Field of Science

Findings: How memory changes with age


It's well-known that both long-term and short-term memory decline with age. However, most of these data come from verbal memory tests. The evidence for visual short-term memory is less clear. A few studies (Adamowicz, 1976; 1978; Fahle & Daum, 1997) show age-related declines, but more recent studies do not (Faubert & Bellefeuille, 2002; McIntosh et al., 1999; Sara & Faubert, 2000; Thompson, Cengelci & Ozekes, 1999).

In one of our longest-running experiments -- now archived -- we looked at visual short-term memory across a wide age range: from 14 years old to 90 years old. This has some advantages over the typical method, which is to test one group of young people (usually college students) and a group of older people (often recruited at a club or function frequented by folk of a certain age). With our data, we can find out not only whether visual working memory declines with age, but when it begins to decline and how rapidly.

The Memory Test


The experiment is simple. Participants are shown four novel objects for one second. Then they have to remember those objects for one second. After that, they are shown one object and asked if that is one of the four they just saw. A diagram of this method is on the right.

By the time the experiment stopped running, 8,374 people had completed the task (plus some who did not make it into this analysis -- for instance, people doing the experiment for the second time). This allowed us to look closely at the results year-by-year for the entire range of ages.

Results

Not surprisingly, performance did decline with age. Our statistical analyses suggest that the decline begins in the 30s (the best estimate was 36.6 years of age, with a 95% confidence interval from 32.2 to 41.1 years). Starting at 37 years old, performance on this task dropped by one percentage point every 2 1/2 years.



Why didn't those other recent studies show an age-related decline in visual short-term memory? One possibility is that the tasks those researchers used were simply too easy for differences to show up (the well-known ceiling effect), whereas our task and the ones used by the older experiments are all much harder.

Future Work

The exciting and novel part of this experiment is not that we showed age-related changes in memory performance. It would have been surprising if we didn't find any. What is more exciting is our ability to estimate the age at which it starts. My collaborators and I are currently running similar studies looking at aging for other types of mental tasks to see whether changes appear at similar ages. If changes appear at approximately the same age for two different tasks, that may suggest a common origin to the changes. We've run several more studies which I'll talk about in the future, and we're nearly ready to write up this work for publication.

Many thanks to the nearly 9,000 people who participated. Of course, we're always running new experiments at GamesWithWords.org. Please stop by.

See Also

This is not the only way the data from The Memory Test has been used. You read a compilation of previous posts on memory here.


Picture credit: http://www.flickr.com/photos/deepblue66/ / CC BY-NC-SA 2.0

Lab Notebook: Shopping Period

Harvard and Yale, in their infinite wisdom and love of tradition, do not register students for classes until the second week of the semester. The first week, called "Shopping Period," in theory gives students a chance to try out different classes. Undergraduates seem to like it.

Shopping Period has several consequences. One is that no schedules can be set in stone until the second -- or often third -- week of the semester. Since nobody knows how many students are going to take a class, much less which students, graduate student-led course sections can't be scheduled until the second week. This makes it difficult for undergraduate research assistants to set their lab schedules until the second or third week of the semester. The same goes for any regular meetings that graduate students and/or undergraduate students attend. Also, one can't reserve rooms for those meetings until after all the courses have rooms assigned and all the sections have rooms assigned. I have a mandatory meeting for my undergraduate research assistants. As should be clear from above, it's not always clear whether an undergraduate will be able to attend that meeting until the third week of the semester.

Again, the students seem to like Shopping Period, so it clearly has its benefits, but it makes the beginning of the semester very busy -- it's a little like packing your bags while you're already on the way to the airport. I am also giving a talk next Thursday and submitting a paper to the Cognitive Science Society annual meeting next Saturday.

Photo credit: http://www.flickr.com/photos/chavals/ / CC BY-NC-ND 2.0

Making research open-access

The US Office of Science & Technology policy is continuing to receive comments on the future of its open-access policy. The comments have been overwhelmingly in favor of making research papers available for free electronically, which many suggesting they be available immediately on publication (or even upon acceptance, which is as much as a year or two before publication). The comment that was most on-point, from my perspective, was one person who wondered what purpose publishers even serve beyond copy-editing, given that all the work is done volunteers (and, come to think of it, I helped with the copy-editing of my last paper myself).


Some comments go even farther, suggesting that all data should be made public immediately. I'm not sure about that idea. Preparing data so that it is easy for others to understand is by no means easy. When I go back to look at data I collected a few years ago, it often takes me hours to interpret it, and I remember what the study was about. In fact, the basic purpose of a paper is to take data and make them easy to understand. Finally, while there are rare cases where I wish I had access to somebody's original data, for most studies I can't even imagine what value having the original data would have.


Certainly, there are cases in which having the raw data would be valuable. But is the value worth the cost of preparing all data from all studies for the public? Maybe in fields in which the data are easier to publish it is. In psychology, I'm not sure.

Birth order and personality

For those who haven't seen it yet, I have a new article in the latest issue of Scientific American Mind. You can of course buy a copy of the magazine off of a news stand, but the article has been posted in full online as well.

More monkey language

The New York Times is running an article trying to pull together recent work on primate communication, including the paper I blogged about last week.

Want to know as soon as results from an experiment are ready?

When I have results from an experiment that I can share, I put it on the blog ... which is great if you constantly check the blog. I also send out an email. If you would like to receive this email, you can join the mailing list here. I also use this mailing list to announce new experiments. On the whole, this means 5-10 emails per year.

I use Google Groups, which is a little bit of a pain if you don't have a Google account -- you'll need one (they're free). On the other hand, Google Groups makes it really easy for you to unsubscribe if, for some reason, you eventually decide you don't want to get emails anymore.

Can we make our body do what we want?

I read Fodor's Language of Thought over the summer. Towards the end of Chapter 1, he says psychological rules must have exceptions, since "even when the spirit is willing the flesh is often weak. There are always going to be behavioral lapses which are physiologically explicable but which are uninteresting from the point of view of psychological theory."

Like many cognitive scientists, I'm a big fan of Fodor. I love his theory of concepts put forth in Language of Thought. I even like his work when I disagree with it. This is a place I disagree: behavioral lapses are fascinating from the point of view of psychological theory.

There's two ways of interpreting this comment. One assumes dualism: there is an immaterial mind that tries to make the physical brain and body do what it wants. This theory is almost certainly wrong, but on this theory, cases in which the brain fails to do what the mind wants are interesting. Why would that happen? Are these errors random stochastic noise, or are there patterns in the failures?

If we assume that all behavior arises from the activity of the brain (probably the right theory), behavioral lapses are even more interesting. We have conscious parts of our mind/brain that make explicit decisions (I'm getting out of bed now; I won't eat that slice of chocolate cake; I'm going to smile when I open this present, no matter what it is), but it's clear to any owner of a consciousness that making a decision is one thing -- making it happen is another (there are more prosaic cases as well, in which we mean to say one word but a different one comes out).

Perhaps wires sometimes get crossed and our decision isn't transmitted to the relevant module of the brain. That seems like a pretty serious design flaw, so why hasn't evolution fixed it? Perhaps there are non-conscious parts of our brain that sometimes override our conscious decisions ... in which case, what is consciousness for (according to some, not for making decisions).

Psychological theory aside, I suspect most people would like to understand why, despite a willing spirit, their flesh is so often weak.

Findings: The funniest pun

Puntastic has been running for a few weeks, and so far participants have contributed 13,748 ratings in total of nearly 2,000 different puns. Currently, the most popular pun is:

College slogan: 'Draft beer, not students.'

53 different puns are tied for last place, supporting the hypothesis that there are a lot more bad puns than good puns.

When the study is done -- hopefully in a few months -- I'll post rankings of the puns used in the experiment. Before that time, though, we need many more people to rate puns.

If you've already participated, feel free to play again: with nearly 2,000 puns, it's unlikely you'll see many of the same ones again (with the exception of a few 'filler' puns that everyone sees). Just be sure that you answer "yes" to the question "Have you participated in Puntastic previously?"