<P> Central stimuli should always be used when attempting to assess if the patient is localising to pain (i.e. moving their arms to the site where the pain is being applied), however it has been suggested that central stimuli are less suitable for the assessment of eye opening, compared to peripheral stimuli, as they can cause grimacing . There is also a statistical reason behind central pain stimuli being inaccurate, especially regarding the GCS, which depending on the patient's eye response, the total score, and thus severity of patients' condition, can be altered with varying prognostic accuracy . </P> <P> If the patient reacts to the central pain stimulus normally, then a peripheral stimulus is unlikely to be required, unless there is suspicion of localised paresthesia or paralysis in a particular limb . </P> <P> Central stimuli are likely to have to be applied for at least 15 and potentially up to 30 seconds in order for the clinician to accurately assess their efficacy . </P> <P> The various acceptable central stimuli have been criticised or deemed suboptimal for various reasons . For instance, the sternal rub may leave bruising (especially on fair skinned patients) and for this reason is discouraged by some . </P>

Which of the following is a form of peripheral painful stimulus