Studying cognitive pyschology is an exceedingly self-referential task. It also poses an interesting question: when using one’s own brain for study, do different observational methods hold any relevance? I’ll be frank—I started writing this article as I read over my second year cognitive psychology text. While I found other topics interesting, such as the basic cognitive structures, I could hardly remember anything about brain-scanning methods. Maybe there’s something in that.
The oldest method for eavesdropping on the brain is termed electroencephalography (EEG). The EEG technique measures fluctuations in electrical activity over time. The experimenter puts electrodes on the head to accomplish this task. While spatial resolution is poor, due to representing a flow of data, temporal resolution is excellent. It also has an advantage that many researchers find appealing: it is inexpensive. Many later developments, such as event-related potential and magnetocenphalography, are variations on EEG.
Professor George Cree, of UTSC’s department of pyschology, gave some insight into the progression of brain examination.
“Functional neuroimaging techniques have really taken off in the last decade as a means of peeking inside the human brain, while it is working, to try to figure out how the brain gives rise to the mind,” said Cree.
Positron emission tomography (PET) is perhaps the most interesting. To perform the PET scan, a radioactive isotope is injected into the blood of the individual. Considered invasive and expensive, this method measures how much blood is detected in the brain when it is active. Like a car’s engine, the brain draws in more blood the higher it functions. As blood flow increases to different areas, the machine picks up the radioactive elements introduced into the blood. These measurements are run through a computer program that constructs a three-dimensional image.
“The research has become really interesting now that researchers have moved beyond ‘mapping the brain’ (i.e., trying to figure out what each region ‘does’) to more interesting questions, such as how different regions work to produce complex cognition,” said Cree.
A well-known technique for studying various parts of the body, magnetic resonance imaging, or MRI, was originally designed to assess structural, rather than functional, components. This tactic is expensive but non-invasive. Researchers also claim that MRI spatial resolution is as good as its temporal resolution. MRI uses magnetic fields to alter the alignment of specific sub-structures. The next step is to distort the alignment, and measure the output as the atoms move back to their original position. Recently, something called fMRI replaced PET to peer into our thoughts. Based on structural MRI, this method follows activity in the brain.
The most current brain observation technique was welcomed to the University of Toronto in the summer of 2007 with the addition of Professor Laura-Ann Petitto, a world expert in Near Infrared Spectroscopy (NIRS).
“[NIRS] combines the strengths of fMRI and EEG to produce excellent spatial and temporal data regarding processing in cortical tissue,” said Cree.
While many find these correlational methods robust, the highly technical methods involved can be difficult to grasp. Correlational methods themselves make claims about their limitations, namely the famous “correlation doesn’t imply causation” argument. As well, there is a lesser-known lesson from behavioural statistics: two variables that appear correlated could have absolutely no effect on each other—they may just be activated simultaneously.
Which brings me to another point: is there a double dissociation between my long-term memory for this material and my recall? I hope not.
