Chapter 3: Perception Flashcards
Which sense has the most dedicated area in the brain?
vision has more cortical area devoted to its perception
Light is based on an _____ continuum
EMR Spectrum
light vision deices make use of ____ light waves to detect heat
infrared
the image appears _______ when it gets projected onto the ____
appears upside down when it gets projected back on the retina
the portion of the retina dedicated to color perception is called the ___
fovea
what photoreceptor cells allow the fovea to detect color?
cones
center of visual field
fovea.
____ acts as a filter for light coming in
cornea
pupil
regulates how muhc light gets passed into the eye
iris
color bant, contains muscles to constrict and dilate the pupil
the ___ bends light to focus ir on the back of the eye
the lens
when elderly people cannot focus on objects, its most likely because:
the lens gets less flexible and cannot focus on objects.
the ___ acts as a projective screen, and is comprised primarily of _____ cells.
the RETINA acts as a projective screen, and is comprised primarily of PHOTORECEPTOR cells.
photoreceptor cells respond to ______, and turn it into a ____-signal
respond to light energy, and turn it into an electrical (NEURAL) signal
rods and cones convert the light stimulus into a neural signal, which is conveyed to the ____, which leave the eye through the ______ to the back of the brain.
rods and cones convert the light stimulus into a neural signal, which is conveyed to the GANGLION CELLS, which leave the eye through the OPTIC NERVE to the back of the brain.
the optic nerve are made of axons of _____.
ganglion cells.
what is the blind spot of the eye
the optic nerve
T/F: the optic nerve contains rods and cones
false. Only ganglion cells, which get their inormation from the rods and cones.
General route of light stimulus
cone/rods —> bipolar cells –> ganglion cells —> optic nerve
Myopia
nearsightedness.
Hyperopia
farsightedness/
as older people lose the flexibility of their lens, they generally suffer from:
hyperopia.
what about the tissue makes the retina so special compared to other eye structures?
it is actually composed of a thin layer of NEURAL TISSUE (ganglion and bipolar cells) lining the back of the eye
the ____ contains a large quantity of cones but has very little rods
the fovea
the periphery of the retina contains a lot of ____ and very little amount of _____
a lot of rods, not many cones.
Why does the optic nerve act as our blind spot?
because there are no photoreceptors, only axons and ganglia.
T/F: we have more cones than rods
false. WE have more rods than cones
what is the general mechanism behind vision loss?
dying out of photoreceptors
macular degeneration mechanism
destruction of cones in the fovea, we cannot see things directly in front of us, we only see the periphery
retinitis pigmentosa
destruction of peripheral rod cells. only see the center of the visual field.
a person can only see whats directly in front of them, but cannot see ther person sitting directly beside them. what condition might they have?
they might have retinitis pigmentosum.
photoreceptor that is responsive to bright light, allowing us to see fine detail
cone cells.
photoreceptor that is more responsive to dim light, mainly used for night vision
rods.
the outer segment of the photoreceptor contains _____ that responds to light energy and intiates the neural signal
the outer segment of the rods and cone contains PIGMENT that responds to light energy
how do rods and cones react to light? What must happen in order for the photoreceptors to function after exhaustion?
rods and cones contain pigment segments that respond to light energy and initiates the neural signal by separation of their two parts from each other.
In order for a rod/cone to trigger another neural signal via segment separation, the two parts must come together in order to receive more light.
Testing light sensitivity (recall logarithim of sensitivity vs time in dark graph): which photoreceptor more light-sensitive?
light sensitivity is tested by putting a person in a dark environment and measuring the time it takes for their vision to adapt to the darkness.
Initially, your eyes adapt to seeing color and depth in the dark. Around 7 minutes, your eyes will no longer adapt to seeing color in the dark. However, the rods will continue to get sensitive over 30 minutes, you will be able to see more and more in the dark (just not the color super well).
Rods are therefore more sensitive to light than cones
Why does it take longer for rods to reach peak sensitivity in the dark?
it takes time for the rod parts to come back together and recover after being exposed to light.
it takes 30 minutes in the dark for all the rods to recover (because some were activated in the light).
Neural convergence
hundreds of millions of rods and cones converge into only 1 million ganglion cells.
Why are rods more sensitive to light than cones?
there is more NEURAL CONVERGENCE of rods than cones. average 120 rods to one ganglion cell, proving greater light sensitivity.
there are only 6 cones to one ganglion cell, but this provides greater visual acuity.
how is better visual acuity gained by cone cells?
there are only 6 cone cells transmitting info to 1 ganglion cell, allowing for the transmission of much more detailed information.
_____ of ganglion cells form the fibers of the optic nerve, transmitting the signals out of the eye toward the brain.
axons.
In terms of visual fields, the right side of EACH EYE looks at the ____ visual field, and gets processed by the ____ hemisphere.
In terms of visual fields, the right side of EACH EYE looks at the LEFT visual field, and gets processed by the RIGHT hemisphere.
the left side of each eye looks at the ____ visual field, and gets processed by the ____ hemisphere.
the left side of each eye looks at the RIGHT visual field, and gets processed by the LEFT hemisphere.
the central part of the visual field is represented at the ____ of the brain, whereas the peripheral areas of the visual field are located more ____. The top part of the visual field is represented in the _____part of the occipital lobe.
the central part of the visual field is represented at the BACK of the brain,
whereas the peripheral areas of the visual field are located more ANTERIORY (closer to the front part of the occipital lobe).
The top part of the visual field is represented in the LOWER PART part of the occipital lobe.
The specific mapping of the occiptal lobe (how the top part of hte visual field is represented in the lower part of the occiptal lobe) allows for:
the image to be flipped rightside up, because when the image was projected on the retina, it was flipped upside down.
Visual recognition of objects and scenes engages the ____
temporal lobe. the occiptal lobe only helps with processing the stimuli, the true perception and making sense of the environment happens in the temporal lobe.
the ____cortex builds the general form of the stimulus such as color lines and shape, but the ____ lobe gives meaning to visual stimulus.
the VISUAL cortex builds the general form of the stimulus such as color lines and shape, but the TEMPORAL lobe gives meaning to visual stimulus.
3 main theories behind visual perception
1) template matching
2) prototype matching
3) feature analysis
describe the visual perception theory of template matching
the idea that the stimuls is matched to an exact previous pattern that is stored in our head “ex/ it looks like an object that I saw before. That object was called a chair. Therefore, the object I am now looking at is most likely a chair”
challenge to the template matching visual perception theory
it is impossible to memorize all the ojbects that we see on a daily basis. Plus, there arae variations to daily objects that do not trip up our ability to identify them.
ex/ hand writing; we can still read the writing, even though it may not look what the “ideal letter” is
describe the visual perception theory of prototype matching
new images are matched to prototype in memory.
-prototype of an object is the “typical” version: the real object might not exactly match the prototype, but we’ll just find the “best fit.”
Whether we rely on the template or prototype matching for visual perception depends on the_____
specificity of the object.
descrive the visual perceptoin theory of feature analyses
perception is achieved after recognition of series of features. Ex/ to see a face, we put together the mouth, eyes, nose, and realize its a face.
evidence that we use feature analysis as a method of visual perception:
1) face recognition
2) letter confusions: rapid presentation of letters; errors that are made often share common features (ex/ G vs C, or E vs F)
3) visual search tasks; how long it takes to identify a letter/object from a group. it is easier to identify an object if it is not similar from the group (ex/ finding a Q in a group of Z’s is easier than finding a Q in a group of Os)
T/F Context can affect speed of recognition. Explain?
true. it’s easier to recognize something if it was presented alone or in a real word/real object.
ex/ if you were presented K alone or in the word “WORK,” and then asked if a D was present, you wuld most likely say no. However, if you were presented K in “GNRFDKDD” and asked if there was an “O or K” present, you might not be sure. there for, a person is SLOWEST TO RESPOND IF A LETTE IS IN A GROUP OF NON-WORDS
What is priming?
a prior experience influences current perception. Can prime ambiguous images into looking like a certain object based on the objects that you saw before. Ex/ if you saw a bunch of animals, you may thing the ambiguous image may look like a mouse. But iif you were primed by human faces, you may be inclined to see a face in the ambiguous image.
T/F: Illusions work on bottom up processes
false. illusions exert their effect by operating on top-down processing and our assumptions.
Describe whites illusion
grey bars may look darker when compared to white bars, but may look lighter when compared to black bars, even though they are actually the same shade
describe the muller lyer illusion
one line may be longer if it the lines around it project the same direction.
entire scene recognition contains both ____ and ___ elements
foreground and background elements.
Figure vs ground has objects organized in a meaningful wat with each other and then background. we determine what is figure and what is ground based on ____
based on schemas.
schemas
narrative regularities. What we assume is in the picture based on experience. you have a present notion of what a scene is supposed to look like. If you’re presented with a schema, you are likely to recognize objects later on if they fit in a schema.
Ex/ you are shown a picture of a kitchen. later you were asked “was there a stove in the picture?” and you may be inclined to say yes, even thoguh there was actually no stove in the picture”
When looking at a scene, when are people most likely to notice or fixate on a particular ojbect?
if that object does not fit in the schema.
What organizing principles were proposed when people thought that every day perception is often too ocmplex to be accomplished via feature analysis? How does this work/?
gestalt principles. We do the opposite of feature analysis: we look at the whole object/scene and then see individual features later on.
(Rather than feature analysis, which looks at individual components to build the whole picture)
people impose ______ to easily explain a scenario
illusory contours. Some stimuli make absolutely no sense if you analyze via feature analysis, but if you look at the whole thing, you see a meaningful image.
5 gestalt principles
1) simplicity; we try and explain things the most easy way
2) continuity; we can extrapolate an object even it is hidden by another object (ex/ we see someone sitting at the table. We know their legs are underneath the table, even though we cannot see it. We would be very distressed if we thought people were cut in half as soon as they disappeared partially under a table”
3) Similarity: we gropu similar objects with one another.
4) Proximity: we group objects that are close to one another together.
5) uniform connectedness: objects that are physically connected to one another are grouped together; has the ability to override other principles
ex/ we see a dumbell with two square weights and a cylinder holding them together. we group the two squares with the cylinder, even though they are not similar to one another, because they are physically connected.
Note on gestalt principle:
some images can employ more than one principle, in which case one principle will usually win out.
figure ground segragation rule and its exception
we are more likely to see a lower part of the image as a figure “OBJECT”, and the upper part as the ground “SKY,” even if it is a nonsense image.
this phenomena does not occur if a nonsense image is shown “portrait view,” like, parts of the nonsense image are separated on either side of the “Y” axis (refer to slide 29 of chapter 3/4 part 2)
although some visual illusions may flip back and forth between 2 different scenes, we are more likely to put the _____ part of the image as the figure
the more “meaningful” part of the image as part of the figure. If there is no meaning assigned to the image, the portion that is thought to be the figure will be 50:50
In terms of sign constancy, smaller image on the retina is perceived to be ____, and a larger image on the retina is perceived to be _____
smaller image on the retina is perceived to be FAR AWAY, and a larger image on the retina is perceived to be CLOSE BY
the size of image projected on the retina is determined by ____
the visual angle. the larger the visual angle, the larger the image will be and we will perceive the object as being larger and thus closer to us.
How does size constancy rely on top down processing?
we use previous experience and top down processing to think about objects that project a small visual angle on the retina. We convince ourselves that a person is not 2 feet tall- they are just far away. our perception is different than sensory information
size constancy illusions rely on _____ cues to achieve deception.
size constancy illusions rely on CONTEXTUAL DEPTH CUES cues to achieve deception.
without context (blank surface) the images may look the same, but wiht a background, figures may look different sizes.
3 main types of cues that allow us to create a 3D image of a 2D stimulus
1) oculomotor cues
2) monocular cues
3) binocular cues
What are oculomotor cues
Convergence and Accomodation
our eyes converge when we are looking at something close, and the accomodate via lens bending when we are looking at something further away.
accommodation oculomotor cue is due to lens ___-
bending
Monocular cues require ___ eyes
only one eye.
Type of monocular cues that allow for depth perception
1) pictorial cues
2) motion-produced cues
3) occlusion and relative size
4) familiar size
5) Relative height
6) Atmospheric perspective
7) Parallel convergence
8) Texture gradient
9) motion parallax
What is pictorial cue?
a type of monocular cue. Depth perception from a 2D image
motion produced cues
a type of monocular cue. depth perception from the movement of an object relative to its SURROUNDINGS
how does occlusion and relative size contribute to depth perception
a type of monocular cue. if one object is behind an object, the object being occluded is FURTHER AWAY and SMALLER than the object that is FULLY VISIBLE.
Familiar size monocular cue for depth perception
relative size helps with determining depth perception because if we know how big the general size of the object is, it can aid in our determination of how far away an object is.
How does relative height (Pictorial cue) create depth perception
relative height is a type of monocular cue. The higher up an object is ON THE GROUND, the further away they are.
an object IN THE SKY that is higher up is CLOSER.
How does atmospheric perspective create depth perception?
atmospheric perspective is a type of monocular pictorial cue. The further we go into the backgroun, the more hazy it appears. Background looks hazy but objects close by are more colorful.
T/F: you can use atmospheric perspective to determine how far away an object is in a room
false. atmospheric perspective only can be used as a depth cue in outdoor scenes.
how does parallel convergence create depth perception
parallel lines come together when they move further away
How does texture gradient create depth perception?
we can see the texture of close up objects, but when they are further away, it is harder to see individual textures.
What are all the pictorial monocular cues?
1) texture gradient
2) parallel convergence
3) atmospheric perception
4) relative height
binocular depth perception cue
binocular disparity: the image on the left eye is slightly different than image on the right eye
a _____ uses binocular disparity to achieve 3D perception from 2D images.
stereoscope
T/F: mammals with lateral eyes have good binocular depth perception
false. animals with lateral eyes (eyes on either side of their heads) have minimal overlapping fields of view and have no binocular disparity. They have a large field of view though and can see a lot more movement because their eyes are so far apart.
T/F mammals with frontal eyes have good binocular depth perception
true. their eye fields of sight overlap with each other, giving good binocular disparity.
motion parallax
a monocular cue. Objects that are moving very fast is closer than somethng that is moving very slow.
How do locusts use motion parallax?
locusts gauge depther perception in objects in their environment by peering. locusts peer to move an object across their visual field. If the objct moves across the visual field when they peer, the locust knows that it is close by and that they are within jumping distance.
