The anchoring heuristic refers to the strong influence of the starting point or first approximation on the final estimate.The prevailing situation and the information available at the time determine the first approximation.Limited or incorrect data will skew the starting point, jeopardizing the path to a correct conclusion. Unfortunately,many murder cases first appear to be something other than what they are.
Tunnel vision (or incrementalism)develops from a narrow focus on a limited range of alternatives. “It results in the[police] officer becoming so focused upon an individual or incident that no other person or incident registers in the officer’s thoughts. Thus, tunnel vision can result in the elimination of other suspects who should be investigated. Equally, events that could lead to other suspects are eliminated from the officer’s thinking.”16 Satisficing is the selection of the first alternative that appears good enough.These heuristics might work well for simple errands, such as buying a hammer, but they are ill suited to the task of solving complex investigations.
23-year-old female whose 2-year-old son was the only witness can illustrate these hazards. Detectives received a tip regarding a man who, for the next year, became their investigative focus. After a covert operation to obtain further incriminating information, they finally arrested him. At the trial, the judge quickly threw out most of the prosecution’s evidence,calling the covert operation misconceived. The charges were withdrawn, and the man was released. One detective later commented, “Maybe the team got an idée fixe. Maybe they got stuck thinking it had to be [him]. No one dared to challenge that thinking until it got to the judge. But, it’s a terrible mess.”18 Several years later, enhanced DNA from the victim’s clothing pointed toward a psychopath now detained indefinitely in a secure hospital.