methods in experimental psychology Flashcards
Experimental Research
-The main method of inquiry in science
• Systematic variation of one or more independent variables (IV) to determine the effect on one or more dependent variable (DV).
• An independent variable (the cause) is manipulated and the dependent variable (the effect) is measured; any confounding variable (alternative explanation) is controlled.
• Scientific testing of hypotheses:
• A hypothesis (plural hypotheses) is a precise, testable statement of what the researchers predict will be the outcome of the study.
key features of experimental research
• Control over variables
• Careful measurement
• Objectivity (replicability)
• Establishing functional relations between the independent and the dependent variables
Values in the DV change systematically according to changes in values of the IV
Only experimental research method allows to establish cause-effect mechanisms
overt and covert behaviors
Overt behavior is observable by other people (measurable)
Covert behavior is not observable by other people (ex. Thinking, emotions, etc)
Methods and procedure in experimental psychology
- Traditional experiments (non-neuroscience methods)
- Methods in neuroscience
- Computer modeling
Traditional experiments (non-neuroscience methods)
Most common experiments
IV: what is manipulated
DV: what is measured
Common procedures:
- Finding the solution to a problem
- Counting how many words or pictures an individual remembers from some previous presentations
- Number of successes or errors in a set of problems
- Time to solve a problem
- Duration: how long it takes to solve some problem or remember some situation
- Making choices, etc
How to record:
- paper and pencil
- stopwatches
- Pictures
- Video
- Computers, etc.
Traditional experiments examples
T and Y maze
Radial maze
Water maze or morris pool
Skinner box / operant chamber
Methods in neuroscience
- brain lesions
- direct stimulation
brain lesions phineas cage
Accidents, strokes, illnesses, injuries, surgery (tumor removals), …
Phineas Cage
-Survived in 1848 an explosives accident in which an iron rod was driven completely through his head.
-Influenced 19th-century discussion about the mind and brain debate on cerebral localization.
-Sparked the interest on the relation between brain structure and function.
-Reports about the impact of his lesions on cognitive and behavioral functioning has been grossly misrepresented in the literature most of the time.
-Seemingly, most serious mental changes were temporary. Later life he was functional and socially well adjusted.
-Held a job working as a stagecoach driver in Chile for 7 years,
-Died of epilieptic seizures in 1860
-Physical damage affected his cognitive and behavioral functioning. But also, example of neuroplasticity
brain lesions henry molaison
HM (Henry Molaison)
-Epileptic seizures since the age 16 Had to stop work at 27 because his seizures could not be controlled
-Seizures originated in medial temporal lobes
-In 1953 a neurosurgeon removed medial temporal lobe bilaterally much of hippocampus and amygdala removed
-Cognitive functions seemed correct, but
-Global anterograde amnesia: Inability to form new memories
-Role of hippocampus in formation of new memories.
-Experimentally induced brain lesions
Provides key insights into the neural basis of behavior
-Involves destroying a part of the brain
By - surgical removal - inserting an electrode into a brain structure and using a high-frequency electric current to burn the tissue
- radiofrequency, radiosurgery, ultrasound. liquid nitrogen, …
- e.g., Karl Lashley’s search for the engram (1950)
- trained rats to solve a maze
- cut different parts of the cortex
- no significant learning-memory impairment
- any impairment depended more on the amount of brain damage than on its location
- Learning and memory are distributed across all parts of the brain
Direct simulation
-Weak electric signals are administered to the exposed brain
-Very small regions are triggered (sensations, memories, etc)
-Research done with animals. Most recently, done on humans for medical purposes
-Patients in brain surgery remained conscious during surgery
-Implants can be used for continuous monitoring
Advantages:
-Mapping brain location with function
-Played a major part in mapping the brain
-Can also be used in therapeutic practices
Limitations:
-Extremely invasive
Electroencephalography (EEG) and Event-related potentials (ERP)
-Electroencephalography (EEG) Electrodes are attached to the subject’s scalp, and they record the ongoing electrical activity in the brain as patterns of brain waves
B. fast temporal resolution, low invasiveness, poor spatial resolution
Positron Emission Tomography (PET)
-Measures brain activity based on the utilization of radioactive glucose or oxygen
-Small amount of radioactive substance is injected or inhaled.
Advantages:
-Mapping brain function with location
-Good spatial resolution
-Sensitive in detecting areas of brain damage
Limitations:
-Exposure to radiation
-Cannot be used while pregnant or breastfeeding
-Allergic reaction to tracer (rare)
-Many trials are needed to average the responses
-PET scans are often conducted in conjunction with other types of scan, such as CT or MRI scans, which show anatomical structure.
A. shows function, good spatial resolution, poor temporal resolution, highly invasive, expensive
Functional Magnetic Resonance Imaging (fMRI)
- Based on Magnetic Resonance Imaging (MRI)
- MRI detects strong magnetic fields from hydrogen atoms.
- MRI does not show function, just structure.
- fMRI shows brain function
- Tracks changes in flow of oxygen & blood (still using hydrogen)
- Uses a series of images taken over & over in a short period of time to analyze brain activity (slicing)
- Slices can be taken of any part of the body in any direction
Advantages:
- Mapping brain function with location
- Good spatial resolution 2D & 3D
- Low invassiveness
Limitations:
- Poor temporal resolution
- Many trials are needed to average the responses.
- Claustrophobia, sensitivity to the loud noise, to the magnetic field
- No metallic objects
D. shows function, good spatial resolution, low invasiveness, expensive
Transcranial Magnetic Stimulation (TMS)
- Direct brain stimulation method that sends a magnetic pulse through the skull to temporarily disrupt the normal activity of the neurons
- It helps to demonstrate causality by “knocking out”
C. it helps to demonstrate casualty by interfering with brain regions .
Functional near-infrared spectroscopy (fNIR)
Relatively non-invasive, safe, portable, & low cost method of indirect and direct monitoring of brain activity
By measuring changes in near-infrared light,
