optical scan voting, just like the other kinds of voting we've discussed.
One of the more prominent issues has to do with the way people interact with optical
scan ballots. So, ballot's generally provide some
instructions for how to fill them out. For instance, use only a number two
pencil, completely fill in the oval, etc. If you give directions like these to
people, how well do you think they're going to follow them?
The, the, answer is that not everyone follows them exactly right.
Here's a collection of marks from real voted ballots in one particular election.
And you can see how much variation there is here.
Some people use blue ink, some people marked an x instead of filling in the
oval. At least, one person used red ink, and
each pencil mark is slightly different. So, this is a challenge for optical scan
machines because it's possible that the machines are not going to interpret every
one of these marks as a valid vote. Well, here, here are some of the problems.
One, one issue is that these simple emitter detector sensors, the ones that
can only sense brightness, respond differently to different colors of marks.
They're going to be more sensitive to certain parts of the visible spectrum than
others. So, certain things that might look very
dark to the voter, to a human might not look like they're marked very darkly at
all to the machine, in particular, certain kinds of sensors that are very sensitive
to infrared might not see a red as a mark on the ballot at all, it might not be able
to distinguish between red or white. Another kind of problem is that the older
style of optical scanner that uses the sensors that essentially form a grid of
potential target locations are very sensitive to the alignment of the ballot.
So, if the ballot slightly changes size, because a, it's a, a very humid or a very
dry day, this cause paper to expand or contract.
Some of those bubble targets aren't going to be perfectly underneath the physical
locations of the sensors anymore and they might be read less well.
Another problem is the directional alignment on the page.
If the ballot's inserted into the machine's slightly crooked as you can see
in this illustration, that's another case where the sensors might not be perfectly
over the targets. Another issue is calibration.
Each of those sensors in the machines might respond slightly differently to the
same intensity of light because of physical variations in the electronics.
So, calibrating them make sure, making sure they're all responding appropriately
is a really tricky maintenance task. And then, there are different kinds of
marks. As you see here, certain kinds of marks
that are not completely filling in the oval might not be detected when compounded
with other factors like a slightly crooked ballot.
Where they might sometimes be detected and sometimes not.
It seems that because of all of these factors compounded, an optical scan ballot
has some chance of having errors in the scanning process.
And in an election of any size, you are almost certainly going to have some
fraction of ballots, and some fraction of votes that are misread or lost because of
problems like these. This is fundamentally a challenge to
almost every voting system though. We don't yet know how to make a voting
system that will work on a very large scale with absolutely zero error.
The problem with optical scan though, is there are a lot of different and somewhat
tricky errors like these that, that could potentially add up to, to a problem,
especially in a very, very tight race. So, it's important to do things to, to
make sure voters fill out the instructions correctly.
We'll talk a bit about that in a later lecture when we discuss usability issues.
Another kind of problem with the optical scan is something that some colleagues of
mine from Princeton pointed out in a paper just a couple of years ago.
And that is that they, they looked at the styles of ways that different people fill
out those little circles, those ovals, on an optical scan form.
And they found that different people had a distinct enough style, you know, all of
these different ways of filling it out, that you could actually identify two marks
that came from the same person. So, this a somewhat theoretical attack
today, but in the long run you do worry that these small differences in how people
fill out these forms might be something that could be used to compromise voter
privacy. There's one more category of problems with
optical scan and perhaps, this is what you thought of when you asked what could go
wrong. And that has to do with the fact that
these machines are counting votes by computer.
So, if you think about how these machines work, the parts we've talked about so far
are mostly the electronic parts, the actual scanning apparatus.
But also inside the optical scan machine is a computer that's responsible for
reading the signals from the scanner, figuring out which candidates should
receive the votes and maintaining totals, running totals of the number of votes for
each candidate. This is the equivalent of those gears and
counters inside the lever machine. But unlike gears and counters, all of this
in an optical scan voting machine is controlled by computer software.
And computer software can be changed. It can be changed in ways that are, are
invisible. And we'll talk much more about that kind
of problem later in this and the next lecture.
But first, I wanted to give you an example.
An example of a demonstration of a way a computer voting machine could be used to
cheat. And this a an attack that was conceived
and demonstrated by a voting researcher named Harri Hursti about five years ago.
Harri Hursti's attack was against a, a, an optical scan voting machine made by
Diebold. And Harri's attack looked at what would
happen if the, the criminal, an attacker had access to that memory card.
The, the card that's used to that's used to hold an electronic copy of the results
and take it back to the central office for counting.
So, let's assume that the card is going to be very well protected after the voting
process finishes. Because after the voting process, everyone
knows their vote's stored on it. This is an important part of election
integrity. But what if someone was able to get access
to the card before all of those votes were cast?
When maybe people aren't realizing that it's it has important security properties.