▁Although ▁the ▁neural ▁mechan isms ▁of ▁sch iz op hren ia ▁are ▁not ▁yet ▁clear , ▁one ▁influ ential ▁hypothesis ▁is ▁that ▁there ▁is ▁a ▁break down ▁in ▁brain ▁systems ▁that ▁compare ▁motor ▁commands ▁with ▁the ▁feedback ▁received ▁from ▁the ▁body ▁( known ▁as ▁proprio ception ), ▁leading ▁to ▁att endant ▁hall uc in ations ▁and ▁del us ions ▁of ▁control . ▁ ▁Ex perimental ▁psych ology ▁ ▁Ex perimental ▁psych ology ' s ▁contributions ▁to ▁the ▁free ▁will ▁debate ▁have ▁come ▁primarily ▁through ▁social ▁psych ologist ▁Daniel ▁Weg ner ' s ▁work ▁on ▁conscious ▁will . ▁In ▁his ▁book , ▁The ▁Ill usion ▁of ▁Cons cious ▁Will , ▁Weg ner ▁summar izes ▁what ▁he ▁bel ieves ▁is ▁empir ical ▁evidence ▁supporting ▁the ▁view ▁that ▁human ▁per ception ▁of ▁conscious ▁control ▁is ▁an ▁ill usion . ▁Weg ner ▁summar izes ▁some ▁empir ical ▁evidence ▁that ▁may ▁suggest ▁that ▁the ▁per ception ▁of ▁conscious ▁control ▁is ▁open ▁to ▁modification ▁( or ▁even ▁manip ulation ). ▁Weg ner ▁obser ves ▁that ▁one ▁event ▁is ▁infer red ▁to ▁have ▁caused ▁a ▁second ▁event ▁when ▁two ▁requirements ▁are ▁met : ▁ ▁The ▁first ▁event ▁immediately ▁preced es ▁the ▁second ▁event , ▁and ▁ ▁The ▁first ▁event ▁is ▁consistent ▁with ▁having ▁caused ▁the ▁second ▁event . ▁For ▁example , ▁if ▁a ▁person ▁he ars ▁an ▁explos ion ▁and ▁sees ▁a ▁tree ▁fall ▁down ▁that ▁person ▁is ▁likely ▁to ▁infer ▁that ▁the ▁explos ion ▁caused ▁the ▁tree ▁to ▁fall ▁over . ▁However , ▁if ▁the ▁explos ion ▁occurs ▁after