Heuristics in Judging Probabilities

Need help preparing for the Psych/Soc section of the MCAT? MedSchoolCoach expert, Ken Tao, will teach everything you need to know about Heuristics in Judging Probabilities for cognition. Watch this video to get all the MCAT study tips you need to do well on the psychology section of the exam! Heuristics are practical methods for solving problems that, while not being optimal or perfect, will on average be sufficiently able to accomplish some immediate goal. Our topic in these notes will be mechanisms by which heuristics can fail or be subject to bias and error. Base Rate Fallacy The first of these is the base rate fallacy. This is a decision-making error that occurs when base rate information is ignored or disregarded in favor of more specific information. Consider an example where participants were asked to determine if a person described as being shy is either a salesperson or librarian. Statistically, it is far more likely that the person will work in sales rather than being a librarian, by a factor of nearly fifty-fold. That would be the scenario’s base rate. However, participants are more likely to ignore that, focusing instead on the specific information that the person is shy, thus classifying them as a librarian. These participants have demonstrated the base rate fallacy. Representative Heuristic A common heuristic that we might expect to be tested on by the MCAT is the representative heuristic, a problem-solving approach that seeks to estimate the probability of an uncertain event by comparison to a representative idea of how the event should look. While the representative heuristic is not itself a fallacy, it can often fall prey to the same base rate fallacy that we discussed above. Consider an example where we flip four coins, and record, in order, whether they landed on heads or tails. Each coin flip is an independent event, with a fifty percent chance of landing on either heads or tails. As a result, when asked what the most likely results of the procedure would be, most participants indicated a result with an event number of heads and tails, such as two heads followed by two tails (HHTT), or alternating tails and heads (THTH). However, these outcomes, each of which has a 1/16th likelihood of occurring, are no more likely than a less ‘representative’ outcome, such as all heads (HHHH), or a single head at the end of a string of tales (TTTH). In this case, participants have ignored the base rate (the same 1/16th probability for any sequence of four ordered flips) and instead focused on the specific information of the representativeness of the end results. Availability Heuristic The availability heuristic, also called the availability bias, is a problem-solving shortcut that estimates the probability of an event based on the ease with which relevant instances of such an event come to mind. This is commonly studied with respect to the perception of crime statistics. In most parts of the United States, crime, especially violent crime, has been steadily decreasing since the 1990s. However, news coverage of violent crime has not experienced a corresponding decrease: if anything, lower crime levels result in a greater media spotlight on high sensationalizing crime. As a result, when polled, participants tend to report a perception of crime as being either steady or increasing over the last years and decades, despite the actual trend pointing in the opposite direction. MEDSCHOOLCOACH To watch more MCAT video tutorials like this and have access to study scheduling, progress tracking, flashcard and question bank, download MCAT Prep by MedSchoolCoach IOS Link: https://play.google.com/store/apps/details?id=com.htd.medschoolcoach&hl=en_US Apple Link: https://apps.apple.com/us/app/mcat-prep-by-medschoolcoach/id1503000883 #medschoolcoach #MCATprep #MCATstudytools