chapter 5 lecture Flashcards
transduction
the process by which sensory stimuli are converted to neural signals the brain can interpret
transduction in electromagnetic
light is converted from electromagnetic energy to energy in the form of action potential (neural impulses)
what is a subjective process, sensation or perception
preception
sensation
the stimulation of sense organs
involves the absorption of energy (light sound waves) by sensory organs (eyes and ears)
perception
the selection, organization and interpretation of sensory information
- involves the translation of sensory information into something meaningful
what physical property matches with the hue of a colour
wavelength/frequency
what related preception of colour matches with amplitude
brightness
what related perception matches with purity
saturation
timbre
purity of sound. A pure tone that has only one frequency and one amplitude
what sets apart sound of a piano from sound of flute
what physical property of sound relates to the perception of pitch
wavelength/ frequency
what related perception does amplitude match with
loudness
what physical property matches with timbre
purity
blind spot
the nerves that run from the retina to the brain converge at a spot this spot has no receptor cells
- any image that falls on this spot cannot be seen
- each eye has a blind spot, but you are not aware of the spot because each eye compensates for the blind spot of the other
the retina contains millions of ____ cells. they are where in the retina, what does this mean
receptor
innermost layer
means only 10% of light arriving at the cornea reaches the receptor
receptor cells are sensitive to
light or photoreceptors
do humans have more rods or cones, how many
more rods
rods= 100-125 million
cones =5 to 6.4 million
What are the two types of receptor cells. what classifies them
rods and cones
- shape classifies them
what is the fovea
tiny spot in the center of retina that contains only cones
the periphery of the retina is outnumbered by
rods
cones are responsible for
colour vision
daylight vision
visual acuity
rods are responsible for
peripheral (area right outside of the fovea) vision
night vision
how many light absorbing pigments do rods and cones have
rods - have the same
cones- three different (which any one cone has one of )
four in total
where is visual information processed
retina and brain
in the retina, where is visual information processed
in the receptive field of a ganglion cell
processes- perception of light/dark contrasts
in the brain where it visual information isual information processed
the visual cortex
- the thalamus, occipital lobe, parietal lobe, and temporal lobe
processes- perception of brightness, orientation, form (face body parts), colour motion depth)
each ganglion cell has its ______ _______ when stimulated what is it responsible for seeing
receptive field- light/dark contrast
center-surround antagonism is a receptor field property on a ____ cell
ganglion
The rate of firing a nerve impulse increases when
light falls in the center of a receptive field
Feature of the receptive field
Center excitatory; surrounding inhibitory
The rate of firing a nerve impulse decreases when
light falls on the surrounding area.
In this figure, shading indicates the area stimulated with light. The largest response
occurs when the entire center (an excitatory area) is illuminated.
thalamus processes
perception of brightness
primary visual cortex in the occipital lobe controls the process of
perception of orientation
inferior temporal lobe processes
perception of form and colour
parietal lobe processes
perception of motion and depth
explain the perception of orientation through the cat experiment
A cat was shown a line in various orientation.
* A microelectrode was placed in the cat’s primary visual cortex.
Action potentials from individual neurons were recorded by an
oscilloscope.
* Findings: A vertical line elicited rapid firing rate; a horizontal line
elicited no response (firing rate was at baseline measure); a tilted line
elicited moderate firing rate
* Conclusion: Neurons are highly specialized; they respond to very
specific stimuli.
After visual
information is
processed in the
primary visual cortex,
it is sent to two other
cortical areas for
further processing. what are the two pathways
dorsal stream
and the ventral stream
ventral stream leads to the
temporal lobe
the ventral stream processes the details of
(including color & form) of “what” objects are
out there—the “what” pathway
when the ventral stream is damaged the person suffered from
agnosia
explain the different types of agnosia
visual-form agnosia (inability to
recognize visual forms or familiar objects), color agnosia (inability to
recognize colors), face agnosia (inability to recognize faces
D.F., a 35-year-old-woman, suffered extensive lesion in her occipital &
temporal lobes as a result of carbon monoxide poisoning. Her ventral
pathway was damaged. She experienced visual-form agnosia.
D.F. was unable to copy objects with simple
contours.
* Interestingly, she could draw them from
memory. But when doing so, she did not
recognize what she was drawing.
* Although she could see grids of lines on a
screen, she could not tell whether they
were vertical or horizontal.
* She could not identify objects based on
their forms and shapes
* D.F. did not have an integrated visual
experience.
* Her visual world had no forms and shapes.
the dorsal stream leads to
the parietal lobe
the dorsal stream processes
“where” the objects are and “how” to interact with these
objects—the “where” or “how” pathway
the dorsal stream is a _____ ___ _______ pathway
vision for action pathway
when this pathway is damaged an individual cannot
guide bodily movements based on visual information
L.M., a woman suffered a lesion in her “how” pathway, was unable to pour
water into a cup why
because the water appeared to be frozen in mid-air
R.V., another patient with her “how” pathway damaged, had difficulty
picking up objects
R.V., another patient with her “how” pathway damaged, had difficulty
picking up objects
D.F., a 35-year-old-woman, suffered extensive lesion in her occipital &
temporal lobes as a result of carbon monoxide poisoning. Her ventral
pathway was damaged. She experienced visual-form agnosia.
The performance of D.F. was similar to
that of the control subject (a healthy
individual).
* D.F. (with injury to the “what” pathway)
could not see the shape and form of the
object; but she could somehow choose
the stable grasping points.
* D.F.’s hand movements were guided by
the “how” pathway, which was intact in
her case.
* The “what” and “how” pathways
function independently.
what is color
Color is a psychological representation of a mixture of lights in
different wavelengths
two models of colour mixing
Additive color mixing
* Subtractive color mixing
additive colour mixing
colour systems that start without light (black) light sources of various wavelengths combine to make a colour
subtractive colour mixing
start with light (white). coloured inks, paints, or filters between the viewer and the light source of the reflective surface subtract wavelengths from the light, giving it the colour
additive colour mixing is mixing of _____ so it gets _____
light so it gets light
subtractive mixing is mixing of ____ so it gets _____
pigments, subtracting light, which makes it darker
colour sensation additive color mixing
Additive color mixing
* Subtractive color mixing
colour sensation subtractive color mixing
Superimposing one light filter (e.g., cellophane) on top of another
(or adding one pigment on another). Each filter blocks out certain
wavelengths. When one filter is put on top of another, a larger
categories of wavelengths are blocked. Color mixing works by
filtering out unwanted light sources.
Trichromatic theory
Human eye has three types of receptors with differing sensitivities to different
light wavelengths.
* Light of different wavelengths stimulates the three different types of cone
receptors in different ways.
* The ratio of the activity of these three receptor types creates our impression
of different colors
Opponent process theory
Color perception depends on receptors that make antagonistic responses to
three pairs of colors
A color-blind individual is one who is born with
only one or two cone
receptors
what is the colour in which an colour blind person cannot see depend on
the receptor that is missing
what is the most common colour blind defiency
red or green receptor
what happens if the person is missing two types of receptors (in terms of colour blindness)
the person cannot create any colours
what is the weakness of trichromatic theory
One weakness of the
trichromatic theory is
that it fails to explain
complementary
afterimage
opponent-process cells are _______ by a colour and have a burst if activity when its removed
inhibited
physical realities can be measured ______
quantitatively
Psychophysics is the study of
how physical stimuli are related or
translated into psychological experience.
Absolute Threshold- who found it
The minimum amount of stimulation that an
organism can detect.
- gustav fechner
unlike neurons researchers found that the absolute threshold is not a
single stimulus intensity at which the subject jumps from no detection to complete accusation detection
In absolute threshold, what is the relationship between detecting a stimulus and stimulus intensity
The chance of
detecting a stimulus
increases gradually
with stimulus intensity
absolute threshold is defined as the intensity level at which the probability of detection is what percent?
50%
single detection theory
- how decisions are made under conditions of uncertainty
the detection of a stimulus depends on
1. intensity of the stimulus
2. the psychological state of the individual or context of the situation
what two processes are in the single detection theory
two processes involved
1. sensory process
2. decision making process
four possible decision outcomes
hit, false alarm, miss, correct rejection
the decision is based on __________ only
- results not affected by
sensory information only
not affected by psychosocial/individual factors
biased responses - the yea-sayers
high hit rate and high false alarm rate
decision making unbiased responses
hit rate= correvt rejection rate and miss rate= false alarm rate
decision-making biased - nay-sayers
high correct rejection rate and high miss rate
just a noticeable difference (JND)
A just noticeable difference (JND) is the smallest difference in the
amount of stimulation that a specific sense can detect
weber’s law
The size of a Just Noticeable Difference (JND) is a constant proportion
of the size of the initial stimulus
change in stimulus intensity needed for the difference to be detcted divided by the orginal intensity of the stimulus
= k (webers fraction)
Constant increments in stimulus intensity produce
smaller and
smaller increases in the perceived magnitude of sensation
fechner’s law
Subjective sensation is proportional to the logarithm of the
intensity of the stimulus.
R=reiz or -
stimulus
implications of fechner’s lae
S = K Log R
Psycho = Physical
Psychological reality correlates with a physical reality—
psychophysical parallelism.
Fechner Law - explain relationship between arithmetic progression and geomatic progression
JND or level of sensation goes up by adding a fixed number which correlates to x or intensity of stimulation which goes up by geometric progression (multipled by a fixed factor)
sensation
The stimulation of sense organs.
* Involves the absorption of energy (e.g.,
light and sound waves) by sensory
organs (e.g., eyes and ears
perception
The selection, organization, and
interpretation of sensory information.
* Involves organization and translation of
sensory information into something
meaningful.
factors that affect the outcome of perception
Clarity of the stimulus
* Context in which the stimulus appears
* Way of presentation
* Viewing perspective
* Background knowledge of the viewer
* Focus of attention
* Schema
(And many other factors)
bottom-up versus top-down processing- decision making
-response or action
-decision
-thought processes
- perception
-attention
-stimulus
bottom-up versus top down processing - text comprehension
- comprehension
- phrase processing
- word processiing
- letter processing
- feature processing
Bottom-up
versus top-
down
processing
- Visual Perception
bottom-up - taking sensory information and then assembling and integrating it what am I seeing?
top-down- using models, ideas, and expectations to interpret sensory information= is something i have seen before
explain the top-up versus bottom-down processing of a music note
top-down = see note, expect to hear the chord, recognize that it is indeed that chord
bottom-up = listen to notes, recognize the notes, be able to say what letter
bottom-up processing
Perception based on the physical
features of the stimulus.
- data-driven processing- Examples:
Identify letters isolated from words
or words isolated from sentences.
Complete the Stroop task without
being affected by the meanings of
the words (with no Stroop effect)
top-down processing
The interpretation of sensory
information based on knowledge,
expectations, and experience
- concept-driven processing - Examples: Context effect, word-
superiority effect, Stroop effect
structualism
Breaks down the whole into its
parts/ a compound into its
elements.
* Method: Introspection
(experimental: systematically
varied the stimulus and then
recorded the subject’s subjective
feelings about the change)
explain of structuralism in everyday life
how do you use primary colours to create orange
gestalt psychology
The whole is more than the sum of its
parts.
* Integrating elementary components to
form a whole—the opposite of
structuralism.
* Humans have basic tendencies to organize
what they see into a coherent whole.
* Organization is guided by some general
principles.
* A form of top-down/conceptually driven
processing
the early study of perception had two schools of thought
structuralism and gestalt psychology
principle of closure
people may complete figures that actually have gaps in them
principle of continuity
people tend to connect points that result in straight or gently curved lines that create smooth paths
our default assumption of continuity- is it true
When one object partially covers another, the
contours of the partially covered object “comes out the other side”
(assumption of continuity)
false
principle of similarity
People tend to group items that are similar in color, shape, brightness,
etc., to form a unit.
Principle of figure-ground
The figure is more “thing-like” and
more memorable than the ground.
The figure is seen in front of the
ground.
The ground is more uniform and
extends behind figure.
Principle of proximity
Things that are close to one another seem to belong together (i.e., they
form a unit).
What
distinguishes a
human from a
robot is the
capability to do
top-down
processing
primary visual cortex damaged - make them say what shape they saw- they got 1 in three right, proving that they could still partially see - what is this called
blindsight
blindsight
a condition where people are still able to process visual stimuli despite being cortexly blind- they lack the conscious ability to see
the visual abilities in blindsight patients are limited and specific
true
types of blindsight (4)
- follow moving object with eyes
- attention-blindsight - sense object in visual field
- agnosopsia - colour shape category
- affective-blindight- bodily face expression
each blind sight ability uses a different pathway than V1
true
affective blindsight uses the
amygdala
