The American Journal of Physics adopted a policy of double-anonymous reviewing on September 1, 2020. Most scientific journals use single-anonymous peer reviews, meaning that the reviewers know the identity of the authors, but the authors do not know the identity of the reviewers. Single-anonymous reviews have long been accepted as necessary to enable reviewers to share their opinions without fear of retribution from an offended submitter.

Why is the submitter's identity normally known to reviewers? The reason is primarily historical—this is the way it has always been. If we were designing a review system from scratch today, it is doubtful that we would choose single-anonymous review. We know too much about human nature and the potential for bias. Unconscious bias in favor of people who are “like us” is well documented, as is bias against members of many minority groups. But we are not designing a review system from scratch, and changing an existing system is difficult.

Despite the difficulty, several organizations have committed to double-anonymous reviewing in recent years. It was introduced for Hubble proposal reviews in 2018, and the results thus far suggest that it has eliminated the gender bias that had persistently been observed in previous review cycles. NASA is now expanding this practice to additional programs. More recently, the Institute of Physics announced that all its journals will adopt double-anonymous reviewing by the end of 2021.

These changes are all the more impressive given the challenges of double-anonymous reviewing for research journals and funding organizations. In physics research, frequently new papers and projects are closely tied to the submitter's previous work. These challenges are eased for pedagogical journals such as AJP. Indeed, The Physics Teacher has used double-anonymous reviewing since 2002. Many of the papers in AJP can easily be evaluated anonymously. While a few of our authors are recognizable through multiple publications on the same topic, the majority of papers contain few if any self-references, making the process of anonymizing the manuscript fairly straightforward.

For many years, AJP has given authors the option of submitting their manuscripts anonymously, but authors have seldom taken advantage of that option. Similar reluctance has been observed for other journals with optional anonymous reviewing. Authors may fear that choosing optional anonymity implies that they have something to hide. This concern is alleviated if anonymity is required of all submitters. And that's why AJP has adopted this new policy. All manuscripts have been submitted anonymously since September 1, 2020. We are still in the process of getting the bugs out of the system (as some of our recent reviewers and submitters are aware). Here is some guidance for both groups. More details are on the AJP website, aapt.org/ajp.

We ask reviewers to work within the spirit of double-anonymous reviewing. If you suspect that the reference list may reveal the identity of the submitter, consider reading the whole manuscript before checking the reference list so that you can form an unbiased initial opinion. If an internet search for background information leads you to a copy of the submitted manuscript on arXiv, do not check it. Do not look for metadata in the electronic document that would reveal the author's identity. In the event that previous work by the author is essential for evaluating the manuscript, the editor may be able to provide an anonymized copy of that work.

Besides removing your name, institution, and email address, remove any acknowledgements that reveal your identity. If you need to refer to your institutional setting, use descriptors, such as “a small midwestern university.” Avoid, or try to minimize, self-citation. (Some citations can be added after acceptance, if the editor agrees that they will provide useful background information to readers.) If you need to refer to previous work of your own that is relevant to this paper, do it in the same way as you would refer to someone else's work: “Jones et al. have demonstrated….” If you are unable to avoid referring to your earlier work anonymously, simply list “Author's previous work” in the references. If the reviewer needs to read it, then the editor can provide an anonymized copy.

All reviewers strive to evaluate manuscripts objectively on the basis of their content, but it is easy to be unconsciously affected by factors ranging from the prestige of the author's institution to assumptions about their race or gender. Even in the case that there is no actual bias, the perception of bias may discourage researchers from under-represented groups. The physics profession has been struggling for many years to increase the representation of marginalized groups, but with little success. At this point, we cannot afford to leave any stone unturned. Double-anonymous reviewing has the potential to improve the fairness of the review process for all manuscripts and especially to help physicists from persistently marginalized groups. It is the right thing to do.