3 - Recognition Flashcards
Define bottom-up processing
Processes that are directly shaped by the stimulus
(Not expectations)
Is bottom up only processing realistic?
No we do most likely have some way to understand the world beyond just visual input
Describe apperceptive agnosia
Impaired early vision (can’t organize basic features)
- results in difficulties of processing stimuli at different stages
- could not copy what they were seeing, somewhere in visual system they could not put the features together to see a complete picture
- doesn’t mean they don’t know what the object is because they are able to draw from memory
**Problem is translation of visual input
Describe associative agnosia
Impaired late vision (can see object but not recognize/name it)
- no issues perceiving the visual input
- applying a label to object they are seeing is where the issue is
- ex. If you give someone a glove they would name the features but couldn’t see it as a glove (man seeing wife as a hat)
Perception is constructive. What does this mean
Perception is affected by our assumptions about the context
- visual system breaks down our world into features + perceptive fields and puts it all together
- the difference in perception is the reconstruction of this image in your brain
(Ex. Assumption of lighting conditions in controversial dress, top down influence)
Define top down influences
knowledge and expectations that influence and enhance our interpretation of sensory input
What two things play an important role in shaping perception?
Context and experience
(Lifetime experience can even influence colour perception! Lighting assumptions making illusions, interpreting blurry object as hair dryer based on bathroom context)
When do top down influences have more of an influence on perception?
When the brain doesn’t really know what’s going on (ex. When stuff is blurry)
What are visual search tasks?
Tasks in which participants examine a display and judge whether a particular target is present
* Efficient in examples where you spot lines with only 1 difference vs lines with 2 features
Type of processing guides visual search tasks?
Top down
- looking for a target that has different feature(s)
What are tachistoscopic presentation experiments?
Present an image on the wall super quickly and ask participants about the stimulus
- replace visual input with random letters after showing word so it limits processing time on the word
- later ask questions about the words they saw & if they recognize them
What categories do we sort words in for word recognition?
High frequency/low frequency words
- unprimed/primed within high/low frequency
How is recognition different between high frequency words and low frequency words
High frequency words come up a lot in articles and are better recognized and low frequency words
- suggests there is a role of experience
What effect did primed versus unprimed words have on recognition? What is this called?
A little presentation gave you an advantage for recognizing words
- get an advantage of recognizing words after little exposure even if they are low frequency words
= Repetition priming!
What is the word superiority effect?
It’s easier to perceive and recognize words in the context of a word rather than isolation
- people are better at recognizing letters within words
What task is used to look at the word superiority effect?
Two alternative forced choice (2AFC) where participants are shown a word (EG. dark) or a single letter (eg. E) and asked if it contained a certain letter (e or k?)
- even then we are able to finish the word correctly doesn’t even have to be an actual word, just words that sound like words
Define well-formedness (word recognition)
How closely a letter sequence conforms to the typical patterns of spelling in the language
- ex. HZYW vs FIKE vs HIKE
- CAN ALSO INFLUENCE ERRORS (dpum read as drum bc brain wants it to be real) *generally this helps us though
How can feature nets be used to recognize words?
- detect features of letters, combined to form the features themselves
- each detector has starting activation level (it’s just affected by recency and frequency of its firing)
- input increases activation level
- detector fires when response threshold reached
Describe the order of components in a feature net
Feature detectors>letter detectors>bigram detectors>word detector
How can feature nets explain well-formedness?
May have a representation of pairs of letters that typically occurring succession