We find especially in multiple testimonies relating to proven facts (lanterns for example) that many stories are altered by emotion. Most often by surprise, sometimes by fear or terror even enthusiasm when it comes to passionate UFO witnesses. In these cases perception of distance, size, and speed may be inaccurate but this alteration does not contradict the existence of the phenomenon. The sincerity of the witnesses is very rarely questioned. The cases of hoaxes are very rare (less than 1%) but human testimony is never 100% reliable. Sometimes, the GEIPAN may conclude that the testimonies are not reliable. This may cause some witnesses to feel unbelieved by the GEIPAN or even that they are being accused of lying. This is not the case because the GEIPAN knows that the testimonies, although sincere, remain subjective and personal. Some cases may seem like hallucinations but there can be no certainty without the intervention of a professional psychologist which the GEIPAN refuses to be.