Lecture 2 (Cognitive Methods).pptx
Transcript
Studying the Mind With the Scientific Method Lecture 2 Overview of Major Topics Covered in Chapter 2 • • • • • Measuring information processing The information processing approach The modern cognitive approach Neurocognition Neural Net Models Guiding Principles • One metatheory, that was used u...
Studying the Mind With the Scientific Method Lecture 2 Overview of Major Topics Covered in Chapter 2 • • • • • Measuring information processing The information processing approach The modern cognitive approach Neurocognition Neural Net Models Guiding Principles • One metatheory, that was used until recently, was the information processing approach. This framework suggests that cognition equals the coordinated operation of active mental processes within a multi-component memory system. How do we determine what happens in mind? Measuring Information Processing • Reaction time (RT) The time elapsed between some stimulus and the person’s response to the stimulus. • Typically measured in milliseconds. • 1000 milliseconds = 1 second. Assumption: Mental events take time. Problem Size Effect Problem Size Effect Measuring Information Processing • Accuracy Measures • How many errors the participant makes. • Often measured as proportion or percent correct. e.g., What was the proportion of errors on small versus large problems? • It can also be important to examine the types of errors that participants make. Measuring Information Processing Analogies • The channel capacity/bandwidth analogy: Like a telephone wire, which can only carry a limited number of messages, humans are limitedcapacity information processors. • The computer analogy: Human information processing may be similar to the way computers work. The Computer Metaphor Information Processing Approach to Cognition Computers and the Human Mind share similar properties The Mind-Brain Relationship • The Mind is a label/description for what the brain does…. • The Software Program is a label/description for what the Computer does… What are the problems with the computer analogy? • Capacity issues: practice and generalizability (i.e., automatization). • Memory: Faithful record vs. perpetual reconstruction (detail or gist). • Intelligence: more than symbol manipulation. The Status of the Computer Analogy • The computer analogy still has a privileged status in cognitive psychology. • However, instead of comparing human cognitive processes to the physical input, mediating, and output devices, cognitive psychologist now compare human cognitive processes to explicitly defined programs that run on computers (e.g., neural nets). Information Processing Claims About Cognition 1. Processing Proceeds in stages. 2. Higher level processing can be broken down into more elemental operations. 3. Limited processing capacity. 4. Cognition is “rule-based” Standard Theory (Atkinson & Shiffrin, 1968) This is a general model in that it can be used to explain many cognitive phenomena. Process Models • A hypothesis about the specific mental processes that take place when a particular task is performed. • Process models are specific models of how people perform specific tasks. The Lexical Decision Task • Yes or no, do the following letter strings form valid English words? • 1) Robin _____ • 2) Manty _____ • 3) Nurse ______ • 4) Trock ______ A Process Model of the Lexical Decision Task Assumptions of Strict Information Processing • Sequential stages of processing • Independent and non-overlapping stages of processing Difficulties of Strict Information Processing • Solid evidence exists for parallel processing • Context effects • Not useful for studying complex cognition (e.g., problem solving tasks) Context Effects Top-Down Processing A.K.A. Conceptually-driven processing: • When existing context has an influence on earlier or simpler forms of mental processes Cognitive Science: The Modern Approach • The strict information-processing approach was too restrictive. • Cognition is now seen as the coordinated, often parallel, operation of mental processes within a multi-component memory system. • Today, cognitive science involves many methods of investigation (e.g., computer simulations, neuroimaging). It is truly interdisciplinary. Updating the Standard Atkinson & Shiffrin Model Cognitive Science • Cognitive scientists need to understand both thought processes and structures as well as the neural structures and processes that underlie them. Neurocognition • Dissociation: A disruption in one component of memory but no impairment of another. • Simple versus double dissociations • Lack of dissociation = an association Dissociation Evidence Dissociation: A disruption in one component of memory but no impairment of another. 1) Association – Patient A is impaired on task X and task Y 2) Single Dissociation – Patient A is impaired on task X but not on task Y 3) Double Dissociation – Patient A is impaired on task X, Patient B is impaired on task Y Basic Neurology • In lecture 1, we argued that the mind has a material basis. • To fully appreciate cognitive processing we need to delve into the material basis of cognition. That is, we need to explore the brain. Neurons Major Brain Regions Principles of Function • Contralaterality: The receptor and control centers for one side of the body are in the opposite hemisphere of the brain. Borowsky, Owen, and Sarty (2002) left hand R right hand L R a b Z = 48 L Principles of Function • Hemispheric Specialization: Different brain functions tend to rely more heavily on one hemisphere or the other. Example: The left hemisphere controls language for most right-handed people. Methods of Investigation • Structural Measures – e.g., Lesions • Electrical Measures – e.g., Direct Stimulation, Electroencephaplograms (EEGs) and Eventrelated Potentials (ERPs) • Imaging Technology (fMRI and PET) Connectionism • AKA Parallel distributed processing, or Neural net models. • Contain a system of interconnected nodes, with knowledge represented by the interconnections between units. • Processing in the model is massively parallel. Processing Five Principles of Neurally Inspired Cognitive Processing 1. Neurons integrate information. 2. Neurons pass information about the level of their input. 3. Brain structure is layered. 4. The influence of one neuron on another depends on the strength of the connection between them. 5. Learning is achieved by changing the strengths of the connections between neurons.
