There are many factors which influence symptoms and symptom perception. An experiment is done to show this. Factors like temperature, background information and cognition, colours of the objects and environment are examples. The experiment consists of two parts. During the first part of the experiment, the scientist said touching the ice water with chemical substances in the tank would increase pain and during the second part of the experiment, the scientist said the water tank was filled with pain reducing substance. This kind of information and the different appearances of the substances in the tanks can influence one’s perception of their symptoms and stated level of pain. ComplaintsAbout two third of the general practitioner’s come across patients’ complaints which they have no explanation for. Somatically unexplained physicial symptoms are quite common in general practice. About 20-50% of the complaints are somatic. This means that no objective physical distortions or disrupted bodily processes can explain the complaints. These complaints often disappear spontaneously, usually after reassurance by the general practitioner. The Symptom Perception Model describes how psychological factors influence symptom perception. One of these factors is negative affectivity. Negative affectivity is the tendency to experience negative mood, feel distressed and feel critical about oneself, and to view the self and the world in generally negative terms. It is related to neuroticism. Symptom perception can lead to long-term activation and reactivation of symptom related cognitive networks, like paying attention to and earlier detection of somatosensory signals, interpretation of ambiguous internal and external information in terms of somatosensory symptoms and attribution of signals as somatosensory symptoms. There is a bidirectional relationship between the attention paid to the symptoms and the perception of those symptoms. An overview of this...