week 6 - perception and action

Question 1

optic flow

Answer 1

appearance of objects as observer moves past them

Question 2

What are the two features of optic flow?

Answer 2

gradient of flow and focus of expansion

Question 3

gradient of flow

Answer 3

• difference in flow as a function of distance from observer
• objects closer to focus of expansion appear to move quicker
• objects far from focus of expansion seem to move slower

Question 4

focus of expansion

Answer 4

point in distance where there is no flow

Question 5

Gibson plane experiment

Answer 5

• red dots characterized focus of expansions
• blue arrows represented different aspects of gradient of flow
• pilots would want to land where there is no movement aka focus of expansion

Question 6

How does movement create perceptual information?

Answer 6

• as we are moving, we are presented with various kinds of stationary objects
• movement creates more perceptual information

Question 7

invariant information

Answer 7

properties that remain constant while the observer is moving (such as the focus of expansion)

Question 8

self-produced information

Answer 8

flow is created by the movement of the observer

Question 9

Describe how movement from a car creates perceptual information?

Answer 9

1. movement from car creates optic flow
2. creating optic flow gives us more visual information
3. flow: object moving relative to car
4. flow provides information for guiding further movement

Question 10

Why is a novice gymnast able to do a backflip with their eyes closed better than an advanced gymnast?

Answer 10

Advanced gymnast learns to rely on focus of expansion and are very reliant on the visual information that comes in while doing a backflip

Question 11

Lee and Anderson experiment (infant swinging room)

Answer 11

• 13-16 month children placed in swinging room
• the movement of a stationary floor and a wall/ceiling that swings back and forth created optic flow
• researchers manipulated optic flow information which infants were heavily reliant on

Question 12

What were the results of the Lee and Anderson experiment?

Answer 12

showed that vision has a powerful effect on balance and even overrides other senses that provide feedback about body placement and posture

Question 13

optic flow neurons

Answer 13

neurons in the medial superior temporal area (MST) that respond to flow patterns

Question 14

Britten and van Wezel experiment

Answer 14

monkeys were trained to view flow of dots on a screen and report which way they perceived the optic flow of information

Question 15

What were the results from the Britten and van Wezel experiment? (monkey and dots)

Answer 15

• were able to find subset in temporal lobe reacting as a result as well as particular neural response
• specific neurons were essentially responding to particular patterns of movement or different optic flow patterns

Question 16

What occurred when specific MST neurons were microstimulated?

Answer 16

judgements were shifted in the direction of the stimulated neuron

Question 17

Land and Lee experiment (car)

Answer 17

fitted car with different instruments to measure angle of steering wheel, speed of vehicle, and driver’s direction of gaze

Question 18

What did Land’s and Lee’s experiment suggest?

Answer 18

• rather than focusing on focus of expansion, we pay attention to different focus points to gain different optic flows of information to determine where we will move
• drivers also use other info to determine their heading

Question 19

blind walking experiment

Answer 19

• participants viewed target, were blindfolded, and were prompted to walk to target
• participants were able to make it to the target for the most part
• showed that people can navigate without any visual stimulation from the environment

Question 20

landmarks

Answer 20

objects on a route that serve as cues to indicate where to turn

Question 21

Mary Heyho experiment (maze landmarks)

Answer 21

• subjects were placed in a virtual maze containing non-decision and decision point landmarks
• measured eye tracking to record what they focused on

Question 22

What were the results of Mary Heyho’s experiment?

Answer 22

• When all landmarks were present, performance did not differ. Least fixated landmarks (non-decision landmarks) did not contribute much to performance. But most fixated (decision landmarks) had a bit of increase in maze performance.
• when half of the non-decision point landmarks were removed, their maze performance was not affected
• when half of the decision point landmarks were removed, their performance decreased

Question 23

What part of the brain is highly active when we encounter landmarks?

Answer 23

parahippocampal gyrus (place area)

Question 24

Janzen and van Turennout experiment (virtual museum)

Answer 24

• observers studied a film that moved through a virtual museum and were told to act as guide
• exhibits appeared at both decision points where turns were necessary and non-decision points
• observers were given a recognition task while in an fMRI and were presented with objects seen in exhibits and objects they had not seen

Question 25

What were the results of the Janzen and van Turennout experiment?

Answer 25

• observers claimed they did not recognize objects from exhibit, however, there was still a high amount of brain activation
• results showed that the greatest activation for objects at decision points (landmarks) in the parahippocampal gyrus

Question 26

Restrosplenial cortex damage

Answer 26

• study with someone who had damage to RC
• took pictures of her own garden and asked where the shots were taken from
• even having lots of experience with her own garden, she still had issues determining directions (where picture was taken)

Question 27

Maguire experiment (taxi driver)

Answer 27

• taxis drivers have a larger and more connected hippocampus (helpful for wayfinding)
• taxi driver with damage to hippocampus had trouble finding their way around the neighborhood

Question 28

affordances

Answer 28

affordances of objects are made up of information that indicates what an object is used for

Question 29

brain damage and affordances

Answer 29

people with certain types of brain damage may not be able to nam objects but they can still describe how they are used

Question 30

affordances cup of coffee example

Answer 30

• perception of cup: ventral stream
• reaching for cup: dorsal
• grasping cup: both

Question 31

Connolly experiment

Answer 31

• evidence for parietal reach region (PRR)
• used monkeys to find that neurons in PRR were responding specifically to different types of grasps
• monkeys looked at fixation light, light turned on sees object and then they are off, and monkeys had to grasp object

Question 32

Connolly experiment results

Answer 32

• for each different types of grips, a specific neuron will respond
• neurons in PRR respond to different kinds of grips which helps us out with locating a particular object

Question 33

Fattori

Answer 33

• found that 3 different regions are used while grasping
• when monkey is adjusting grip in the dark, they use the neuron to facilitate its movement

Question 34

Schindler experiment (cylinder)

Answer 34

• obstacle avoidance is controlled by parietal regions
• two patients with parietal lobe and damage and control subjects were given two cylinders and asked to reach between them to touch gray strip behind them

Question 35

What were the results of Schindler’s experiment?

Answer 35

• control group: moved hand in order to avoid cylinders and touch strip
• two patients: did not differ in movement; not able to use dorsal stream and did not do well on task
• parietal lobe does not only allow us to make appropriate hand grips, but is also helps us avoid particular obstacles

Question 36

mirror neurons

Answer 36

• located in frontal lobe
• respond when watching someone perform an activity as if we were doing the activity ourself

Question 37

mirror neurons in monkeys’ cortex experiment

Answer 37

• respond when a monkey grasps an object and when experimenter grabbed object
• response to observed action “mirror” the response of actually grasping
• diminished response when object is grabbed by a tool

Question 38

What are the possible functions of mirror neurons?

Answer 38

• to help understand another animal’s actions and react to them appropriately
• to help imitate the observed action

Question 39

audiovisual mirror neurons

Answer 39

• respond to action and the accompanying sound
• mirror neurons fire the same way in monkeys when they watch the experimenter break the peanut, when they hear the peanut being broken, and when they break the peanut themselves

Question 40

Lacoboni experiment

Answer 40

• mirror neurons can be influenced by intentions
• had subjects look at shot film clips and showed different context clips as well as action clips
• intent of action was different based on circumstance

Question 41

What were the results of the Lacoboni experiment?

Answer 41

• singal changes based on intent (drinking vs. cleaning)
• more active for cleaning/drinking than the actual action