If the directory does NOT already contain a .DS_Store file, it will be created as you navigate thorugh directories via the Finder.
If .DS_Store is created, this will require modifying the directory to enter the .DS_Store name into the directory, thus a modification to the directory.
If .DS_Store already exists, then no new file should be created in the directory, so the directory modification date should not change.
The Finder does not show any file beginning with . (dot), so you will either need to use a Terminal session, or use a utility such as Onyx or TinkerTool to enable the Finder option for showing hidden files.
I'm using a MacBook (13-inch, Mid 2009) and it's running OS X 10.8.2 Mountain Lion.
I was browsing my old computer files imported from my old Windows PC. Those folders storing the files, obviously, didn't have any OS X's unique, hidden '.DS_Store' files in them.
As BobHarris mentioned, since '.DS_Store' didn't exist in those folders, OS X created '.DS_Store' in those folders when I opened them, thus modifying those old folders coming from my old Windows PC (adding '.DS_Store' files in them).
This causes annoyance to me as I don't want the 'Date Modified' being changed because of the '.DS_Store' file. I want to know when the real 'Date Modified' was.
I know '.DS_Store' is useful for OS X itself as it stores metadata. But it seems there is no way it won't affect the 'Data Modified'.
Finder is such an incredibly poor tool compared to Windows Explorer that Macs are banned from our servers and our organization generally. I recently acquired a lone Mac to create and maintain OS X software for a new hardware product that works on both OS X and Windows. The Finder's date modification problem means that once Mac development work is complete, we have to use Windows machines to maintain our code and documentation libraries. This rather sad state of affairs with Finder mimics what we see throughout our Mac development process. Instability and strange corruption problems are far more prevalent on the Mac than on Windows - the exact opposite of the popular reputation of these OSes.
As for the exact problem at hand, I can confirm that the issue relates to the .DS__Store files. We think that often the .DS_Store files are deleted and replaced, explaining why folders with previously existing .DS_Store files still have their modified dates altered whenever they are traversed by Finder. We have also observed Finder changing file dates in Apple .bundle files and similar data structures which are nothing more that specialized folders. As noted above, this plays havoc with software version control since our software is distributed as a bundle file.
Windows uses a similar technique, placing hidden desktop.ini files in folders to track and remember folder display characteristics. However, Windows does not change the folder modified dates when these hidden files are created or updated. Apple could learn a thing or two about usability from Microsoft.
XP is 12 years old. Get with the program. I haven't seen a BSOD, had driver issues, or seen any kind of instability since I started using Windows 7. Windows has its own set of frustrations, but instability and Explorer (Finder) problems aren't among them. Can't say the same for the Mac I'm using for development. Plus, the same software we developed for Windows has experienced far more "gotcha's" in the OS X development process. OS X is simply not as mature or stable.
Finder hasn't had a significant UI update ever, to my knowledge. It can't even do simple things that people have been requesting forever, such as displaying folders first (or last) when looking in alpha order. This makes folder organization unecessarily difficult in OS X. Yes, I know all the work-arounds, including third-party Finder replacements, which have instability problems of their own. All lack the simple elegance of Windows Explorer. (Wow, did I just say that?)
Hey I didn't say I was *still* using Windows! Get with the program? Shouldn't you be on Windows 8?
The thing that bothered me was that you either had to jump all the way into a folder, or open up a stupid list on the side. There was no way to just open/close disclosure triangles to see the whole file system in one window.
I guess it's a matter of preference for someone to want to see all the folders in their own alphabetical order, and then the files. But that also never made any sense to me. Just different ways of doing things I guess.
Also, as the originator of this thread, I will say that my problem was an isolated incident that only lasted a day. I am not sure what the problem was, but it went away. I usually have no problem with the Finder.
I find the "stupid list on the side" visually superior to the Finder method. The visual separation for folder contents makes it clear what is in the folder and what is not. Results in far fewer mistakes in moving files to their proper folders and confirming folder contents, IMX. Since Windows Vista, you no longer have to do anything to get the folder list on the left side. It is now there by default.
I'm not religious about one OS over the other. Both are quite capable these days. Macs are fun to use, where Windows continues to be work-a-day and boring (though it has gotten much better). That said, I find Windows much more efficient for business use. And, surprising to say, Macs haven't kept pace in many key areas. Finder continues to be one area that needs significant attention to catch up. Internationalization and non-English language support is another. In the early days, Macs used to be better about this, but that hasn't been true since XP Service Pack 2. I know that from personal experience creating our software. If you need to type in a non-Latin alphabet, Macs are not the best choice.