Source: Man In Traffic by Sun-anda; Creative Commons http://www.flickr.com/photos/13073558@N03/2073457769/ Twins; Public Domain http://bit.ly/16PsGr
Hello, class. So in today's lesson, we're going to be talking about a famous debate. And it's a debate that we've seen throughout history in psychology, but also in other areas of thinking, things like religion, philosophy, and science.
And that's a debate that's been phrased in a lot of different ways, either destiny versus free will. We've got determinism versus indeterminism. In psychology, we call it nature versus nurture, so that's a good term for you to know.
What does that mean? Well, nature refers to our biological sort of workings, which is to say our genetics and the way our brain is structured, all those different sorts of things, evolutionary. And nurture refers to our environment and the role that has on our development.
So the idea is, which one has a more significant effect on our development as people? As an example of this, I'm going to use the idea of personality versus mood. Personality is our ongoing, stable, long-term sorts of characteristics, things that are sort of built into ourselves or our nature side of things.
This is, for example, to say that a person is irritable. They're just an irritable kind of person. Over time, that's the kind of characteristics they display.
And this is versus mood, which is to say our day-to-day sorts of feelings. And this can be affected by the environment. For example, if someone's stuck in traffic, if somebody was just cut off in traffic, they might be in an irritable kind of mood. They might not be an irritable person. But for that time or for a short period of time, they're going to be irritable.
So which one has the bigger effect? That's the question. To understand this debate a bit further, let's frame it in terms of things that we've been studying up to this point.
First, let's talk about genetics. Now, under genetics, we say that there's a certain biological basis for psychology. It's in our genes, right? And an example of this is the fact that when we have brain damage, it can influence our behavior and our personality.
There's a famous case of a worker named Phineas Gage who in 1848 received significant brain damage to his frontal lobe when a tamping iron that he was using shot up through his brain. He still survived, so don't worry. And he experienced after that significant changes in his personality.
People said he was a completely different person as a result of that. So we know that there's some biological basis to his personality in that part of his brain that was damaged. Hence, again, nature side.
On the other hand, though, people have noted that there's a certain environmental influence on the way that our genetics work. The biologist Barbara McClintock researched how certain genes are displayed, they're turned on or off, as a response to environmental influences. So if there are certain stresses-- in her case, she was studying maize, or corn, and the way that it was colored. Certain stresses from the environment, either extreme heat or cold, would change the way that these would influence or they would express their colors. So that's got both sides of the debate.
Another term that we might remember is the idea of twin studies. Twin studies are where we compare identical or fraternal twins to see similarities or differences between them. When we're comparing twins of the same parents, we noticed that there were significant similarities-- again nature-- significant similarities in identical twins. They had similar IQs, similar personalities. They would even have similar disorders. They were more likely to acquire those disorders.
However, with twin studies when twins of different parents were compared, if they were split at birth, then these similarities tended to drop off. So again, taking a look at the nurture side of things. So you see, there's a little bit on both sides for each one of these.
Now, the takeaway point for today is that, as with most psychology today, to understand all of the different sorts of things that are happening, we have to understand a range of influences, not just one or the other. In other words, it's not nature versus nurture. It's nature and nurture. We need both to create a complete picture of all our psychological concepts.
A helpful way of thinking of it is the idea of a reaction range. A reaction range is the limits that the environment places on the effects of heredity. In other words, it's our aptitude to be able to do something in response to the environment.
As an example, if a child shows a certain artistic aptitude, a certain biological predisposition to being artistic, they can only develop that if they're being given an environment where they have art supplies in it. If they aren't given any kind of art supplies, they won't be an artistic m because they can't develop those abilities, whereas if they are given art supplies, then they might be a very artistic and very creative person, because they have that nature and nurture together. This same sort of concept also applies to different types of addiction, where we say there's a biological predisposition to having alcohol addiction or different kinds of narcotic addictions, where it's important to not have that environmental response, to not drink, so that we don't develop those kinds of disorders.
Innate or biological influences on behavior such as genetics.
Environment influences on behavior such as society and learning from experiences.
Because identical twins have the same DNA, comparing the behavior of identical twins with that of fraternal twins or siblings from the same parents allows psychologists to determine if certain behavior has a genetic predisposition.