MIND: The Cognitive Side of Mind and Brain
“… the mind is not the brain, but what the brain does…” (Pinker, 1997)
COGNITIVE PSYCHOLOGY emerged late 1960s:
The scientific study of higher mental processes, from perception and action through memory, language, thinking, and problem solving. These mental activities involve the processing of information.
COGNITIVE PSYCHOLOGY
GOAL: To understand how the mind works
METHODS: Based on scientific experimentation
EXPLANATION: Focuses on the nature of mental representations and the processes that operate on them
INFORMATION PROCESSING METAPHOR:
Both brain and computers process information
Information (knowledge, representation, symbols) is independent of the physical medium
COGNITIVE SCIENCE: Interdisciplinary study of the mind emerged late 1970s Cognitive Psychology Artificial Intelligence Neuroscience Linguistics Philosophy Anthropology
NEUROSCIENCE
GOAL: To understand how the brain works
METHODS: Based on scientific experimentation
EXPLANATION: Focuses on nervous system function and performance
Cognitive Psychology and Neuroscience Together
Initially, interest, but little direct contact Two sides of a coin; burning a candle at
both ends Very difficult to map cognitive level of
explanation onto brain Today, the cumulative advances in our
scientific knowledge and technology have opened new possibilities for collaboration.
Cognitive Psychology provides: Logical analysis of the mental structures and
processes presumed to be involved in the performance of many tasks (task analysis).
This analysis used to develop cognitive tasks to assess aspects of perception, attention, and memory.
Models of mental structures and processes of human perception, attention, memory, etc. based on data obtained from solid experimental procedures
Cognitive Psychology and Neuroscience:
1990s: Neuroimaging studies demonstrate activation of specific brain areas when people perform classic cognitive tasks.
2000s: Some neuroimaging studies help distinguish between alternative theoretical accounts of cognitive performance.
COURSE OVERVIEW
Visual Perception: We are visual animals
Visual Attention: We select some, but not all, stimuli for processing
Visual Awareness: We are conscious of some, but not all, experiences
PERCEPTION
Ramachandran video: Phantom limb, blind sight, unilateral
neglect, Capgras syndromes reveal that visual perception is not the same as sensation.
IMPOSSIBLE OBJECTS
Objects to right initially look like coherent objects, but they are not physically possible.
Vision does not simply register what is present. It actively constructs percepts
VISUAL PERCEPTION
ACTIVE INTERPRETATION of sensory input
“We perceive the world through the filter of our knowledge and experience”
VISUAL PERCEPTION
GOAL: To understand the 3D structure of the world around us by identifying: What objects are out there Where they are located What they are doing
Recognizing Things
Single Objects: My mug in different places, orientations,
lighting conditions changes location, size. Letters & Words:
Type fonts, all other above variations.
Faces: Different views (frontal, side), all other
above variations
Three Levels of Perceptual Identification Superordinate: Fruit Entry level: Apple Subordinate: Granny Smith Apple
Sensory input identified at the level appropriate for the task at hand: If we want to eat an apple, we identify the object as an apple, not as a fruit or a Granny Smith apple.
Stages of Processing
Each stage (i.e., box) is a different level of processing.
Two classes of processes:
Bottom-up (data-driven, sensory-driven)
Top-down (conceptually driven)
Dimensional analysis
A large set of “detectors” operating in parallel to code edges, color, movement (covered in lectures on Chapters 1 and 2).
Analyzers operate in parallel.
Figure Construction Mechanism
Organizes the image by segmenting (parsing) it into parts and grouping the parts appropriately.
How do we know which parts go together in the figure to the right?
Figure Construction Mechanism
Organizes image by binding attributes together
Gestalt Principles of Grouping
Multiple glimpses, binocular disparity
Shape from shading, depth from texture
Figure Construction Mechanism
Organizes image by determining what is figure (that which we attend to) and what is ground.
Ambiguous figures: two equally good figures constructed, as in the Necker cube.
Perceptual Representation and Comparison Mechanism
Perceptual Representation: The organized percept, ready for identification.
The perceptual representation is compared to our stored shape knowledge (i.e., shape representations) by the Comparison Mechanism.
Top-down Influences
Local context and our expectations influence perception.
We do not yet know how early in visual processing top-down influences of context operate.
Definitions Bottom-up processing
(BU): The sequence of mental events is largely determined by the pattern of incoming information.
Top-down processing (TD): The sequence of mental events is influenced by our knowledge and expectations.
In perception: processing initially
starts with sensation and BU processing.
thereafter, BU and TD processing occur simultaneously.
VISUAL PERCEPTION
GOAL: To understand the 3D structure of the world around us by identifying what objects are out there, where they are located, and what they are doing.