Links for the week of 2/8/2010

Physical sciences:
Scientists from the Weizmann Institute of Science in Rehovot, Israel figure out how to get water to freeze at different temperatures by modifying the electric charge on the surface it is sitting on. (ScienceNews)

Plastic water? misc.ience describes how scientists are able to make hydrogels that retain their shape, but are made almost entirely out of water.

Biology:
Researchers at the University of Maryland shed light on how Egyptian bats track their prey. Rather than firing sound waves directly at it, they shoot to either side. This makes them less likely to locate prey, but once they have found it, they can follow it more accurately. (EcoTone)

Beware mussels bearing "gifts": Neuroskeptic describes a study of amnesia caused by toxins in shellfish.

It's now fairly common knowledge that bees dance to tell other bees where to find food. But a recent study in Current Biology shows that they also use short buzzes to tell each other not to go to a dangerous location. Ed Yong at Not Exactly Rocket Science describes the study.

Female crickets can apparently warn their young of environmental dangers: baby crickets born to mothers hunted by wolf spiders are more likely to freeze and hide when they detect the spiders. (Not Exactly Rocket Science)

Sociology/human psychology:
Also from Neuroskeptic: A study of whether antipsychotic medication can reduce psychotic experiences in marijuana users.

If you want to encourage altruism, lead by example...and cleaning that bathroom might not hurt, either. A recent study suggests that watching other people perform good deeds increases the observer's altruistic tendencies. Interestingly, smells associated with cleaning also seem to increase altruism. (Psych Central; Not Exactly Rocket Science)

Daniel Hawes at Ingenious Monkey-20 two 5 has an excellent pair of posts on factors affecting girls' success in math.

A number of bloggers have written about Inuk, an ancient Greenlander whose entire genome was recently sequenced. Gene Expression describes the genetic relationships between Inuk's people (which anthropologists call the Saqqaq) and other human groups. Ed Yong describes what we know about his appearance, and how we know it.

John Tierney of The New York Times describes a sociological study conducted using the Times' own records. As it turns out, articles that inspire awe and those that deal with complex topics are the most likely to be forwarded on. (I wonder if there might be selection bias--perhaps readers of The New York Times are more likely to be interested in complex or awesome topics?)

Is religion necessary for morality? A common belief (for lack of a better word) is that religions originally developed to provide a basis for morality--i.e., to give the members of the society rules to follow to keep the society functioning. A recent analysis of studies in moral psychology, however, suggest that religious training and beliefs do not affect how people make moral decisions. Instead, the authors suggest, religion may have filled other needs in early society, such as the need to feel in control of one's surroundings. (björn brembs blog)

New NSF-funded site on science education

I just got this update from a friend (via LinkedIn):

A new NSF-funded site has just launched. According to the release:

"[The site is] dedicated to cataloging best practices in media-based science education and getting the word out about--and discussing--innovative new media-based science education programs and concepts (where media includes both traditional and new media). The site is located at:

http://www.mediasciencelearning.com/

To celebrate its launch (and help get its discussion areas quickly up to critical mass), the grantees (at their own expense, not NSF's) are giving away Zingerman's gift certificates to the best (and most prolific) contributors to the site's case discussions, located at:

http://www.mediasciencelearning.com/CaseStudies

Related to this, if you know of any great media-based science education programs that ought to be highlighted by this site (or you run one yourself and are looking for feedback, publicity, collaborators, or funders), you can submit it at:

http://www.mediasciencelearning.com/addacase/
"

More evidence that simple classroom interventions can have positive effects on achievement

Reading the article I summarized yesterday reminded me of a pair of articles I read recently on a related topic. The first was published in the 1 September 2006 issue of Science, and the second was published in the 17 April 2009 issue. Both describe the results of affirmation exercises on student achievement.

For the first article, Cohen et al. studied two groups of seventh graders (approximately 120 students per group), about half European-American and half African-American. They randomly assigned students to one of two groups (an experimental group or a control group). Students in both groups were given short (~1 paragraph) writing assignments. Students in the experimental group were instructed to choose and write about values that were important to them; those in the control group wrote about values that were unimportant to them.

The intervention occurred at the beginning of the fall semester during the experimental year. Researchers followed up on students' fall semester grades to evaluate the effectiveness of the intervention.

In the second article, the researchers describe the results from a third experiment (a third set of students given the assignment), plus additional data on the students from the original groups, two years later.

This is where it gets interesting. As you read the following, keep in mind that this intervention took about 15 minutes and involved no special equipment, no curriculum modification, and no teacher preparation at all.

African-American students in the treatment group showed significant increases in GPA (~0.24 points) compared to their peers in the control group. African-American students with the lowest achievement going into the class (and the lowest expectation for achievement in the class) had an increase in GPA of 0.41 points compared to their peers in the control group. These effects were present even two years later. What's more, students in the treatment group were less likely to be held back or assigned to remedial classes. Students in the treatment groups also reported more positive self-perceptions, even over the long term.

European-American students showed no differences between control and experimental groups. In fact, the treatment reduced the "achievement gap" (the observed difference in performance between African-American students and their white classmates) by approximately 40%.

The researchers hypothesize that the affirmation exercises act to break a recursive cycle of failure. To quote, "A feedback loop, with psychological threat and poor performance reinforcing one another, can create worsening performance over time. Students' poor performance may also cause them to be seen as less able by their teachers and less worthy of attention and mentoring, increasing the likelihood of lower performance." In other words, students who fail early--and therefore assume that they are less capable--have lower expectations of achievement. Those low expectations can become a self-fulfilling prophecy: students expect to do poorly, so they do.

Because the affirmation exercises focus students on things they value, the exercises can increase students' feelings of self-worth. By reinforcing students' self-esteem, the exercises help to break students out of the failure feedback loop.

The differential effects of the treatment on African-American and European-American students may arise because of the so-called "stereotype threat." A common stereotype is that African-American (and other minority) students perform poorly compared to white students. Therefore, minority students are more likely to fall into a feedback loop when confronted with failure--students' awareness of the stereotype makes them more conscious of their performance, and if they do poorly, they think they're conforming to the stereotype, which puts them under more pressure, which makes them do even more poorly...you get the idea. Even minority students who perform well may experience negative stereotyping effects--their awareness of the stereotype (again) puts pressure on them, which negatively affects performance.

The researchers hypothesize that doing the affirmation exercises helps to reduce the psychological "threat" of stereotyping, allowing students to perform better.

Together, these two papers provide additional evidence that even short-term, simple interventions can make significant strides in closing the achievement gap between white and minority students. As in the article I reviewed yesterday, the effects of this simple exercise were most pronounced for the most at-risk students (low-achieving African-American students), and the exercise had no downside for high-performing students. The results also suggest that such interventions might have long-lasting positive effects. Obviously, these kinds of exercises will not solve all of the educational issues facing the country--but they are cheap (in terms of both time and money), easy, and effective.

(And by the way, the older article is available--full text--for free online at www.sciencemag.org.)


Cohen, G., Garcia, J., Purdie-Vaughns, V., Apfel, N., & Brzustoski, P. (2009). Recursive Processes in Self-Affirmation: Intervening to Close the Minority Achievement Gap Science, 324 (5925), 400-403 DOI: 10.1126/science.1170769

Cohen, G. (2006). Reducing the Racial Achievement Gap: A Social-Psychological Intervention Science, 313 (5791), 1307-1310 DOI: 10.1126/science.1128317

Focusing students' attention on the relevance of science improves educational outcomes

In the discussion about improving science education, the focus often falls on large-scale programs. However, some studies are suggesting that even short-term, small interventions in classrooms can have significant effects on student achievement. In the 4 December 2009 issue of Science (okay, I'm a little behind in my reading...), Hulleman and Harackiewicz investigate the efficacy of short writing assignments on student interest and achievement in science.

It's generally well accepted (and logical) that students with an interest or stake in the material they are learning perform better, work harder, and retain more of what they learn. However, it can be difficult to identify causal relationships between various interventions and student success, because many programs that do produce good results include a lot of different components, not all of which are focused on increasing student interest in the topic.

Hulleman and Harackiewicz hypothesized that activities that draw students' attention to the relevance of instruction to their everyday lives would lead to an increase in achievement. They also hypothesized that the increase in achievement would be largest among students who started out with low expectations of their own abilities--that is, students who think they will do poorly in science would benefit more from these interventions than students who already think they will do well.

To test these hypotheses, the researchers performed an experiment involving 262 high school students. The students attended two different high schools, were taught by seven different teachers, and were enrolled in three different science courses (biology, physical science, or integrated science). Nearly all (92%) of the students were ninth-graders (the remaining 8% were tenth-graders). About half (52%) were female. The majority (66%) were white; 15% were African-American, 12% were Asian, and 8% were Hispanic. The experiment spanned a single academic semester, but data were also collected on about 40% (100/262) of the students' grades for the following semester.

The students were randomly divided into two groups (one experimental group and one control group). Slightly more than half (136/262) of the students were in the experimental group. The teachers did not know which group each student had been assigned to. Each group was assigned to write between one and eight short essays over the course of the semester. Students in the control group wrote summaries of the content they were learning in the class. Students in the experimental group wrote essays describing the relevance of what they were learning to their own lives. (It was not clear whether that context was provided to the students or whether they were expected to identify it themselves.)

At the beginning of the semester (before the experiment), the researchers surveyed students to learn their expectations of success in the course and their interest in science. They also surveyed the students at the end of the semester to reassess their level of interest in science and to learn their future plans for careers in scientific fields. Students' grades during the semester were also monitored.

The results suggest that even this type of simple, short-term intervention can significantly improve student results, at least for those students who start the class with low expectations. Students with low expectations who were in the experimental group had significantly higher grades--"nearly two-thirds of a letter grade", to be exact--than those in the control group. Low-expectation students in the experimental group also showed significantly increased interest in science compared to those in the control group.

Among students with high initial performance expectations, there were no statistically significant performance or interest increases from the intervention. In other words, students who thought they'd do well in the class generally had the same grades (and post-class interest in science), regardless of which group they were in.

Although these results are encouraging--they suggest that teachers can increase the likelihood of student success, especially for the most at-risk students, through a few simple writing assignments--the sample size was small, and relatively homogeneous. Larger studies involving more students, especially minority students, would increase the reliability of the results. Until then, though, these results certainly suggest that these kinds of assignments can't hurt, and could be very helpful.

Hulleman, C., & Harackiewicz, J. (2009). Promoting Interest and Performance in High School Science Classes Science, 326 (5958), 1410-1412 DOI: 10.1126/science.1177067