PYSCH 105: Week 3 Flashcards

Video 1:

our sensus help us to take in the world
around us by converting stimuli or
sensory information into electrical
signals that are processed by the brain
in fact we're constantly bombarded by
stimuli even though we're only aware of
what our own senses can pick
up we Define the absolute threshold of a
sensation as the minimum stimulation
needed to register a particular stimulus
50% of the time if I play a series of
tiny beeps at different decb or levels
of loudness randomly but repeatedly over
a period of time

and you tell me that you hear one of
those beeps 50% of the times it was
presented that would be the loudness
considered to be your absolute
threshold examples of absolute threshold
that you'll find in almost any textbook
include our ability to see a candle from
30 Mi on a dark clear night or to hear
the tick of a watch at 20 ft under quiet
conditions to taste one teaspoon of
sugar in 2 gallons of water to smell one
drop of perfume diffused into a three-
room apartment or to feel the wing of a
fly falling on your cheek from a
distance of half an inch but picking up
weak sensory signals isn't only about
the strength of the stimulus it's also
about your psychological State your
alertness and expectations in the moment
this is the basis of the signal
detection Theory model for predicting
how and when a person will detect a weak
stimulus partly based on
context for example when you walk to
your car that is parked in an empty
parking lot late at night all by
yourself you might be much more aware of
the noises around you because the
situation is somewhat threatening you
are primed and listening carefully to
hear anything and everything in this
case you might hear some slight noises
that you might otherwise not hear if you
were in a different situation that was
not as threatening on the other hand if
you've ever been expecting an important
call that you didn't want to miss you
probably had the experience where you
think you hear your phone ringing or
feel it vibrating in your pocket and
then you realize no one was calling so
it's important to remember that our
ability to detect signals or Noises by
any of our five senses is almost always
affected by factors unrelated to the
intensity of the stimuli itself I might
go out at night and look up at the sky
and while I know that no two stars could
have exactly the same brightness some
some may still seem to look exactly
alike that is I know there must be a
difference but I just can't detect the
difference in their
brightness the point at which one can
tell the difference is known as the
difference threshold but it's not
linear instead if that tiny point of
light was just a little bit brighter
than another tiny point of light I would
be more likely to detect the difference
than if a larger light was brighter in
exactly the same small amount
this is known as Weber's law and it says
that we perceive differences on a
logarithmic rather than linear scale
it's not the amount of change but rather
the percent of change that
matters so what are the biological
processes involved in sensation and how
are Sensations converted into
perceptions we'll try to answer these
questions in the context of one of our
most powerful senses Vision your eyes
taken energy from light and transform
that energy into neural messages that
your brain processes and organizes into
what you actually see this process is
called
transduction but how do we transform
light waves into meaningful
information light itself what we humans
see as light is only a small fraction of
the full spectrum of the electromagnetic
radiation that ranges from gamma to
radio
waves light travels in waves the waves
length and frequency determines the Hue
that is the color or shade that we
see and the wave's amplitude determines
its brightness or
value its Purity what we perceive as
saturation or richness of color is
determined by the number of distinct
wavelengths that make up the light for
instance short waves with high frequency
are registered by our eyes as bluish
colors while we see long low frequency
wavelengths as reddish Hues it's the
eyes lens that is responsible for
focusing these incoming light waves onto
the retina But the lens must constantly
change its shape so that the light is
focused correctly this change in the
curvature of the lens is also based on
the wavelength with red light the long
lowfrequency wavelengths requiring the
greatest curvature and blue light with
its short high frequency waves the least
curvature this means that if pure blue
and pure red Hues are intermixed the
lens is constantly changing shape and
the eye actually becomes tired as you
can see from focusing on these circles
for even a few seconds in the case of
text the effect is even more pronounced
with blue or green text on a red
background here again two opposing
wavelengths enter the lens forcing it to
either focus on one or the
other a related effect is called
chromostereopsis
which is that pure colors located at the
same distance from the eye appear to be
at different distances for example Reds
appear closer and blues more
distant if you put Violet next to
yellow or green next to
Orange the violet and green
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retreat in general the warm colors such
as red orange and yellow come forward
and the cool colors such as blue green
and purple retreat in this sense the
Chromo stereoptic effect gives shapes
plasticity and allows for depth
perception through simple color
manipulation okay so as we said a
color's Hue is determined by the length
and frequency of the light waves but the
brightness of a color is determined by
the amplitude of those waves the
contrast between the red of an apple and
the red of a fire Tru is based on their
amplitudes that is the amount of energy
in a given light
wave greater amplitude means higher
intensity means brighter
color so the length and frequency of a
light wave determines the Hue and the
wave's amplitude determines intensity or
brightness at the same time a color's
saturation or Purity depends on light
complexity the range of wavelengths in
light the color of a single wavelength
is pure spectral color such lights are
called fully
saturated outside a laboratory light is
rarely Pure or of a single wavelength
light is usually a mixture of several
different wavelengths the greater number
of spectral colors in a light the lower
the saturation light of mixed
wavelengths looks duller or paler than
pure
light when a light is reflected from
from the lens onto the retina it is not
by means of a full image instead visual
information is encoded as separate
neural impulses from Tiny portions of
the world so that eventually the brain
can reconstruct in great detail fine
visual differences from locations at
which you're directly
looking the retina contains over 200
million photo receptor cells called rods
and cones
rods give us sensitivity under dim
lighting conditions and allow us to see
at night cones allow us to see fine
details in bright light and gives us the
sensation of

color cones are tightly packed around
the fobia the central region of the
retina and more sparsely elsewhere rods
populate the periphery the region
surrounding the phobia and are almost
absent from the phobia when stimulated
ated the rods and cones trigger chemical
changes that spark neural signals which
in turn activate the cells behind them
called bipolar cells whose job it is to
turn on the neighboring ganglion cells
the long axon Tales of these ganglions
braid together to form the ropey optic
nerve which is what carries the neural
impulses from the eye to the brain that
information then slips through a chain
of progressively complex levels as it
travels from optic nerve to the thalamus
and onto the brain's visual
cortex the visual cortex sits at the
back of the brain in the occipital lobe
where the right cortex presses as input
from the left eye and the left cortex
processes input from the right
eye what happens next well you might
think that the eye would do something
like record the amount of light at each
location in the world and then send this
information to the visual processing
areas of the brain but in fact that is
not what eyes do as soon as photo
receptors capture light the nervous
system gets busy analyzing differences
in light and it is these differences
that get transmitted to the brain the
brain it turns out cares little about
the overall amount of light coming from
a specific part of the world or in the
scene overall rather it wants to know
does the light coming from this one
point differ from the light coming from
the point next to it as a demonstration
place your hand on the table in front of
you the Contour of your hand is actually
determined by the difference in light
the contrast between the light coming
from your skin in your hand and the
light coming from the table underneath
to find the Contour of your hand we
simply need to find the regions in the
image where the difference in light
between two adjacent points is maximal
two points on your skin will reflect
similar levels of light back to you as
will two points on the table on the
other hand two points that fall on
either side of the boundary Contour
between your hand and the table will
reflect very different
light we actually see objects by Edge
detection where an edge can be created
by a difference in color brightness or
both edges formed by color differences
alone with no brightness differences
appear fuzzy and unfocused so we need to
add changes in brightness to get sharp
edges in addition to analyzing these
differences in light your visual cortex
also has specialized nerve cells called
feature detectors that respond to
specific features like shape angles
movements and even faces some cells in a
region May respond to just one type of
stimulus like posture or movement or
facial expression while other clusters
of cells weave all that separate
information together in an instant
analysis of the situation this ability
to process and analyze many separate
aspects of the situation at once is
called parallel processing
in the case of visual processing this
means that the brain simultaneously
works on making sense of form depth
motion and color it links together
individual features into whole objects
allows us to recognize what those
objects are organizes objects into
visual scenes and detects motion and
change in those
scenes wow that's a lot
huh and that is where we need to begin
to talk about the complicated and
sometimes even ambiguous world of
perception watch the image on your
screen closely which of the two gray
sections is darker the top one or the
bottom one try holding up your hands and
blocking this section of the
image how can what appear to be two
distinct Shades of Gray actually be the
same color this happens because your
brain uses Shadows to make decisions
about what it's seeing take a look at
this object how do you know what it is
and where it's positioned in space your
visual cortex is first cross referencing
the information about this object with
memories of past experiences stored
throughout your brain after identifying
the object your brain also has to
determine how it is positioned in space
and one of its most reliable ways of
doing this is to use Shadows take a look
at the basketball
again now let's add a a
shadow is it still moving in the same
way what if we change the position of
the
Shadow now it looks as if the ball is
rising and sinking let's tweak the
shadow one more
time now it appears as if the ball is
bouncing in this world with a single
natural light source your brain has
learned to trust shadows as a near
foolproof way to know the behavior of
objects in space so what happened here
the gradient and Shadow painted here
have given your brain cues that the top
is a well-lit gray surface and the
bottom is a poorly lit light surface
Clues Your Brain Trust because of past
experience with
shadows other than using Shadow to
construct reality what other perceptual
tools do we have available to
us for one re anal disparity when
viewing an object or scene allows our
left eye and right eye to view slightly
different images this binocular signal
specifically provides information about
distance and yet based on only two
dimensional images that fall on our
retinas we are still somehow able to see
three-dimensional
objects seeing objects in three
dimensions also known as depth
perception allows us to estimate
distances between those objects and
ourselves depth perception cues that
don't require both eyes are called
monocular cues these include occlusion
relative size relative height texture
gradient familiar size linear
perspective aerial perspective and
relative brightness let's consider each
of these depth cues on this famous album
cover of The Beatles first let's look
for occlusion this is the idea that an
object that blocks the view of another
object must be in front of it so when
looking at the White Volkswagen and
George Harrison we know that George
Harrison is in front of the Volkswagen
because there's a portion of it that is
being blocked by
him relative size in this photo also
suggests depth this is the idea that
smaller objects are further away and it
can be seen in the many cars in the
image not all cars are the same size but
because the White Volkswagen is larger
than all of the others we can conclude
that the other cars are progressively
further away similarly in texture
gradient as a texture gets further away
it forms smaller visual angles or
pictures on the retina and is less
noticeable if you look at the road at
the bottom of the picture the texture is
made up of larger shapes compared to the
texture of the road in the middle of the
photo in the middle the texture is less
obvious suggesting it is further
away relative height gives us the
impression that objects that appear
higher in our visual field are further
away than objects object that appear
lower notice that the Beetles themselves
are lower in the visual field and appear
much closer than the trees buildings and
cars that appear higher in our visual
field familiar size is the idea that
knowledge of the normal size of certain
objects can provide cues to depth for
example we are familiar with the size of
people in the picture there's a man
standing on the sidewalk we know that
this man is roughly the same size as the
members of The Beetles because we have
experience with the size of people this
Clues us into the fact that the smaller
looking man is probably just further
away from the band members and is not
actually a miniature person linear
perspective which is the idea that
parallel lines seem to converge as they
move into the distance is also clear in
this image this CU can be seen when
looking at the way the edges of the road
converge we know that the road isn't
actually getting narrower it's just
getting further away aerial perspective
is actually a far subtler depth cue in
this picture with aerial perspective
objects that are further away also
appear to be hazier and Bluer this is
somewhat true though for the trees and
cars in the middle of the
picture finally relative brightness
gives the impression that Brighter
Images are closer and more shaded images
are further away although John Lennon is
probably directly in front of Ringo Star
his bright white suit gives the
impression that he is somewhat closer
than the other members of the band I
should mention that like Shadow and
color depth cues can also sometimes
provide misinformation take a good look
at this image known as The Shepherd's
Table which table is thinner and longer
the one on theal cues do not generally
work in this kind of isolation instead
we combine information about shading and
color and depth cues in an effort to
build up an accurate perception
perception is also Guided by many
organizational principles originally
laid out by gal psychologists for
example we tend to group things together
according to a principle of similarity
meaning that all things being equal we
group together figures that resemble
each other so here we tend to group
these dots into columns rather than rows
by grouping dots of similar
colors form is also commonly perceived
in the simplest way possible for example
we would see this form as two
intersecting rectangles
rather than as a single 12-sided
irregular
polygon we are also influenced by
proximity the closer figures are to each
other the more we tend to group them
together perceptually here we perceive
three groups linking the dots that are
closer together and separating the dots
that are farther apart perceptual
organization is also Guided by the
principle of good continuation a
preference for organizing form in a way
where Contours continue smooth smoothly
along their original course for example
we tend to see a continuous green bar
rather than two smaller
rectangles in another example this looks
like this not like this we're also
absolute masters of perceiving closure
in the presence of incomplete
information as you can see in this image
though the edges of the circle are not
defined entirely our minds continue the
edges and it appears to be a white
Circle surrounded by spikes of various
sizes some theorists actually interpret
these subjective Contours as a special
case of good continuation in their view
the Contour is seen to continue along
its original path in either case human
per receivers seem to have a very strong
tendency to impose completeness on small
amounts of input our brain unconsciously
Works to construct meaning and patterns
even in the absence of either for
instance we often see images in clouds
or rock formations this tendency to
organize incomplete and even random
images into meaningful images is called

parolia an amazing graphic artist
Kristoff nean who is a master at
creating fun and compelling images has
taken parolia in a particularly Charming
Direction he uses art to make meaning
and Whimsy out of everyday objects here
are just a few
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it's not a coincidence that paradia
predominantly affects the perception of
animate figures like animals human
bodies and human or human-like faces
this shows the strength of these
templates in our visual memory and the
strong significance of seeing these
objects in our environments in fact
there is ample evidence that our
tendency towards closure that is filling
in information to complete perceptions
is particularly powerful in the context
of seeing human form particularly faces
in this way surprisingly incomplete
images are built by our brains into rich
and complete images
now let's look at closure in the context
of movement take a look at these
dots perceptual closure along with the
fact that we are hardwired to recognize
biological motion again helped to
explain these impressive
skills have these gal principles
impressed you I hope so truly an endless

number of examples of our brains
tendency towards Simplicity coherence
and
wholeness as a final topic I will
describe one particularly vigorous
debate in the field of perception that
came to inspire countless experimental
studies across centuries the debate
centered around the question of whether
perception of the world is a set of
innate abilities or instead a set of
acquired or learned skills these
opposing views have been termed nativism
and empiricism also known as bottom up
versus top- down processing it was
psychologist Richard Gregory who first
argued that perception is a constructive
process which relies on top- down
processing stimulus information from an
environment is frequently ambiguous so
to interpret it we require higher
cognitive information either from past
experience or stored information in
order to make inferences about what we
perceive for Gregory perception is a
hypothesis which is based on our prior
knowledge in this way we are actively
constructing our perception of reality
based on our environment and stored
information for example understanding
difficult handwriting is easier when
reading complete sentences than when
reading single and isolated words this
is because the meaning of the
surrounding words provides a context to
Aid understanding read the following
quote out
loud notice anything odd while you were
reading the text in the Triangle did you
notice the
secondth if not it's likely because you
were reading this with a top- down
processing approach having a secondth
doesn't make sense our brain knows this
and it doesn't expect there to be a
second one so we have a tendency to skip
right over it your past experience has
changed the way you perceive the writing
in the Triangle a beginning reader one
who is using a bottomup approach by
carefully attending to each piece would
be less likely to make this error
Gregory argued perception involves a lot
of constant unconscious hypothesis
testing to make meaning of the
information presented to our senses and
there are several types of evidence that
seem to support this idea of how
perceptions are created first highly
unlikely objects tend to be mistaken for
likely objects Gregory famously
demonstrated this with a Hollow Mask of
a face such a mask is generally seen as
normal even when you know and can feel
the real mask there seems to be an
overwhelming need to reconstruct the
face based on past
experience we also see objects as whole
and complete even when parts of them are
obscured for example a person walking
toward us carrying let's say a tuba does
not look fractured a top a bottom and a
gap in the middle caused by the tuba we
see the whole person but the outline of
the person is incomplete as it is in
this example Gregory would argue that we
must be using knowledge of people that
is they can't be in parts to go beyond
the sensory evidence delivered from this
visual
image additional evidence for this top-
down view is supported by ambiguous fig
figures during continued observation of
an ambiguous figure sudden perceptual
reversals occur while the stimulus
itself stays
unchanged a good example is the Necker
cube when you stare at the crosses on
the cube the orientation can suddenly
change or flip it becomes unstable and
again shows that a single sensory
pattern can produce two perceptions if
you are a proponent of top- down
processing you might say that this
object appears to flip between
orientation s because the brain develops
two equally plausible hypotheses and is
unable to decide between them when the
perception changes though there is no
change of sensory input the change of
appearance cannot be due to only the
static pattern that we're sensing it
must be built top down by our current
prevailing perceptual hypothesis of what
is near and what is far in other words
if one physical display can induce two
different perceptions then this is an
example of when perception cannot be
tied directly to stimulation alone there
is also however evidence to refute a
top- down hypothesis testing view of
perception first if perceptions make use
of hypothesis testing the question can
be asked what kind of hypotheses are
they are we as perceivers also able to
modify our hypothesis in some cases it
would seem the answer is yes for example
this probably looks like a random
arrangement of black shap Apes in fact
there's a hidden figure in there can you
see
it what if I had shown you this
first now can you see it once the dog is
discovered very rapid perceptual
learning takes place and the ambiguous
picture now obviously contains a dog
each time we look at it while this is
arguably a very good example of a direct
relationship between modifying
hypothesis and perception in other cases
this process is not evident for example
Illusions persist even when we have full
knowledge of
them remember the gray squares in
inverted
face one would expect that the knowledge
we have gained from covering the center
line between the squares or touching the
mask would modify our hypothesis but in
this case learning does not change our
perception another perplexing question
for The empiricist Who propose
perception is essentially topd down is
how can newborns ever perceive in fact
newborn infants as soon as 5 minutes
after birth already show a preference
for normal facial features rather than
scrambled features infants also show
shape constancy that is the ability to
perceive the shape of a rigid object as
constant despite differences in the
viewing angle taken together this
evidence has been put forward in support
of a nativist or bottomup view of
perception in which nothing more is
needed beyond the stimulus set within
the rich visual context of the world
world around us first articulated by
James Gibson bottomup processing
suggests that perception involves innate
mechanisms forged by Evolution and that
no learning is required Gibson argued
that perception is direct and not
subject to hypothesis testing as Gregory
had proposed there is enough information
in our environment to make sense of the
world in a direct way for Gibson
sensation is perception what you see is
what you get there there's no need for
processing or interpretation as the
information we receive about size shape
distance Etc is sufficiently detailed
for us to interact directly with the
environment put simply he proposed that
this is possible due to something called
affordances affordances for humans
include such things as surfaces that are
standable or sit on objects that are
graspable or Thor objects that afford
hitting substances that afford pouring
in short affordances are meanings that
an environment has as meanings they
guide Behavior telling the Observer what
is and what is not possible Gibson would
say that there has in fact been learning
in the perception of affordances but
that this has taken place over the
course of millions of years of
evolutionary history not the course of
particular
lifetimes he believes that individual
learning is only involved in terms of
figuring out which affordances to attend
to neither top down or bottom up
theories of perception on their own seem
capable of explaining all perception all
of the time perceptual research over the
last several decades has in fact shown
convincing evidence for both types of
processing top down and bottom up
processes are interacting with each
other to produce the best interpretation
of the world around us

Video 2:

Color.
It plays a vital role in design and everyday life.
It can draw your eye to an image…
evoke a certain mood or emotion… even communicate something important without using words at

all.
So how do we know which colors look good together, and which ones don't?
The answer is simple: Color theory.
Artists and designers have followed color theory for centuries, but anyone can learn
more about it.
It can help you feel confident in many different situations, whether it's choosing colors for

a design, or putting together the perfect outfit.

All it takes is a little insight, and you'll be looking at color in a whole new way.

Let's start at the beginning—the very beginning—with a refresher on the basics.

Remember learning about primary and secondary colors in school?
Then you already have some knowledge of color theory.
Red and yellow make orange; yellow and blue make green; and blue and red make purple.

If we mix these colors together, we get even more in-between shades, like red-orange and

yellow-green.
All together, they form what's called a color wheel.
(You can probably see where it gets its name.)
Now, let's take it one step further with hue, saturation, and value.

These are terms you might not encounter in daily life, but they're the key to understanding
more nuanced colors—like all those little paint chips at the home improvement store.

Hue is the easiest one; it's basically just another word for "color."

Saturation refers to intensity—in other words, whether the color appears more subtle
or more vibrant.
Value has to do with how dark or light the color is, ranging from black to white.

As you can see, this gives us many different shades, from a deep reddish brown… to light

pastel pink.
So how do we put this all together to create professional-looking color schemes?
There are actually tried and true formulas based on something called color harmony that
can help.
All you need is the color wheel.
The easiest formula for harmony is monochromatic because it only uses one color or hue.

Just pick a spot on the color wheel, and use your knowledge of saturation and value to
create variations.
The best thing about monochromatic color schemes is that they're guaranteed to match.

An analogous color scheme uses colors that are next to each other on the wheel, like

reds and oranges... or cooler colors, like blues and greens.

Don't be afraid to play with the palette and create your own unique interpretation.
That's what these formulas really are: starting points to help guide and inspire you.

Complementary colors are opposite each other on the wheel; for instance, blue and orange...

or the classic red and green.
To avoid complementary color schemes that are too simplistic, add some variety by introducing

lighter, darker, or desaturated tones.
A split-complementary color scheme uses the colors on either side of the complement.

This gives you the same level of contrast, but more colors to work with (and potentially
more interesting results).
A triadic color scheme uses three colors that are evenly spaced, forming a perfect triangle

on the wheel.
These combinations tend to be pretty striking—especially with primary or secondary colors—so be mindful

when using them in your work.
Tetradic color schemes form a rectangle on the wheel, using not one but two complementary

color pairs.
This formula works best if you let one color dominate while the others serve as an accent.

There are a few classic do's and don'ts when it comes to color.

For instance, have you ever seen colors that seem to vibrate when they're placed next to
each other?
The solution is to tone it down—literally—and there's a simple way do it.

Start with one color, and try adjusting its lightness, darkness, or saturation.

Sometimes, a little contrast is all your color palette needs.

Readability is an important factor in any design.
Your colors should be legible and easy on the eyes.
Sometimes that means not using color—at least not in every little detail.
Neutral colors like black, white, and gray can help you balance your design, so when
you do use color, it really stands out.

Every color sends a message.
It's important to consider the tone of your project, and choose a color palette that fits.
For example, bright colors tend to have a fun or modern vibe.
Desaturated colors often appear more business-like.
Sometimes it just depends on the context—you'd be surprised how flexible color can be.

You can find ideas for color schemes in all kinds of interesting places, from advertising

and branding to famous works of art.
You can even use a web resource to browse color palettes or generate your own.

Even experienced designers take inspiration from the world around them.
There's nothing wrong with finding something you like, and making it your own.

Everywhere you look, there's color, color, and more color.
It can be intimidating to use it in your work, but it doesn't have to be.

Just keep experimenting and remember what you've learned about color theory.
Soon, choosing great-looking colors will feel like second nature.