The Von Restorff Effect
The Von Restorff effect predicts that when multiple, homogeneous (similar) stimuli are presented in close proximity to each other the stimulus that is distinct from the other stimuli will make that one more memorable than the others. For instance, it's lunchtime and you are short of time. You're hungry and have a choice of fast food restaurants to choose from. Which one do you choose? If the Von Restorff effect occurs your choice would be the one that has the most distinctive appearance when compared to the other restaurants. So, if the Taco Bell sign is brighter and more prominent then the Wendy's sign, then you'd probably end up at Taco Bell.