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Okay. Now, I want to show you a few examples on
how to express the idea of order with different channels.
So, when you have ordinal data,
what are the best channels or the channels
that are available to express the idea of order.
So, order.
The first channel that you can use is the same that
I have described in the previous set of examples which is position.
Position is always the best channel and the channel
that is available for all kinds of information that you want to express.
So, how do you express order with position?
Well, a good example is anything that resembles a list or a table.
Okay, we naturally perceive a list as an ordered set of elements.
Of course, these could be vertical like this,
or something horizontal like this.
But the idea is that,
anything that is expressed as a list or
a table is actually perceived as an ordered set of elements.
So, position is a very powerful,
is actually the most powerful channel you can use to express the idea of order.
Now, if we want to use other channels,
there is a little problem.
So, the fact is that in principle,
every channel that I described as a way to
express quantity can be used to express the idea of order.
Because when you want to express the idea of order,
the information that you need is that something comes before or after something else.
Okay, but the problem is that,
if we use the channels that I described when I
presented out the information about how to express quantity,
it's very hard to distinguish or it's very hard to perceive
this information without also perceiving at
the same time the idea that there is a quantity attached to these values.
Let me give you a practical example to make these clearer.
So, if I want to express order as the size of bubbles,
similar to what I have shown before,
you can't help but perceive the area of these bubbles as communicating to you a quantity.
So in a way, there is a mismatch.
There is an expressiveness,
a breakdown of the expressiveness principle. What do I mean here?
What I mean is that if you are
encoding ordinal information with a channel like area size,
you will also be conveying the idea that these elements have a quantity attached,
even if this is not the case.
So, this is a little bit of a problem.
So, what are good channels to express the idea of order without at the same time
giving too much of an impression that
these elements also have a quantity attached to them?
Well, the best way to do that is to use channels that can,
in principle, express the idea of
quantity but they are not particularly good at doing that.
And let me give you an example of two channels that can do that pretty well.
The first one is texture or density.
So, say that I have three graphical elements or patches like this one.
So, I can use a texture like this one,
or one that has higher density like this one,
or another one that has even higher density like this one.
So now, you naturally perceive these three elements as ordered.
In principle, you could also attach a quantity or express
a quantity with them but they are not particularly good at doing that.
And because of that,
they are good at expressing order without necessarily conveying the idea of quantity.
A similar feature, we find a similar feature with
color intensity which is exactly what we saw before.
So, if I have patches of color like these ones,
once again you perceived them as ordered,
and they are not particularly good at expressing
the idea of quantity even if they can, okay?
So, order is a little bit of a,
it's a little tricky.
But one thing to keep in mind,
is the idea that position is by far once again,
the most powerful channel or technique that you can use to express the idea of order.
Enrico BertiniAssociate Professor
Cristian FelixPhD. Candidate
