Psychology, 5/e   Wortman, Loftus & Weaver
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Frequently Asked Questions

1. What are the most important things to remember about neurotransmitters?

Though researchers have identified dozen of chemicals which appear to act as neurotransmitters, many of them are based on similar chemical structures, and are therefore closely related. Furthermore, although transmitters are more prevalent at certain sites in the central nervous system, most have actions in numerous sites throughout the CNS. Therefore, drugs which alter functioning of one transmitter are likely to induce numerous effects--not all of them desired. Finally, almost an drugs which have psychological effects do so by functionally altering the levels of various neurotransmitters.

2. What can an MRI scan show that a PET scan cannot?

In general, PET scans are used to look at the functions of various brain regions while MRI scans provide information about the structure of the brain. PET scans are comparatively simple instruments, showing which parts of the brain are active at any one time. To do this, a small amount of radioactive tracer (usually glucose, which is the primary fuel source of neurons) is injected in the bloodstream. Those cells which are most active take in these radioactive tracers, and these active regions are detected by the PET scan. MRIs are usually more time-consuming and are not generally used monitor brain activity. But MRIs provide images that more clearly show the structure of different brain regions, and are invaluable for diagnosing brain abnormalities such as those caused by tumors or disease.

3. Are certain aspects of personality such as sexual preference inherited? If so, how can they be changed?

Behavioral geneticists have found that many aspects of personality do indeed have powerful genetic components. However, don’t make the mistake of assuming genetic INFLUENCE means that a certain trait is entirely genetically determined. It’s clear that sexual orientation has a strong genetic component, but like other personality traits this is only a PREDISPOSITION. Environmental influences still play a significant role in how (and if) this predisposition is ultimately expressed.

Having said that, most psychologists believe that sexual orientation is not a conscious decision, and thus see no reason to change it. In fact, the American Psychiatric Association’s Diagnostic and Statistical Manual, 4th ed. (DSM IV), the universally recognized reference for classifying psychological disorders, does not list homosexuality as a disorder (and hasn’t for nearly two decades). Though some anecdotal evidence exists which suggests sexual orientation can be changed, scientific research indicates otherwise.

4. Is it true that different hemispheres of the brain control the artistic and logical parts of thinking and behavior? Are “left-brained” people really more scientific?

Though the two hemispheres do have somewhat different functions, the magnitude of these differences has been greatly exaggerated. Individuals do differ with respect to their cognitive abilities, of course, and some of those are related to differences in global hemispheric differences. But these hemispheric differences are quite small.

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