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Thanks. I've been wondering for a while: How much do we know about human psychology is based on studies performed only on 20-year-olds?

tedks 12y ago
...well, quite a lot actually, because 20 year olds are more like other humans than different. Humans don't have life stages. We don't wrap ourselves in cocoons and change from grubs into butterflies from ages 16-20. For most of human existence, 20-25 year olds were the substantial power holders. There's a branch of psychology called developmental psychology. It has to do with how humans change over time. If developmental psychologists only studied undergraduates, we wouldn't have a good grasp of the area, but they don't. It's pretty easy to get kids and elderly people to study. It's even pretty easy to get adults to study. It's more expensive than undergraduates, but it's doable. Beyond that, what sort of differences do you expect to see in areas like, say, input attention, working memory, fluid intelligence, social behavior, perception, motor control, etc.? 18-22 year olds are pretty much normal adults in all of those regards. The thing that makes this really insignificant is that we know so little about how minds work. Psychology has only really existed since Skinner and behaviorism made it a real science. If I spent 10 seconds I could think of nice, clever-sounding retorts as to why the perception system of a 22 year old is vastly different from the perception system of a 32 year old, but in reality we know almost nothing and learning anything is good. As Heinlein said, it's wrong to think the world is a sphere, but it's much better than thinking the world is flat. These discussions about replication always sadden me, because they miss the point by so much. Psychology is one of the least respected and yet most vital sciences. The problem is that everyone is a lay expert, because everyone has a mind and thinks they understand how minds work. Psychology has taught us so many valuable, horrible and beautiful things about ourselves. If you're reasonably intelligent, you can come up with reasons not to believe anything. It's easy to discredit things. It's hard to build things. (It's also false that psychology studies are only performed on undergrads, usually undergrads are a good pilot testing base and then you move on to externally recruited populations, unless there's really no reason to do so based on the field.)
- pacaro 12y ago
  This may be a "get off my lawn" comment, but my understanding is that pediatric psychiatrists and psychologists will treat patients up to 25 years old. The boundary between childhood and adulthood is labile and varies from person to person. From my own experience, re-reading books like "100 years of solitude" or "the unbearable lightness of being" at ten year intervals shows me how much I have changed
  - tedks 12y ago
    ...but the optic nerve of a 20 year old is the same from a scientific perspective in almost all respects to the optic nerve of a 30 year old. Maybe if that optic nerve signaled some horribly deep work of literature like 100 years of solitude, the older brain behind it would interpret it differently, but that nerve is the same. When you remember the amazing swelling feelings of being ~adult~ you had when you last read 100 years of solitude, your semantic and episodic memory systems are, functionally, identical to what they were when you read it the first time. Maybe your fluid intelligence is a little less fluid, but that doesn't really start until you've aged a lot. I'm sure you've changed as a person. I'm sure you have a wealth of new experiences and are entirely different from your past self. This is irrelevant to the physics, chemistry, and psychology of your body.
    - pacaro 12y ago
      In general I agree with you. It is important to separate experience from capability (there's probably a better word here). Much of the social psychology may not fit easily into that division though. To pick on a common whipping boy in these arguments, Milgram's obedience study, what is the role of experience in any set of choices like those given to the participants. The asymmetric responsibilities when there is a power dynamic is something that some people learn somewhere along the line. I'm rambling a little but I feel that some of the observed effects in these experiments may be things for which experience may provide a learned immunity
      - tedks 12y ago

tedks 12y ago

...well, quite a lot actually, because 20 year olds are more like other humans than different. Humans don't have life stages. We don't wrap ourselves in cocoons and change from grubs into butterflies from ages 16-20. For most of human existence, 20-25 year olds were the substantial power holders. There's a branch of psychology called developmental psychology. It has to do with how humans change over time. If developmental psychologists only studied undergraduates, we wouldn't have a good grasp of the area, but they don't. It's pretty easy to get kids and elderly people to study. It's even pretty easy to get adults to study. It's more expensive than undergraduates, but it's doable. Beyond that, what sort of differences do you expect to see in areas like, say, input attention, working memory, fluid intelligence, social behavior, perception, motor control, etc.? 18-22 year olds are pretty much normal adults in all of those regards. The thing that makes this really insignificant is that we know so little about how minds work. Psychology has only really existed since Skinner and behaviorism made it a real science. If I spent 10 seconds I could think of nice, clever-sounding retorts as to why the perception system of a 22 year old is vastly different from the perception system of a 32 year old, but in reality we know almost nothing and learning anything is good. As Heinlein said, it's wrong to think the world is a sphere, but it's much better than thinking the world is flat. These discussions about replication always sadden me, because they miss the point by so much. Psychology is one of the least respected and yet most vital sciences. The problem is that everyone is a lay expert, because everyone has a mind and thinks they understand how minds work. Psychology has taught us so many valuable, horrible and beautiful things about ourselves. If you're reasonably intelligent, you can come up with reasons not to believe anything. It's easy to discredit things. It's hard to build things. (It's also false that psychology studies are only performed on undergrads, usually undergrads are a good pilot testing base and then you move on to externally recruited populations, unless there's really no reason to do so based on the field.)

pacaro 12y ago
This may be a "get off my lawn" comment, but my understanding is that pediatric psychiatrists and psychologists will treat patients up to 25 years old. The boundary between childhood and adulthood is labile and varies from person to person. From my own experience, re-reading books like "100 years of solitude" or "the unbearable lightness of being" at ten year intervals shows me how much I have changed
- tedks 12y ago
  ...but the optic nerve of a 20 year old is the same from a scientific perspective in almost all respects to the optic nerve of a 30 year old. Maybe if that optic nerve signaled some horribly deep work of literature like 100 years of solitude, the older brain behind it would interpret it differently, but that nerve is the same. When you remember the amazing swelling feelings of being ~adult~ you had when you last read 100 years of solitude, your semantic and episodic memory systems are, functionally, identical to what they were when you read it the first time. Maybe your fluid intelligence is a little less fluid, but that doesn't really start until you've aged a lot. I'm sure you've changed as a person. I'm sure you have a wealth of new experiences and are entirely different from your past self. This is irrelevant to the physics, chemistry, and psychology of your body.
  - pacaro 12y ago
    In general I agree with you. It is important to separate experience from capability (there's probably a better word here). Much of the social psychology may not fit easily into that division though. To pick on a common whipping boy in these arguments, Milgram's obedience study, what is the role of experience in any set of choices like those given to the participants. The asymmetric responsibilities when there is a power dynamic is something that some people learn somewhere along the line. I'm rambling a little but I feel that some of the observed effects in these experiments may be things for which experience may provide a learned immunity
    - tedks 12y ago