The passive voice and comprehensibility of biomedical texts: An experimental study with 2 cohorts of chiropractic students

Authors in the health sciences are encouraged to write in the active voice in the belief that this enhances comprehensibility. Hence, the purpose of this study was to compare objectively measured and subjectively perceived comprehensibility of texts in which one voice or the other was highly prevalent. Objectively rated comprehensibility was obtained by presenting 161 2nd-year chiropractic students with questions pertaining to 2 methods sections of biomedical articles, each presented in its original form with high prevalence of the passive voice, and in a manipulated form with all main verbs in the active voice. The difficulties and sensitivities of questions were compared for the 2 forms of each text. Comprehensibility was obtained by asking students to rate the comprehensibility of authentic sentences from biomedical manuscripts and matched manipulated form in which the voice of the main verb had been changed. Differences in comprehensibility between the 2 texts were assessed with a dependent t test. There were no significant differences in the difficulties or sensitivities of questions pertaining to the 2 original texts written in the passive voice versus the active voice ( p > .35 for all comparisons). Students rated sentences written in the passive voice as marginally more comprehensible than sentences written in the active voice ( p = .003 per 2-tailed paired t test). The texts written in the active voice were not more comprehensible than texts written in the passive voice. The results of this study do not support editorial guidelines that favor active voice over passive voice.