Review Questions – Sensation and Perception
From the text: (These questions are covered in your textbook, but we did not discuss them in
class.)
What is the difference between qualitative and quantitative sensory coding? (Stop Light
Example)
Qualitative: Information consisting of the most basic qualities of a stimulus. For example,
the difference between a tuba’s sound and a flute’s sound, difference between salty and
sweet taste.
o If you were approaching a traffic light, qualitative info might include whether the
light was red or green
Quantitative: Information consisting of the degree, or magnitude, or those qualities: the
loudness of the sound in the tuba or flute, the relative saltiness or sweetness. Respond to the
rate of a particular neuron’s firing.
o If you were approaching a traffic light, quantitative info would include the brightness
of the light
Describe absolute thresholds, difference thresholds, and Weber’s law.
Absolute Threshold: The minimum intensity of stimulation that must occur before you
experience a sensation
o Stimulus intensity you would detect more often than by chance (how loudly must
someone in the next room whisper for you to hear it?). The absolute threshold for
auditory stimuli would be the quietest whisper you could hear half the time
Difference Thresholds: The just noticeable difference between two stimuli.
o It is the minimum amount of change required for a person to detect a difference. If
your friend is watching tv while you are reading and a commercial comes on that is
louder than the show, you might look up, noticing that something had changed. The
difference threshold is the minimum change in volume required for you to detect a
difference
Weber’s Law: States that the just noticeable difference between two stimuli is based on a
proportion of the original stimulus rather than on a fixed amount of difference
o The more intense the stimulus, the bigger the change needed for you to notice (i.e.
picking up 1 ounce and 2 ounce letter = you can tell difference in weight. Pick up 5
pound package and another package than is 1 more ounce heavier, can’t really tell
the difference)
Describe the role of human judgment in signal detection theory. What are the four possible
outcomes in a trial of a signal detection experiment? How could response bias affect these
outcomes?
Signal Detection Theory: This theory states that detecting a stimulus requires making a
judgment about its presence or absence, based on a subjective interpretation of ambiguous
information.
o If you are put in a dark room and asked if you feel, smell, or see anything, you may
convince yourself that you are sensing a weak stimulus when you really are not. This
is because you are mentally judging the sensation of the stimulus in its presence
Outcomes:
o Hit: If the signal is presented and the participant detects it
o Miss: If the participant fails to detect the signal
, o False Alarm: If the participant “detects” a signal that was not presented
o Correct Rejection: If the signal is not presented and the participant does not detect
it
Response Bias: A participant’s tendency to report detecting the signal in an ambiguous trial.
o The participant might be strongly biased against responding and need a great deal of
evidence that the signal is present. Under other conditions, the same participant
might need only a small amount of evidence.
In audition, what characteristics of the sound wave determine intensity and pitch?
Sound Wave: A pattern of changes in air pressure during a period of time; it produces the
percept of a sound
o Amplitude: The wave’s amplitude determines its loudness: We hear a higher
amplitude as a louder sound
o Frequency: The wave’s frequency determines its pitch: We heard a higher
frequency as a sound that is higher in pitch
How are sound waves converted into neural activity in the brain? What role do the following
parts of the ear play in this conversion? auditory canal, eardrum, ossicles, cochlea, oval
window, basilar membrane, hair cells, auditory nerve.
Like all other sensory experiences, the sensory experience of hearing occurs within the
brain, as the brain integrates the difference signals provided by various sound waves
Auditory Canal: When changes in air pressure produce sound waves within a person’s
hearing distance, those sound waves arrive at the person’s outer ear and travel down the
auditory canal
Eardrum: A thin membrane that marks the beginning of the middle ear; sound waves cause
it vibrate (the sound wave makes the eardrum vibrate)
Ossicles: Vibrations are transferred, next, to the Ossicles, which are three tiny bones
commonly called the hammer, anvil, and stirrup
Cochlea: A membrane in the inner ear that holds the oval window. It is a fluid filled tube
that curls into a snail-like shape, with a membrane at the end called the round window
Oval Window: The Ossicles transfer the eardrum’s vibrations to the oval window (located
in the cochlea). The oval window’s vibrations create pressure waves in the cochlear fluid;
these waves prompt the basilar membrane to oscillate
Basilar Membrane: Running through the center of the cochlea is the thin basilar membrane
Hair Cells: Movement of the basilar membrane stimulates hair cells to bend and to send
information to the auditory nerve. These hair cells are the primary auditory receptors.
Auditory Nerve: Where the hair cells send the information. Sound waves hit the eardrum
and are concerted to neural signals that travel to the brain along the auditory nerve. This
conversion of sound waves to brain activity produces the sensation of sound
o Cochlear implants stimulate the auditory nerve to help deaf people with their hearing
Explain the difference between bottom-up and top-down processing.
Hierarchical model of pattern recognition
Bottom-up Processing: Data are relayed from one level of mental processing to the next,
always moving to a higher level of processing
Top-down Processing: Information at higher levels of mental processing can also influence
lower, “earlier” levels in the processing hierarchy
Describe the common monocular and binocular depth cues.
Monocular Depth Cues: Cues of depth perception that are available to each eye alone and
provide organizational information for top-down processing
, Binocular Depth Cues: Cues of depth perception that arise from the fact that people have
two eyes and contribute to bottom-up processing
Other questions: (These questions were covered in class, or in class and the text.)
How are sensation and perception different? What is sensory coding? (Stop Light Example)
Sensation: Our sense organs’ detection of external stimulus energy, such as light, air
vibrations, and odors. It is also our sense organs’ responses to the external stimulus energy
and the transmission of those responses to the brain. Sensation is an elementary experience,
such as color or motion, without the more complex perceptual experience of what is being
seen or what is moving. The essence of sensation is detection.
Perception: The brain’s further processing of these detected signals. It results in internal
representations of the stimuli, representations that form a conscious experience of the world.
The essence of perception is construction of useful and meaningful information about a
particular environment. How we perceive things is also based on past experiences
Sensory Coding: Our sensory organs translate the physical properties of stimuli into
patterns of neural impulses. The different features of the physical environment are coded by
patterns of impulses in different neurons.
Explain the basic process of sensory adaptation and give an example.
Sensory Adaptation: A decrease in sensitivity to a constant level of stimulation
o Studying near a construction sight when the equipment starts up, the sound
seems particularly loud. After a few minutes, the noise seems to have faded into the
background. This is because if a stimulus is presented continuously, the responses of
the sensory systems that detect it tend to diminish over time.
o Similarly, when a continuous stimulus stops, the sensory systems usually respond
strongly as well. If the construction noise suddenly halted, you would likely notice
the silence
Know the basics regarding the stimulus for vision (light) -- i.e., what characteristics of light
determine what we see?
Stimulus = light, only humans can see “visible light” on the spectrum
WAVELENGTH DETERMINES COLOR!!!!!!!!!
Hue (color): Determined by wavelength:
o Longer Wavelength= red
o Shorter Wavelength = blue
White: All of the colors combined are being reflected off of the eye
Black: All of the colors combined are being absorbed by the eye
Brightness: Determined by intensity or amount of energy in light wave (amplitude)
You see photons reflecting off objects (would be invisible if something reflected no photons)
Color is subjective
In vision, what is the process of accommodation?
Accommodation: Behind the iris, muscles change the shape of the lens. They flatten it to
focus on distant objects and thicken it to focus on closer objects (accommodation).
o This lens and cornea work together to collect and focus light rays reflected from an
object, to form on the retina an upside-down image of the object. The world looks
right-side up to us even though the image of the world projected on the retina is
upside-down
From the text: (These questions are covered in your textbook, but we did not discuss them in
class.)
What is the difference between qualitative and quantitative sensory coding? (Stop Light
Example)
Qualitative: Information consisting of the most basic qualities of a stimulus. For example,
the difference between a tuba’s sound and a flute’s sound, difference between salty and
sweet taste.
o If you were approaching a traffic light, qualitative info might include whether the
light was red or green
Quantitative: Information consisting of the degree, or magnitude, or those qualities: the
loudness of the sound in the tuba or flute, the relative saltiness or sweetness. Respond to the
rate of a particular neuron’s firing.
o If you were approaching a traffic light, quantitative info would include the brightness
of the light
Describe absolute thresholds, difference thresholds, and Weber’s law.
Absolute Threshold: The minimum intensity of stimulation that must occur before you
experience a sensation
o Stimulus intensity you would detect more often than by chance (how loudly must
someone in the next room whisper for you to hear it?). The absolute threshold for
auditory stimuli would be the quietest whisper you could hear half the time
Difference Thresholds: The just noticeable difference between two stimuli.
o It is the minimum amount of change required for a person to detect a difference. If
your friend is watching tv while you are reading and a commercial comes on that is
louder than the show, you might look up, noticing that something had changed. The
difference threshold is the minimum change in volume required for you to detect a
difference
Weber’s Law: States that the just noticeable difference between two stimuli is based on a
proportion of the original stimulus rather than on a fixed amount of difference
o The more intense the stimulus, the bigger the change needed for you to notice (i.e.
picking up 1 ounce and 2 ounce letter = you can tell difference in weight. Pick up 5
pound package and another package than is 1 more ounce heavier, can’t really tell
the difference)
Describe the role of human judgment in signal detection theory. What are the four possible
outcomes in a trial of a signal detection experiment? How could response bias affect these
outcomes?
Signal Detection Theory: This theory states that detecting a stimulus requires making a
judgment about its presence or absence, based on a subjective interpretation of ambiguous
information.
o If you are put in a dark room and asked if you feel, smell, or see anything, you may
convince yourself that you are sensing a weak stimulus when you really are not. This
is because you are mentally judging the sensation of the stimulus in its presence
Outcomes:
o Hit: If the signal is presented and the participant detects it
o Miss: If the participant fails to detect the signal
, o False Alarm: If the participant “detects” a signal that was not presented
o Correct Rejection: If the signal is not presented and the participant does not detect
it
Response Bias: A participant’s tendency to report detecting the signal in an ambiguous trial.
o The participant might be strongly biased against responding and need a great deal of
evidence that the signal is present. Under other conditions, the same participant
might need only a small amount of evidence.
In audition, what characteristics of the sound wave determine intensity and pitch?
Sound Wave: A pattern of changes in air pressure during a period of time; it produces the
percept of a sound
o Amplitude: The wave’s amplitude determines its loudness: We hear a higher
amplitude as a louder sound
o Frequency: The wave’s frequency determines its pitch: We heard a higher
frequency as a sound that is higher in pitch
How are sound waves converted into neural activity in the brain? What role do the following
parts of the ear play in this conversion? auditory canal, eardrum, ossicles, cochlea, oval
window, basilar membrane, hair cells, auditory nerve.
Like all other sensory experiences, the sensory experience of hearing occurs within the
brain, as the brain integrates the difference signals provided by various sound waves
Auditory Canal: When changes in air pressure produce sound waves within a person’s
hearing distance, those sound waves arrive at the person’s outer ear and travel down the
auditory canal
Eardrum: A thin membrane that marks the beginning of the middle ear; sound waves cause
it vibrate (the sound wave makes the eardrum vibrate)
Ossicles: Vibrations are transferred, next, to the Ossicles, which are three tiny bones
commonly called the hammer, anvil, and stirrup
Cochlea: A membrane in the inner ear that holds the oval window. It is a fluid filled tube
that curls into a snail-like shape, with a membrane at the end called the round window
Oval Window: The Ossicles transfer the eardrum’s vibrations to the oval window (located
in the cochlea). The oval window’s vibrations create pressure waves in the cochlear fluid;
these waves prompt the basilar membrane to oscillate
Basilar Membrane: Running through the center of the cochlea is the thin basilar membrane
Hair Cells: Movement of the basilar membrane stimulates hair cells to bend and to send
information to the auditory nerve. These hair cells are the primary auditory receptors.
Auditory Nerve: Where the hair cells send the information. Sound waves hit the eardrum
and are concerted to neural signals that travel to the brain along the auditory nerve. This
conversion of sound waves to brain activity produces the sensation of sound
o Cochlear implants stimulate the auditory nerve to help deaf people with their hearing
Explain the difference between bottom-up and top-down processing.
Hierarchical model of pattern recognition
Bottom-up Processing: Data are relayed from one level of mental processing to the next,
always moving to a higher level of processing
Top-down Processing: Information at higher levels of mental processing can also influence
lower, “earlier” levels in the processing hierarchy
Describe the common monocular and binocular depth cues.
Monocular Depth Cues: Cues of depth perception that are available to each eye alone and
provide organizational information for top-down processing
, Binocular Depth Cues: Cues of depth perception that arise from the fact that people have
two eyes and contribute to bottom-up processing
Other questions: (These questions were covered in class, or in class and the text.)
How are sensation and perception different? What is sensory coding? (Stop Light Example)
Sensation: Our sense organs’ detection of external stimulus energy, such as light, air
vibrations, and odors. It is also our sense organs’ responses to the external stimulus energy
and the transmission of those responses to the brain. Sensation is an elementary experience,
such as color or motion, without the more complex perceptual experience of what is being
seen or what is moving. The essence of sensation is detection.
Perception: The brain’s further processing of these detected signals. It results in internal
representations of the stimuli, representations that form a conscious experience of the world.
The essence of perception is construction of useful and meaningful information about a
particular environment. How we perceive things is also based on past experiences
Sensory Coding: Our sensory organs translate the physical properties of stimuli into
patterns of neural impulses. The different features of the physical environment are coded by
patterns of impulses in different neurons.
Explain the basic process of sensory adaptation and give an example.
Sensory Adaptation: A decrease in sensitivity to a constant level of stimulation
o Studying near a construction sight when the equipment starts up, the sound
seems particularly loud. After a few minutes, the noise seems to have faded into the
background. This is because if a stimulus is presented continuously, the responses of
the sensory systems that detect it tend to diminish over time.
o Similarly, when a continuous stimulus stops, the sensory systems usually respond
strongly as well. If the construction noise suddenly halted, you would likely notice
the silence
Know the basics regarding the stimulus for vision (light) -- i.e., what characteristics of light
determine what we see?
Stimulus = light, only humans can see “visible light” on the spectrum
WAVELENGTH DETERMINES COLOR!!!!!!!!!
Hue (color): Determined by wavelength:
o Longer Wavelength= red
o Shorter Wavelength = blue
White: All of the colors combined are being reflected off of the eye
Black: All of the colors combined are being absorbed by the eye
Brightness: Determined by intensity or amount of energy in light wave (amplitude)
You see photons reflecting off objects (would be invisible if something reflected no photons)
Color is subjective
In vision, what is the process of accommodation?
Accommodation: Behind the iris, muscles change the shape of the lens. They flatten it to
focus on distant objects and thicken it to focus on closer objects (accommodation).
o This lens and cornea work together to collect and focus light rays reflected from an
object, to form on the retina an upside-down image of the object. The world looks
right-side up to us even though the image of the world projected on the retina is
upside-down
