Undergraduate students' neurophysiological reasoning: what we learn from the attractive distractors students select

The basis for mastering neurophysiology is understanding ion movement across cell membranes. The Electrochemical Gradients Assessment Device (EGAD) is a 17-item test assessing students' understanding of fundamental concepts of neurophysiology, e.g., electrochemical gradients and resistance, synaptic transmission, and stimulus strength. We collected responses to the EGAD from 534 students from seven institutions nationwide, before and after instruction. We determined the relative difficulty of neurophysiology topics and noted that students did better on "what" questions compared to "how" questions, particularly those integrating concentration gradient and electric forces to predict ion movement. We also found that, even after instruction, students selected one incorrect answer, at a rate greater than random chance for nine questions. We termed these incorrect answers attractive distractors. Most attractive distractors contained terms associated with concentration gradients, equilibrium, or anthropomorphic and teleological reasoning, and incorrect answers containing multiple terms were more attractive. We used χ² analysis and alluvial diagrams to investigate how individual students moved or did not move between answer choices on the pre- and posttest. Interestingly, students selecting the attractive distractor on the pretest were just as likely as other incorrect students to move to the correct answer on the posttest. In contrast, of students incorrect on both the pre- and posttest, students who selected the attractive distractor on the pretest were more likely to stick with this answer on the posttest than students choosing other incorrect answers. Combining the EGAD results with alluvial diagrams can inform neurophysiology instruction to address points of student confusion.NEW & NOTEWORTHY Investigating students' alternative reasoning in neurophysiology, this research is the first to investigate how analyzing the most common incorrect answer can shed light on the concepts students struggle with when reasoning about neurophysiological problems, especially those dealing with both chemical and electrical driving forces to predict ion movement across cell membranes.