Is an Online Exam Harder?

Last Fall, I offered my undergraduate students a choice: the could take the exam on paper OR the could take it online. The questions would be identical. The only difference would be the "medium". I was surprised to discover that more than 50% of students opted for paper. I tried the experiment again this semester -- with the same result.

This experience left me to wonder: Why would a so-called millennial student choose paper over a computer?

Below are my theories based on casual conversations with students and my observations during the exams:

• Students like to hold the exam in their hands to gauge the length of the test and to have indicators of space to determine the length of individual answers.
  
• Students like to flip through their exam to check their answers. Some students flip through 3 or 4 times before handing in the exam. While they can do this on the computer, it somehow doesn't "feel" the same to them.
  
• Students don't like the countdown timer ticking away the minutes. Even with a clock in the room where they take the paper exam, they don't feel as intimidated as they do looking at a digital clock telling them how much time is left.
  
• Students don't trust the technology. My guess is that this is the biggest barrier. They are afraid that they system will "crash" and they will lose their work and have to start over.
  

I wonder if this will change with the coming generations? Is it similar to my desire to hold a book in my hand and my reluctance move to an e-reader?