Decision-making processes: the case of collective movements
Résumé
Besides focusingontheadaptivesignificanceofcollectivemovements,itiscrucialtostudythemech- anisms anddynamicsofdecision-makingprocessesattheindividuallevelunderlyingthehigher-scale collective movements.Itisnowcommonlyadmittedthatcollectivedecisionsemergefrominteractions between individuals,buthowindividualdecisionsaretaken,i.e.howfartheyaremodulatedbythe behaviour ofothergroupmembers,isanunder-investigatedquestion.Classically,collectivemovements are viewedastheoutcomeofoneindividual'sinitiation(theleader)fordeparture,bywhichallorsome of theothergroupmembersabide.Individualsassumingleadershiphaveoftenbeenconsideredtohold a specificsocialstatus.Thishierarchicalorcentralizedcontrolmodelhasbeenchallengedbyrecent theoretical andexperimentalfindings,suggestingthatleadershipcanbemoredistributed.Moreover, self-organized processescanaccountforcollectivemovementsinmanydifferentspecies,eveninthose that arecharacterizedbyhighcognitivecomplexity.Inthisreview,wepointoutthatdecision-making for movingcollectivelycanbereachedbyacombinationofdifferentrules,i.e.individualized(basedon inter-individual differencesinphysiology,energeticstate,socialstatus,etc.)andself-organized(based on simpleresponse)onesforanyspecies,contextandgroupsize.