~Chapter 5 - Lecture Section 5.2 Flashcards
What is a Scene?
Something that is acted within
A Scene contains ___.
Many objects
What is an Object?
Something that is acted upon
People are able to get the gist of what’s in a scene with ___ exposure to each picture.
Very little
People are ___ at perceiving scenes
Good // fast // accurate
When subjects are given either a target image, or just the description of some object, and are flashed a number of images in rapid succession, they have ___% accuracy in detecting the target image when these images are presented for ___ each.
90-100 // ¼ of a second
What is a Visual Mask?
Something that has contours or texture to stop the processing of the original picture due to Persistence of Vision
Why is a Visual Mask required?
Because of Persistence of Vision
What can subjects detect at 27ms?
Subjects can pick out the light and dark bits
What can subjects detect at 40ms?
Subjects can pick out the light and dark bits
What can subjects detect at 67ms?
Subjects can describe large objects
What can subjects detect at 500ms?
Subjects can describe small objects and details
How are we able to perceive the gist of a scene so rapidly?
The use of Environmental Regularities in a Gestalt-like way to obtain Global Image Features
With these different Global Image Features, you can quickly put together the gist of a scene
What are examples of Global Image Features?
- Degree of Naturalness
- Degree of Openness
- Degree of Roughness
- Degree of Expansion
- Colour
What is Degree of Naturalness?
Whether it is Natural vs. man-made
Example: A forest is natural whilst a city is man-made
What is Degree of Openness?
Open space vs. Cluttered
Example: A forest is cluttered whilst a beach is open
What is Degree of Roughness?
The # of small elements / clutter
Example: A forest and city are cluttered whilst an empty beach is relatively smooth and homogenous
What is Degree of Expansion?
Visible horizon
What is Color?
Different scenes have different characteristic colors
Example: Forests are predominantly green and brown, beaches tend to have a lot of blue and yellow, and city colours are cement colours, greys and browns.
We also rely on ___ about physical regularities, that is to say, how objects normally operate in the environment
Top-Down information
What is the Light-from-above Heuristic?
This is how light usually interacts with surfaces.
Whether a normal lighting circumstance is outdoors, where the sun is usually the brightest thing, illuminating things from above, OR indoors where the lightbulbs are typically up high, light tends to come from above downward
What is the effect when the light is from above?
If there is lighting at the top of the circle, this is often interpreted as a bump that is poking out of the surface
What is the effect when the light is from below?
If there is lighting at the bottom of the circle, this produces a dent, where there is shadow at the top and illumination reaching the bottom of the dent
What are Semantic Regularities
Characteristics associated with the functions associated with different types of scenes. These characteristics are learned from experience. For example, most people are aware of the kinds of activities and objects that are usually associated with kitchens.
Top-down understanding of regularities based on the meaning of the scene
How do we create a Scene Schema?
Through Semantic Regularities
What are Scene Schemas?
An observer’s knowledge about what is contained in typical scenes. An observer’s attention is affected by knowledge of what is usually found in the scene. Certain objects are associated with particular scenes, when people imagine individual objects, they usually have some background too
What is an example of a Scene Schema?
When you visualize a microscope, you don’t envision it floating in a white blank space, it’s often sitting on a desk in a lab
With Scene Schemas, what happens once you obtain a little bit of information about a scene?
It’s like an avalanche of Top-down information that is providing you with other things that you can expect to come along with that scene
In Hollingsworth’s Semantic Regularity and Scene Schema study, what did subjects report when the barbell was present in the image they studied for 20s?
They localized it in the correct vicinity.
In Hollingsworth’s Semantic Regularity and Scene Schema study, what did subjects report when there was no barbell?
When they had to guess where it would be appropriate to put it, subjects were still pretty good at localizing it
What does Palmers (1975) test make use of to increase object identification accuracy?
Perceptual Priming & Scene Schemas
What happens in Palmer’s test?
Subjects were primed with the image of the kitchen and then were asked to identify rapidly flashed pictures
What happened in Palmer’s test when subjects were shown a loaf of bread?
Subjects could identify it with about 80% accuracy.
In Palmer’s test, subjects were ___ when the pictures were consistent with the kitchen Scene Schema
More accurate
What happened in Palmer’s test when subjects were shown a mailbox?
Subjects were only 40% accurate. A mailbox has a fairly similar shape to a loaf of bread
What happened in Palmer’s test when subjects were shown a drum?
Subjects were only 40% accurate
When the object matches the Scene Schema, the identification is ___
Better
Semantic Regularities can be used to assign ___ an identity depending on what other information is in the scene
ambiguous objects
What theories did Hermann von Helmholtz (1858) propose?
Theory of Unconscious Inference & The Likelihood Principle
What is Theory of Unconscious Inference?
The idea that some of our perceptions are the result of unconscious assumptions that we make about the environment.
What is the Likelihood Principle?
The idea that we perceive the object that is most likely to have caused the pattern of stimuli we have received.
An observer will tend to perceive the most likely interpretation of a visual stimulus (i.e., the one with the highest probability of being correct).
The Likelihood Principle sounds a lot like the ___
Gestalt Law of Primats
The Likelihood Principle is a form of ___ testing.
Hypothesis
When you look at this collection of shapes, the way we tend to perceive it is based on the ___ that we’re making based on similar types of things we’ve seen in the past
Unconscious assumptions
What is Bayesian Inference?
A statistical approach to perception in which perception is determined by taking probabilities into account. These probabilities are based on past experiences in perceiving properties of objects and scenes.
What is the Prior?
The initial estimate of the probability of an outcome. Top-down information
The Prior is related to ___.
Gestalt-like image statistics
What is the Likelihood?
The extent to which the available evidence is consistent with a particular outcome. Bottom-Up information
Why are people better at object perception than computers?
Application of knowledge or perception to the perceptual process
When using a Bayesian Inference description, we are building our ___ about how things should normally look
Priors
What did Gestalt Psychology tap into?
The normal statistics of how different features are combined
Until computer programs are able to contain this many ___, their performance will lag biological systems.
Priors/this much info about how the world looks
