object much faster than Britta. What does this suggest about Annie’s tactile perception?
Annie has higher discriminability for touch, meaning her k value in Fechner’s function is higher than Britta’s.
51
What did Stanley Smith Stevens seek to understand?
Stevens sought to understand how much more or less intense two stimuli of different intensities are perceived to be, using his formula:
psy(l) = kl^a
where psy is the subjective percept, l is the stimulus intensity, a controls the curvature of the function, and k corrects for measurement scaling.
52
What is cross-modality matching?
Cross-modality matching is measuring one sensation using a scale typically used for a different sensation. Example: Rating the sweetness of a Coke using a decibel scale.
53
What is the difference between prothetic and metathetic sensations?
- Prothetic sensations vary in intensity or magnitude (e.g., loudness, brightness, weight) and can be studied scientifically.
- Metathetic sensations vary in quality or kind (e.g., pitch, color, taste) and are more subjective, making them harder to study scientifically.
54
What is thresholding?
Thresholding is a technique used to measure the Just Noticeable Difference (JND) or the absolute detection threshold. Since perception is probabilistic, a threshold is defined as the intensity difference that is detected 50% of the time.
55
What are the three main methods of thresholding?
- Methods of constant stimuli – Present random intensities and determine the probability of detection (most accurate).
- Method of limits – Start high or low, gradually increase/decrease intensity until perception reverses (faster but less accurate).
- Method of adjustment – Participant manually adjusts stimulus intensity until they detect it (least accurate but fastest).
56
Harvey is arguing with Louis about how pain scales work. Harvey says his "10/10 pain" might not be the same as Louis’s "10/10 pain," making their pain ratings incomparable. What psychological concept is he describing?
Absolute magnitude ratings—individuals may interpret scale values differently, making comparisons across people difficult.
57
Shawn and Gus are asked to compare how sweet a Coke is compared to how bright a light is. What concept is being tested?
Cross-modality matching—measuring one sensation (sweetness) using a scale typically used for another sensation (brightness).
58
Fiona is testing Michael’s ability to distinguish small changes in loudness. She starts with a quiet tone and slowly increases it until Michael hears a change. What thresholding method is she using?
The method of limits—gradually increasing stimulus intensity until a perceptual shift occurs.
59
Jane is testing a suspect’s ability to distinguish between different shades of red. He randomly shows them various shades and records when they notice a difference. What thresholding method is he using?
The method of constant stimuli—randomized intensities are presented to determine detection probability.
60
Abed wants to test the study group’s reaction times to a flashing light. He gives them a dial to adjust the light’s brightness until they can just barely see it. What method is he using?
The method of adjustment—participants manually change stimulus intensity to determine their detection threshold.
61
Luke is adjusting the heat in the diner. He asks Rory to tell him when she notices a change in temperature, and she does so after a slight increase. What psychological principle explains this?
The Just Noticeable Difference (JND)—Rory detected a small change in stimulus intensity.
62
Michael Westen needs to gauge how well a contact can distinguish between different weights of explosives. If his contact struggles to notice small weight differences, what does this suggest about their discriminability?
They have a high Weber fraction, meaning low discriminability for weight differences.
63
Gus claims he can tell the difference between a 60-decibel and a 62-decibel sound, but Shawn cannot. What does this suggest about Gus’s auditory perception?
Gus has a lower Just Noticeable Difference (JND) for auditory stimuli, meaning he can detect smaller changes in loudness than Shawn.
64
Jane is investigating a case where a suspect insists they saw a color change in a dimly lit room, but another witness disagrees. What psychological concept might explain this?
Metathetic sensations—differences in how individuals perceive qualitative changes like color make it hard to verify the suspect's claim.
65
The study group is blindfolded and given different weights to hold. Annie accurately distinguishes between them, while Troy struggles. What psychological principle is at play?
Annie has a lower Weber fraction, meaning she has high discriminability for weight perception.
66
What is the Generalized Labeled Magnitude Scale (glMS)?
The glMS is a personalized scale calibrated to an individual’s experience of various senses, allowing for better comparison of subjective ratings like pain tolerance.
67
What are the two types of sensory thresholds?
- Difference threshold (Just Noticeable Difference, JND): The smallest detectable difference between two stimuli.
- Detection threshold (Absolute threshold): The minimum intensity required to register a stimulus.
68
What are the four primary methods for measuring sensory thresholds?
1. Method of constant stimuli: Randomized stimulus intensities presented to determine detection probability (most accurate but time-consuming).
2. Method of limits: Gradually increasing or decreasing intensity until the participant detects (or stops detecting) the stimulus.
3. Staircase method: Adjusting stimulus intensity based on prior responses to efficiently converge on the threshold.
4. Method of adjustment: Participant manually adjusts intensity until they detect (or stop detecting) the stimulus (fastest but least accurate).
68
Why are thresholds considered probabilistic rather than absolute?
Because perception is not perfect—there is no intensity level at which a stimulus is detected 100% of the time. Instead, thresholds are defined as the intensity at which a stimulus is detected 50% of the time.
69
What is Signal Detection Theory (SDT)?
SDT is a framework for understanding how people detect signals amid noise. It separates true sensory input (signal) from random physiological or psychological interference (noise) to analyze perceptual decision-making.
70
What are some examples of physiological and psychological noise in SDT?
- Physiological noise: Random nerve activity that interferes with sensory signals.
- Psychological noise: Fluctuations in attention that unpredictably affect perception.
71
What is response bias?
Response bias refers to a participant’s tendency to over-report (liberal bias) or under-report (conservative bias) stimuli, affecting their perceived sensory threshold.
72
What is sensitivity in Signal Detection Theory?
Sensitivity refers to how well an individual can distinguish signal from noise. High sensitivity means better discrimination between actual stimuli and background noise.
73
What is criterion in Signal Detection Theory?
Criterion is the individual’s decision threshold for reporting a stimulus. It reflects response bias and is influenced by factors like expectations or the cost of false alarms.
74
What are the four possible outcomes in Signal Detection Theory?
1. Hit: Stimulus is present, and it is detected.
2. Miss: Stimulus is present, but it is not detected.
3. False alarm: Stimulus is not present, but it is mistakenly detected.
4. Correct rejection: Stimulus is not present, and it is correctly not detected.
75
How does an ROC curve illustrate decision-making in Signal Detection Theory?
The ROC curve shows the trade-off between hit rate and false alarm rate as the decision criterion shifts
- Moving the criterion left increases hits but also increases false alarms.
- Moving the criterion right decreases false alarms but also decreases hits.
76
Shawn and Gus are testing whether they can hear a faint tone in a noisy environment. Shawn frequently says he hears the tone even when it’s not there, while Gus only responds when he's certain. What psychological concept describes this difference?
Response bias—Shawn has a liberal response bias (more false alarms), while Gus has a conservative response bias (fewer false alarms but more misses).
77
Harvey and Mike argue about whether their pain tolerances are comparable. Mike suggests using a scale that accounts for individual differences in perception. What psychological tool would help?
The Generalized Labeled Magnitude Scale (glMS), which calibrates personal experiences for better comparison.
78
The study group is participating in an experiment where they listen to beeps at various volumes. The volume level at which they detect sound 50% of the time is recorded. What concept is being measured?
The detection threshold (absolute threshold), which defines the minimum intensity at which a stimulus is detected 50% of the time.
79
Jane is analyzing a witness’s ability to distinguish between two shades of red. If the witness can only detect differences when the colors are very distinct, what psychological principle applies?
Difference threshold (JND)—the witness has a high Just Noticeable Difference, meaning they require a larger color difference to perceive a change.
80
Michael is interrogating a suspect in a dimly lit room. He subtly increases the brightness of a lightbulb until the suspect notices. What thresholding method is he using?
The method of limits, where stimulus intensity is gradually increased until the participant detects it.
81
Rory and Paris are listening to a faint beeping sound. Rory reports hearing it frequently, while Paris only acknowledges it when it is very clear. In SDT, what is different about their responses?
Rory has a liberal response criterion (more hits and false alarms), while Paris has a conservative response criterion (more correct rejections but also more misses).
82
Louis claims he can hear a dog whistle, but Harvey suspects he’s making it up. If Louis were tested using SDT, which outcomes would confirm Harvey’s suspicion?
If Louis reports hearing the whistle when no sound is present, that would be a false alarm—suggesting he is over-reporting.
83
Fiona wants to train Michael to detect subtle background noises in a crowded environment. Which SDT metric should she focus on improving?
Sensitivity—Michael needs to improve his ability to distinguish between real signals and background noise.
84
Gus correctly detects a faint smell in 75% of trials, while Shawn detects it only 40% of the time. What does this suggest about Gus’s sensory perception?
Gus has a lower detection threshold, meaning he can perceive weaker stimuli more reliably than Shawn.
85
Annie is better than Troy at distinguishing between different scents. What SDT metric is higher for Annie?
Sensitivity—Annie is better at distinguishing signal from noise.
86
What do the X-axis and Y-axis represent in a Signal Detection Theory (SDT) test?
- X-axis: Strength of the felt sensation (high, medium, low) on a given trial.
- Y-axis: Probability that a given sensation will be perceived as high, medium, or low.
87
In an SDT test, why is stimulus intensity kept constant?
To examine how subjective perception of intensity varies due to noise and fluctuations in sensory processing.
88
What is light?
A narrow band of electromagnetic radiation that can be conceptualized as both a wave (when traveling through space) and a stream of photons (when interacting with the retina).
89
What is a photon?
A quantum of visible light (or other electromagnetic radiation) that exhibits both particle and wave properties.
90
What is light scattering?
The redirection of light due to its interaction with particles or molecules, causing deviation from its original path.
91
What are the three main types of light scattering?
1. Rayleigh scattering: Scattering by particles much smaller than the light’s wavelength (e.g., why the sky is blue).
2. Mie scattering: Scattering by particles comparable in size to the light’s wavelength (e.g., white or grayish clouds).
3. Non-selective scattering: Scattering by particles much larger than the light’s wavelength (e.g., fog appears white).
92
What is the difference between light absorption and light reflection?
- Absorption: Light energy is taken up by a material and converted into heat.
- Reflection: Light bounces off a surface instead of being absorbed
93
What are the two types of light reflection?
- Specular reflection: Light reflects off a smooth surface in a single direction.
- Diffuse reflection: Light reflects off a rough surface and scatters in multiple directions.
94
What is light transmission?
The process by which light passes through a material without being absorbed or reflected.
95
What is refraction?
The bending of light as it moves between materials with different refractive indices, causing a change in speed and direction.
96
What is the function of the cornea?
The cornea is a transparent, dome-shaped layer at the front of the eye that helps focus light onto the retina.
97
What is the pupil and how does it regulate light intake?
The pupil is the opening in the eye through which light enters. It is regulated by the iris, which expands or contracts to control the amount of light entering the eye.
98
What is the function of the lens in the eye?
The lens refracts (bends) light to focus it on the fovea (a specialized part of the retina for sharp vision).
99
What is the retina?
A layer at the back of the eye containing photoreceptor cells that convert light into neural signals.
100
What is the choroid?
A vascular layer behind the retina that supplies blood and nutrients to the eye.
101
What is the sclera?
The white outer layer of the eye that provides structure and protection.
102
What is emmetropia?
The condition where the eye naturally focuses light from distant objects onto the retina without needing additional accommodation.
103
What is accommodation in vision?
The process by which the lens changes shape (controlled by ciliary muscles) to focus light on the retina for near or far vision.
104
What is focal length?
The distance between a lens’s optical center and its focal point, determining how well it can focus on objects at different distances.
105
The study group is participating in a perception test where they hear identical tones in different trials, but sometimes they report hearing the tone louder or softer than it really is. Why does this happen?
This variation in reported loudness is due to signal detection noise, where psychological or physiological factors influence sensory perception.
106
While investigating a case, Gus and Shawn notice the sky looks red at sunset. What phenomenon explains this?
Rayleigh scattering—as the sun sets, its light passes through more atmosphere, scattering shorter wavelengths (blue) and leaving longer wavelengths (red).
107
Fiona notices that Miami’s humidity makes the sky appear hazy and white, unlike the clear blue of drier days. What is happening?
Mie scattering—moisture in the air scatters all wavelengths of light more equally, leading to a white or grayish haze.
108
Harvey wears sunglasses that make his eyes appear darker, even in bright light. What optical process is at work?
Light absorption—the sunglasses absorb some of the incoming light instead of allowing it to pass through or reflect.
109
Jane is watching a suspect through a window. He notices the suspect's face appears distorted. What is causing this?
Refraction—light bends as it passes through the glass, altering the apparent shape of the suspect’s face.
110
Rory and Paris are sitting by a lake. Rory notices that the lake's surface reflects the sky perfectly, while Paris observes that from a different angle, she can see into the water. What optical principle is at play?
Specular reflection (at Rory’s angle) and transmission (at Paris’s angle). The angle of view determines whether light reflects off the surface or passes through it.
111
Troy is confused about why clouds appear white instead of blue like the sky. What type of scattering is responsible?
Mie scattering—clouds contain water droplets that are comparable in size to light’s wavelength, scattering all wavelengths more equally.
112
Mike and Harvey are discussing why fog appears white and makes it hard to see distant objects. What optical process explains this?
Non-selective scattering—large water droplets in fog scatter all wavelengths equally, causing a uniform white appearance.
113
Michael needs to read a tiny document, so he uses a magnifying glass. What optical property of the lens allows him to see details more clearly?
Focal length—the magnifying glass bends light to make the image appear larger and in focus.
114
While on a case, Shawn realizes that a suspect’s contacts are making their vision blurry because their eyes aren’t adjusting properly to close objects. What vision process is malfunctioning?
Accommodation—the lens isn’t adjusting correctly to focus on near objects.
115
Lorelai is trying on different sunglasses. She notices some make everything appear dimmer, while others cause colors to shift. What two optical effects could explain this?
Light absorption (for the dimming effect) and selective wavelength filtering (for the color shift).
116
What is presbyopia?
An age-related condition where the eye gradually loses the ability to focus on nearby objects due to reduced lens elasticity and weakened ciliary muscles.
117
What is hyperopia (farsightedness)?
A refractive error where distant objects appear clearer than near ones because light focuses behind the retina, often due to a shorter eyeball.
118
What is myopia (nearsightedness)?
A refractive error where near objects appear clearer than distant ones because light focuses in front of the retina, often due to a longer eyeball.
119
What is astigmatism?
A refractive error caused by an irregularly shaped cornea or lens, leading to blurred or distorted vision at all distances.
120
Who was Hermann von Helmholtz?
A 19th-century physicist and physiologist who studied perception and vision, emphasizing that perception is an unconscious inference made by the brain from incomplete sensory input.
121
What is the fundus?
The interior surface of the eye, visible through an ophthalmoscope, which includes the retina, optic disc, macula, and blood vessels.
122
What is the optic disc?
The blind spot of the eye, where the optic nerve exits and blood vessels enter, containing no photoreceptors.
123
What is the macula?
The central area of the retina responsible for sharp central vision, with a high density of photoreceptors and few blood vessels.
124
What is the fovea?
A small depression within the macula that contains only cone cells, providing the sharpest visual acuity and color vision.
125
What is visual acuity?
The clarity or sharpness of vision, measured by the ability to discern fine details, often tested with standardized eye charts.
126
What is visual angle?
The angle formed by an object at the eye, determined by its size and distance, used to quantify how large it appears in the field of view.
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What are ganglion cells?
Retinal neurons that receive visual input from bipolar cells and send signals to the brain via their axons, which form the optic nerve.
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What are bipolar cells?
Intermediate neurons in the retina that connect photoreceptors (rods and cones) to ganglion cells, transmitting visual signals.
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What are rods?
Photoreceptor cells in the retina that are highly sensitive to low light levels, responsible for scotopic (night) vision.
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What are cones?
Photoreceptor cells responsible for color vision and fine detail in bright light (photopic vision).
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What are the three segments of rods and cones?
1. Outer segment – contains light-sensitive pigment molecules (photopigments).
2. Inner segment – contains the nucleus and synaptic terminals.
3. Synaptic terminal – transmits signals to bipolar cells.
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What are photopigments?
Light-sensitive molecules in photoreceptors, composed of:
- Opsin (a protein sensitive to specific wavelengths).
- Chromophore (a molecule that absorbs light).
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What is phototransduction?
The conversion of light into electrical signals by photoreceptor cells in the retina.
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What is opsin?
A protein in photopigments that determines wavelength sensitivity, allowing photoreceptors to detect color and light.
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What is a chromophore?
The light-absorbing molecule in photopigments. In mammals, this is 11-cis retinal, which changes shape upon light absorption.
136
Harvey starts holding his legal documents farther away to read them clearly. What condition is he likely experiencing?
Presbyopia—age-related loss of near vision due to reduced lens elasticity.
137
Abed notices that Britta’s glasses make it easier for her to read small text up close but don’t significantly change how she sees distant objects. What condition does she likely have?
Hyperopia (farsightedness)—distant objects are clearer because light focuses behind the retina.
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Fiona’s target is a sniper who wears glasses for nearsightedness. What does this mean about his vision?
He has myopia, meaning he can see near objects clearly, but distant objects appear blurry because light focuses in front of the retina.
139
Gus notices that Shawn complains about seeing lights as streaks instead of clear points. What refractive error might he have?
Astigmatism—caused by an irregularly shaped cornea or lens, leading to distorted vision.
140
Jane is conducting an experiment in a dimly lit room. Which photoreceptors in his retina are most active?
Rods, since they are specialized for low-light (scotopic) vision.
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Rory is reading in bright daylight. Which photoreceptors are primarily being used?
Cones, since they function best in bright light and provide sharp color vision.
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Jeff is reading an eye chart but struggles to see small letters at a distance. What term describes the ability to discern fine details in vision?
Visual acuity—the sharpness of vision, measured by the ability to see fine details.
143
Michael is tracking a suspect at night. Why does he have trouble distinguishing colors?
Rods are active in low-light conditions, but they do not detect color—only brightness and contrast.
144
While watching a sunset, Shawn realizes that his central vision is clear, but details in his peripheral vision are blurrier. Why?
The macula (including the fovea) is responsible for central vision, while peripheral vision relies more on rods, which are less precise.
145
Donna visits an ophthalmologist who looks inside her eye using an ophthalmoscope. What structure is the doctor examining?
The fundus, which includes the retina, optic disc, macula, and blood vessels.
146
While testing a suspect’s vision, Jane places an object at various angles from their eye. What concept is he measuring?
Visual angle—the apparent size of an object in the field of view, based on its size and distance.
147
Paris is conducting a vision experiment and wants to measure when a participant can no longer see fine details. What is she testing?
Visual acuity—the ability to distinguish fine details.
148
Troy is looking at a diagram of the eye and asks, “What’s that spot where the optic nerve exits?” What is the answer?
The optic disc, also known as the blind spot, because it contains no photoreceptors.
149
Gus explains that in phototransduction, a molecule in the retina absorbs light and changes shape, starting the visual process. What molecule is he describing?
Chromophore (11-cis retinal)—a light-absorbing molecule that changes shape upon exposure to light.
150
What is photoisomerization?
The process where 11-cis retinal changes to all-trans retinal upon light exposure, initiating phototransduction and temporarily "bleaching" the photoreceptor.
151
What is photopigment regeneration?
The process of converting all-trans retinal back to 11-cis retinal in the retinal pigment epithelium, allowing photoreceptors to recover from bleaching.
152
How do photoreceptors signal light detection?
When a certain threshold of photopigments becomes "bleached," the photoreceptor modifies its neurotransmitter release, signaling that light has been detected.
153
What is the function of rhodopsin?
A light-sensitive pigment in rods, enabling vision in low-light conditions.
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What are the three types of photopsin in cones?
- S-cones (short-wavelength) → Perception of blue
- M-cones (medium-wavelength) → Perception of green
- L-cones (long-wavelength) → Perception of red
155
What is melanopsin?
A light-sensitive protein found in some photoreceptors that helps regulate ambient light detection and influence circadian rhythms.
156
What is the ‘duplex’ retina?
The idea that vision is mediated by two systems:
- Rods (highly sensitive, work in dim light but saturate in brightness).
- Cones (function in bright light but are ineffective in darkness).
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Why does the eye have a duplex retina?
The difference in light intensity between night and day is vast, requiring two systems: rods for night (scotopic vision) and cones for day (photopic vision).
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What is photopic vision?
Bright-light vision, mediated by cones, allowing for color perception and high visual acuity.
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What is scotopic vision?
Low-light vision, mediated by rods, providing high sensitivity to light but no color perception.
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What is dark adaptation?
The process by which the eyes adjust to darkness, increasing rod sensitivity and shifting from cone-dominated to rod-dominated vision. It takes up to 30 minutes.
161
What is the rod-cone break?
The point (around 7-8 minutes in darkness) when rods become more sensitive than cones, dominating vision.
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What are the three mechanisms that allow vision in dim lighting?
1. Pupil dilation – allows more light in (fast but limited).
2. Increased photoreceptor sensitivity – more photopigment regeneration leads to better light detection.
- Cones reach max sensitivity in 5-8 minutes.
- Rods reach max sensitivity in 25 minutes.
3. Rod-cone break – 7-8 minutes in darkness, rods become dominant.
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What is lateral inhibition?
A neural mechanism where active neurons suppress the activity of neighboring neurons, enhancing contrast and edge detection.
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Why is lateral inhibition useful?
It enhances contrast, making edges and fine details more visible in both bright and dim light.
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What is the general principle of lateral inhibition?
The brain subtracts and divides by the average luminance, improving contrast perception.
166
Troy walks into a dark movie theater from bright sunlight and initially can't see anything. After a while, his vision improves. What process is responsible for this?
Dark adaptation, where rods gradually increase sensitivity, allowing vision in low light.
167
Louis suddenly walks into a dark room and complains that Harvey can see better than him. What is likely happening?
Harvey's eyes have undergone dark adaptation, while Louis’s cones are still adjusting, and his rods haven’t reached full sensitivity yet.
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Jane notices that someone in a dimly lit room can still distinguish edges and shapes clearly. What neural mechanism is helping them?
Lateral inhibition, which enhances contrast and edge detection.
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Michael is trying to spot an enemy in the dark. What will help him see better?
Looking slightly to the side rather than directly at the target—this allows rod-dominated peripheral vision to work more effectively in low light.
170
Gus is explaining vision to Shawn. He says that at night, our vision switches from cones to rods after about 7-8 minutes. What is this transition called?
The rod-cone break, where rods become the dominant photoreceptors in low light.
171
Lorelai wakes up in the middle of the night and turns on a bright light. At first, she’s completely blinded. Why?
Her rods were maximally adapted to the dark, but the sudden light overwhelmed them, causing temporary blindness.
172
Abed wants to design a scene where a character suddenly adjusts to darkness. How long should he make the transition for realism?
About 30 minutes, as that’s how long dark adaptation takes for full rod sensitivity.
173
Harvey is in a bright room, but he notices the edges of objects appear sharper. What mechanism enhances this effect?
Lateral inhibition, which increases contrast and improves edge detection.
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Fiona needs to quickly adjust her vision in the dark. What’s the fastest way to improve low-light vision?
Pupil dilation—it allows more light into the eye, though its effect is limited compared to full dark adaptation.
175
Shawn claims he can see better than Gus at night. If true, what could explain this?
Shawn’s rods may have adapted more efficiently, or he has a higher number of rods in his retina.
176
Jane is investigating a suspect who claims they saw a person’s red shirt in the dark. What’s suspicious about this?
Rods don’t detect color, meaning true scotopic vision wouldn’t allow someone to distinguish a red shirt in the dark.
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What is a receptive field?
The region on the retina where stimuli can influence a neuron’s firing rate.
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What are ON-centre/OFF-surround cells?
Retinal ganglion cells that are activated by light in the centre and inhibited by light in the surround.
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What are OFF-centre/ON-surround cells?
Retinal ganglion cells that are inhibited by light in the centre and activated by light in the surround.
180
How do neurotransmitter levels change in response to light?
- No light → High neurotransmitter release
- Light → Reduced neurotransmitter release
181
What happens to photoreceptors when photoactivation starts?
They become hyperpolarized (more negatively charged).
182
What are graded potentials?
Continuous variations in signal amplitude used by photoreceptors and bipolar cells to communicate changes in light intensity.
183
How do bipolar cells communicate with retinal ganglion cells?
Bipolar cells use graded potentials, while retinal ganglion cells fire action potentials (all-or-none response).
184
What happens to centre and surround cones when exposed to light?
- Light hyperpolarizes (inhibits) the centre cone.
- Dark depolarizes (excites) surround cones.
185
How does lateral inhibition enhance contrast?
1. Dark excites surround cones → activates horizontal cells.
2. Horizontal cells inhibit all cones, but the centre cone receives more inhibition.
3. This amplifies ON-centre bipolar cell activity, enhancing contrast detection.
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What are the two types of bipolar cells?
- ON-centre bipolar cells → Reverse the sign of the photoreceptor.
- OFF-centre bipolar cells → Keep the same sign as the photoreceptor.
187
What are the two types of retinal ganglion cells?
- ON-centre ganglion cells → Fire more when the centre is lit and the surround is dark.
- OFF-centre ganglion cells → Fire more when the centre is dark and the surround is lit.
188
Why is contrast perception important?
It allows black-on-white to stand out as much as white-on-black, improving object detection.
189
What is visual acuity?
The smallest spatial detail that can be resolved by the visual system.
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What two factors influence visual acuity?
Spatial frequency and contrast.
191
How do optometrists measure visual acuity?
Using a distance-based system (e.g., 20/20 vision).
192
What does 20/20 vision mean?
The smallest letter you can read at 20 feet is the same size that an average person can read at 20 feet.
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What does 20/15 vision mean?
You can read at 20 feet what an average person can only read at 15 feet (better than normal vision).
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What does 20/40 vision mean?
You can read at 20 feet what an average person can read at 40 feet (worse than normal vision).
195
Gus is explaining ON-centre and OFF-centre cells to Shawn. If a ganglion cell fires more when the centre is lit and less when the surround is lit, what type of cell is it?
ON-centre/OFF-surround ganglion cell.
196
Harvey is reading in dim light and notices that black text on a white page seems just as readable as white text on a black screen. What mechanism allows this?
ON-centre and OFF-centre receptive fields, which make contrast detection independent of background color.
197
Jane is investigating a case where a suspect claims to have seen details of a person’s face in near darkness. What principle suggests this is unlikely?
Visual acuity depends on contrast and spatial frequency, and in low light, acuity is poor due to rod dominance.
198
Michael is trying to detect movement at night. What kind of retinal ganglion cells are helping him most?
ON-centre/OFF-surround and OFF-centre/ON-surround cells, which enhance contrast detection and movement perception.
199
Abed is directing a film scene and wants to simulate how the human eye naturally enhances contrast. What neural process should he consider?
Lateral inhibition, which amplifies contrast by inhibiting neighboring neurons.
200
Rory gets her eyes tested and finds she has 20/15 vision. What does this mean?
She can read at 20 feet what an average person can only read at 15 feet—meaning her vision is better than normal.
201
Shawn is looking at an eye chart and can only read at 20 feet what an average person can read at 40 feet. What is his vision measurement?
20/40 vision, which means his vision is worse than normal.
202
Louis is bragging that he has better vision than Harvey. If his visual acuity is 20/10, what does this mean?
Louis can read at 20 feet what an average person can only read at 10 feet, meaning he has exceptional vision.
203
Jane wants to test a suspect’s vision. If they have 20/50 vision, what does this indicate?
The suspect can only read at 20 feet what an average person can read at 50 feet—indicating poor vision.
204
What is the degree of visual angle?
The space that an object occupies on the retina, representing its size relative to the entire visual field.
205
What is the relationship between visual acuity and degrees of visual angle?
Visual acuity is the smallest cycle of a pattern that can be resolved, measured in degrees of visual angle.
206
What is the hard limit of human visual acuity?
Approximately 1/60th of a degree (one minute of arc), due to the spacing of photoreceptors in the fovea.
207
Why do we need at least three photoreceptors to detect a repeating pattern?
To distinguish between alternating contrasts (e.g., black, white, black), a third receptor is needed to perceive the pattern correctly.
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What happens when the frequency of a grating is smaller than 1/60 degrees?
The pattern is perceived as grey because each cone receives a mixture of black and white.
209
What is the optimal spatial frequency for visual acuity in low-contrast environments?
~7 cycles per degree of visual angle.
210
What is a sine wave grating?
A pattern of alternating light and dark bars that follows a smooth sinusoidal variation in intensity.
211
How do sine waves relate to square waves?
Square waves can be decomposed into sine waves, and sine waves can be combined to create complex patterns, including square waves.
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What role do low-frequency sine waves play in vision?
They provide a blurry, general picture of an image.
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What role do high-frequency sine waves play in vision?
They provide detailed information in an image.
214
Why do cones function well for photopic vision?
Cones are optimized for bright light conditions, allowing for high visual acuity and color perception.
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What is the Hermann Grid illusion?
A visual illusion where dark spots appear at the intersections of white lines, caused by retinal ganglion cells’ receptive field organization.
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Why does the Hermann Grid illusion disappear in central vision?
Because retinal ganglion cells in the fovea have smaller receptive fields, reducing the effect of lateral inhibition.
217
What is convergence in the visual system?
The degree to which multiple photoreceptors synapse onto a single bipolar or ganglion cell.
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What is high convergence, and where does it occur?
Multiple rods synapse onto a single bipolar cell, which then connects to a single parasol ganglion cell. This occurs in the periphery and increases light sensitivity but reduces acuity.
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What is low convergence, and where does it occur?
A single cone synapses onto a single bipolar cell, which then connects to a single ganglion cell. This occurs in the fovea, improving visual acuity but reducing light sensitivity.
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Why do retinal ganglion cells in the periphery have low visual acuity?
Because multiple photoreceptors synapse onto each ganglion cell, making them sensitive to light but poor at resolving fine details.
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Why do retinal ganglion cells in the fovea have high visual acuity?
Because of low convergence (a 1:1 connection between cones and ganglion cells), allowing for fine detail perception.
222
Gus is explaining why Shawn can’t see small details in dim light. What principle best explains this?
Rod dominance in low light reduces visual acuity because rods have high convergence, leading to low detail resolution.
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Harvey is looking at a blurry image and notices that when he squints, he can see the general shapes but not the fine details. What visual principle explains this?
Low spatial frequency components provide the general picture, while high spatial frequency components add detail.
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Jane observes that a suspect claims to see fine details in near darkness. Why is this unlikely?
Low convergence in the fovea means cones require bright light for high acuity, and rods, which work in dim light, have poor resolution.
225
Michael is in a dark alley, trying to spot someone in the shadows. Why does he rely more on his peripheral vision?
Rods dominate peripheral vision, and since rods are more sensitive to light, they are better suited for low-light conditions.
226
Abed is designing a film shot and wants to emphasize only the low spatial frequencies in an image. What effect would this create?
The image would appear blurry and lacking fine details, emphasizing general shapes and contrast.
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Rory is reading a high-contrast vision test. If the contrast is reduced, what will happen to her ability to distinguish fine details?
Visual acuity decreases in low-contrast environments, making it harder to resolve fine details.
228
Shawn sees the Hermann Grid illusion and notices that the dark spots disappear when he looks directly at an intersection. What visual principle explains this?
Receptive fields in the fovea are smaller, reducing the lateral inhibition effect that causes the illusion.
229
Louis claims his fovea has the best vision in the world. What feature of the fovea gives it superior acuity?
Low convergence (1:1 connections between cones and ganglion cells), allowing for high spatial resolution.
230
A witness claims they saw fine details of a suspect’s face in a dark alley. What aspect of the retina makes this unlikely?
Rod-dominated vision in dim light lacks the high acuity needed to resolve fine facial details.
231
Fiona is scanning a crowded room for a target. Why should she use peripheral vision to detect motion?
Peripheral vision is more sensitive to motion due to high convergence of rods, which respond well to changes in light.
232
Abed wants to make an optical illusion that depends on receptive field size. Where should he place the illusion for the strongest effect?
In the periphery, because retinal ganglion cells have larger receptive fields there, making illusions like the Hermann Grid more pronounced.
233
What is the optic nerve?
A bundle of retinal ganglion cell axons that transmits visual information from the eye to the brain.
234
What is the optic chiasm?
The junction where optic nerves from both eyes meet, and nasal retina fibres cross to the contralateral side.
235
What is the function of the nasal retina?
The nasal halves of the retina are responsible for viewing the opposite visual field and their axons cross at the optic chiasm.
236
What is the function of the temporal retina?
The temporal halves of the retina view the same-side visual field, and their axons do not cross at the optic chiasm.
237
What is the optic tract?
Retinal projections beyond the optic chiasm, containing visual information from the opposite visual field.
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Where do most optic tract nerve fibres synapse?
90% synapse in the lateral geniculate nucleus (LGN) of the thalamus, while 10% project to the superior colliculus (SC).
239
What is blindsight?
A phenomenon in which patients with primary visual cortex (V1) damage cannot consciously perceive stimuli but can accurately guess locations of moving objects.
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What does blindsight suggest about conscious perception?
Conscious visual perception requires the primary visual cortex (V1), but other brain regions (like the superior colliculus) can still process motion.
241
Where is the lateral geniculate nucleus (LGN) located?
In the thalamus, acting as a relay station for visual information before it reaches the primary visual cortex (V1).
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What are the magnocellular layers of the LGN?
Layers 1 & 2 of the LGN, receiving input from parasol retinal ganglion cells, specializing in motion and peripheral vision.
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What are the parvocellular layers of the LGN?
Layers 3 – 6 of the LGN, receiving input from midget retinal ganglion cells, specializing in central vision and fine details.
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What are the koniocellular layers of the LGN?
Small layers in the intralaminar regions of the LGN, specialized for colour perception due to their sensitivity to wavelengths.
245
What are optic radiations?
Axons from the LGN that project to the primary visual cortex (V1) in the occipital lobe.
246
What is the role of the primary visual cortex (V1)?
Processes basic visual information like edges, orientations, and motion, serving as the first stage of conscious visual perception.
247
How does the right visual cortex process information?
It processes stimuli from the left visual field of both eyes (and vice versa).
248
Shawn is blindfolded but can still guess where Gus is waving his hands. What neurological phenomenon might explain this?
Blindsight – motion perception can still occur via the superior colliculus, even without conscious visual awareness.
249
Harvey is explaining why an injury to the left primary visual cortex affects vision in the right visual field. Why does this happen?
The right visual field is processed by the left visual cortex, due to nasal retinal fibres crossing at the optic chiasm.
250
Jane is investigating a witness who claims they “saw something” even though they’re legally blind. What neurological explanation might account for this?
Blindsight – damage to V1 prevents conscious perception, but the superior colliculus allows for unconscious visual processing.
251
Michael is trying to dodge an attack from his peripheral vision. What part of his visual system is most responsible for this quick reaction?
The magnocellular pathway (Layers 1 & 2 of the LGN) and the superior colliculus, which process motion and peripheral vision.
252
Abed is designing a visual illusion that relies on fast motion detection. Which pathway should he emphasize?
The magnocellular pathway, since it processes motion and low-light conditions.
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Rory is reading fine print and notices that her central vision is sharper than her peripheral vision. Which LGN layers are responsible?
The parvocellular layers (3 – 6), which process central vision and fine detail.
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Gus explains to Shawn that color perception is different from motion detection. Which LGN layer specializes in color?
The koniocellular layers, which are sensitive to wavelengths and color processing.
255
Louis is worried about his peripheral vision while driving. Which LGN layers help him monitor motion at the edges of his vision?
The magnocellular layers (1 & 2), which process peripheral vision and movement.
256
A patient has damage to their LGN but retains some ability to react to fast-moving objects. What explains this?
The superior colliculus, which processes motion and reflexive eye movements, is still functional.
257
Fiona needs to quickly locate a moving target in her peripheral vision. What retinal ganglion cell type helps her the most?
Parasol retinal ganglion cells, which send motion-related information to the magnocellular layers of the LGN.
258
Abed wants to create a film effect that disrupts depth perception but keeps motion intact. Which pathway should he suppress?
The parvocellular pathway, since it processes fine details and depth, while magnocellular pathways handle motion.
259
Rory is reading in dim light, but her ability to perceive fine details is reduced. Why?
Parvocellular pathways require bright light, so low-light conditions reduce fine detail perception.
260
What are oculomotor depth cues?
Depth cues based on eye movement, including vergence and accommodation.
261
What is vergence?
The simultaneous movement of both eyes to maintain focus on an object:
- Convergence for near objects
- Divergence for distant objects
262
What is the vergence limit?
Vergence cues are reliable only up to ~2 meters; beyond this, eyes no longer converge/diverge for depth estimation.
263
What is accommodation?
The process by which ciliary muscles adjust the lens shape to focus on objects at different distances.
264
What is the accommodation limit?
Accommodation is effective up to ~6 meters; beyond this, everything is at optical infinity and the lens no longer adjusts.
265
What is binocular disparity?
The difference in the images perceived by each eye due to their horizontal separation, which the brain uses for depth perception.
266
What is stereopsis?
The sense of depth created by the brain using binocular disparity, giving a three-dimensional perception of the environment.
267
What is the Vieth-Müller circle?
An imaginary geometric circle that passes through the fixation point and both eyes' optical centers, representing locations with zero binocular disparity.
268
What is the horopter?
The region in visual space where objects project onto corresponding retinal points, appearing at the same depth as the fixation point.
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How does the horopter relate to depth perception?
Objects on the horopter are seen without binocular disparity, while objects off the horopter create binocular disparity, allowing depth perception.
270
What is Panum’s fusional area?
The small region around the horopter where slight binocular disparities are fused into a single image instead of appearing double (diplopia).
271
What is crossed disparity?
When an object is closer than the fixation point, its image appears on the outer (temporal) side of the retina in both eyes.
272
How does crossed disparity affect perception?
The brain interprets it as the object being in front of the fixation point, making it appear closer in 3D space.
273
What is uncrossed disparity?
When an object is farther than the fixation point, its image appears on the inner (nasal) side of the retina in both eyes.
274
How does uncrossed disparity affect perception?
The brain interprets it as the object being behind the fixation point, making it appear farther in 3D space.
275
Gus notices that when he focuses on a nearby object, his eyes move inward, but when he looks at something far away, they move outward. What is happening?
This is vergence, where eyes converge for near objects and diverge for distant objects to maintain focus.
276
Harvey is trying to determine how far a client is sitting from him based on eye movement. What depth cue is he using?
Vergence, which allows for absolute depth perception up to ~2 meters.
277
Jane is looking at a blurry object and his vision sharpens when his eye muscles adjust. What is happening?
Accommodation, where ciliary muscles adjust the lens shape to focus on different distances.
278
Fiona is looking at a nearby car, but Michael is looking at a car farther away. Michael sees the closer car as double. Why?
It is outside Panum’s fusional area, causing diplopia (double vision) because its disparity is too large to be fused into one image.
279
Abed is designing a VR game and wants objects to pop out toward the player. How should he manipulate binocular disparity?
He should use crossed disparity, making objects appear closer than the fixation point.
280
Rory notices that when she closes one eye, depth perception becomes harder. Why?
She loses binocular cues like stereopsis, which relies on binocular disparity for depth perception.
281
Shawn plays a game where objects appear farther back in a 3D space. What type of disparity is being used?
Uncrossed disparity, where images appear on the nasal side of the retina, making objects seem farther away.
282
Louis complains that things look “weird” when he wears 3D glasses. How do 3D movies trick the brain?
They manipulate binocular disparity, creating crossed or uncrossed disparity to simulate depth perception.
283
A suspect claims they saw a person “pop out” in their vision. What binocular depth cue might explain this?
Crossed disparity, which makes objects appear closer than the fixation point in 3D space.
284
Michael is using binocular vision to judge if a target is moving toward or away from him. What depth cue is he relying on?
Binocular disparity, allowing him to perceive stereopsis and depth differences.
285
Abed wants to make a film effect where objects gradually fade into the background. What depth cue should he minimize?
Binocular disparity, since reducing the difference between each eye’s view makes objects appear farther away.
286
Rory is reading but notices she can’t tell how far her book is from the table without moving her eyes. Why?
She relies on accommodation and vergence for absolute depth cues, which require eye movement.
287
What do binocular neurons in V1 encode?
They encode all categories of retinal disparity:
- Zero disparity (on the horopter)
- Crossed disparity (objects in front of the horopter)
- Uncrossed disparity (objects behind the horopter)
288
What is a stereoscope?
A device that presents one image to each eye to create a 3D visual effect by mimicking binocular disparity.
289
How did early 3D movies work?
They used anaglyphic glasses with red and blue lenses to create separate images for each eye.
290
How do modern 3D movies work?
They use polarized light and polarizing glasses to present slightly different images to each eye.
291
What is the correspondence problem in stereopsis?
The challenge of determining which image features in the left eye correspond to which features in the right eye to create depth perception.
292
What are the two possible solutions to the correspondence problem?
- Object-first theory: The brain recognizes objects first, then integrates the two images.
- Integration-first theory: The brain integrates images first, then recognizes objects.
293
What is a random dot stereogram (RDS)?
A visual pattern of random dots that, when viewed stereoscopically, creates a 3D shape or object due to binocular disparity.
294
How is a random dot stereogram created?
- Two similar random-dot patterns are generated.
- A section of one pattern is shifted horizontally in one eye’s image.
- This shift creates binocular disparity, making the section appear 3D when viewed with both eyes.
295
What does a random dot stereogram demonstrate?
It shows that the brain can perceive depth from binocular disparity alone, even without recognizing specific objects first.
296
What is binocular rivalry?
A phenomenon where two different images are shown to each eye, causing visual competition where one image dominates perception while the other fades.
297
Shawn looks through an old ViewMaster and sees images pop out in 3D. What depth cue is responsible?
Binocular disparity, created by the stereoscopic images presented separately to each eye.
298
Harvey and Mike watch a 3D movie with polarized glasses. Why do the images appear 3D?
Polarized light ensures each eye sees a slightly different image, creating stereopsis and depth perception.
299
Jane is shown two different images in each eye and notices they seem to switch back and forth instead of blending. What is happening?
Binocular rivalry, where the brain alternates between the two competing images.
300
Michael is trying to detect a hidden 3D shape in a random dot stereogram but can’t see it. What should he do?
He should try crossing or uncrossing his eyes to let his brain fuse the two images and perceive the 3D shape.
301
Abed wants to create a VR experience that tricks the brain into seeing depth. What visual principle should he use?
Binocular disparity, providing slightly different images to each eye to create stereopsis.
302
Rory is reading about early 3D movie technology and wonders why red-blue glasses were used. What was their function?
They filtered the image so each eye saw a different color layer, creating binocular disparity for depth perception.
303
Gus is looking at a stereogram but can’t tell what the hidden image is. What does this reveal about stereopsis?
It suggests that his brain needs binocular disparity processing to extract depth before recognizing the object.
304
Louis complains that watching 3D movies gives him headaches. What might be causing this?
His brain struggles to fuse the two images due to binocular disparity issues or misalignment between his eyes.
305
Jane is shown a pattern of random dots but suddenly sees a hidden shape. What does this reveal?
His brain is using binocular disparity to perceive depth before recognizing objects.
306
Fiona notices that when two different images are presented to each eye, her perception keeps shifting. What phenomenon is this?
Binocular rivalry, where the brain switches between competing visual inputs instead of combining them.
307
Abed wants to make a psychological experiment where participants see alternating images when presented with different stimuli in each eye. What effect is he studying?
Binocular rivalry, which shows how the brain resolves conflicting visual input.
308
Rory is reading a book about vision and sees an image that pops out in 3D when she stares at it a certain way. What type of illusion is this?
A random dot stereogram, which creates depth perception through binocular disparity.
