I was looking at how my students did on my Intro Psych exam questions this past fall. One item on split-brain jumped out at me. I have such a question on the first exam and another on the final. Both questions posit that something is briefly shown in the left visual field and another something is briefly shown in the right visual field of someone who has had split brain surgery. The answer choices ask the student to identify what the person can do, e.g., use their right hand to point at the first something, say what the other something was.
Last fall, how did my students do on the split brain questions? Not so well. On the module exam, about 50% of my students got the question right. On the final exam, about 20% did.
I know this is a tricky concept. Initially I was thinking I could do some sort of in-class demo to help students see the difference. I had some ideas that involved student volunteers, but then when it came time to do it in class, I thought, "There is no way this is going to work. They're going to leave being more confused." So I didn't do it.
At my next department meeting, I said that I was trying to find a way to help students grasp split brain and was wondering if anyone had ideas. Rod Fowers said that he had created a worksheet [download here] that helps students think it through. He acknowledged that a 2-page worksheet for this concept may feel like overkill, but he was also trying to model to students how to break something that is complex into smaller chunks to make it more digestible. That makes sense.
I sent the worksheet to my students as a 5-point extra credit opportunity (over 600 points in the course) via our course management system on Friday. The instructions were to print it out (or manipulate it digitally), follow the instructions (which includes drawing), and get it to me by the beginning of class on Monday (day of their first exam, an exam that included a split brain question).
About half of my students completed the worksheet correctly. (Only one student who turned it in didn't earn credit for it.) How did they do on that first exam split brain question? Of the 26 who successfully completed the worksheet, 69% answered the question correctly. Of the 28 who didn't do the worksheet, 25% answered the question correctly. I can see that difference even without a statistical test.
Now, I know what you're thinking. "But Sue, it's the students who tend to do better on tests who do the extra credit." I removed the split brain question from my students' total exam scores. Was there a difference in their adjusted exam scores? Nope.
Next up is the final exam. Will I see an increase in performance on that split brain question as well? I'll let you know in a couple months.
I have data at this point to include this split brain worksheet in my classes next term as a required assignment. I may even make it part of an in-class small group activity like my colleague Ruth Frickle did yesterday. Although I will probably modify the worksheet, removing the questions about how each eye is halved since that's a bit more than I really want my students to know.
If you try this worksheet, I'd love to hear how it works for you!