2.10 Cognitive Science Flashcards
cognitive science
Interdisciplinary scientific study of the mind and its processes
cog sci: disciplines
psychology, computer science/AI, anthropology, neuroscience, linguistics, philosophy
CHALLENGES TO STUDYING MIND
Subjective - interpretation of cognitive processes differs from person to person
Difficult to study - e.g. infants, songbirds
phrenology
(mid-1800s) - different cognitive processes are related to skull shape and size, craniometer, functional specialization
structuralism
(1880s - early 1900s): study cognition by having participants reflect and break down their conscious experiences into basic elements of thoughts and sensations, analytical introspection, William Wundt (developed first psych lab), Edward Titchener
behaviorism
(1913 - 1960): reject structuralism, abandon studying conscious experiences in favor of studying behavior, John Watson (blank slate), Little Albert Experiment (bunnies and loud noise), B.F. Skinner
-classical and operant conditioning
Classical conditioning
pair neutral stimulus with second stimulus associated with a reflexive response
operant conditioning
pair behavior with reward or punishment (Skinner boxes)
cognitive revolution
(late 1950s): analyze cognitive processes through behavioral experiments, likened to computer outputs; Noam Chomsky (language is biologically innate, not learned bc incorrect grammar and hateful language are never reinforced but still repeated), information processing
cognitive neuroscience
(1976 - ): understand mind by understanding brain
cog sci approach
How can we relate experimental tasks → brain and behavior correlates → human and societal outcomes (e.g. DSM-5 diagnoses, etc.)
subjects
Most people are not WEIRD (Western, Educated, Industrialized, Rich, Democratic), unlike most subjects of cog sci/neuroscience
spatial resolution
precision with measuring where brain activity occurs when a specific cognitive process is engaged
temporal resolution
precision with measuring when a part of the brain is engaged as a result of a cognitive process
measurement technique
approximate neural representations associated with psychological phenomena (e.g. language formation); correlations
E.g. MRI to correlate blood flow with brain activity and cognitive processes
perturbation technique
: simulate/remove brain region and observe behavioral response; causal relationships
E.g. surgical legion approach of removing hippocampus and observing effect on memory (purposefully destroying part of brain and observing behavior)
fMRI
Use large magnet to detect changes in magnetic properties (oxygenated/deoxygenated hemoglobin) in the brain to correlate blood flow/oxygen delivery with cognitive processes
When certain parts of the brain are stimulated, blood flows to that part of the brain to deliver oxygen via oxygenated hemoglobin, deoxygenated hemoglobin will then leave the brain
fMRI: subtraction method
: compare brain activity b/w different task conditions (e.g. experimental and control)
Blood flow in condition A (e.g. auditory stimulus) - blood flow in condition B (e.g. visual stimulus)
fMRI: resting state functional capacity
observing brain activity (fluctuations in blood flow) at rest to see which cognitive processes are related and function together
fMRI: advantages
Minimally invasive
High spatial resolution (allow us to observe correlations b/w cognitive processes and brain locations)
fMRI: disadvantages
Poor temporal resolution (blood flow lags behind cognitive processes)
Costly
Loud/disruptive (may interfere with language/auditory studies)
Requires patients to stay still (not well-suited for epilepsy patients, babies, etc.)
PET
Detect gamma rays emitted by radioactive ligands (tracers) injected in the body that bind specifically to receptors in the brain
PET: advantages
Detect early onset of diseases
Allows for image distribution and degree of neurotransmitter signaling
PET: disadvantages
Poor temporal resolution: tracers take time to degrade in the body and bind to receptors
Expensive
Invasive: requires highly functional kidney
EEG
Record electrical brain activity (neuronal ensembles) from electrodes placed on the scalp
E.g. gamma, beta, alpha rays that differ based on states of consciousness, sleeping and wakefulness
EEG: event related potentials
average of EEG signals across trials of the same task condition (small voltages generated in the brain as a result of tasks)
EEG: advantages
High temporal resolution (direct measure of neural activity, plotting, electrical potentials vs. time)
Noninvasive
Relatively mobile and inexpensive
Better for certain populations (e.g. infants)
EEG: disadvantages
Poor spatial resolutions (bc many electrodes are being used, can’t pinpoint exact location, scalp produces signal distortion so can’t specifically identify where cognitive processes occur)
Lesions
brain injury, often due to strokes or injury
-E.g. Phineus Gage (railroad spike penetrated skull), Patient “H.M.” (had hippocampus removed b/c of severe seizures → posterior and anteriorgrade amnesia), Broca’s and Wernicke’s aphasia
neurophysiology
study to characterize cognitive effects of naturally-occuring lesions
Often due to strokes or injury
lesions: advantages
infer causality
lesions: disadvantages
Patients can be hard to find (not ethical to induce lesions)
Lesions are not local, but spread out
Patients are case studies
Transcranial Magnetic Stimulation
Experimental method to temporarily induce brain lesions (inhibit/stimulate brain activity)
Emit electric pulses → converted into electrical current → varies pulse frequency to stimulate or inhibit brain activity
Clinical treatment applications (e.g. depression) over repeated sessions
Transcranial Magnetic Stimulation: advantages
Noninvasive, but repeated TMS at high frequencies can alter brain
Less expensive
Reveals necessary role of brain regions
Transcranial Magnetic Stimulation: disadvantages
Sometimes painful
Poor spatial resolution (targets cortex, can’t reach subcortical structures)
Why do humans outperform computers when identifying objects?
- image on the retina is ambiguous (inverse projection problem)
- images can be obscured or blurry (harder for computers to identify)
- objects look different from different viewpoints (viewpoint invariance)
perception
conscious experience that follows sensory stimulation
Based on our previous experiences/context, what we choose to focus on (e.g. vase or two faces), heavily influenced by expectations (predictive coding) and statistical regularities in our environment
Hemholtz: influence of regularities in the environment
postulated that we make unconscious assumptions about our environment based on past experiences (e.g. blue rectangle is on top of red rectangle, not a red rectangle cutout, people are better at identifying horizontal and vertical objects than objects of other orientations, harder to identify abnormalities in upside down faces than right side up)
inverse projection problem
objects of different orientation are projected as the same image on the retina
Why are people better at identifying verticals and horizontals than slanted objects?
slanted objects are less common, especially in natural world
Why are people better at identifying abnormalities in right side up faces, not upside down faces?
we are not used to seeing inverted faces
Visual Process (beyond V1)
visual system is organized hierarchically: larger receptive fields code for more complex shapes and objects moving further away from the subject
hierarchical coding hypothesis
as you move up hierarchy (LGN –> V1 –> V4 –> ventral temporal cortex), neurons coding for more rudimentary features synapse onto neurons coding more complex features
Downtream Pathways from V1: dorsal stream
“where/how”
-allows us to spatially locate and interact w/ objects
-extends into parietal lobe (and ultimately dorsal frontal cortex)
E.g. allows me to locate and reach out towards water bottle
Downtream Pathways from V1: ventral stream
“what”
-allows us to perceive/identify objects, extends into anterior temporal lobe
E.g. allows me to identify the object on my desk is a water bottle
Two streams: water bottle
Picking up the water bottle integrates both streams (ventral: identify, weight, adjust how tightly I hold onto water bottle/dorsal: where do I reach out towards, move it upwards)
