PSYC 230 UIUC EXAMINATION SET 2025 QUESTIONS WITH
ANSWERS GUARANTEE A+
✔✔Magnitude estimation - ✔✔The participant assigns values according to perceived
magnitudes of the stimuli
- EX: give observers series of sugar solutions and ask them to assign numbers to each
sample.
- i.e. Solution 2 is 2x as sweet as Solution 1
✔✔Stevens' power law - ✔✔Magnitude estimates are well described by
________________ .
- S = aI^(b)
(S) is related to stimulus intensity
(I) by an exponent (b)
- A principle describing the relationship between the stimulus and resulting sensation
that says the magnitude of subjective sensation is proportional to the stimulus
magnitude raised to an exponent.
- exponent for brightness is 0.3, so change from 1 candle to 11 is quite dramatic,
but adding 10 to 100 results in only a modest change
Adding 10 to 10,000 wouldn't even be noticeable
VS.
Apparent length = 1.0
- exponent for electric shock is quite large (3.5), meaning that the pain grows with
I^(3.5), so a 4-fold increase in the electrical current is experienced as a 128-fold
increase in pain
✔✔Weber's law vs. Fechner's law vs. Stevens' power law - ✔✔Weber's law: involves a
clear objective measurement . We know how much we varied the stimulus, and either
the observers can tell that the stimulus changed or they cannot.
Fechner's law: begins with same objective measurements as Weber's, but the law is
actually a calculation based on some assumptions about how sensation works.
- assumes that all JNDs are perceptually equivalent
(they are not)
Stevens' power law: describes rating data well BUT the rating data are qualitatively
different from the data that supported Weber's law.
- no way to know whether subjects' ratings are objectively right or wrong
,✔✔Propylthiouracil (PROP) - ✔✔molecule that some people experience as very bitter,
while others experience it as tasteless
✔✔Cross-modality matching - ✔✔The participant matches the intensity of a sensation in
one sensory modality with the intensity of a sensation in another
Ex: Ask participant to adjust the brightness of a light so it matches the perceived
loudness of a particular tone
✔✔Signal detection theory - ✔✔A psychophysical theory that quantifies the response of
an observer to the presentation of a signal in the presence of noise
- internal noise (when close your eyes still see grey with occasional brighter flashes)
- external noise (when looking at a mammogram there are similar regions that look like
the signal (cancer) but aren't
- makes a distinction between an observers' ability to perceive a signal and their
willingness to report it
✔✔Hit - ✔✔(Signal detection theory)
Stimulus is present and observer responds "Yes"
✔✔Miss - ✔✔Stimulus is present and observer responds "No"
✔✔False alarm - ✔✔Stimulus is not present and observer responds "Yes"
✔✔Correct rejection - ✔✔Stimulus is not present and observer responds "No"
✔✔Criterion - ✔✔An internal threshold that is set by the observer. If the internal
response is above _________ , the observer gives one response. Below _________ ,
the observer gives another response
✔✔Sensitivity - ✔✔A value that defines the ease with which an observer can tell the
difference between the presence and absence of a stimulus or the difference between
stimulus 1 and stimulus 2
- Sensitivity defines the ease with which we are able to tell the difference between the
presence and absence of a stimulus.
✔✔d' - ✔✔In SDT d' is a measure of how discriminable two distributions are.
- the distance between the distribution means...
- large when two distributions are very discriminable.
Small when not
✔✔Doctrine of specific nerve energies - ✔✔- Handbook of Physiology
, A doctrine formulated by Johannes Müller (1801-1858) stating that the nature of a
sensation depends on which sensory fibers are stimulated, not on how the fibers are
stimulated
- central idea: we cannot be directly aware of the world itself, we are only aware of the
activity in our nerves.
Ex: We experience vision because the optic nerve is stimulated, but it does not matter
whether light, or something else, stimulates the nerve.
✔✔Cranial nerves - ✔✔Twelve pairs of nerves (one for each side of the body) that
originate in the brain stem and reach sense organs and muscles through openings in
the skull
Sensory information
Olfactory (I) nerves
Optic (II) nerves
Auditory (VIII) nerves
• Muscles that move the eyes Oculomotor (III)
Trochlear (IV) nerves
Abducens (VI) nerves
✔✔Hermann von Helmholtz (1821- 1894) - ✔✔- Invented the ophthalmoscope to look
inside of people's eyes!
- Helmholtz argued that all behavior could be explained by only physical forces
- First to measure the speed of neural transmission. He proved that neurons obey the
laws of physics and chemistry
✔✔Santiago Ramón y Cajal (1852-1934) - ✔✔- Created incredibly detailed drawings of
neurons
and neural structures
- Was the first person to discover the synapse
✔✔Otto Loewi - ✔✔- German pharmacologist who received a Nobel Prize for
demonstrating that neurons communicate with one another by releasing chemicals
called neurotransmitters.
- essentially demonstrated the "chemical nature" of synaptic communication (1920)
✔✔Synapse - ✔✔The junction between neurons that permits information transfer
✔✔Neurotransmitter - ✔✔A chemical substance used in neuronal communication at
synapses
ANSWERS GUARANTEE A+
✔✔Magnitude estimation - ✔✔The participant assigns values according to perceived
magnitudes of the stimuli
- EX: give observers series of sugar solutions and ask them to assign numbers to each
sample.
- i.e. Solution 2 is 2x as sweet as Solution 1
✔✔Stevens' power law - ✔✔Magnitude estimates are well described by
________________ .
- S = aI^(b)
(S) is related to stimulus intensity
(I) by an exponent (b)
- A principle describing the relationship between the stimulus and resulting sensation
that says the magnitude of subjective sensation is proportional to the stimulus
magnitude raised to an exponent.
- exponent for brightness is 0.3, so change from 1 candle to 11 is quite dramatic,
but adding 10 to 100 results in only a modest change
Adding 10 to 10,000 wouldn't even be noticeable
VS.
Apparent length = 1.0
- exponent for electric shock is quite large (3.5), meaning that the pain grows with
I^(3.5), so a 4-fold increase in the electrical current is experienced as a 128-fold
increase in pain
✔✔Weber's law vs. Fechner's law vs. Stevens' power law - ✔✔Weber's law: involves a
clear objective measurement . We know how much we varied the stimulus, and either
the observers can tell that the stimulus changed or they cannot.
Fechner's law: begins with same objective measurements as Weber's, but the law is
actually a calculation based on some assumptions about how sensation works.
- assumes that all JNDs are perceptually equivalent
(they are not)
Stevens' power law: describes rating data well BUT the rating data are qualitatively
different from the data that supported Weber's law.
- no way to know whether subjects' ratings are objectively right or wrong
,✔✔Propylthiouracil (PROP) - ✔✔molecule that some people experience as very bitter,
while others experience it as tasteless
✔✔Cross-modality matching - ✔✔The participant matches the intensity of a sensation in
one sensory modality with the intensity of a sensation in another
Ex: Ask participant to adjust the brightness of a light so it matches the perceived
loudness of a particular tone
✔✔Signal detection theory - ✔✔A psychophysical theory that quantifies the response of
an observer to the presentation of a signal in the presence of noise
- internal noise (when close your eyes still see grey with occasional brighter flashes)
- external noise (when looking at a mammogram there are similar regions that look like
the signal (cancer) but aren't
- makes a distinction between an observers' ability to perceive a signal and their
willingness to report it
✔✔Hit - ✔✔(Signal detection theory)
Stimulus is present and observer responds "Yes"
✔✔Miss - ✔✔Stimulus is present and observer responds "No"
✔✔False alarm - ✔✔Stimulus is not present and observer responds "Yes"
✔✔Correct rejection - ✔✔Stimulus is not present and observer responds "No"
✔✔Criterion - ✔✔An internal threshold that is set by the observer. If the internal
response is above _________ , the observer gives one response. Below _________ ,
the observer gives another response
✔✔Sensitivity - ✔✔A value that defines the ease with which an observer can tell the
difference between the presence and absence of a stimulus or the difference between
stimulus 1 and stimulus 2
- Sensitivity defines the ease with which we are able to tell the difference between the
presence and absence of a stimulus.
✔✔d' - ✔✔In SDT d' is a measure of how discriminable two distributions are.
- the distance between the distribution means...
- large when two distributions are very discriminable.
Small when not
✔✔Doctrine of specific nerve energies - ✔✔- Handbook of Physiology
, A doctrine formulated by Johannes Müller (1801-1858) stating that the nature of a
sensation depends on which sensory fibers are stimulated, not on how the fibers are
stimulated
- central idea: we cannot be directly aware of the world itself, we are only aware of the
activity in our nerves.
Ex: We experience vision because the optic nerve is stimulated, but it does not matter
whether light, or something else, stimulates the nerve.
✔✔Cranial nerves - ✔✔Twelve pairs of nerves (one for each side of the body) that
originate in the brain stem and reach sense organs and muscles through openings in
the skull
Sensory information
Olfactory (I) nerves
Optic (II) nerves
Auditory (VIII) nerves
• Muscles that move the eyes Oculomotor (III)
Trochlear (IV) nerves
Abducens (VI) nerves
✔✔Hermann von Helmholtz (1821- 1894) - ✔✔- Invented the ophthalmoscope to look
inside of people's eyes!
- Helmholtz argued that all behavior could be explained by only physical forces
- First to measure the speed of neural transmission. He proved that neurons obey the
laws of physics and chemistry
✔✔Santiago Ramón y Cajal (1852-1934) - ✔✔- Created incredibly detailed drawings of
neurons
and neural structures
- Was the first person to discover the synapse
✔✔Otto Loewi - ✔✔- German pharmacologist who received a Nobel Prize for
demonstrating that neurons communicate with one another by releasing chemicals
called neurotransmitters.
- essentially demonstrated the "chemical nature" of synaptic communication (1920)
✔✔Synapse - ✔✔The junction between neurons that permits information transfer
✔✔Neurotransmitter - ✔✔A chemical substance used in neuronal communication at
synapses
