The ‘cock­tail party effect’ is the name given to our unusu­ally adept abil­ity of sep­a­rat­ing out con­ver­sa­tions from one another. How­ever it appears that we are unusu­ally bad at retain­ing infor­ma­tion from the dis­carded conversation(s):

Cherry [1953] found his par­tic­i­pants picked up sur­pris­ingly lit­tle infor­ma­tion [from the ‘rejected’ con­ver­sa­tions], often fail­ing to notice bla­tant changes to the unat­tended mes­sage. When asked after­wards, participants:

  • could not iden­tify a sin­gle phrase from the speech pre­sented to the rejected ear.
  • weren’t sure the lan­guage in the rejected ear was even English.
  • failed to notice when it changed to German.
  • mostly didn’t notice when the speech to the rejected ear was being played back­wards (though some did report that it sounded a bit strange).

via Mind Hacks