Anchoring — Tversky & Kahneman (1974), Science: the first number/claim heard becomes a reference point subsequent judgments insufficiently adjust away from; operates even with arbitrary, known-irrelevant anchors

Claim: The first number or claim a person hears becomes a reference point that subsequent judgments insufficiently adjust away from. Tversky & Kahneman's famous "wheel of fortune" experiment had participants estimate the percentage of African countries in the UN after watching a wheel land on an arbitrary number — and the wheel's number influenced the estimate, even though everyone could see the wheel was rigged.

For new-site owners, the anchor is typically a vendor's "you'll see results fast" promise — which sets the reference point for how quickly the site "should" perform.

Source: Tversky, A., & Kahneman, D. (1974). "Judgment Under Uncertainty: Heuristics and Biases." Science 185(4157):1124–1131.

Confidence: Verified. One of the most robust effects in judgment research; replicated thousands of times in many contexts.

Caveat: Magnitude varies by context; anchoring is a direction, not a fixed quantity. Treat it as: "this anchor will shift the judgment toward itself" — never as "this anchor will shift the judgment by N%."