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”

Consider THIS ROOM from the perspective of:  Our eyes  Pre-school child Moose  Moose

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: A Generic Symbolic Model

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.

What’s next?  Dr. Carolyn Harley completes coverage of Chapters 1 & 2 Chapter 1: Early Vision: Retina and Retinal Ganglion Cells, LGN, Primary Visual Cortex Chapter 2: From Local to Global Image Recognition: Color, Motion, Image Segmentation, Two Cortical Systems