Psych Exam: Sensation and Perception 10/23
Module 18: Sensation and Perception
Sensation: The process by which our sensory receptors and nervous system receive
and represent stimulus energies from the environment (biological process)
Perception: The process of organizing and interpreting sensory information,
enabling us to recognize meaningful objects and events (psychological process)
Bottom Up Processing: the analysis of the stimulus begins with the sense receptors
and works up to the level of the brain and mind. This is taking the sensory
information and then assembling it and integrating it. The question being asked is:
“what am I seeing?”
Top down processing : this is using models, ideas and expectation to interpret
sensory information. The question being asked is “have I seen this before?”
Prosopagnosia: The inability to recognize faces of familiar people
Transduction: Conversion of one form of energy to another. In sensation the
transformation of stimulus energies, such as sight, sounds, and smells, into neural
impulses brain can interpret
Psychophysics: Study of relationships between detectable physical energy and its
effects on psychological experiences. It is the study of the relationships between
the physical energy we can detect and its effects on our psychological experiences.
Detection question: What is the minimum amount of energy in a stimulus that
humans can detect? It is concerned with the limits on our ability to detect very faint
signals. Ex. How intense does light have to be for us to see it? Ex. How intense
does a sound have to be for us to hear it?
Signal Detection Theory: Predicts how and when we will detect a faint stimulus
amid background noise
Absolute Threshold: this is the faintest detectable stimulus. It is defined as the
intercity at which a stimulus was detected in 50% of the trials. Less than 50% is
considered subliminal.
Individual Absolute Threshold: This varies depending on the strength of the signal
and also on our experience, expectations, motivation, and alertness
Subliminal: input, below the absolute threshold for conscious awareness.
Priming: This is activating, often unconsciously, associations in our minds, setting
us up to perceive, or respond in a certain way.
,The difference question: What is the minimum difference in stimulus energy
between two stimuli that humans can detect? This is concerned with our ability to
detect very small differences between stimuli. Ex. What is the smallest difference
in brightness between two lights that we can see? What is the smallest difference in
loudness between two sounds that we can hear?
The difference threshold (JND): this is the just noticeable difference. This is the
minimal difference in magnitude (or intensity) between two stimuli that is required
for a person to detect them as different.
Weber's Law: For an average person to perceive a difference, two stimuli must
differ by a constant minimum percentage (not a constant amount); exact proportion
varies depending on the stimulus
Shrinkflation: Same price for a food or item but you get less. Many companies do
this, such as lays chips.
The Scaling Question: How are human perceptual scales of measurement related to
physical scales of measurement? This is concerned with how we perceive the
magnitudes (intensities) of clearly detectable stimuli. Ex. What is the relationship
between the actual physical intensities of stimuli and our psychological perceptions
of these intensities?
Steven’s Power Law: The perceived magnitude of a stimulus is equal to its actual
physical intensity raised to a constant power for each type of judgment. For
instance, to perceive a light as twice as bright, its actual intensity has to be
increased between 8 and 9 times.
McGurk Effect: The brain integrates visual and auditory input to create the
perception. It illustrates the role of both of these modalities in speech perception.
Example was done in class (what you see contrasts with what you hear). When
watching the person talking with eyes closed it sounds like ba ba ba. When you
watch with eyes open it sounds like da da da. When you turn the sound off and
watch, it looks like ga ga ga.
Perceptual Set: This is the mental predisposition to perceive one thing and not
another. This is the mental tendencies and assumptions that affect (top-down) what
we hear, taste, feel, and see. Culture influences our perceptual set. Experience
helps us organize and interpret unfamiliar information by using learned schemas or
categories. Pre-existing schemas influence top-down processing of ambiguous
sensation interpretation, including gender stereotypes. Also influenced by context
effects.
, Sensory Adaptation: This is the diminished sensitivity due to constant stimulation.
Ex. Putting a bandaid on your arm and after awhile you don't sense it
Module 19: Sensation and Perception
Wavelength: distance in one cycle of a wave, from one crest to the next. With
respect to vision, humans can see wavelengths of about 400 to 700 nanometers
Amplitude: this is height. This is the amount of energy in a wave, its intensity,
which is the height of the wave at its crest. For light waves, amplitude determines
its brightness
Properties of waves:
Perceptual processing in vision: Light energy is transduced into neural messages.
Receptor cells for the eyes are the Rods and Cones. Only a tiny slice of a wide
spectrum of electromagnetic energy is perceived by humans. The portion visible to
humans extends from the blue-violet to the red light wavelengths.
Rods and Cones: These are the receptor cells for the eyes. They provide special
sensitivity-cones to detail and color and rods to faint light and peripheral motion
Cornea: This is the clear covering of the eye through which light rays pass. It can
be very painful when scratched
Pupil: This further filters the light rays through the lens before being passed to the
retina at the back of the eye
Lens: focuses the light waves from objects of different distances directly on the
retina, known as accommodation
Module 18: Sensation and Perception
Sensation: The process by which our sensory receptors and nervous system receive
and represent stimulus energies from the environment (biological process)
Perception: The process of organizing and interpreting sensory information,
enabling us to recognize meaningful objects and events (psychological process)
Bottom Up Processing: the analysis of the stimulus begins with the sense receptors
and works up to the level of the brain and mind. This is taking the sensory
information and then assembling it and integrating it. The question being asked is:
“what am I seeing?”
Top down processing : this is using models, ideas and expectation to interpret
sensory information. The question being asked is “have I seen this before?”
Prosopagnosia: The inability to recognize faces of familiar people
Transduction: Conversion of one form of energy to another. In sensation the
transformation of stimulus energies, such as sight, sounds, and smells, into neural
impulses brain can interpret
Psychophysics: Study of relationships between detectable physical energy and its
effects on psychological experiences. It is the study of the relationships between
the physical energy we can detect and its effects on our psychological experiences.
Detection question: What is the minimum amount of energy in a stimulus that
humans can detect? It is concerned with the limits on our ability to detect very faint
signals. Ex. How intense does light have to be for us to see it? Ex. How intense
does a sound have to be for us to hear it?
Signal Detection Theory: Predicts how and when we will detect a faint stimulus
amid background noise
Absolute Threshold: this is the faintest detectable stimulus. It is defined as the
intercity at which a stimulus was detected in 50% of the trials. Less than 50% is
considered subliminal.
Individual Absolute Threshold: This varies depending on the strength of the signal
and also on our experience, expectations, motivation, and alertness
Subliminal: input, below the absolute threshold for conscious awareness.
Priming: This is activating, often unconsciously, associations in our minds, setting
us up to perceive, or respond in a certain way.
,The difference question: What is the minimum difference in stimulus energy
between two stimuli that humans can detect? This is concerned with our ability to
detect very small differences between stimuli. Ex. What is the smallest difference
in brightness between two lights that we can see? What is the smallest difference in
loudness between two sounds that we can hear?
The difference threshold (JND): this is the just noticeable difference. This is the
minimal difference in magnitude (or intensity) between two stimuli that is required
for a person to detect them as different.
Weber's Law: For an average person to perceive a difference, two stimuli must
differ by a constant minimum percentage (not a constant amount); exact proportion
varies depending on the stimulus
Shrinkflation: Same price for a food or item but you get less. Many companies do
this, such as lays chips.
The Scaling Question: How are human perceptual scales of measurement related to
physical scales of measurement? This is concerned with how we perceive the
magnitudes (intensities) of clearly detectable stimuli. Ex. What is the relationship
between the actual physical intensities of stimuli and our psychological perceptions
of these intensities?
Steven’s Power Law: The perceived magnitude of a stimulus is equal to its actual
physical intensity raised to a constant power for each type of judgment. For
instance, to perceive a light as twice as bright, its actual intensity has to be
increased between 8 and 9 times.
McGurk Effect: The brain integrates visual and auditory input to create the
perception. It illustrates the role of both of these modalities in speech perception.
Example was done in class (what you see contrasts with what you hear). When
watching the person talking with eyes closed it sounds like ba ba ba. When you
watch with eyes open it sounds like da da da. When you turn the sound off and
watch, it looks like ga ga ga.
Perceptual Set: This is the mental predisposition to perceive one thing and not
another. This is the mental tendencies and assumptions that affect (top-down) what
we hear, taste, feel, and see. Culture influences our perceptual set. Experience
helps us organize and interpret unfamiliar information by using learned schemas or
categories. Pre-existing schemas influence top-down processing of ambiguous
sensation interpretation, including gender stereotypes. Also influenced by context
effects.
, Sensory Adaptation: This is the diminished sensitivity due to constant stimulation.
Ex. Putting a bandaid on your arm and after awhile you don't sense it
Module 19: Sensation and Perception
Wavelength: distance in one cycle of a wave, from one crest to the next. With
respect to vision, humans can see wavelengths of about 400 to 700 nanometers
Amplitude: this is height. This is the amount of energy in a wave, its intensity,
which is the height of the wave at its crest. For light waves, amplitude determines
its brightness
Properties of waves:
Perceptual processing in vision: Light energy is transduced into neural messages.
Receptor cells for the eyes are the Rods and Cones. Only a tiny slice of a wide
spectrum of electromagnetic energy is perceived by humans. The portion visible to
humans extends from the blue-violet to the red light wavelengths.
Rods and Cones: These are the receptor cells for the eyes. They provide special
sensitivity-cones to detail and color and rods to faint light and peripheral motion
Cornea: This is the clear covering of the eye through which light rays pass. It can
be very painful when scratched
Pupil: This further filters the light rays through the lens before being passed to the
retina at the back of the eye
Lens: focuses the light waves from objects of different distances directly on the
retina, known as accommodation
