Notes on Module 5
Sensation
● Sensory receptors are specialized neurons that respond to specific types of stimuli.
When sensory information is detected by a sensory receptor, sensation has occurred.
● The conversion from sensory stimulus energy to action potential is known as
transduction.
● We also have sensory systems that provide information about balance (the vestibular
sense), body position and movement (proprioception and kinesthesia), pain
(nociception), and temperature (thermoception).
● Absolute threshold refers to the minimum amount of stimulus energy that must be
present for the stimulus to be detected 50% of the time.
-Another way to think about this is by asking how dim can a light be or how soft can a sound be
and still be detected half of the time.
● It has been estimated that on a clear night, the most sensitive sensory cells in the back
of the eye can detect a candle flame 30 miles away
-Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a
clock 20 feet away (Galanter, 1962).
● It is also possible for us to get messages that are presented below the threshold for
conscious awareness these are called subliminal messages
● A stimulus reaches a physiological threshold when it is strong enough to excite sensory
receptors and send nerve impulses to the brain: This is an absolute threshold.
- A message below that threshold is said to be subliminal: We receive it, but we are not
consciously aware of it.
● Research evidence shows that in laboratory settings, people can process and respond
to information outside of awareness. But this does not mean that we obey these
messages like zombies; in fact, hidden messages have little effect on behavior outside
the laboratory
● Sometimes, we are more interested in how much difference in stimuli is required to
detect a difference between them. This is known as the just noticeable difference (jnd)
or difference threshold. Unlike the absolute threshold, the difference threshold changes
depending on the stimulus intensity.
Perception
● Perception refers to the way sensory information is organized, interpreted, and
consciously experienced.
, ● Perception involves both bottom-up and top-down processing.
● Bottom-up processing refers to sensory information from a stimulus in the environment
driving a process
● Top-down processing refers to knowledge and expectancy driving a process
● That attentional capture would be caused by the sound from the environment: it would
be bottom-up.
● Top-down processes are generally goal directed, slow, deliberate, effortful, and under
your control
● One way to think of this concept is that sensation is a physical process, whereas
perception is psychological
-For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the
sensation is the scent receptors detecting the odor of cinnamon, but the perception may be
“Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.”
● We don’t perceive stimuli that remain relatively constant over prolonged periods of time.
This is known as sensory adaptation.
● Attention plays a significant role in determining what is sensed versus what is perceived.
-Motivation can also affect perception.
-Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life
experiences.
, ● Inattentional blindness is the failure to notice something that is completely visible
because the person was actively attending to something else and did not pay attention
to other things
● The ability to identify a stimulus when it is embedded in a distracting background is
called signal detection theory. This might also explain why a mother is awakened by a
quiet murmur from her baby but not by other sounds that occur while she is asleep.
● Individuals who are deprived of the experience of binocular vision during critical
periods of development have trouble perceiving depth
● The shared experiences of people within a given cultural context can have
pronounced effects on perception.
-For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963)
published the results of a multinational study in which they demonstrated that
individuals from Western cultures were more prone to experience certain types of visual
illusions than individuals from non-Western cultures, and vice versa. One such illusion
that Westerners were more likely to experience was the Müller-Lyer illusion
, ● These perceptual differences were consistent with differences in the types of
environmental features experienced on a regular basis by people in a given
cultural context.
● Research has demonstrated that the ability to identify an odor, and rate its
pleasantness and its intensity, varies cross-culturally
● Children described as thrill seekers are more likely to show taste preferences for
intense sour flavors which suggests that basic aspects of personality might affect
perception.
5.2
Amplitude and Wavelength
Sensation
● Sensory receptors are specialized neurons that respond to specific types of stimuli.
When sensory information is detected by a sensory receptor, sensation has occurred.
● The conversion from sensory stimulus energy to action potential is known as
transduction.
● We also have sensory systems that provide information about balance (the vestibular
sense), body position and movement (proprioception and kinesthesia), pain
(nociception), and temperature (thermoception).
● Absolute threshold refers to the minimum amount of stimulus energy that must be
present for the stimulus to be detected 50% of the time.
-Another way to think about this is by asking how dim can a light be or how soft can a sound be
and still be detected half of the time.
● It has been estimated that on a clear night, the most sensitive sensory cells in the back
of the eye can detect a candle flame 30 miles away
-Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a
clock 20 feet away (Galanter, 1962).
● It is also possible for us to get messages that are presented below the threshold for
conscious awareness these are called subliminal messages
● A stimulus reaches a physiological threshold when it is strong enough to excite sensory
receptors and send nerve impulses to the brain: This is an absolute threshold.
- A message below that threshold is said to be subliminal: We receive it, but we are not
consciously aware of it.
● Research evidence shows that in laboratory settings, people can process and respond
to information outside of awareness. But this does not mean that we obey these
messages like zombies; in fact, hidden messages have little effect on behavior outside
the laboratory
● Sometimes, we are more interested in how much difference in stimuli is required to
detect a difference between them. This is known as the just noticeable difference (jnd)
or difference threshold. Unlike the absolute threshold, the difference threshold changes
depending on the stimulus intensity.
Perception
● Perception refers to the way sensory information is organized, interpreted, and
consciously experienced.
, ● Perception involves both bottom-up and top-down processing.
● Bottom-up processing refers to sensory information from a stimulus in the environment
driving a process
● Top-down processing refers to knowledge and expectancy driving a process
● That attentional capture would be caused by the sound from the environment: it would
be bottom-up.
● Top-down processes are generally goal directed, slow, deliberate, effortful, and under
your control
● One way to think of this concept is that sensation is a physical process, whereas
perception is psychological
-For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls, the
sensation is the scent receptors detecting the odor of cinnamon, but the perception may be
“Mmm, this smells like the bread Grandma used to bake when the family gathered for holidays.”
● We don’t perceive stimuli that remain relatively constant over prolonged periods of time.
This is known as sensory adaptation.
● Attention plays a significant role in determining what is sensed versus what is perceived.
-Motivation can also affect perception.
-Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life
experiences.
, ● Inattentional blindness is the failure to notice something that is completely visible
because the person was actively attending to something else and did not pay attention
to other things
● The ability to identify a stimulus when it is embedded in a distracting background is
called signal detection theory. This might also explain why a mother is awakened by a
quiet murmur from her baby but not by other sounds that occur while she is asleep.
● Individuals who are deprived of the experience of binocular vision during critical
periods of development have trouble perceiving depth
● The shared experiences of people within a given cultural context can have
pronounced effects on perception.
-For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963)
published the results of a multinational study in which they demonstrated that
individuals from Western cultures were more prone to experience certain types of visual
illusions than individuals from non-Western cultures, and vice versa. One such illusion
that Westerners were more likely to experience was the Müller-Lyer illusion
, ● These perceptual differences were consistent with differences in the types of
environmental features experienced on a regular basis by people in a given
cultural context.
● Research has demonstrated that the ability to identify an odor, and rate its
pleasantness and its intensity, varies cross-culturally
● Children described as thrill seekers are more likely to show taste preferences for
intense sour flavors which suggests that basic aspects of personality might affect
perception.
5.2
Amplitude and Wavelength
