Lecture 9 Flashcards
What is the inverse projection problem? And what is the Likelihood principle?
- Our retina’s see in 2D while reality is in 3D
- We have to make inferences about the real 3D image is
- But there are many possible 3D realities that could lead to the same perception.
- The likelihood principle says we perceive the most likely solution to the inverse projection problem.
What are these 7 gestalt laws: Symmetry, Similarity, Common fate, proximity, closure, good continuation and familiarity?
- Symmetry means that symmetrical things are more likely to be a figure than background
- Similarity means similar objects (like color or shape) are an object
- Common fate means that parts moving in the same direction ar an object
- Proximity means that objects close together are an object
- Closure means that objects that we group objects together if they form a closed area, even if there are gaps
- Good continuation means we assume things keep going in the same direction and angle
- Familiarity means that if we are familiar with something, we are more likely to interpret it that way
What is Ruben’s Vase?
A vase that can be seen as either two heads or a Vase because of ambiguity.
What is a contour and what does it belong to?
- A contour is the the outline of something
- We assume that this contour belongs to an object and that the background continues behind it.
How to Bottom-up and Top-down interact in perception
- Bottom-up is the incoming information from the outside world
- Top down is the expectancy based on knowledge
- Perception is the result of the interaction between the two.
What is Object constancy and Size constancy and Brightness constancy and color constancy
- Objects are perceived to be the same no matter the orientation
- Objects are perceived to keep the same size when they are further away- Objects are perceived to stay the same brightness or color in different lighting conditions.
What is viewpoint dependence and non accidental property? What are (straight) lines?
- Viewpoint dependence means Objects are only perceived in that way from a specific angle
- Non accidental property means that it appears the same no matter the orientation (it is not accidental)
- (Straight) lines are non accidental properties. We base our perception on these properties.
What happens when more non accidental properties are visible
- It will be more easy to recognize the object.
What do we need to know for size constancy?
- We need to interpret what is nearby and what is further away
What are the following pictorial depth cues for size constancy: Relative height, linear perspective, texture gradient, occlusion, atmospheric perspective, relative size, shading, knowledge?
- Relative height means that objects that are higher in the image are further away.
- Linear perspective means that parallel lines converge in the distance
- Texture gradient means that texture becomes denser when it is further away
- Occlusion means that the occluded part is farther away
- Atmospheric perspective means that objects that are further away get a haze
- Relative size means that when to similar sized objects appear different sized, the smaller one is further away
- Shading shows where something stands in front of.
- Knowledge means you know what the size of something is supposed to be.
Why is color not the property of an object?
Because it is the way that light is refracted from it. this differs based on the lighting conditions.
What did Meredith and Stein study about multi sensory integration? What does this depend on?
- They measured neurons in the superior collicus, which does auditory and visual processing even before V1.
- The firing rate increased when there was both an auditory and a visual stimulus so AV > A + V.
- So they are integrated at a very early stage.
- This depended on temporal and spatial alignment.
What is the McGurk Effect?
- It shows the integration of visual and auditory information
- When someones hears “ba” and is shown “ga”, they will perceive it as “ba”
What is the Ventriloquist illusion?
When we hear a sound we connect it to the corresponding mouth movements
- So if someone controls the mouth of a puppet, the sound seems to come from the puppet.
What is unconscious inference?
- you unconsciously make inferences about reality that you cannot consciously alter
- So even if you know why something is an illusion and what reality is, you cannot see it differently
