Perception - Chapter 3 Content Flashcards
Describe the 3 main things of perception.
Perception (recognition of a book), the proximal stimulus (image of a book that is 2D, reverse and flipped) and the distal stimulus (book)
What is size constancy?
The result of cognitive scaling enables us to perceive an object as having the same size even when presented at different angles or distances. The close the object, the more space it takes up on your retina, but our brains know when two things are the same size almost automatically.
What is pattern recognition?
Recognize a particular object, or event as belonging to a class of objects or events.
What is form perception?
Differentiated the whole display into objects (figure) and the background (ground). Examples are reversible images that are able to flip between figure and ground to give two different images.
What is a main part of Gestalts theory with perception?
That we do not identify individual features or parts, we rather see it as an object or unit of a whole. Also focuses on how we come to recognize objects as forms with form perception.
What are the 5 principles of Gestalt’s perceptual organization?
- Proximity - grouping things together when they are nearer
- Similarity - grouping items that are similar
- Continuation - grouping objects whose contours form continuous straight or curved lines
- Closure - mentally fill gaps to give a closed, whole figure
- Common fate - elements move together when grouped together
What are the bottom-up processes?
Bottom-up or data-driven means how you start with small features of the object and then the stimulus determines the final general percept that you perceive it as. This only works in one direction.
What is the template matching model (bottom-up)?
Thinking that pattern recognition proceeds by the correspondence between a stimulus (external) and a stored pattern in memory (internal template). The stimulus is compared to all templates and then paired with what one matches it best. This is not limitless, as we only have so many templates stored.
Describe feature analysis (bottom-up)
This focuses on finding features (small templates that can be combined in many different ways) and creating an object from them. We must first recognize what features we have and create an object based on them. This is very flexible as you can create many different objects as it depends on the way they are combined. This is also very consistent with critical feature detectors that are based on colour, size, motion, etc.
Explain what prototype matching is (bottom-up).
The stored representation is a prototype, an idealized representation of some class of objects/events (everyone has different ones based on their experiences). When registering new stimuli, it is compared (not matched) to its previously stored prototypes, giving lots of flexibility. The more prototypical an object is, the faster we can categorize it.
What are the terms used by Marr to describe how perception proceeds?
Primal sketch (constructing different mental representations), then using a primal sketch you create a 2 and a 1/2 D sketch that is relying on the bottom-up process. The final 3D sketch is created with the top-down process.
What has changed blindness (top-down)?
This is a phenomenon of visual perception that occurs when a stimulus is undergoing a change without being noticed by its observer when it is right in front of you. Examples are in lots of movies when actors are changed during a scene but we are just focusing on the superficial level and just trying to take the importance of the general idea, not the little things.
What is the word superiority effect?
This is another top-down process and this is how letters are apparently easier to perceive in a familiar context than in an unfamiliar or no context at all.
Explain the constructivist approach to perception.
It talks about how people are adding and distorting the info in the proximal stimulus to obtain a percept (meaning incoming info). People are seen as active constructors of information.
What are visual agnosias and their types?
It is the impairment in the ability to interpret visual information. Apperceptive - problem with generating a percept from the retinal image such as missing elements or different orientations, cannot form pre-semantic images of the object
Associative - can generate percept but can not categorize it to know what it is, cannot identify objects visually
Explain prosopagnosia.
Specific visual agnosia for faces. Usually, damage to the right hemisphere could not recognize members of their family or their own faces in photos. They can see all the specific details but can’t recognize a face as a coherent unit. There is still unconscious face recognition.
What are the top-down processes?
Top-down, meaning theory-driven, is how the perceiver’s knowledge, experiences, and expectations guide the selection/combination of the information in the pattern recognition process.
What are some problems with template matching?
The brain is not limitless and we need a lot of templates in order to correctly match all objects. This theory also does not explain how we recognize new objects and this does not deal well with a surface variation (the difference in handwriting) of stimuli.
Describe the visual search that occurs with feature analysis.
With non-overlapping features, we are able to tell the difference automatically by using different cortical parts of the brain to detect differences. When it comes to overlapping features, we have to do it in a more conscious way because our brain needs to work harder and process everything more. The more distractions and differences, the longer it takes us to recognize them.
What is the context effect (top-down)?
This describes how we perceive things much easier when they are in their normal context as it helps to guide us up to what the object is. Also with pointillism, this explains how we doing seeing paintings as just dabs of paint, but we generate the whole cohesive object into the painting.
What are perceptual illusions?
It is an image that when in a certain context, makes you perceive it as something different in terms of size, colour, etc.
What is the law of Pragnanz?
How we separate objects from the background into the simplest and easiest form.
How do we recognize faces?
We can recognize faces in the proper position automatically, but if the orientation is flipped then we switch to using bottom-up processing.
How was neuropsych used to study how perception goes wrong?
They studied patients with acquired brain damage and put more effort into the preserved cognitive abilities and deficits.
