How the view narrows
- Early theory
- Selecting fitting facts
- Explaining away discomfort
- Theory takes over
It starts sensibly: in the first few hours, you need a working hypothesis, or it is unclear where to go next. The problem is not that it appears, but that it rarely gets a fair competitor.
Then an ordinary feature of attention comes into play. Evidence that fits the theory seems weighty; evidence that contradicts it seems random, mistaken, or in need of an explanation that can always be found.
Pressure amplifies all of this many times over. Public attention, accountability, and the expectations of superiors and relatives push toward a result, while a theory that has already absorbed time begins to defend itself.
How to break the pattern
- Record alternative theories at the start and keep them in the case
- Give the evidence to experts who do not know the investigation's theory
- Assign someone to look for weak points in your own theory
- Return to the case later with fresh eyes
- Tell the expert whom investigators consider guilty before the examination
- Treat a confession as the end of the work: check it like any other evidence
- Declare contradictory evidence mistaken without checking
- Stick with a theory because months have already been invested in it
Giving an expert a hint is especially dangerous. If a specialist knows what answer is expected, the likelihood of seeing a match increases - which is why modern practices try to pass on evidence blindly.
Reviews of wrongful convictions regularly find the same pattern: an early theory, discarded testimony, and evidence interpreted in its favor. Reconsideration usually comes from outside the case, not from within it.
The same mechanism works far beyond investigations: in diagnosis, accident analysis, and finding someone to blame in a company. Everywhere, the same thing helps - making it part of the procedure to consider another theory.
What is investigative tunnel vision?
What helps break it?
Sources
- Tunnel vision in investigations is described in research on wrongful convictions as a combination of confirmation bias, the anchoring effect of the first theory, and organizational pressure. Measures include documenting alternative theories, passing evidence to experts blindly, and conducting an independent review. The influence of contextual information on experts' conclusions has been confirmed experimentally
Next in the “Cold Cases” series
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