Chapter 5: The Research Methods of Biopsychology
Methods of studying the nervous system
Contrast X-ray techniques: involve injecting into one compartment of the body a
substance that absorbs X rays either less than or more than the surrounding tissue.
These are good for visualizing the brain.
cerebral angiography: a contrast x ray technique uses the infusion of a radio-
opaque dye into a cerebral artery to visualize the cerebral circulatory system during
X ray photography. These are most useful for localizing vascular damage and also
can locate tumors.
Computed tomography (CT): developed in the early 1970s, revolutionized the
study of the brain. Takes numerous x rays of an individual’s head, produces a 3D
image of the brain.
Magnetic Resonance Imaging (MRI): a procedure in which high resolution
images are constructed from the measurement of waves that hydrogen atoms emit
when they are activated by radio-frequency waves in a magnetic field. It provides
high spatial resolution (the ability to detect and represent differences in
spatial location); MRI can produce images in three dimensions.
-provides a clearer image of the brain than does CT
Positron Emission Tomography (PET): the first brain imaging technique to
provide images of brain activity rather than images of brain structure.
fMRI: the most influential tool of cognitive neuroscience. It produces images
representing the increase of oxygen flow in the blood to activate areas of the brain.
The BOLD signal stands for blood-oxygen-level-dependent signal.
fMRI has four advantages over PET:
1. nothing has to be injected into the subject
2. it provides both structural and functional information in the same image
3. its spatial resolution is better
4. it can be used to produce three dimensional images of activity over the
Magnetoencephalography (MEG): measures changes in magnetic fields on the
surface of the scalp that are produced by changes in underlying patterns of neural
activity. Its major advantage over fmRI is its temporal resolution: it can record
fast changes in neural activity.
The disadvantage of all of these creations is that they cannot be used to prove
that the brain activity caused the cognitive activity
Transcranial Magnetic Stimulation (TMS): a technique for affecting the activity
in an area of the cortex by creating a magnetic field under a coil positioned next to
the skull. In effect, the magnetic stimulation temporarily turns off part of the brain
while the effects of the disruption on cognition and behavior are assessed
Recording Human Psychophysiological Activity
Electroencephalography: a measure of the gross electrical activity of the brain
by the EEG (electroencephalogram). Psychophysiologists are often more interested
in the EEG waves that accompany certain psychological events than they are in the
background EEG signal. These accompanying EEG waves are generally referred to
as event-related potentials (ERPs). One common studied type of event related
potential is the sensory evoked potential- the change in the cortical EEG signal that is elicited by the momentary presentation of a sensory stimulus. A method
used to reduce the noise of the background EEG is signal averaging.
Electromyography: the usual procedure for measuring muscle tension. EMG
activity is usually recorded between two electrodes taped to the surface of the skin
over muscle of interest.
Electrooculography (EOG): technique for recording eye movement. It is based on
the fact that there is a steady potential difference between the front and back of the
Emotional thoughts and experiences are associated with increases in ability of the
skin to conduct electricity. The two most commonly employed indexes of
electrodermal activity are the skin conductance level (SCL) and the skin