Final answer:
People might estimate the Mississippi River to be longer or shorter based on the initial number they are given due to anchoring bias. Misconceptions about the river's source historically affected its perceived length.
Step-by-step explanation:
People give larger estimates of the length of the Mississippi River when asked if it is shorter or longer than 5000 miles versus 500 miles due to an influence known as anchoring bias. This cognitive bias occurs when individuals rely too heavily on an initial piece of information offered (known as the 'anchor') when making decisions. Since the Mississippi River's actual length is around 2,340 miles, both provided numbers (5000 and 500) are incorrect, but the anchoring number influences the respondent's estimation.
Historically, the actual source of the Mississippi River was a subject of misconception which at times affected geographical and political understandings. It was not until 1832 that the area of the headwaters of the Mississippi River was discovered and explored by non-Indians, clearing up some prior uncertainties about the extent of the river. The misconception that the source of the Mississippi River lay further north might have contributed to longer estimates of its length historically. Today, exercises in understanding the Mississippi River help people to comprehend river systems throughout the world.