One of the earliest sensations is the olfactory sensation. Such severed arms remain sensitive to stimuli and move away from unpleasant sensations. Heterosexual women said that they got the same pleasurable sensations as watching heterosexual sex scenes. Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they produce. Abnormal sensations and itching may also occur. Electrical stimulation of the insula in the human elicit gustatory sensations. The mindfulness therapy technique attempts to teach clients acceptance of bodily sensations and emotions. Some individuals report experiencing synesthesia, such as tactile sensations when viewing colors. Following administration of erythromycin, repetitive hallucinations and abnormal bodily sensations developed. The plexus of Raschkow monitors painful sensations. Other symptoms may include difficulty walking, speaking or with sensations. Both proprioception and interoception allow individuals to be consciously aware of various sensations. CO2 inhalation, which are designed to mimic labored breathing sensations. We perceive only our own sensations or ideas. This suggests that there is a central representation of the limb responsible for painful sensations.