I can't really find any information on this that doesn't have to do with color blindness, but I notice that many people (who are not color blind) often mix up red and orange in casual speech. I noticed this a lot when watching playthroughs of Portal and Portal 2, but there's also other cases too. In each case when confronted the person says they don't know why they said the wrong color.
Lighting and contrast have a huge impact on how colors are perceived. Look at the whole Blue&Black vs. White&Gold dress thing.
I don't notice this happening particularly more often with red/orange specifically... but maybe it does. Red and Orange are kind of similar -- but I could easily see the same thing happening with certain shades of blue and purple. Or even dark blue and black.
As far as Portal goes... I wonder if it is because Red and Blue are primary colors. Given a blue portal, red seems more "opposite" (colloquially speaking), thus more readily used in contrast to blue.
I've never noticed such a trend of mixups, though.
With Portal, I've heard people call the orange portal orange and red in the same sentence. They clearly know it is orange, but they have a slip of the tongue and accidentally call it red.
@Disch: I never really considered red and orange as similar colors, but I guess they are.
I still think Okrand had it more-or-less right.
When it doesn't really matter, what's the difference?
Ever have an argument with a child about whether something was blue or green?
Ever notice that the argument is never about something that is really blue or really green. It's about something that is somewhere in-between.
Orange is an in-between color (between red and yellow). The canonical 'orange' is that of an orange (fruit), of course, but many of the oranges we live with are more saturated and or closer to red in hue.
If you are standing with two reds, and one is more orange, you call the first red and the second orange.
That same orange, compared to two oranges, might be called red while the other called orange.
I'm starting to feel crazy here - I've never considered orange to be anywhere near red in terms of similarity. I mean, just look at the color palettes on the wikipedia articles:
They don't even look remotely similar to me. I mean, I know that in terms of wavelengths and RGB representation they are similar, but in terms of how my brain processes them they are unrelated. Is this just me? Do red and orange really look similar to all of you?
Semi off topic, but my friend has a cone deficiency that makes him see yellow where this is green, sometimes. It's so slight that for the 10 years he knew about it, it never caused any problems... Until we were playing this RPG where skills come in the form of colored gems that go into like colored sockets on items. For 3 weeks we played and he kept complaining he couldn't find any green gems. Eventually he yelled out "god dammit! Another yellow!"
In this
http://blog.nag.com/2010_11_01_archive.html
the orange spots (and the grey squares they are on) are the same. It doesn't matter what the colour is, it is more about what you brain tells you it is.
I scored an 89, I suck with colors considering I have Deuteranopia color blindness and 75% of the colors on those palettes look the same to me.
As far as that video L B linked, it looks red to me if it is orange its a super red orange. If it was closer towards the middle or yellow side maybe I would say it looks orange.
And yes the far left and far right look completely different to me. But the 3-5 shades in each section are all the same color to me and about the 8-10 or so in the very middle.