decisions that knew that a second plane was coming in 16 minutes but rather by a mass decision, a mass exodefrom the floor that prompted many people's lives to be saved. tavis: if you have found this conversation at all fascinating, as i certainly have, let me assure you, you will enjoy the text. it is called prison prison. -- "the hidden brain." it is written by shankar vedantam. congratulations on the book. >> thank you for having me. tavis: that is our show for the night. catch us on our radio pod cast through our website at pbs.org. i'll see you next time on pbs.org. as always, keep the faith. >>> for more information on today's show, visit tavis smiley at pbs.org. >> hi, i'm it was a smiley. join me next time with grammy-winning artist dee dee bridgewater. that's next time. see you then. >> there are so many things that wal-mart is looking forward to doing, like helping people live better, but mostly we're looking forward to helping build stronger communities and relationships because with your help, the best is yet to come. >> nationwide insurance proudly supports tavis smiley. tavis a