At first glance, mail-in ballot numbers seem to presage a coming disaster: During the primaries, more than 550,000 mail ballots were rejected, many disqualified for seemingly small errors, like envelopes sealed with tape. But these numbers don't signal an inevitable November Nightmare. In fact, the science of human behavior can help explain both why these rejection rates were so high and how state and local officials can reduce them in November.

The usual reasons for rejecting mail ballots are: They arrive too late, administrators can't match a voter's signature with the one on file, or the signature is missing altogether. Notably, rejection rates are typically higher in states where fewer people use mail ballots. With effective design and outreach, these problems can all be overcome.

Take first the problem of missed deadlines.

Voters often rely on past experiences of voting in person, their mental model of how voting works, to set their expectations for the vote-by-mail process. For many, that mental model includes a reasonable assumption that Election Day is voting day — whether by mail or in person. Unfortunately, more than half of all states require ballots to be received, not just postmarked, by Election Day — or in some cases the day before. Many people simply don't know about this.

Even voters who know the deadline may procrastinate or don't account for how long delivery may take. For example, in California's March primary — where voters could mail their ballot on Election Day as long as it was received within three days — 70 percent of rejected ballots were due to late arrivals. The complexity of the mail system — both how long delivery takes and the nuances of postmarks — makes it difficult for even the most enthusiastic voters to ensure their ballots are received on time.

A clear fix for this problem is to relax that delivery constraint while still letting people mail their ballot on Election Day — a day set firmly in many voters' minds. Since the primaries, California and many other states, recognizing the new COVID-19 voting reality, created more flexible deadlines for ballot return. As long as they are postmarked by Election Day, ballots in California now have up to 17 days after the election to arrive and still be counted. This takes the onus off of voters to calculate how long postal delivery takes, which may vary and is out of their control.

Another option is to institute more flexible ballot-return options. While some states, such as Georgia, haven't adjusted their deadline statutes, they have created dropboxes and other non-mail return methods where voters can return their ballots on or before Election Day. Dropboxes are already popular in universal vote-by-mail states like Colorado and Washington, and have blossomed across the U.S. with the rise in mail ballot demand.

Finally, just-in-time reminders, delivered across multiple channels (mail, text, email and more) when voters have ballots in hand and are able to act, combined with simple heuristics about when voters should return them, can both help solve the problem. In Oregon and Arizona, both states with high or universal vote-by-mail usage and deadlines that required ballots to be received by Election Day, election officials and their partners widely publicize two different deadlines. The first deadline is the last day when voters can reliably return their ballot by mail and the second is Election Day, the deadline for voters to hand-deliver their ballots to a dropbox or other return location.

There are also predictable — and solvable — behavioral patterns at the root of the other most common reason ballots are rejected: voter signatures.

People can only take in so much information at once — and mail ballots tend to have a lot of information to sift through: long and confusing instructions, and sometimes dozens of different contests to vote on. It's easy in this context for voters to hone in on the "big" pieces of the process — like marking their choices — without accounting for other nuanced features, like signing properly or at all.

Some will simply forget to sign. For others, their signature may not match their official signature on file (often the signature on their driver's license or voter registration record), which can lead to rejection. People may not realize that the signatures need to match. Many of us sign our names without much conscious thought or concern about how it looks. But our "habitual" signature, the one we might use to quickly sign our names on digital pads at the grocery store or a restaurant, may look different from the one we carefully signed on our driver's license several years ago.

Ballot design and accompanying outreach materials can provide timely guidance (on the envelope itself in the best cases) reminding voters they need to sign and making it hard to forget by using strategically redundant messaging. Officials and advocates can also offer heuristics, like "sign the ballot like you would an official contract, not how you would at the grocery store," to alert voters that the quality of their signature matters in order for their vote to be counted. Lastly, where possible, states should be transparent about the signature verification process and build in opportunities for voters to fix mistakes, or "cure" their ballots. These programs make it clear why following the rules are important, provide clear and easy paths to correct mistakes, and assure voters that ballot rejections are not arbitrary.

Even with Election Day fast approaching, it's not too late for state officials to make simple adjustments to voter outreach messaging strategies and operational policies. Making evidence-based changes now can help prevent unnecessary ballot rejections and ensure everyone who intends to cast a ballot has their chance to have their voice heard.

This article was originally published on the ideas42 blog.