The topic of load bearing walls has come up dozens of times on this forum over the past few years. A wall is load bearing if it carries more than its own weight. Typically the load comes from floor joists above, possibly from another wall directly above, or sometimes from braces in the attic above that bear on the wall.
In order to definitively determine if a wall is load bearing, it is necessary to examine the framing above to see if any load is being transmitted down through the wall in question. Your wall looks like it was constructed as a non-load bearing wall, however as was pointed out by a previous post, that does not mean the wall is correctly constructed. You need to get into the attic to see how the floor joists run, and to see if any structural elements bear on the wall. You may be able to see by removing some of the ceiling wallboard and looking through the opening.