▁objects ▁in ▁the ▁back ▁of ▁the ▁mouth ▁may ▁cause ▁the ▁ph ary n ge al ▁ref lex . ▁Some ▁people , ▁for ▁instance ▁sword ▁sw allow ers , ▁have ▁learned ▁how ▁to ▁suppress ▁it . ▁In ▁contrast , ▁trigger ing ▁the ▁ref lex ▁is ▁sometimes ▁done ▁intention ally ▁to ▁indu ce ▁vom iting , ▁by ▁those ▁who ▁suffer ▁from ▁bul im ia ▁nerv osa . ▁ ▁According ▁to ▁one ▁study , ▁one ▁in ▁three ▁people ▁la cks ▁a ▁g ag ▁ref lex . ▁However , ▁on ▁the ▁other ▁end ▁of ▁the ▁spectrum ▁are ▁people ▁with ▁a ▁hyp ers ens itive ▁g ag ▁ref lex . ▁This ▁hyp ers ens itivity ▁can ▁lead ▁to ▁issues ▁in ▁various ▁situations , ▁from ▁sw allow ing ▁a ▁pill ▁or ▁large ▁bit es ▁of ▁food ▁to ▁visit ing ▁the ▁dent ist . ▁Hyp ers ens itivity ▁is ▁generally ▁a ▁condition ed ▁response , ▁usually ▁occurr ing ▁following ▁a ▁previous ▁experience . ▁There ▁are ▁a ▁variety ▁of ▁ways ▁to ▁des ens it ize ▁one ' s ▁hyp ers ens itivity , ▁from ▁relax ation ▁to ▁num bing ▁the ▁mouth ▁and ▁thro at ▁to ▁training ▁one ' s ▁soft ▁pal ate ▁to ▁get ▁used ▁to ▁being ▁touched . ▁ ▁Abs ence ▁In ▁certain ▁cases , ▁absence ▁of ▁the ▁g ag ▁ref lex ▁and ▁ph ary n ge al ▁sens ation ▁can ▁be ▁a ▁sympt om ▁of ▁a ▁number ▁of ▁severe ▁medical ▁conditions , ▁such ▁as ▁damage ▁to ▁the ▁gl oss oph ary n ge al ▁n erve , ▁the ▁v