Cog Psych Ch. 4

Bottom up (data-driven) processing

Stimulus driven effects and analysis of form

Top down (concept-driven) processing

Knowledge or expectation driven effects, knowledge of word formation in English guides interpretation of ambiguous letters

Visual Search Tasks

Pattern recognition begins with features (priority in perception)

Conjunctive Search

A search for an item with a combination of features

Feature Search

A search for one salient characteristic of the target

Integrative Agnosia

Caused by parietal cortex damage, difficulty recognizing and interpreting objects

Associative Agnosia

No difficulty in perceiving entire object but cannot recognize it for what it is

Tachistoscope

Presenting stimuli for precisely controlled amounts of time

Mask

Stimulus designed to disrupt further sensory processing of words, random strings of letters

Repetition Priming

Words recently seen are better recognized

Word Superiority Effect

Words in general better recognized compared to strings of letters

Over Regularization Errors

People can perceive stimuli as being more regular than they actually are

Feature Net

How visual system recognize words

Detectors

initial layer at the bottom, (neural network) receptive fields fire a signal when a threshold of stimulation is reached, complex assemblies of neurons

Frequency and Repetition

F leads to higher recency, R increases recency

Bigrams

Letter pairs such as TH and CO

Parallel Distributed Processing (Distributed Knowledge)

Letters and bigrams not represented locally but distributed across the network as a whole

McClelland and Rumelharts model of Word Recognition

Excitatory and inhibitory connections between detectors, top down and bottom-up communication between levels

Activation Levels

Repeated stimulus increases activation level of detectors responding to stimulus, higher activation level = lower response threshold (recent/frequent words/letters)

Recognition by Components Model (RBC)

Geons (basic shapes) building blocks for all 3d forms

Geometric Ions

Objects defined as relationships between geons

Geon Assemblies

Brain combines basic shapes into more complex arrangements based on edges, axis, position, and arrangement defining the geon

Viewpoint Independent

A geon can be identified from virtually any angle, most objects recognized from just a few geons