Cognitive Daily has been chosen to respond to the first question in a newly revised feature on ScienceBlogs: Ask a ScienceBlogger. Readers can submit questions, and they’ll be answered by an expert in the field of inquiry (even though it’s posted under Dave’s name, Dave and Greta worked together on this one). Then, hopefully, discussion among the various ScienceBlogs will ensue. This week’s question:
What’s the difference between psychology and neuroscience? Is psychology still relevant as we learn more about the brain and how it works?
The main difference between psychology and neuroscience is the object of study: psychologists study behavior; neuroscientists study the nervous system. The disciplines overlap in an area usually referred to as the mind, the unseen “software” that controls behavior. But you can’t have a mind without a nervous system, and most particularly, a brain, so perhaps you could learn everything you need to know about psychology just by studying neuroscience. That said, studying only the brain to understand behavior will be slow going if you skip over psychology and its direct study of behavior. In our view, studying both psychology and neuroscience is the best way to understand the mind, behavior, and the nervous system.
With modern neuroimaging tools, neuroscientists can tell us amazing things about the brain. They can show, for example, that the same region of the brain is activated when we listen to music or language, thus suggesting an important link between music and language. They have identified the precise regions of the brain responsible for processing hearing, sight, and smell. Armed with this knowledge, neurosurgeons can better treat conditions like brain cancer (so they can avoid damaging critical areas) and mental illness (by creating drugs or even implants that target specific areas). With the help of neuroscience, so many advances have been made in understanding the human brain that it’s indeed tempting to argue that psychologists aren’t needed at all.
Yet human behavior itself is so complex that trying to understand it from an anatomical perspective alone simply doesn’t make sense. You wouldn’t try to learn how use a complicated computer program like Adobe Photoshop by taking the computer apart, or even by analyzing the lines of its computer code. If all you want to do is remove the red-eye from junior’s Christmas portrait, all that stuff is irrelevant. And even if you want to understand the underlying computer system and programming, you still need to know what the software does.
Psychology is needed because we can learn useful, important things about human nature without knowing a thing about what goes on in the brain. A purely psychological understanding of how the visual system processes color, for example, led to the development of color photography and television–well before an MRI showed us which areas of the brain were active while watching TV. Stanley Milgram’s psychology experiments showed how ordinary people would commit atrocious acts simply because an authority figure told them to–demonstrating that we all have the capacity to commit atrocities. More recent studies on vision and language help us build better computer interfaces, or understand why talking on a cell phone while driving is a bad idea–all without directly drawing on knowledge of the brain.
Even more advances can be made when psychologists and neuroscientists work together. A psychologist can conduct studies with large numbers of participants very cheaply. To return to the example of color vision, in the early 19th century, Thomas Young and Hermann von Helmholtz found that if you give someone three lights of different colors and let them adjust the intensity, they can match virtually all the colors we can see. This behavioral evidence showed that we only need three receptors, but they do have to be able to vary in reactivity. Then a hundred years later, when George Wald and Paul K. Brown finally had the technology to go in and test individual cones in the eye, they had good reasons to look for three types. This kind of converging evidence helps create better explanations of how the brain and perceptual system works, and it’s still happening today.
Psychologists have identified many phenomena for which neuroscientists have yet to find analogous activity in the brain. For example, both musical experts and non-experts display the same brain response to atonal (out of tune) music, yet experts believe this music sounds terrible, while many non-experts do not. Neuroscientists can use research like this to guide their work–perhaps soon they will identify the brain mechanisms for this difference between musical experts and non-experts. Then they can move on to the next problem identified by psychologists, and together, psychology and neuroscience can help us all understand how the brain shapes behavior.
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