Perceiving Objects Flashcards
week 5
true or false: the process of detecting features is innate?
true- Pre-attentive, We combine the features to understand the overall object
* Can identify objects specifically based on its features
what is bottom-up processing?
Bottom up processing= identifying an object through looking at its features.
§ Stimulus driven
* Bottom-up processing can get more complex depending on the stimulus given.
○ Quite basic
○ Can require own perception of an object
May have to guess what ab object is
what is gestalt psychology?
(derived from German word meaning ‘form’ or ‘appearance’)
* Concerned with how perceptual organisation is achieved
○ How we perceive and identify objects
* Describe how we separate and link (or parse) into individual objects
Parse= how we separate and link different stimulus and features into different objects.
what are the guiding priciples of gestalt psychology (Prägnanz)?
- similarity
- proximity
- good continuation
- closure
- simplicity
- figure-ground segregation
what is the guiding priciple (prägrnanz) similarity?
- Group together objects that resemble each other
- Seem to have similar features
How we group objects based on their similar features.
what is the guiding priciple (prägrnanz) proximity?
- The closer objects are to each other, the more likely we are to group them together perceptually
Closer the objects are, more likely we are to see them as one whole object rather than sperate objects.
what is the guiding priciple (prägrnanz) good continuation?
- Prefer to organise objects where contours continue smoothly
○ Brain has a bias/preference towards continuing contours/lines.- Continuation of feature or stimulus
what is the guiding priciple (prägrnanz) closure?
- Bias toward perceiving closed objects rather than incomplete ones
Doesn’t like seeing gaps in objects, would rather try to complete it.
what is the guiding priciple (prägrnanz) simplicity?
- Interpret an object in the simplest way possible
Simplify object perception
what is the guiding priciple (prägrnanz) figure-ground segregation?
- Separating an object from its background
- Reversible figure-ground pattern
- Reversible processes that isn’t processing both at the am time but rather switching between each one.
what are the strengths of prägnanz?
- Focuses on fundamental issues
○ For object perception- Principles applicable to complex images
○ Can start to identify and clarify the principles using complex images - Simplicity is key!
○ Simple processes and principles to determine object perception.
Easy to understand.
- Principles applicable to complex images
what are the weaknesses of prägnanz?
Deemphasised the importance of past experience
○ Object perception is very innate
§ Acquired it from birth
○ Doesn’t account for how we interpret objects due to experiences
* Provide descriptions (not explanations) of perceptual phenomena
○ No explanation for how and why we perceive objects in such ways.
* Principles of perceptual organisation based on 2D drawings
Cant be applied to real life scenarios with 3D objects.
what was Barense et al (2011)’s study on figure-ground segregation?
- Participants have to indicate which region (black or white) is the figure.
- Exposed to experimental stimuli and control stimuli
- Easy to identify if it’s the foreground or background that is the object (top row)- experimental stimuli
- Control stimuli (bottom row)- harder to identify which is foreground or background, same shapes jumbled up (novel configurations), harder for our brain to decide which is which.
- Health controls successfully able to identify the similar configurations in comparison to novel configurations more times than those with amnesia.
- Amnesia patients had no difference between familiar and novel objects- couldn’t identify the experimental objects.
- Indicate which region (black or white) is figure
○ Healthy controls = identified regions containing familiar configuration as figure more often than novel configuration
○ Amnesia (limited memory for familiar objects) = no difference in figure-ground decisions for familiar or novel configurations- Figure-ground perception relies on past experience/learning
○ To be successful= must know what they are before.
Proved that we aren’t naturally born with object perception but it relies on past experiences.
- Figure-ground perception relies on past experience/learning
what is the feature detection theory?
- A simple pattern, fragment or component
○ How we combine it to make sense of what the object is.
○ Appears in combination with other features across a variety of stimuli
§ Helps to understand what the object is
§ Looks at all the components and features of the object.- One component shared equally between them all= horizontal line
- Object recognition first involves identifying “building-block” features
○ Bottom up processing= stimulus-driven
what is the viual search?
Treisman (1986)
* Indicate as quickly as you can whether a particular target is present
* Takes longer when searching for a combination of features
* Target is one vertical line (black picture)
* Difficult with a conjunction of features (3rd example)
○ Have a mixture of colours and features
○ One of the red lines is vertical.
Takes brain longer to recognise target.
what are feature nets (bottom-up)?
Example of bottom-up processing
* Brain naturally looks at the feature detectors- understands the basic features
* Combines shapes together to understand what the letter is.
○ Detect the features
○ Then detect the letters
Then move up to detect the word that the features and letters create.
what are feature nets (top-down)?
- Participants are initially primed with pictures before seeing the word
- Idea= if primed first with pictures of animals, it will automatically assume that is it a word that is an animal.
- Top-down processing
○ Goes from the whole concept through priming the response and shaping their expectations
Goes beyond just looking at the stimulus itself.
what was Goolkasian & woodberry’s (2010) study on top-down feature nets?
○ If initially primed with boy in winter scene= more likely to see an eskimo
○ If initially primed with tomahawk and peacock feathers= more likely to see the Indian picture
○ If initially primed with words on a page= more likely to see the world liar written
○ If initially primed with glasses and businessman= more likely to see a face in the picture
Depending on how an individual is primed will depend on what they are more likely to see in the photos.
what are geometric ions?
- Recognition-by-components (RBC) theory
- All objects reduced to geometric ions (“geons”)
- Every object is a conjunction of a geometric ion.
what is recognition by components (RBC)?
- Perceiving components is the first major step in object recognition
○ Every shape we see is perceived through geometric ions.- Object recognition is a joint effort between two processes:
- One responsible for features and components (features)
Another for overall shape and global patterns (overall shape and pattern)
- One responsible for features and components (features)
- Object recognition is a joint effort between two processes:
