Complex sentence: If an object of interest is in the right side of space people will mainly use their right hand to reach for it and the further to their right it is, the more likely they become to use their right hand and the faster the decision is made.
Split into simpler sentences: If an object of interest is in the right side of space people will mainly use their right hand to reach for it. The further to their right it is, the more likely they become to use their right hand and the faster the decision is made.