26 October 2017

Throwaway lines


For one student, it was, “Keep it simple. Science is hard enough as it is.”

For another student, it was, “It’s a skill, like anything else. You can learn it and get better at it.”

There were both things I said to students in part of bigger conversations about something else. I thought were throwaway lines. But these students told me that those comments were important to them.

One student kept going back and thinking, “Simplify.” And had success when he did so.

The other student had a “fixed mindset”: that there was a certain amount of skill you had, and when you reached that point in a subject, you were done. Your intellectual ladder was only so tall, it only let you climb over so many walls. My throwaway line helped her switch to a “growth mindset”: practice. Work at it. You can improve.

Sometimes, as an educator, you put a lot of work into the content of courses. You have to write learning objectives, figure out how to explain some tricky concept, work on grading rubrics... and sometimes, the course content is absolutely not the thing sticks with the students.

Sometimes, it’s the random, tangential comments that students tell you later were the things that mattered to them. And I think are highly undervalued in education. You can’t predict or plan for those. But they can happen in the little unscripted moments, particularly when you have a good working relationship and dialogue with students.

For me, it was, “Don’t let the perfect be the enemy of the good.” It was reading an article or letter in a journal someplace, but that became a mantra for me when I was working on manuscripts. I realized I was waiting too much to make things just so when they were never going to get that way. It was a throwaway line that dramatically changed my productivity.

04 October 2017

I come to bury the GRE, not to praise it

I’ve seen a few graduate programs announce that they are not going to require students submit GRE scores any more. These announcements are widely met with praise. The GRE has minimal predictive value in long term grad school success, and it is biased against a lot of groups. And the costs stops a lot of people from applying to grad school.

Interestingly, at the start of last year, the dean of our graduate college announced that several programs were being required to add the GRE to their admission requirements. This was imposed on at from outside the institution at the state level. I can’t remember if it was UT System or the THECB.

Full disclosure. When I became the graduate program coordinator of our master’s program, I pushed and got our department to start requiring the GRE. My rationale at the time was that this was the “industry standard.” We wanted our students to go into doctoral programs, and we reasoned that we would be helping students pave the way for doctoral work by having them do it sooner rather than later.

Also, I was reacting to students who would come in the day before classes started and say, “Can I be a grad student?” At the time, there was no application deadline. And students who did that tended not to persist in the program. So requiring the GRE forced students to plan ahead, not go a grad school because there was nothing good on television that day.

I have since come around to see the many problems with the GRE. But I don’t think our department would be allowed to get rid of it, seeing how many departments were force to require it.

But this is something I think about.

The GRE tried to solve a couple of problems. It failed to solve them, but those problems still exist. And I don’t know how to solve them. The problems are:

  • Grading policies vary wildly across institutions. (See this blog post.)
  • People interpret the same grades in different ways depending on the institution’s perceived rigour and prestige. (See this blog post.)
  • Recommendation letters are usually uniformly glowing.
  • People tend to trust recommendations “in network” from people they know either personally or by reputation.

Students from famous universities who have rubbed shoulders with famous professors and can convince them to send a form letter get deep advantages in grad school acceptance. In other words, we end up selecting for students for grad school who already have a lot of “social capital.” If we want to diversity science, this is not the way to go about it. Diverse students come from diverse institutions, as Terry McGlynn has noted.

In theory, the GRE could have acted as a leveler for the playing field. It didn’t. But the problem it could have tackled is one that we still need to tackle. What can help level the playing field for students against “prestige”?

Related posts

What grades should look like
The “Texas transcript” is a good idea, but won’t solve grade inflation

External links

Students, Rejoice — Standardized Testing May Soon Be Dead

02 October 2017

The little known ways neurons communicate


I just looked in the introductory textbook we use for general biology, and it provides a good explanation of chemical neurotransmission between neurons. If you’ve studied basic biology, a diagram like this probably looks familiar:


I was impressed that the textbook mentioned for chemical neuromodulation. The presynaptic cell releases chemicals across the synaptic cleft, but the receptors don’t open ion channels. Instead, they interact with metabotropic receptors that cause biochemical cascades inside the neurons. These cause any variety of slow, long-lasting effects.

But there are at least three more ways that neurons can communicate.

Third, there are gasotransmitters: small, short lived gases that are made on the spot and zip through cell membranes like they weren’t even there. There are at least four different gases that do this (reviewed in Wang 2014). Nitric oxide is the best known in nervous systems.

Fourth there are electrical synapses. Neurons can be connected by gap junctions, which create pores in the membranes that allow ions to flow freely from one neuron to another. Consequently, an action potential spreads from one cell to the next as though they were one big cell. These were first described in crayfish, by the way (Furshpan & Potter 1957).

Fifth, there are ephatic signals, where the electrical potentials generated by spikes in one neuron create electrical potentials in adjacent neurons, even with no synapses or gap junctions between them. It’s just a spread of electrical activity. This was described at least as early as 1940 (Katz & Schmitt 1940), but I am ashamed to admit I had never heard of this until a few years ago (Su et al. 2012), even though the original effect was shown in the 1940s using motor neurons in crab legs! And learning about those was a big chunk of my doctorate.

I often find myself griping about how many people assume that brains work like computers. And I think part of that is because signalling by chemical neurotransmission seems very computational. I wish more people knew that there are at least four other ways that neurons can interact and influence each other. Maybe they wouldn’t be so quick to think that downloading our brain activity into computers is going to be easy.

References

Furshpan EJ, Potter DD. 1957. Mechanism of nerve-impulse transmission at a crayfish synapse. Nature 180(4581): 342-343. http://www.nature.com/nature/journal/v180/n4581/pdf/180342a0.pdf

Katz B, Schmitt OH. 1940. Electric interaction between two adjacent nerve fibres. The Journal of Physiology 97(4): 471-488. https://doi.org/10.1113/jphysiol.1940.sp003823

Su C-Y, Menuz K, Reisert J, Carlson JR. 2012. Non-synaptic inhibition between grouped neurons in an olfactory circuit. Nature 492: 66-71. https://doi.org/10.1038/nature11712

Wang R. 2014. Gasotransmitters: growing pains and joys. Trends in Biochemical Sciences 39(5): 227-232. https://doi.org/10.1016/j.tibs.2014.03.003

Picture from here.