Chapter 4: Recognizing Objects Flashcards
Visual search tasks
Tasks in which study participants are asked to examine a display and judge whether a particular target is or is not present
I Spy, Where’s Waldo, etc.
Test yourself
What is the difference between bottom-up and top-down processing?
Bottom-up processing refers to the process of starting with the stimulus itself while top-down is the process of starting with background knowledge
“Data driven” vs. relying on knowledge
Bottom-up processing
Sequence of events governed by the stimulus input itself, often contrasted with top-down processing
Tachistoscope
A device that allows the presentation of stimuli for precisely controlled amounts of time, including very brief presentations
Word superiority effect (WSE)
We are better at recognizing letters if they appear in a word than if they appear in isolation
Top-down processing
Sequence of events governed by the knowledge and expectations an individual brings to a situation, often contrasted with bottom-up processing
Mask
Visual presentation used to interrupt the processing of another visual stimulus
Priming
A process through which one input or cue prepares a person for an upcoming input or cue
Repitition priming
A stimulus is presented again as a form of priming
Test yourself
What is repetition priming and how is it demonstrated?
Repetition priming is a pattern of priming that occurs because the stimulus appears a second time
For example, if participants read a list of words aloud and are then presented with a series of words (some new some old), they’ll recognize the primed words at a higher rate
Test yourself
What procedure demonstrates the WSE?
Word-superiority effect
Two-alternative forced-choice procedures
Test yourself
What’s the evidence that word perception is somehow governed by rules of ordinary spelling?
- Errors are systematic
- Strong tendency to misread less-common letter sequences as if they were more-common sequences (Eg. “TPUM” as “TRUM”)
Activation level
A measure of current status for a node or detector
Increased if the node or detector receives the appropriate input from its associated nodes or detectors
High if input received frequently or recently
Feature nets
Systems for recognizing patterns involving a network of detectors
Detectors for features serve as the initial layer in each system
Response threshold
Quantity of information/activation needed to trigger a response in a node or detector
AKA a response from a neuron
Bigram detectors
Hypothetical units in a recognition system that respond or fire when a specific letter pair is in view
Dectors of pairs
Locally represented
Mode of representation in which information is encoded in a small number of identifiable nodes
“One idea per node”
Contrast with distributed representation
Distributed representation
There is no one node or specific group representing the content, and no one place where it is stored
Contrast with local representation
Test yourself
How does a feature net explain the word-frequency effect?
Detectors reach their threshold faster if a word has been used recently/frequently
Test yourself
How does a feature net explain the types of errors people make in recognizing words?
Some letters have very similar features, so if we see a nonword like “CQRN” briefly, it looks a lot like “CORN” and the feature net is based on recognizing these features
“Q” and “O” are nearly identical at a quick glance
What are the benefits and what are the costs associated with the feature net’s functioning?
We easily recognize familar features
It is easy to mistake similar features at a glance
The McClelland and Rumelhart model
Excitatory and inhibitory connections
Better able to identify characters in context as opposed to characters in isolation
Excitatory connection
A link from one node/detector to another, such that activation of one activates the other
Contrast with inhibitory connection
Inhibitory connection
A link from one node/detector to another, such that activation of one decreases that of another
Contrast with excitatory connection
Recognition by components (RBC) model
A model of object recognition
Geons (hypothesized basic building blocks) compose all objects we recognize
Geons (Geometric ions)
Basic shapes proposed as the building blocks of all complex 3D forms
Take the form of cylinders, cones, blocks, and the like, combining to create geon assemblies and then entire objects
Prosopagnosia
Syndrome in which individuals lose the ability to recognize faces and to make other fine-grained discriminations within a highly familiar category
Other visual abilities seem intact
Inversion effect
We have a much harder time recognizing an upside-down face than a rightside-up one
The effect is much less pronounced for objects compared to faces interestingly
Holistic perception
Ability to identify an object depends on the whole rather than its parts
The composite effect
When asked to id the top half of a face, participants have difficulty focusing on just the top instead of the whole
Test yourself
What’s the evidence that word recognition is influenced by processes separate from what has been seen recently or frequently?
We rely on outside information, context to develop a complete understanding
