Motion Perception - Exam #4 Flashcards
(90 cards)
1
Q
Who is Motion Perception important to?
A
Everyone! Except maybe plants, but everyone needs to be able to see motion! Both Prey and Predators!
2
Q
Who has a good sense of motion?
A
Almost everyone! Except maybe plants, but both prey and predators both have good motion perception, even the ones with poor color and form/object perception!
3
Q
Where does Motion Perception occur?
A
The brain!
4
Q
How do we know that Motion Perception occurs in the brain?
A
We can perceive motion even when nothing in the world is physically moving!
5
Q
Can we influence our motion percepts? How?
A
Yes! Through our actions!
6
Q
What explains the relationship between Perception and our actions?
A
The Perceptual Cycle!
7
Q
What is the jist of the Perceptual Cycle?
A
XXXXXXXXXXXXXXXXXXXXGET BACK TO
8
Q
How many categories of motion are there?
A
6!
9
Q
What are the two types of motion percepts?
A
Real and Illusory
10
Q
What is “Real” motion?
A
Motion percept that requires something in the world to be moving (something needs to physically move to see the motion)
11
Q
What is “Illusory” motion?
A
Motion percept/motion that you experience that isn’t actually happening in the world
12
Q
How many Real motion percepts are there?
A
3
13
Q
How many Illusory motion percepts are there?
A
3
14
Q
What are the 3 types of Real motion?
A
Autokinetic Motion, Image Motion, and Self Motion
15
Q
What are the 3 types of Illusory motion?
A
Induced Motion, Motion Aftereffects, and Apparent Motion
16
Q
What kind of motion is Autokinetic Motion?
A
Real
17
Q
What is an example of Autokinetic Motion? What did psychologists use this for?
A
Seeing an LED in a dark room move; they used this to look into people’s minds (they asked what it spells)
18
Q
What is Autokinetic Motion created by? Why is it real?
A
It’s created by an artifact of eye movement, it’s real because something is actually moving to create the motion percept (our eye)
19
Q
What is the theory that explains why we don’t always see Autokinetic Motion? (Why can we see things as staying still if our eyes are always moving?)
A
Corollary Discharge Theory! (CDT)
20
Q
What is Corollary Discharge Theory (CDT) responsible for? What is it?
A
It’s a neural circuit responsible for canceling motion signals generated by eye movement
21
Q
What is a Image Motion Signal(IMS) in Corollary Discharge Theory(CDT)?
A
A signal created by (stimulus) movement across the retina in response to object motion or eye movement
22
Q
Where does a Image Motion Signal(IMS) in Corollary Discharge Theory(CDT) bring it’s signal to?
A
To the Comparator
23
Q
What is a Motor Signal(MS) in Corollary Discharge Theory(CDT)?
A
It’s the signal indicating the motor command to move the eyes
24
Q
What is a Corollary Discharge Signal(CDS) in Corollary Discharge Theory(CDT)?
A
It’s a neural copy of the Motor Signal (MS) to move the eye
25
Where does a Corollary Discharge Signal(CDS) in Corollary Discharge Theory(CDT) bring it's information?
To the Comparator
26
What causes a Corollary Discharge Signal(CDS) on a neural level?
Changes in the photoreceptor array
27
What does the Comparator do in Corollary Discharge Theory(CDT)? What is it?
It's the system that compares the Corollary Discharge Signal(CDS) to the Image Motion Signal(IMS) and cancels motion percepts
28
What happens if the Comparator gets both a Corollary Discharge Signal(CDS) and a Image Motion Signal(IMS) at the same time in Corollary Discharge Theory(CDT)?
It cancels the motion percept
29
What happens if the Comparator gets either a Corollary Discharge Signal(CDS) or a Image Motion Signal(IMS) in Corollary Discharge Theory(CDT)?
Motion is perceived
30
How is motion perceived in Corollary Discharge Theory(CDT)?
If the Comparator gets either a Image Motion Signal(IMS) or a Corollary Discharge Signal(CDS)
31
How is motion canceled in Corollary Discharge Theory(CDT)?
If the Comparator gets both a Image Motion Signal(IMS) and a Corollary Discharge Signal(CDS) at the same time
32
What are some Behavioral Supports for Corollary Discharge Theory(CDT)?
Perceiving Motion in Afterimages, Motion from Eye Displacement, Motion during Object Tracking, and Motion Perception Following Eye Paralysis
33
What is an Afterimage?
The picture you see after you look at something bright
34
What happens to an Afterimage once you're no longer looking at the bright object? What is this?
It appears to jump around as you move your eyes; this is a motion percept
35
Why can we see the Afterimage moving according to Corollary Discharge Theory(CDT)?
The Comparator is receiving a Corollary Discharge Signal(CDS), but is not perceiving a Image Motion Signal(IMS)
36
Why does the Comparator receive a Corollary Discharge Signal(CDS) during an Afterimage?
Your eye is making multiple movements!
37
Why doesn't the Comparator receive a Image Motion Signal(IMS) during an Afterimage?
There's nothing moving in the world around you, so nothing is changing on the photoreceptor array!
38
So, overall, why do you see the Afterimage moving according to Corollary Discharge Theory(CDT)?
The Corollary Discharge Signal(CDS) is not cancelled out by a Image Motion Signal(IMS)
39
What is the basic idea of Motion from Eye Displacement?
Pushing on your eye causes a motion percept
40
So how does Motion from Eye Displacement support Corollary Discharge Theory(CDT)?
The eye remains in a fixed pattern despite being pushed on (so there's no Image Motion Signal(IMS)), but in order to compensate for the push an eye muscle flexes (which means a motor command creates a Corollary Discharge Signal(CDS))
41
So, why is motion perceived overall in Eye Displacement?
Because the Corollary Discharge Signal(CDS) (caused by an eye muscle movement) isn't cancelled by a Image Motion Signal(IMS)
42
What is the basic idea of Motion During Object Tracking?
When we're tracking an object with our yes, the object we're tracking appears to move despite the fact it's stationary in the retina
43
So, why is motion perceived overall in Object Tracking?
The Corollary Discharge Signal(CDS) from the eye movement isn't being cancelled by a Image Motion Signal(IMS) (because the object isn't moving on our retina)--so a motion percept occurs
44
What is the basic idea of Motion Perception Following Eye Paralysis?
If the eye muscles are paralyzed you will still perceive motion based on the Corollary Discharge Signal (CDS) because you're still getting the motor command, but not an actual Image Motion (IMS) in the world
45
So, why is motion perceived overall in Eye Paralysis?
The Corollary Discharge Signal(CDS) from the eye motor signal isn't being cancelled by a Image Motion Signal(IMS) (because an object isn't moving)--so a motion percept occurs
46
What is a Neurophysiological support for Corollary Discharge Theory(CDT)?
Real Movement Neurons
47
What are Real Movement Neurons? What do they respond and not respond to?
They're neurons that respond to a moving pattern, but do not respond to that pattern when stimulus motion is caused by eye movement
48
What do Real Movement Neurons differentiate between?
Real movement and motion caused by eye movement
49
What is an example of a Real Movement Neuron not activating as much to a motion? What about a time it will fire a lot?
If your eyes move over a line vs. The line moving in your stationary reception field
50
What type of motion is Image Motion?
Real
51
What's the gist of Image Motion?
It's a motion percept created by things in the world changing their position on the retina over time
52
When is our threshold for Image Motion detection worst? What does this mean?
When something's moving across a homogenous field; at this point it's hard to tell if something's moving
53
When is our threshold for Image Motion detection best? What does this mean?
When something's moving across a place with visual landmarks; at this point it's easy to tell if something's moving
54
What is it called when something's moving across a homogenous background?
Absolute motion detection
55
What is it called when something's moving across a background with landmarks?
Relative motion detection
56
Is Absolute Motion Detection or Relative Motion Detection better?
Relative Motion Detection, by a factor of 10! 1/6th of a degree per second to 1/60th of a degree per second!
57
What is something important to note about Image Motion in the world?
The perceived size of an object effects how we estimate the object velocity (how fast it's going)--we tend to underestimate large object's speed
58
What kind of motion is responsible for some train accidents? What kind of motion is it? Why are they common?
Image Motion (real); we underestimate how fast large object are going
59
Since we underestimate large objects' speed, why is Image Motion Real motion?
Because something is actually moving to create a motion percept
60
What kind of motion are Reichardt Detectors (RDs) related to?
Image Motion (Real)
61
What is the ganglion system made of?
Photoreceptors --> Horizontal Cells --> Bipolar Cells --> Ganglion Cell
62
What kind of connections do photoreceptors make and to what?
They make excitatory connections to Horizontal Cells
63
What are Horizontal cells connected to? What kind of connection to they make?
They receive signals from photoreceptors and output inhibitory signals to a bipolar cell
64
What are Bipolar Cells connected to? What kind of connection to they make?
They receive excitatory signals from photoreceptors and inhibitory signals from Horizontal Cells and output excitatory signals to Ganglion Cells
65
What happens if a stimulus move from left to right on a Reichardt Detector?
No Motion Percept!
66
Why will a Reichardt Detector not detect motion if a stimulus moves left to right?
The stimulus will activate a photoreceptor attached/signaling to an inhibitory horizontal cell first, causing the signal to not be well retrieved by the Ganglion cell (since it blocks the other photoreceptor's signal directly to the Bipolar Cell)
67
What happens if a stimulus motion goes from right to left on a Reichardt Detector?
It will perceive motion!
68
Why will a Reichardt Detector detect motion if a stimulus motion goes from right to left?
The Photoreceptor will send a signal straight to the Bipolar Cell, which will go directly to the Ganglion cell and send a motion percept. After the signal is already sending, then the stimulus will activate the Photoreceptor connected to the inhibitory Horizontal cell--but it'll be too late to cancel the signal!
69
What is the basic mechanism of Image Motion detection?
Reichardt Detectors (RDs)
70
What is a slight limit of Reichardt Detectors(RDs)?
A given circuit can only code motion in one direction and at a specific velocity
71
What do all the variants of the same basic RD circuits create in our brains?
The ensemble that gives us our motion perception abilities
72
Where are Reichardt Detectors (RDs) located in the brain for animals? Why?
Peripherally in lower animals, very front and center so they can react to motion quickly without thinking
73
Where are Reichardt Detectors (RDs) located in the brain for humans? Why?
Most are in the cortex of our brain, more centrally so we can think about the motion we're perceiving before we do something about it
74
Where are Reichardt Detectors (RDs) NOT in humans?
Our Retinas! Not in there!
75
The more peripherally Reichardt Detectors (RDs) are located, the...
...faster one can detect motion
76
What type of motion is the Kinetic Depth Effect related to? (name and type)
Image Motion (Real)
77
What is the gist of the Kinetic Depth Effect?
It's hard to recover the 3D of a structure on the 2D retina, but we can regain that information (even with just static moving) from motion!
78
What is type (and name) of motion is connected to Biological Motion?
Image Motion (Real)
79
What is the gist of Biological Motion?
Even with just glowing dots on someone we can tell a lot about the person is moving!
80
What is the gist of Self Motion? What type of Motion is this?
It's Real! It's a motion percept resulting from movement of our head/body (us moving through space)
81
Why is Self Motion Real?
It's caused by physical motion! By a change in Photoreceptor activity over time! It's not corresponding to something in the world this time, it's us!
82
What is the gist of Induced Motion? What type of Motion is this?
It's Illusory! If you move a big object that's surrounding a smaller object, it'll look like the smaller object is moving! Think of Superman! (And/or you'll see both the small and big object moving!)
83
What is a key cause of Induced Motion?
We're predisposed to see small objects moving (buildings don't move!)
84
Why is Induced Motion Illusory?
You and the object you're looking at (the small one) is not moving, but the small object still seems to move
85
What is the gist of Motion Aftereffects? What type of Motion is this?
It's Illusory! If you stare at a moving pattern and then look at something stationary, the stationary object will look like it's moving the opposite way of the other object!
86
What causes Motion Aftereffects?
Selective Neural Fatigue in the motion system! Cells coding for one motion direction "get tired", so the opposite motion precept dominates! Reichardt Detectors no longer even each other out(we're wired to see motion so these guys are always doing something!)!
87
What is the gist of Apparent Motion? What type of Motion is this?
It's Illusory! Motion can be perceived from a rapid presentation of still stimuli! Like a cartoon!
88
What are the two types of Apparent Motion?
Short-range Apparent Motion and Long-range Apparent Motion
89
What is Short-range Apparent Motion?
This is the type that's used on tv, it's very small stimulus displacement (meaning small change in distance) and believed to be implemented by Reichardt Detectors (RDs)
90
What is Long-range Apparent Motion?
This is like a neon sign waving it's hand, it's large stimulus displacement (meaning large change in distance) and longer temporal gaps; and believed to be implemented by chained together Reichardt Detectors (RDs) and influenced by higher level factors (like grouping and context)
