Both "In the back of my mind" and "At the back of my mind" are commonly used expressions, and they are often used interchangeably. However, there is a subtle difference in their meaning and usage:
- "In the back of my mind": This phrase suggests that something is not at the forefront of your thoughts or immediate focus, but it's still present in your mind as a subtle or lingering thought or idea. It implies that the thought or information is not actively being considered or dealt with, but it's not completely forgotten either.
Example: "I have a feeling that I've met him before, but it's just in the back of my mind."
- "At the back of my mind": This expression is very similar to "in the back of my mind" and is often used interchangeably. It also refers to something not being at the forefront of your thoughts, but it's still present in your mind as a faint or subdued thought.
Example: "The possibility of a promotion is always at the back of my mind, but right now, I'm focusing on my current tasks."
In general, both expressions convey the same idea of something being subconsciously present in your thoughts without being at the center of your attention. You can use either of them based on personal preference or context, as they are largely interchangeable.