Midterm 1

Question 1

What is the study and measurement of perception?

Answer 1

It involves understanding how humans process sensory information and measure subjective experiences.

Question 2

What is the perceptual process?

Answer 2

A continuous, dynamic process where sensory systems interact with the environment to produce perception.

Question 3

How can human sensory systems be best thought of?

Answer 3

As actively engaging with sensory stimuli, dynamically interacting with the environment using multiple exposures and top-down information.

Question 4

What is the principle of transformation?

Answer 4

The environmental stimulus changes (is transformed) before it is perceived.

Question 5

What is the proximal stimulus?

Answer 5

The pattern formed on the sensory organ after transformation of the distal stimulus.

Question 6

What is the principle of representation?

Answer 6

Perception of an object is based on the interaction between the sensory system and the transformed stimulus.

Question 7

What is transduction in perception?

Answer 7

Conversion of energy from a stimulus (light, sound, motion) into electrical signals used by the nervous system.

Question 8

Which principle states that the proximal stimulus is not the same as the distal stimulus?

Answer 8

The principle of transformation.

Question 9

To what does transduction and neural processing apply?

Answer 9

The proximal stimulus.

Question 10

What is perception?

Answer 10

The conscious experience or detection of a stimulus resulting from sensory stimulation.

Question 11

What is the difference between perception and recognition?

Answer 11

Perception is detecting something, while recognition involves categorizing or identifying it.

Question 12

What is top-down processing?

Answer 12

Perception influenced by prior knowledge, experience, or expectations.

Question 13

What is bottom-up processing?

Answer 13

Perception driven primarily by the properties of the stimulus.

Question 14

How do we measure perception?

Answer 14

By defining theoretical constructs and operational definitions that relate observable behavior to mental experiences.

Question 15

What is a theoretical construct?

Answer 15

An unobservable entity that explains sensory experiences (qualia) shared across individuals.

Question 16

What is an operational definition?

Answer 16

A measurable behavior used as a proxy to infer the presence of a theoretical construct.

Question 17

Can we assume two people experience colors the same if they respond similarly to tests?

Answer 17

No, operational definitions may match, but subjective experiences (qualia) may differ.

Question 18

What are qualitative psychophysical methods?

Answer 18

Description (phenomenological) and recognition of stimuli; useful in clinical contexts.

Question 19

What are quantitative psychophysical methods?

Answer 19

Detection tasks, difference thresholds, magnitude estimation, visual search, and reaction time measures.

Question 20

What is absolute threshold?

Answer 20

The smallest amount of stimulus energy required for detection.

Question 21

What are the classical methods to measure absolute threshold?

Answer 21

Method of limits, method of adjustment, method of constant stimuli.

Question 22

What is the method of limits?

Answer 22

Present stimuli in ascending or descending order; threshold is mean of crossover points.

Question 23

What is the method of adjustment?

Answer 23

Observer adjusts stimulus intensity until detection; faster but less precise.

Question 24

What is the method of constant stimuli?

Answer 24

Present stimuli randomly across different intensities multiple times; threshold at 50% detection rate.

Question 25

What is an adaptive staircase method?

Answer 25

Stimuli dynamically converge on the observer’s threshold; average reversals determine threshold.

Question 26

What is a difference threshold (just-noticeable difference, JND)?

Answer 26

The smallest detectable difference between two stimuli.

Question 27

What is the point of subjective equality (PSE)?

Answer 27

The point where two stimuli are perceived as the same despite physical differences.

Question 28

What is Weber's Law?

Answer 28

DL/S = K, describing that JND increases proportionally with stimulus magnitude.

Question 29

What is magnitude estimation?

Answer 29

Quantifying perceived differences between stimuli by assigning numerical values relative to a standard.

Question 30

What is Stevens's Power Law?

Answer 30

P = K * S^n; relationship between perceived magnitude (P) and stimulus intensity (S).

Question 31

What is visual search?

Answer 31

Measuring the time and accuracy to detect a target stimulus to infer perceptual mechanisms.

Question 32

How is visual search applied in medicine?

Answer 32

Used to study tumor detection and identification, often with eye-tracking and threshold estimates.

Question 33

How is visual search applied in UX?

Answer 33

Eye tracking measures attention and interest, helping design web interfaces and accessibility features.

Question 34

What are key psychophysical methods summary?

Answer 34

Qualitative: description, recognition. Quantitative: detection, difference threshold, magnitude estimation, visual search.

Question 35

What is the range of the human visual spectrum?

Answer 35

Approximately 400 to 700 nanometers.

Question 36

What is the basic function of the eye?

Answer 36

To detect light and transmit visual information via distal and proximal stimuli to the retina.

Question 37

What does the iris do?

Answer 37

It constricts or dilates to regulate light input to the eye.

Question 38

What is the pupillary light reflex?

Answer 38

An automatic response to environmental light intensity, causing constriction in one eye to also constrict the other (consensual response).

Question 39

What nervous systems control pupil size?

Answer 39

Parasympathetic and sympathetic nervous systems.

Question 40

What is anisocoria?

Answer 40

A condition where some people (~20%) have unequal pupil sizes.

Question 41

What provides ~80% of the eye's focal power?

Answer 41

The cornea.

Question 42

What accounts for ~20% of focusing power?

Answer 42

The lens, through accommodation.

Question 43

What is the far point?

Answer 43

The point at which a relaxed eye makes an object appear clear.

Question 44

What is the near point?

Answer 44

The closest you can bring an object and keep it in focus.

Question 45

What happens to the lens when focusing on something near?

Answer 45

Ciliary muscles constrict, making the lens fatter/more convex.

Question 46

What is presbyopia?

Answer 46

Age-related decrease in lens flexibility and increased near point distance.

Question 47

What causes myopia?

Answer 47

Distant images focus in front of the retina; due to cornea/lens or axial length.

Question 48

What causes hyperopia?

Answer 48

Nearby images focus beyond the retina; due to cornea/lens shape or short eye.

Question 49

What is the vitreous humor?

Answer 49

A gelatinous substance that helps maintain the shape of the eye.

Question 50

Where is fine detail vision focused?

Answer 50

On the fovea, the center of the macula, which contains only cones.

Question 51

What is the role of ipRGCs?

Answer 51

They regulate circadian rhythms, influence the pupillary light reflex, and may modulate alertness and mood.

Question 52

What molecule in photoreceptors reacts to light?

Answer 52

Retinal, part of the visual pigment molecule opsin.

Question 53

How many photons can a person detect under ideal conditions?

Answer 53

About 100 photons, activating roughly 7 rod receptors.

Question 54

What are the differences between rods and cones?

Answer 54

Rods: ~120 million, sensitive in periphery, scotopic vision; Cones: ~6 million, concentrated in fovea, photopic vision.

Question 55

What is the blind spot?

Answer 55

The optic disc where the optic nerve exits; brain fills in the missing information.

Question 56

What is glaucoma?

Answer 56

Damage to the optic nerve due to increased intraocular pressure.

Question 57

What is macular degeneration?

Answer 57

Damage to the fovea/macula; dry (drusen buildup) or wet (abnormal blood vessels).

Question 58

What is retinitis pigmentosa?

Answer 58

Genetic disease affecting retinal receptors; rods affected first.

Question 59

What is the Purkinje shift?

Answer 59

Shift in sensitivity from cones to rods in darkness, enhancing perception of shorter wavelengths.

Question 60

How does light exposure from screens affect sleep?

Answer 60

Blue light (~450-480 nm) suppresses melatonin via ipRGCs.

Question 61

What is sensory modularity?

Answer 61

Specific brain regions process certain types of sensory information independently.

Question 62

What is the doctrine of specific nerve energies?

Answer 62

Perception depends on which nerves are stimulated, not just the stimulus itself.

Question 63

What is an EPSP?

Answer 63

Excitatory post-synaptic potential; influx of positive ions pushes neuron toward depolarization.

Question 64

What is an IPSP?

Answer 64

Inhibitory post-synaptic potential; efflux of positive ions hyperpolarizes the neuron.

Question 65

What is neural convergence?

Answer 65

Multiple receptors send signals to a single neuron; higher in rods, lower in foveal cones.

Question 66

What is lateral inhibition?

Answer 66

Activity of neighboring neurons suppresses firing, enhancing contrast and edge detection.