Learning Effects?

My study is set up such that my research participants perform a set of 10 tasks that are similar and aimed at finding the same thing. For example, they are asked 10 questions pertaining to brands and their response latencies recorded. All the items are aimed at measuring the same thing and have small variations (for example, in the above example, the 10 questions are the same but about 10 different brands). I see a trend in the data:
there is a significant downward trend in response latencies for the later questions. Could this be just a simple learning effect where participants take a bit longer to make their selections in the first few questions but get faster on the later ones? If it is, then that is an alternative explanation and is not a measure of the unconscious processes/inherent biases etc.
Thanks

It would not be unusual for response times to pick up (get faster) as a session continues. Of course, you can also find tedium effects under other situations. This is not a serious problem in most cases so long as you are able to apply appropriate strategies with respect to randomization, counter balancing, and such. Please let me know if it would help to elaborate on any of this for you.