Why is the term "depressed" often used to describe a button which is pressed?
In several books that mention GUI, keyboard, or mouse buttons (e.g. the book Programming Windows by Charles Petzold), the authors refer to the state of a pressed button as depressed. Why is this term used instead of the word pressed, which has a simple and intuitive meaning?
Some alternative terms that could be a better fit are pushed, clicked, or activated. As someone who is not a native-English speaker, the term depressed is unintuitive to me because it resembles the opposite meaning: not pressed.
From TheFreeDictionary.com:
depression 1. a. The act of depressing. b. The condition of being depressed.
And the verb:
depress 4. to press or push down
So ... depressed works just fine for the state of a button being pushed in.
"De" is also used as a prefix meaning "down to the bottom" or "away", which can also lead to "completely", as in the examples here: denude, denigrate.
It may count as an auto-antonym, also called contronym. But I can't think of an example of un-pressing something.
Not sure, but my guess is that it's because technical writers are trying to make a distinction between the act of pressing something and the state of something being down/pressed/depressed.
depress and press are pretty much exact synonyms, but almost no one ever uses the term "depress" to describe the act of pressing something. It's correct, but the usage is rare. It's usually used to refer to the state of something. The word pressed is used both ways. But technical writers exploit the rarity of the usage of "depressed" to emphasize the distinction between between the state-word and the action-word.
So:
He pressed the button, and it was pressed.
Was the button actually in a down-state after it was pressed, or is the sentence just saying the same thing twice, that he attempted to press it?
He pressed the button, and it was depressed.
Okay, got it, his attempt to press the button was successful, and it left the button in a down-state.
Depressed can also mean the the button is in a lowered state, which is the result of pressing it.
To "press" a button often implicitly means to push it down and then release it. If I instruct you to "press" the A key on your keyboard, you'll probably push it down and then let go.
To "depress" a button unambiguously refers only to the act of pushing it down.
Consequently, if you need to describe a series of actions involving buttons in unusually intricate detail, it can be useful to use "depress". For instance, it could be problematic I ask you to:
- Press the A button, then
- Right-click, then
- Release the A button
because you may have assumed you were meant to release the A button in step 1, and only realised your mistake when you got to step 3. On the other hand, if I say:
- Depress the A button, then
- Right-click, then
- Release the A button
then the ambiguity in step 1 is eliminated. This makes the word "depress" useful when talking about the act of depressing a button.
There's less ambiguity between the states of being "pressed" or "depressed" than there is between the acts; it's clear that both mean the same thing as long as it's clear that the word is being used to refer to a state. However, there are still at least a couple of reasons that a writer might still sometimes prefer to use "depressed" to refer to the state of a button being held down.
One such reason is to retain consistency with how they refer to the act of pushing down a button, for which they may elsewhere use the word "depress".
Another reason is to reduce ambiguity with the act of pressing the button. Note that the grammar of a sentence will often not convey whether the word "pressed" refers to an act or a state. For instance, consider a sentence like:
The green LED should remain on as long as the button is depressed.
Here, the most natural interpretation is that "depressed" refers to a state; in other words, that as long as I continue to hold down the button, the LED should remain on. But if I said:
The green LED should remain on as long as the button is pressed.
then a possible alternative interpretation becomes more salient, where "pressed" refers to an act; that is, that as long as I perform the act of pressing the button, then the LED should thereafter remain on (even if I release the button).
Thus, if the former meaning is intended, using "depressed" instead of "pressed" here is one way to avoid confusing the reader. (There are, of course, plenty of others; a phrase like "is held down" or "remains pressed" would serve the same purpose as "is depressed" here. But such is the nature of English; there are usually several different ways to say anything.)