User Interfaces
Are there more words in the English language that begin with the letter 'R' or that have 'R' as the third letter?
Do more people die each year from shark attacks or falling airplane parts?
Supporting what is known as "dual-process theory," psychology experiments have identified two separate modes of human thought, dubbed System 1 and System 2. These two systems involve different situations, levels of effort, thought processes, and accuracy of results.
System 1
System 1 is associated with fast judgments based on what are known as "heuristics." This term, borrowed from computer science, refers to general "rules of thumb" that are often accurate and are typically much faster to use than a full analysis of the problem. However, often these heuristics can be misleading or simply incorrect. For instance, the "Availability Heuristic" describes the phenomenon that humans often base their estimation of frequency on how readily examples come to mind. The answer to the question above is that there are far more words that have 'R' as a third letter, but the vast majority of people will answer that more words begin with 'R', simply because it's easier to come up with examples of words beginning with 'R' than it is to come up with examples of words in which 'R' is some internal letter. Similarly, most people will answer that shark attacks are more common, because no one has ever heard of someone being killed by falling airplane parts. Yet in truth, the latter is about 30 times more likely.
System 2
Humans do not always rely on heuristics. Many people be skeptical, for example, if a lottery winner proclaimed they had used a strategy to win the lottery. While stories like this can be very persuasive (look no further than the cases of parents suing vaccine companies because their children developed autism), many people can recognize that with a small enough sample size, anything can happen. This type of reasoning is typical of System 2 thought: slow, reasoned, and analytical. System 2 tends to be more accurate than the hasty System 1, but it takes significantly more effort. Some tasks are more likely to produce System 2 thought, for example if the evidence is easily quantified, or if certain key "trigger" words are used. Additionally, some forms of education, such as in statistics, tend to encourage System 2 thought. Overall, most people will use System 2 thought to solve some problems, but it is all too easy to rely on System 1 shortcuts.