Field of Science

Is psychology a science, redux

Is psychology a science? I see this question asked a lot on message boards, and it's time to discuss it again here. I think the typical response by a researcher like myself is an annoyed "of course, you ignoramus." But a more subtle response is deserved, as the answer depends entirely on what you mean by "psychology" and what you mean by "science."

Two Psychologies

First, if by "psychology" you mean seeing clients (like in Good Will Hunting or Silence of the Lambs), then, no, it's probably not a science. But that's a bit like asking whether engineers or doctors are scientists. Scientists create knowledge. Client-visiting psychologists, doctors and engineers use knowledge. Of course, you could legitimately ask whether client-visiting psychologists base their interventions on good science. Many don't, but that's also true about some doctors and, I'd be willing to bet, engineers.

Helpfully, "engineering" and "physics" are given different names, while the research and application ends of psychology confusingly share the same name. (Yes, I'm aware that engineering is not hte application of physics writ broadly -- what's the application of string theory? -- and one can be a chemical engineer, etc. I actually think that makes the analogy to the two psychologies even more apt). It doesn't help that the only psychologists who show up in movies are the Good Will Hunting kind (though if paleoglaciologists get to save the world, I don't see why experimental psychologists don't!), but it does exist.

A friend of mine (a physicist) once claimed psychologists don't do experiments (he said this un-ironically over IM while I was killing time in a psychology research lab). My response now would be to invite him to participate in one of these experiments. Based on this Facebook group, I know I'm not the only one who has heard this.


There are also those, however, who are aware that psychologists do experiments, but deny that it's a true science. Some of this has to do with the belief that psychologists still use introspection (there are probably some somewhere, but I suspect there are also physicists who use voodoo dolls somewhere as well, along with mathematicians who play the lottery).

The more serious objection has to do with the statistics used in psychology. In the physical sciences, typically a reaction takes place or does not, or a neutrino is detected is not. There is some uncertainty given the precision of the tools being used, but on the whole the results are fairly straight-forward and the precision is pretty good (unless you study turbulence or something similar).

In psychology, however, the phenomena we study are noisy and the tools lack much precision. When studying a neutrino, you don't have to worry about whether it's hungry or sleepy or distracted. You don't have to worry about whether the neutrino you are studying is smarter than average, or maybe too tall for your testing booth, or maybe it's only participating in your experiment to get extra credit in class and isn't the least bit motivated. It does what it does according to fairly simple rules. Humans, on the other hand, are terrible test subjects. Psychology experiments require averaging over many, many observations in order to detect patterns within all that noise.

Science is about predictions. In theory, we'd like to predict what an individual person will do in a particular instance. In practice, we're largely in the business of predicting what the average person will do in an average instance. Obviously we'd like to make more specific predictions (and there are those who can and do), but they're still testable (and tested) predictions. The alternative is to declare much of human and animal behavior outside the realm of science.

Significant differences

There are some who are on board so far but get off the bus when it comes to how statistics are done in psychology. Usually an experiment consists of determining statistically whether a particular result was likely to have occurred by chance alone. Richard Feynman famously thought this was nuts (the thought experiment is that it's unlikely to see a license plate printed CPT 349, but you wouldn't want to conclude much from it).

That's missing the point. The notion of significant difference is really a measure of replicability. We're usually comparing a measurement across two populations. We may find population A is better than population B on some test. That could be because population A is underlyingly better at such tests. Alternatively, population A was lucky that day. A significant difference is essentially a prediction that if we test population A and population B again, we'll get the same results (better performance for population A). Ultimately, though, the statistical test is just a prediction (one that typically works pretty well) that the results will replicate. Ideally, all experiments would be replicated multiple times, but that's expensive and time-consuming, and -- to the extent that the statistical analysis was done correctly (a big if) -- largely unnecessary

So what do you think? Are the social sciences sciences? Comments are welcome.

Why is learning a language so darn hard (golden oldie)

I work in an toddler language lab, where we study small children who are breezing through the process of language acquisition. They don't go to class, use note cards or anything, yet they pick up English seemingly in their sleep (see my previous post on this).

Just a few years ago, I taught high school and college students (read some of my stories about it here) and the scene was completely different. They struggled to learn English. Anyone who has tried to learn a foreign language knows what I mean.

Although this is well-known, it's a bit of mystery why. It's not the case that my Chinese students didn't have the right mouth shape for English (I've heard people -- not scientists -- seriously propose this explanation before). It's also not just that you can learn only one language. There are plenty of bilinguals out there. Jesse Snedeker (my PhD adviser as of Monday) and her students recently completed a study of cross-linguistic late-adoptees -- that is, children who were adopted between the ages of 2 and 7 into a family that spoke a different language from that of the child's original home or orphanage. In this case, all the children were from China. They followed the same pattern of linguistic development -- both in terms of vocabulary and grammar -- as native English speakers and in fact learned English faster than is typical (they steady caught up with same-age English-speaking peers).

So why do we lose that ability? One model, posited by Michael Ullman at Georgetown University (full disclosure: I was once Dr. Ullman's research assistant), has to do with the underlying neural architecture of language. Dr. Ullman argues that basic language processes are divided into vocabulary and grammar (no big shock there) and that vocabulary and grammar are handled by different parts of the brain. Simplifying somewhat, vocabulary is tied to temporal lobe structures involved in declarative memory (memory for facts), while grammar is tied to procedural memory (memory for how to do things like ride a bicycle) structures including the prefrontal cortex, the basal ganglia and other areas.

As you get older, as we all know, it becomes harder to learn new skills (you can't teach an old dog new tricks). That is, procedural memory slowly loses the ability to learn new things. Declarative memory stays with us well into old age, declining much more slowly (unless you get Alzheimer's or other types of dementia). Based on Dr. Ullman's model, then, you retain the ability to learn new words but have more difficulty learning new grammar. And grammar does appear to be the typical stumbling block in learning new languages.

Of course, I haven't really answered my question. I just shifted it from mind to brain. The question is now: why do the procedural memory structures lose their plasticity? There are people studying the biological mechanisms of this loss, but that still doesn't answer the question we'd really like to ask, which is "why are our brains constructed this way?" After all, wouldn't it be ideal to be able to learn languages indefinitely?

I once put this question to Helen Neville, a professor at the University of Oregon and expert in the neuroscience of language. I'm working off of a 4-year-old memory (and memory isn't always reliable), but her answer was something like this:

Plasticity means that you can easily learn new things. The price is that you forget easily as well. For facts and words, this is a worthwhile trade-off. You need to be able to learn new facts for as long as you live. For skills, it's maybe not a worthwhile trade-off. Most of the things you need to be able to do you learn to do when you are relatively young. You don't want to forget how to ride a bicycle, how to walk, or how to put a verb into the past tense.

That's the best answer I've heard. But I'd still like to be able to learn languages without having to study them.

originally posted 9/12/07

Tenure, a dull roar

Slate ran an unfortunate, bizarre piece on tenure last week. FemaleScienceProfessor has a good take-down.  Among problems, it repeats the claim that the average tenured professor costs the average university around $11,000,000 across his/her career -- a number that is either misleading, miscalculated, or (most likely) an outright lie. But, as FemaleScienceProfessor points out, tenure itself costs next to nothing, so anyone who says eliminating tenure will save money really means cutting professor salaries will save money but doesn't want to be on the record saying so.

If this seems like deja vu, it is. I just wrote a post about a similarly confused feature in the New York Times. That post is still worth reading (imho).

Which raises the question of why tenure is under attack. I have two guesses: 1) it's a way of ignoring the progressive defunding of public universities, or 2) part of the broader war on science. There are possibly a few people who genuinely think tenure is a bad idea, but not because eliminating it will save money (it won't), because it'll soften the publish-or-perish ethos (yes, the claim has been made), or because it'll refocus universities on teaching (absurd, irrelevant, and beside the point). Which leaves concerns about an inflexible workforce and the occasional dead-weight professor, but that's not on my list of top ten problems in education, and I don't think it should be on anyone else's -- there are bigger fish to fry.

Making data public

Lately, there have been a lot of voices (e.g., this one) calling for scientists to make raw data immediately available to the general public. In the interest of answer than call, here's some of my raw data:

female no English English no no yes United States 1148478773 312 0 helped 1 daxed 59 0 1 1
female no English English no no yes United States 1148478773 312 1 heard 2 blied 33 0 0 2
female no English English no no yes United States 1148478773 312 2 decelerated 2 lenked 45.4 1 0 2
female no English English no no yes United States 1148478773 312 3 startled 1 gamped 31.1 1 0 3
female no English English no no yes United States 1148478773 312 4 prompted 2 henterred 59 0 1 4
female no English English no no yes United States 1148478773 312 5 engrossed 2 nazored 31.1 0 1 5
female no English English no no yes United States 1148478773 312 6 obliged 1 ablined 59 1 0 6
female no English English no no yes United States 1148478773 312 7 tantalized 2 bosined 31.1 1 1 7
female no English English no no yes United States 1148478773 312 8 bled for 1 breened 31.3 1 1 8
female no English English no no yes United States 1148478773 312 9 loathed 2 gaubled 31.2 0 0 9
female no English English no no yes United States 1148478773 312 10 mourned for 1 ginked 31.3 1 1 10
female no English English no no yes United States 1148478773 312 11 wounded 2 jarined 31.1 0 0 10

Do you feel enlightened? Probably not. Raw data isn't all that useful if you don't know how it was collected, what the different numbers refer to, etc. Even if I told you this is data from this experiment, that probably wouldn't help much. Even showing you the header rows for these data will help only so much:

sex subject_already nat_language prime_language autism dyslexia psychiatric country randomID startTime trial word choice conclusion wordClass whichLocation because totalCorrect

Some things are straightforward. Some are not. It's important to know that I record data with a separate row for every trial, so each participant has multiple trials. Also, I record all data, even data from participants who did not complete the experiment. If you're unaware of that, your data analyses would come out very wrong. Also I have some codes I use to mark that the participant is an experimenter checking to make sure everything is running correctly. You'd need to know those. It's key to know how responses are coded (it's not simply "right" or "wrong" -- and in fact the column called totalCorrect does not record whether the participant got anything correct).

The truth is, even though I designed this study myself and wrote the program that outputs the data, every time I go back to data from a study I haven't worked with in a while, it takes me a few hours to orient myself -- and I'm actually relatively good about documenting my data.

So if a law were passed -- as some have advocated for -- requiring that data be made public, one of two things will happen: either people will post uninterpretable data like my mini-spreadsheet above, or they'll spend huge amounts of time preparing their data for others' consumption. The former will help no one. And the latter is expensive, and someone has to pay for that. And this all has to be balanced against the fact that there are very few data sets anyone would want to reanalyze.

There are important datasets that should be made available. And in fact there are already mechanisms for doing this (in my field, CHILDES is a good example). This kind of sharing should be encouraged, but mandated sharing is likely to cause more problems than it solves.


It seems that most science bloggers use pseudonyms. To an extent, I do this, though it's trivial for anyone who is checking to figure out who I am (I know, since I get emails sent to my work account from people who read the blog). This was a conscious choice, and I have my reasons.

1. I suppose one would choose anonymity just in case one's blogging pissed off people who are in a position to hurt you. That would be mostly people in your own field. Honestly, I doubt it would take anyone in my field long to figure out what university I was at. Like anyone, I write most about the topics my friends and colleagues are discussing, and that's a function of who my friends and colleagues are.

(In fact, a few years ago, someone I knew was able to guess what class I was taking, based on my blog topics.)

2. I write a lot about the field, graduate school, and the job market. But within academia, every field is different. For that matter, even if you just wanted to discuss graduate student admission policy within psychology, the fact is that there is a huge amount of variation from department to department. So I can really only write about my experiences. For you to be able to use that information, you have a have a sense of what kind of school I'm at (a large, private research university) and in what field (psychology).

I read a number of bloggers who write about research as an institution, about the job market, etc., but who refuse to say what field they're in. This makes it extremely difficult to know what to make of what they say.

For instance, take my recent disagreement with Prodigal Academic. Prodigal and some other bloggers were discussing the fact that few people considering graduate school in science know how low the odds of getting a tenure-track job are. I suggested that actually they aren't misinformed about academia per se, but about the difference between a top-tier school and even a mid-tier school. I point out that at a top-tier psychology program, just about everybody who graduates goes on to get a tenure-track job. Prodigal says that in her field, at least, that's not true (and she suspects it's not true in my field, either).

The difference is that you can actually go to the websites of top psychology programs and check that I'm right. We can't do the same for Prodigal, because we have no idea what field she's in. We just have to take her word for it.

3. I suspect many people choose pseudonyms because they don't want to censor what they say. They don't want to piss anybody off. I think that to maintain my anonymity, I would have to censor a great deal of what I say. For one thing, I couldn't blog about the one thing I know best: my own work.

There is the risk of pissing people off. And trust me, I worry about it. But being careful about not pissing people off is probably a good thing, whether you're anonymous or know. Angry people rarely change their minds, and presumably we anger people precisely when we disagree with them.


So why don't I actually blog under my name? I want people who Google me by name to find my academic website and my professional work first, not the blog.

Joining Twitter. Sigh.

The last few weeks I've been making some changes at this blog. One is to write fewer but higher-quality posts. Hopefully you noticed the latter and not just the former. At the same time, I have been finding more and more articles and posts that demand sharing, but about which I have little or nothing to say, except that you should read it. This has led me to add a twitter feed above the posts. You can read there or follow directly.

We'll see how it goes. Feedback is welcome. After all, I do this for the audience.


Another change: This blog is *relatively* new to FieldOfScience, but posts go back to 2007. Some of those older posts are worth revisiting, and I'll be reposting (occasionally with updates) a few of the better ones from time to time under the label "golden oldies". Again, if people having feelings about this, let me know.

1/3 of Americans can't speak?

A number of people have been blogging about a recent, still unpublished study suggesting that "a significant proportion of native English speakers are unable to understand some basic sentences." Language Log has a detailed explanation of the methods, but in essence participants were asked to match sentences to pictures. A good fraction made large numbers of mistakes, particularly those who had been high-school drop-outs.

What's going on here? To an extent, this shouldn't be that surprising. We all know there are people who regularly mangle language. But, as Mark Liberman at Language Log points out, at least some of these data are no doubt ascribable to the "paper airplane effect":
At one point we thought we had discovered that a certain fraction of the population is surprisingly deaf to certain fairly easy speech-perception distinctions; the effect, noted in a population of high-school-student subjects, was replicable; but observing one group of subjects more closely, we observed that a similar fraction spent the experiment surreptitiously launching paper airplanes and spitballs at one another.
It's worth remembering that, while many participants in an experiment take it seriously and are happy to help out the researcher, some are just there for the money they get paid. Since we're required to pay people whether they pay attention to the experiment or not, they really don't have any incentive to try hard. Does it surprise anyone that high-school drop-outs are particularly likely to be bad at/uninterested in taking tests?

It's probably relevant that the researchers involved in this study are linguists. There are some linguists who run fabulous experiments, but as a general rule, linguists don't have much training in doing experiments or much familiarity with what data looks like. So it's not surprising that the researchers in question -- and the people to whom they presented the data -- weren't aware of the paper airplane effect.

(I should say that psychology is by no means immune to this problem. Whenever a new method is adopted, it takes a while before there's a critical mass of people who really understand it, and in the meantime a lot of papers with spurious conclusions get written. I'm thinking of fMRI here.)

Honestly, Research Blogging, Get over yourself

A few years ago, science blog posts started decorating themselves with a simple green logo. This logo was meant to credential the blog post as being one about peer-reviewed research, and is supplied by Research Blogging. As explains: is a system for identifying the best, most thoughtful blog posts about peer-reviewed research. Since many blogs combine serious posts with more personal or frivolous posts, our site offers away to find only the most carefully-crafted about cutting-edge research, often written by experts in their respective fields.
That's a good goal and one I support. If you read further down, you see that this primarily amounts to the following: if the post is about a peer-reviewed paper, it's admitted to the network. If it's not, it isn't. I guess the assumption is that the latter is not carefully-crafted or about cutting-edge research. And that's where I get off the bus.

Peer Review is Not Magic

One result of the culture wars is that scientists have needed a way of distinguishing real data from fantasy. If you look around the Internet, no doubt half or even more than half of what is written suggests there's no global warming, that vaccines cause autism, etc. Luckily, fanatics rarely publish in peer-reviewed journals, so once we restrict the debate to what is in peer-reviewed journals, pretty much all the evidence suggests global warming, no autism-vaccine link, etc. So pointing to peer-review is a useful rhetorical strategy.

That, at least, is what I assume has motivated all the stink about peer-review in recent years, and's methods. But it's out of place in the realm of science blogs. It's useful to think about what peer review is.

A reviewer for a paper reads the paper. The reviewer does not (usually) attempt to replicate the experiment. The reviewer does not have access to the data and can't check that the analyses were done correctly. At best, the reviewer evaluates the conclusions the authors draw, and maybe even criticizes  the experimental protocol or the statistical analyses used (assuming the reviewers understand statistics, which in my field is certainly not always the case). But the reviewer doesn't can't check that the data  weren't made up, that the experimental protocol was actually followed, that there were no errors in data analysis, etc.

In other words, the reviewer can do only and exactly what a good science blogger does. So good science blogging is, at its essence, a kind of peer review.


Now, you might worry about the fact that the blogger could be anyone. There's something to that. Of course, has the same problem. Just because someone is blogging about peer-reviewed paper doesn't mean they understand it (or that they aren't lying about it, which happens surprisingly often with the fluoride fanatics).

So while peer review might be a useful way of vetting the paper, it won't help us vet the blog. We still have to do that ourselves (and science bloggers seem to do a good job of vetting).

A weakness

Ultimately, I think it's risky to put all our cards on peer review. It's a good system, but its possible to circumvent. We know that some set of scientists read the paper and thought it was worth publishing (with the caveats mentioned above). Of course, those scientists could be anybody, too -- it's up to the editor. So there's nothing really stopping autism-vaccine fanatics from establishing their own peer-reviewed journal, with reviewers who are all themselves autism-vaccine fanatics.

To an extent, that already happens. As long as there's a critical mass of scientists who think a particular way, they can establish their own journal, submit largely to that journal and review each other's submissions. Thus, papers that couldn't have gotten published at a more mainstream journal can get a home. I think anyone who has done a literature search recently knows there are a lot of bad papers out there (in my field, anyway, though I imagine the same is true in others).

Peer review is a helpful vetting process, and it does make papers better. But it doesn't determine fact. That is something we still have to find for ourselves.

Observant readers will have noticed that I use myself for it's citation system. What can I say? It's useful.