This is a learned reaction based on the brains ability to take in a limited amount of stimuli at one time. We have three types of memory; short-term, long-term and working memory. When your brain is trying to complete a task, you are using your working memory which only has a limited amount of information it can take in at once.
You've learned through experience that to maximize your ability to focus on one task (finding the house) you need to reduce other external stimuli.



