Lecture 2 Flashcards
Within subjects
E.g., All participants in the experiment receive 6 levels of making noise.
Between subjects
E.g., multiple samples tested - 3 treatment types for anxiety: none, antidepressants, cognitive therapy.
Randomisation
Assigning participants to a sample is not determined by a third variable; all members of the population of interest have an equal chance to be selected in the sample.
Internal validity
The experiment should be designed and carried out in such a way that inferences about causal relationships between X and Y are accurate.
- Related to factors within the experiment.
External validity
The causal relationship between X and Y should be constant across samples, cultures, etc.
- Related to generalisability of results.
Validity
Measuring what you wish to measure.
Reliability
Consistency of measure
Quantitative measures
Represent values or counts expressed as numbers.
- Systematic scientific investigations in order to quantify phenomenon.
Qualitative measures
Represent assigned names, labels or values.
- Detailed insights into individual experiences, understanding, motivation, thoughts, feelings, etc.
Grey matter
Contains the cell bodies, dendrites and the axon terminals - where all the synapses are.
- 40% of the brain.
- Contains most of the brains neuronal cell bodies.
- Fully develops once a person reaches their 20s.
- Conducts, processes, and sends information to various parts of the body.
White matter
Is made up of axons, which connect different parts of grey matter to each other.
- Makes up 60% of the brain.
- Made up of bundles which connect various grey matter areas.
- Develops throughout the 20s and peaks in middle age.
- Interprets sensory information from various parts of the body.
The neuron - what it contains (6)
- Dendrite
- Nucleus
- Soma (cell body)
- Myelin sheath
- Axon terminal
- Axon
Dendrite and Axon facts (2)
Dendrites receive signals, axons transmit them
Most neurons have a lot of dendrites and only have on axon.
The 4 lobes + location
- Frontal (top, left)
- Parietal (top, right)
- Temporal (bottom, left)
- Occipital (bottom, right).
Gyri and Sulci
Gyri: a ridge on the surface of the brain.
Sulci: fissures surrounding the gyri.
Sulcus are the valleys, gyrus are the hills.
Paul Broca
Patient with specific damage in left frontal lobe lost the ability to produce spoken language, but understanding of speech was intact.
- Broca’s area.
Carl Wernicke
Patient with specific damage in upper-left temporal lobe had impaired understanding of language but had no problem with speech formation.
- Wernicke’s area.
Phineas Gage
Quiet, conscientious, well mannered prior to the accident (frontal lobe damage with a pole going through his head) v. irresponsible, indecisive, irritable, use of profane language after the accident.
Split brain patients
Corpus callosum (thick band of nerve fibres that allow hemispheres to communicate) severed.
Computerised axial Tomography (CT scan)
Multiple X-rays combined into the single image.
Magnetic Resonance imaging (MRI)
Powerful magnet causes charged molecules to re-align to produce field distortions that can be measured.
Single-cell recordings
Activity (action potential or ‘firing’) of a neuron measured by an electrode.
- High temporal resolution, precise localisation.
Electroencephalography (EEG)
Electrodes on the scalp can detect electrical activity.
- Voltage fluctuations resulting from ionic (sodium) currents.
Magnetoencephalography (MEG)
Measures magnetic fields produced by electrical brain activity (e.g., the flow of electrically charged ions through neurons).
- High temporal resolution, good localisation.
Functional Magnetic Resonance imaging (fMRI)
fMRI detects changes in blood flow, because activated brain regions need energy which is supplied by blood.
- Relatively poor temporal resolution, good localisation.
Positron emission tomography (PET)
Measures blood flow in the brain via radioactive markers.
- Relatively poor temporal resolution.
Measuring brain structure methods (7)
- CT scan
- MRI
- fMRI
- Single-cell recordings
- EEG
- MEG
- PET
Altering brain activity methods (2)
- TMS
- tCDS
Transcranial magnetic stimulation (TMS)
Uses magnetic fields to stimulate or inhibit nerve cells.
- Often a therapeutic implementation - can reduce depression.
Transcranial direct current stimulation
Stimulates parts of the brain.
What is ‘sensation’?
Awareness of stimulus due to stimulation of a sense organ.
What is ‘perception’?
Organisation, identification and interpretation of a sensation to a form of mental representation.
Psychophysics (2 key S’s)
Methods that measure the strength of a stimulus and the observer’s sensitivity to that stimulus.
Absolute threshold
Minimal intensity required to just detect a stimulus.
- Threshold = successful detection on 50% of trials.
Weber’s Law (JND)
JND is a constant proportion of the standard - this proportion is called the Weber fraction.
Signal Detection Theory
Assumes that a stimulus is always presented against a background of internal noise.
- Stimulus activity is added to the constant noise signal.
- The individual decides whether the observed activity originates from ‘noise alone’ or from ‘stimulus + noise’.
D-prime
A measure of an individuals ability to detect signals.
- More specifically, a measure of sensitivity or discriminability derived from SDT that is unaffected by response bias.
Liberal response criterion
Many hits, but also many false alarms.
Conservative response
Many correct rejections, but also many misses.
