>>> AND AS WE MENTIONED EARLIER, PRESIDENT BIDEN DISPELLED DOUBTS ABOUT HIS AGE AT LAST NIGHT'S STATE OF THE UNION.

SINCE THE START OF HIS PRESIDENTIAL CAMPAIGN, BIDEN'S EVERY SLIP UP HAS BEEN UNDER THE MICROSCOPE, FROM MOMENTARY FORGETFULNESS TO MISSPOKEN WORDS.

OUR NEXT GUEST BELIEVES WE HAVE BEEN OVERSIMPLIFYING THE WAY WE THINK ABOUT AGE AND MEMORY.

IN HIS NEW BOOK "WHY WE REMEMBER," THE AUTHOR SHARES YEARS OF HIS RESEARCH.

AND HE JOINS HARI SREENIVASAN IN THIS CONVERSATION.

>> CHARAN RANGANATH, THANK YOU FOR BEING HERE.

>> THANK YOU FOR HAVING ME.

>> FIRST OF ALL, I WANT TO TALK ABOUT THE IDEAS YOU DISCUSS IN YOUR BOOK, AND FOR ME IT SORT OF DISTILLS DOWN AS SOMEONE WHO IS ENTERING FULL STRIDE MIDLIFE ABOUT MEMORIES AND HOW MY BRAIN IS FORMING THEM.

WHAT ARE WE GETTING WRONG ABOUT OUR UNDERSTANDING OF MEMORY, HOW WE FORM THEM, HOW IMPORTANT THEY ARE?

>> I THINK THE BIG THING THAT PEOPLE GET WRONG ABOUT MEMORY IS THIS EXPECTATION THAT WE'RE SUPPOSED TO REMEMBER EVERYTHING AND WE'RE SUPPOSED TO REMEMBER EVERYTHING AS IT ACTUALLY HAPPENED.

AND WE KNOW JUST FROM THE SCIENCE THAT THAT'S NOT TRUE.

NOBODY THAT'S EVER BEEN STUDIED REMEMBERS EVERYTHING.

SO RIGHT OFF THE BAT, WE KNOW THAT PEOPLE'S EXPECTATIONS ARE OUT OF WHACK, AND SO THEN THE QUESTION IS, WELL, WHAT IS THE FUNCTION OF MEMORY, AND AS I TALK ABOUT IN MY BOOK, ALMOST ALL THE SIGNS POINT TO THIS IDEA THAT THE FUNCTION OF MEMORY IS REALLY NOT ABOUT THE PAST AT ALL.

IT'S ABOUT THE PRESENT AND ABOUT THE FUTURE.

>> EXPLAIN THAT.

WHAT DOES MEMORY HAVE TO DO WITH THE FUTURE OR THE PRESENT?

>> WELL, SO LET'S JUST TAKE THE PRESENT, FOR EXAMPLE, SO WE AND OTHERS HAVE FOUND THAT WHEN PEOPLE WATCH A MOVIE, SAY, OR THEY LISTEN TO A STORY, WE CAN SEE THE SAME CIRCUITRY THAT'S INVOLVED IN MEMORY THAT IS CURRENTLY BEING INVOLVED IN JUST UNDERSTANDING WHAT PEOPLE ARE SAYING IN THE MOMENT.

AND THE REASON IS THAT EVEN TO UNDERSTAND WHAT'S HAPPENING IN YOUR NEWS SHOW, WHICH IS EXCEPTIONALLY CLEAR, PEOPLE ARE GOING BACK AND ENGAGING IN THIS KIND OF MEMORY RETRIEVAL IN THE MOMENT, JUST TO FOLLOW WHAT'S GOING ON, AND THE REASON THEY'RE DOING THAT IS BECAUSE THEY REALLY WANT TO KNOW NOT WHERE YOU ARE NOW, BUT WHERE YOU'RE GOING, AND SO THAT'S JUST A VERY MUNDANE EXAMPLE OF THE KINDS OF FUNCTIONS MEMORY HAS IN EVERY DAY LIFE.

THINK ABOUT, YOU WAKE UP IN A HOTEL ROOM, FOR INSTANCE, YOUR FIRST QUESTION IS, WHERE AM I.

WITHOUT MEMORY, YOU HAVE NO IDEA.

YOU'RE FLOATING IN TIME AND SPACE, RIGHT.

AND AS MUCH AS THIS IS SOMETHING THAT JUST KIND OF COMES AUTOMATICALLY TO US, IF YOU HAVE A MEMORY DISORDER, THAT'S IT, YOU ARE JUST THERE.

RIGHT.

SO SOMETHING THAT BOTH ANCHORS US IN TIME AND SPACE, AND GIVES US A SENSE OF WHO WE ARE IN THE MOMENT.

>> YOUR BOOK IS CALLED "WHY WE REMEMBER UNLOCKING MEMORY'S POWER TO HOLD ON TO WHAT MATTERS," SO THE WHAT MATTERS, HOW DOES THAT HAPPEN ON FIGURING OUT WHAT'S IMPORTANT AND WHAT'S NOT IMPORTANT SO WE CAN RECALL IT LATER?

>> SO EVENTS THAT TEND TO EVOKE EMOTIONS, LIKE THINGS THAT SCARE YOU OR EVENTS WHERE YOU'RE ANGRY OR EVENTS WHERE YOU'RE SAD, WE CAN SEE CHEMICALS IN THE BRAIN CALLED NEUROMODULATORS, WHICH VIEWERS MIGHT KNOW SOME OF THE CHEMICALS LIKE DOPAMINE, AND SEROTONIN, AND THESE PROMOTE PLASTICITY.

THEY ALLOW THE EXPERIENCES TO BE MORE RESILIENT OVER TIME AND THOSE MEMORIES STICK AROUND.

SO SOMETIMES THERE ARE THINGS THAT YOUR BRAIN HAS JUST DECIDED OFFHAND, AND I DON'T MEAN TO BE MORPHIC WITH THE BRAIN, BUT THESE ARE THE THINGS THAT ARE IMPORTANT, AND ALSO YOUR OWN ATTENTION, THE THINGS YOU PAY ATTENTION TO CAN ALSO TAG THOSE EXPERIENCES AS IMPORTANT.

>> YOU DESCRIBE A PHENOMENON CALLED EVENT BOUNDARIES, EXPLAIN TO OUR AUDIENCE A LITTLE BIT OF WHAT THAT IS.

>> SO EVENT BOUNDARIES IN THE REAL WORLD TEND TO BE THINGS LIKE I SHOW UP IN MY KITCHEN AND ALL OF A SUDDEN I'M LIKE, OH, WHAT AM I DOING HERE, I HAVE NO IDEA.

I GRAB A BAG OF CHIPS, START EATING, GO BACK TO MY HOME OFFICE AND REALIZE, OH, WAIT A MINUTE, I LEFT MY PHONE THERE.

AND I GO BACK, AND IF I'M LUCKY I DON'T FORGET WHY I WENT TO THE KITCHEN AGAIN.

SO THESE EXPERIENCES TEND TO HAPPEN BECAUSE WHEN WE CHANGE OUR MENTAL CONTEXT, THAT IS OUR SENSE OF WHERE WE ARE AND WHAT'S GOING ON, WHAT HAPPENS IS THAT ALL OF THE INFORMATION THAT WE'RE KEEPING IN OUR HEAD TENDS TO GET FLUSHED OUT.

AND SO WHAT I MEAN BY THAT IS LIKE WHEN YOU CROSS A DOORWAY, FOR INSTANCE, YOUR SENSE IS THAT I'M IN ANOTHER ROOM.

YOU DO DIFFERENT ACTIVITIES IN THE KITCHEN THAN YOU DO IN THE HOME OFFICE.

YOUR BRAIN IS ALREADY PREPARING FOR I'M IN THE KITCHEN WHAT AM I SUPPOSED TO DO.

WHAT TYPICALLY HAPPENS IN THE KITCHEN?

I TEND TO GET FOOD.

SO YOU END UP WITH A LOT OF EMPTY CAL CALORIE BECAUSE YOU'VE HIT THIS BOUNDARY AND YOUR BRAIN IS SWITCHING INTO FOOD MODE.

>> I WONDER WHAT'S HAPPENING TO THE BOUNDARIES IN OUR ALLEGED MULTITASKING WORLD WHERE WE SEEM TO REALLY TAKE PRIDE IN DOING SO MANY DIFFERENT THINGS AT ONCE.

I WONDER IF WE'RE KIND OF ERASING THOSE BOUNDARIES AND MAKING IT HARDER FOR US TO RECALL THINGS IN PROPER CONTEXT BECAUSE, WHILE I COULD BE DOING THIS INTERVIEW, I'M ALSO ON MY PHONE.

WHATEVER, THERE'S THREE THINGS GOING ON.

>> I'M SURE YOU'RE ACTUALLY PAYING FULL ATTENTION NOW.

>> I AM.

>> IT'S A GREAT QUESTION, IT'S SOMETHING I'LL STRUGGLE WITH TOO.

I'M SITTING IN CONFERENCES, I'M UNDER STRESS, CHECKING E-MAILS, AND I'M NOT PROUD OF THIS BECAUSE WHAT HAPPENS IS EVERY TIME I SWITCH BETWEEN ONE TASK AND ANOTHER, MY BRAIN IS NOW SHIFTING MY MENTAL CONTEXT AND CREATED AN EVENT BOUNDARY, OKAY, BRAIN, LET'S PACK THIS EVENT INTO MEMORY.

BUT I'M PACKAGING THESE LITTLE IMPOVERISHED EVENTS AND EVERY TIME I SWITCH OVER, MY BRAIN TAKES A LITTLE BIT OF TIME.

I'M USING SOME OF MY MENTAL RESOURCES JUST TO GET CAUGHT UP AGAIN.

NOW IMAGINE WHAT'S HAPPENING AGAIN, YOU'RE GETTING A FRAGMENT OF INFORMATION IN MEMORY EVERY TIME I SWITCH AND THOSE FRAGMENTS ARE NEVER REALLY THERE IN THE FIRST PLACE BECAUSE I'M JUST GETTING CAUGHT UP.

IT'S NO SURPRISE AFTERWARDS YOU HAVE ALMOST THIS SENSE OF AMNESIA, LIKE WHAT HAPPENED.

BUT YOU CAN HAVE THE OPPOSITE PROBLEM OF NOT ENOUGH BOUNDARIES AND I THINK DURING THE PANDEMIC, WE WERE SITTING FOR HOURS AND HOURS AT A TIME IN FRONT OF OUR COMPUTERS AND YOU END THE WEEK AND YOU'RE LIKE WHAT'S HAPPENED.

AND THIS IS BECAUSE WE JUST HAVE THESE LONG EXPERIENCES THAT ARE JUST MONOTONOUS AND NOTHING THAT STICKS OUT AS MEMORABLE.

>> YOU HAD A SECTION OF THE BOOK, YOU WERE COMPARING HUMANS TO RO BOTS.

HUMANS ONE.

>> GENERATIVE AI, THEY REQUIRE GOBS AND GOBS OF DATA TO BE TRAINED APPROPRIATELY, AND THEY USE TONS OF ENERGY.

THINK OF THE CARBON FOOTPRINT OF SOMETHING LIKE CHATGPT, AND NOW YOU LOOK AT HUMANS.

AND SUGGEST THAT OUR ENERGY EXPENDITURES IS 10 TO 20 WATTS SO WE'RE DOING A LOT WITH VERY LITTLE POWER EXPENDITURE, AND PART OF THE REASON IS THAT WE ACTUALLY DO A LOT MORE WITH A LOT LESS, AND HUMANS HAVE THIS CAPABILITY WHICH WE CALL EPISODIC MEMORY, THIS ABILITY TO RECALL OUR LIVED EXPERIENCES THAT HAPPEN AT ONE TIME AND ONE PLACE.

AND SO FOR INSTANCE, YOU HAVE A FAVORITE RESTAURANT THAT YOU GO TO, AND THEN ONE DAY YOU SHOW UP AND YOU SEE A SIGN THAT SAYS UNDER NEW MANAGEMENT.

YOU HAVE A TERRIBLE MEAL.

YOU DON'T HAVE TO GO BACK THERE.

YOU CAN STOP ON A DIME, AND CHANGE.

AND IT'S ALMOST LIKE YOUR BRAIN IS THIS SPORTS CAR, THIS HIGH PERFORMANCE, SOMEHOW IT USES LOW AMOUNTS OF FUEL.

NOW CHATGPT IS MORE LIKE THIS LUMBERING CARGO TRUCK, A CONTAINER SHIP.

YOU HAVE TO STOP IT ON THE DIME AND TURN AND GOOD LUCK TO YOU, IT'S GOING TO TAKE A LOT MORE DATA TO DO THAT.

AND SO THIS IS WHERE HUMANS HAVE REAL OPPORTUNITIES BECAUSE MY EXPERIENCES ARE DIFFERENT THAN YOUR EXPERIENCES.

AND WE ALL HAVE IDIOSYNCRATIC THINGS WE'VE READ AND PEOPLE WE KNOW.

THE MORE WE CAN RELY ON THAT AND DIVERSIFY TRAINING DATA, THE MORE CREATIVE WE CAN BE, AND THE MORE RELEVANT WE CAN BE IN THE AGE OF AI.

>> YOU WROTE AN OPEN ED, I'M A NEUROSCIENTIST, WE'RE THINKING ABOUT BIDEN'S MEMORY AND AGE IN THE WRONG WAY.

FOR PEOPLE THAT MIGHT NOT HAVE READ THAT, WHAT ARE WE GETTING WRONG WHEN WE LOOK AT SOMEBODY LIKE PRESIDENT BIDEN AND WHEN WE CONSIDER THAT MEMORY OR HIS ABILITY TO REMEMBER THINGS IN THE CONTEXT OF WHETHER OR NOT HE'S QUALIFIED TO BE COMMANDER IN CHIEF?

>> WELL, WHEN I READ THE SUMMERIES IN THE NEWS ABOUT THE SPECIAL COUNSEL'S REPORT WHERE THEY DESCRIBED HIM AS AN ELDERLY MAN WITH A POOR MEMORY, I IMMEDIATELY WAS ATTRACTED TO THIS BECAUSE I SAY, WELL, I STUDY MEMORY, LET'S SEE WHAT HAPPENED.

AND SO I WENT INTO THE REPORT AND THE CASES THAT I FOUND AND THE THINGS THAT WERE BEING DISCUSSED IN THE MEDIA WERE NOT THE KINDS OF THINGS THAT WOULD CONCERN ME BECAUSE I THINK WHEN PEOPLE SAY ELDERLY MAN, POOR MEMORY, IT HAS BUTTONS ON STIR OWE TYPES THAT WE HAVE, ESPECIALLY IN THE U.S. ABOUT OLDER ADULTS AND I THINK THE FIRST THING THAT COMES TO MIND FOR MANY PEOPLE IS ALZHEIMER'S DISEASE, AND WHAT I WANTED TO MAKE CLEAR IN THIS EDITORIAL IS NUMBER ONE, THERE'S A LOT OF VARIABILITY IN AGEING.

SOME PEOPLE THEIR MEMORY DROPS OFF PRECIPITOUSLY, OTHER PEOPLE, IT GOES WELL AND THEY PRESERVE A LOT OF THOSE ABILITIES.

THE SECOND THING IS THAT OFTEN AS WE GET OLDER, THERE ARE RETRIEVAL FAILURES THAT WE JUST TALKED ABOUT WHERE THE MEMORY IS THERE, BUT WE JUST CAN'T GET THE DETAILS OR WE'RE STRUGGLING TO PULL UP INFORMATION OR SOMETIMES WE MAKE A MISTAKE AND IT TAKES US A WHILE TO CORRECT IT.

THE EXAMPLES I SAW IN THE SPECIAL COUNSEL'S REPORT WERE ALL OF THESE KINDS OF PHENOMENON WHERE IT'S NOT THAT BIDEN DIDN'T REMEMBER HIS LAST YEAR OF THE PRESIDENCY OR NO MEMORIES OF HI SON'S DEATH, IT WAS THAT HE COULDN'T PULL OUT THE YEAR THAT THESE THINGS HAPPENED WHEN YOU NEED IT.

AND I WOULD BE HARD PRESSED TO FIND SOMEBODY AT HIS AGE WHO DOESN'T HAVE THAT PROBLEM FROM TIME TO TIME.

I LOOK AT THIS, AND OTHER PEOPLE ARE LOOKING AT BIDEN, WHAT ARE THEY SEEING.

SOMEBODY WITH GRAY HAIR.

MAYBE THEY'RE JUDGING HIM ON HIS APPEARANCE OR TRUMP, TOO, I WANT TO BE CLEAR, THIS IS NOT SOMETHING THAT'S A PARTISAN ISSUE.

ONE IN SIX AMERICANS ARE OVER THE AGE OF 65.

AND WHEN PEOPLE LOOK AT SOMEONE WHO'S OLDER, ESPECIALLY IN THIS CONCERN, AND THEY SEE SOMEONE WHO MAYBE IS NOT MOVING AS WELL AS A YOUNG ADULT, THEY'RE NOT SPEAKING AS FLUENTLY AS A YOUNG ADULT, THEY MAKE ASSUMPTIONS ABOUT MEMORY THAT ARE JUST UNTRUE.

>> I WONDER, I MEAN, CONSIDERING THAT WE HAVE TWO OF THE OLDEST CANDIDATES EVER RUNNING FOR THE HIGHEST OFFICE IN THE LAND, THERE ARE PEOPLE SAYING, HEY, MAYBE WE SHOULD HAVE COGNITIVE TESTS BE PART OF THE QUALIFICATIONS OR, I MEAN, YOU KNOW SOME OF THAT SOUNDS JUST AGEIST ON ITS FACE, AND THEN I ALSO WONDER, YOU KNOW, BIOLOGY DOESN'T LIE.

THE PHYSICAL RECOVERY AT 85 FROM EVEN A SUDDEN SLIP AND FALL IS GOING TO BE VERY DIFFERENT THAN IT IS AT 65, WHICH IS DIFFERENT THAN IT IS AT 45, RIGHT.

SO I WONDER WHETHER WE SHOULD BE THINKING ABOUT A CANDIDATE'S COGNITIVE ABILITY AND HOW WE WOULD EVEN MEASURE THAT.

>> SO I BELIEVE THAT IT WOULD MAKE SENSE, AND WE CERTAINLY NEED TO HAVE A NATIONAL CONVERSATION ABOUT THIS.

I'M NOT IN A POSITION TO TELL VOTERS, I'M A SCIENTIST, I'M NOT IN A POSITION TO TELL VOTERS WHAT THEY SHOULD DO.

WHAT I WOULD SAY IS YOU'RE ABSOLUTELY RIGHT.

AS WE GET OLDER OUR RISKS FOR ALL SORTS OF HEALTH PROBLEMS CHANGES, AND PUBLIC PERCEPTION IS OFTEN INACCURATE.

I MEAN, PEOPLE ARE OFTEN MAKING THEIR PERCEPTIONS AND THINGS THAT HAVE NO BEARING ON PEOPLE'S COGNITIVE ABILITIES.

YOU CAN DO A FAIRLY RIGOROUS COGNITIVE ASSESSMENT OVER THE COURSE OF A COUPLE OF DAYS AND THE ABILITY TO PREDICT FUNCTIONING WON'T BE PERFECT BUT IT WOULD BE PRETTY GOOD, AND WHAT I WOULD SAY IS THAT THOSE KIND OF ASSESSMENTS COMBINED WITH PEOPLE, COMBINED WITH A HEALTH ASSESSMENT, AND I LOVE MEMORY BUT THERE'S ALL SORTS OF OTHER ABILITIES AND SOME OF THESE SHOULDN'T CHANGE WITH AGE, LIKE COMPASSION OR THE ABILITY TO REGULATION EMOTIONS SO YOU DON'T GO UNHINGED OR SEMANTIC KNOWLEDGE, KNOWLEDGE OF THE FACTS AND THE PRESIDENT SHOULD BE AWARE OF A LOT OF FACTS THAT ARE NEEDED TO DO THE JOB.

THERE'S NO OBVIOUS LINE AS TO HOW GOOD SOMEONE HAS TO BE IN ANY OF THESE THINGS.

WHAT I CAN TELL YOU IS I HAVE TALKED TO PEOPLE WHO HAVE SERIOUS DISORDERS THAT HAVE NO ABILITY TO FUNCTION IN THE REAL WORLD, AND THEY SOUND FLUENT.

THEY SEEM CONFIDENT.

THEY LOOK GOOD.

AND SO I WOULD SERIOUSLY CAUTION THE PUBLIC, BECAUSE I GOT A LOT OF LETTERS ABOUT THIS SAYING, YOU'RE EXPECTING ME NOT TO BELIEVE WHAT I HAVE SEEN WITH MY OWN EYES.

YES, BECAUSE YOU DON'T KNOW WHAT YOU'RE TALKING ABOUT.

>> WHEN IT COMES TO NOT BELIEVING WHAT WE HAVE SEEN WITH OUR OWN EYES, I WONDER WHAT HAPPENS IN A WORLD WHERE ARTIFICIAL INTELLIGENCE CREATES MORE OPPORTUNITIES FOR YOUR EYES TO BE FOOLED.

HOW DO WE RECONCILE THAT IN THE BRAIN?

>> WE'RE STILL CATCHING UP TO WHERE THE TECHNOLOGY IS IN TERMS OF OUR UNDERSTANDING OF HOW PEOPLE RESPOND TO MISINFORMATION.

WHAT WE KNOW IS THAT IT'S VERY DIFFICULT TO TELL THE DIFFERENCE, EVEN IF WE HAVE BEEN INFORMED, HEY, THIS IS FAKE NEWS.

IT'S VERY DIFFICULT TO TELL IN MEMORY WHETHER OR NOT SOMETHING WAS FAKE OR WHETHER IT WAS REAL.

AND IT TAKES PEOPLE TIME.

YOU HAVE TO USE THESE RESOURCES THAT YOU USE TO KEEP YOUR MEMORY ACCURATE, THESE MENTAL RESOURCES, AND YEAH, IT DOES GET WORSE WITH YOU'RE UNDER STRESS, WORSE WHEN YOU'RE NOT SLEEPING WELL, WORSE WHEN YOU GET OLTDER.

THESE ARE ALL FEATURES OF MODERN LIFE.

WHAT I WOULD SAY IS THAT THERE IS RESEARCH OUT THERE TO MITIGATE THE EFFECTS OF MISINFORMATION, AND DEFINITELY THE MEDIA, ESPECIALLY SOCIAL MEDIA COMPANIES I THINK HAVE A RESPONSIBILITY TO, AND I HOPE THE SUPREME COURT KEEPS THIS IN MIND THAT, YOU KNOW, WE REALLY HAVE A RESPONSIBILITY TO LABEL THINGS THAT ARE OBVIOUS MISINFORMATION.

PEOPLE ALSO NEED TO PLAY THEIR PART IN TERMS OF GIVING THEMSELVES THE TIME TO ACTUALLY CRITICALLY EVALUATE THEIR MEMORY.

>> SO WHAT'S HAPPENING IN OUR BRAINS WHEN WE SEE A PIECE OF FAKE NEWS?

>> WHAT WE CAN SAY IS THAT THERE'S PROBABLY, IF IT'S VERY CONVINCING FAKE NEWS, IT WOULD BE JUST LIKE WATCHING REAL NEWS, RIGHT, YOU'RE STRUGGLING TO UNDERSTAND IT.

YOU MAKE SENSE OF IT SOMEHOW, AND SO SOMETIMES THERE'S A LITTLE BIT OF A SENSE OF MENTAL CONFLICT IF IT DOESN'T AGREE WITH WHAT YOU THINK.

BUT THE PROBLEM IS THAT PEOPLE'S MEMORY BIASES SEEM TO REINFORCE.

IF YOU WATCH TRUE NEWS, YOU'LL SEE TWO PEOPLE WALK A DEBATE, AND THEY'LL WALK AWAY WITH DIFFERENT MEMORIES OF HOW THE DEBATE WENT BASED ON THE PARTISAN BELIEFS THEY HAD TO BEGIN WITH.

YOU GET INTO THE WORLD OF FAKE NEWS, AND IT GETS HARDER, YOU SEE SOMETHING THAT MAKES YOU HAPPY, YOU LIKE IT.

I'LL GO WITH THAT, RATHER THAN PUTTING IN THE WORK TO TRY TO FIGURE OUT IF THIS WAS ACCURATE OR NOT.

>> YOU TALK IN THE BOOK A LITTLE BIT ABOUT HOW WE MIGHT BE SUSCEPTIBLE TO A SOCIETAL OR COLLECTIVE MEMORY.

HOW DOES THAT WORK?

BECAUSE IT DOES SEEM THAT, WELL, IN SOME CASES, WE DON'T LEARN FROM HISTORY, WE REPEAT THE MISTAKES.

BUT THAT EVEN IF IT'S A SPECIFIC INCIDENT GIVEN THE BENEFIT OR COST OF TIME, THAT WE COLLECTIVELY SEEM TO REMEMBER SOMETHING DIFFERENTLY.

>> SO ONE OF THE FACTORS THAT'S BEEN STUDIED IN COLLECTIVE MEMORY, WHICH IS ESSENTIAL HOW PEOPLE'S MEMORIES ARE TRANSFORMED BY SOCIAL INTERACTIONS, ONE OF THE FACTORS THAT'S BEEN STUDIED IS HOW SELECTIVE PEOPLE CAN BE.

OFTEN IF YOU AND I REMEMBER THE SAME EVENT AND WE TALK ABOUT IT, AT THE END OF THE DAY, WE WILL REMEMBER LESS THAN HAD WE EXPERIENCED THESE THINGS ON OUR OWN, AND NOT TALKED ABOUT IT.

SO WHAT THAT SUGGESTS IS THAT SOMEHOW THERE'S A PROCESS BY WHICH YOU AND I TALK ABOUT IT, AND THERE'S SOME PRUNING OF THE MEMORIES, AND SO SUNY STONYBURG HAS STUDIED THIS, FOR INSTANCE.

ONE OF THE THINGS PEOPLE FOUND IS THAT PEOPLE WHO ARE THE DOMINANT NARRATORS, PEOPLE WHO TEND TO BE MORE POWERFUL, TEND TO BE MORE LOUD AND OBNOXIOUS CAN TAKE UP A LOT OF THE DISCUSSION, SO WHAT PEOPLE REMEMBER THAT WOULD NORMAL BY IDIOSYNCRATIC LIKE I TALKED ABOUT BEFORE, TENDS TO HONE IN ON THE SHARED AMOUNT OF INFORMATION THAT OVERLAPS WITH THIS DOMINANT SPEAKER.

SO THE ONLY WAY AROUND THIS IS TO LISTEN TO THE PEOPLE WHO MIGHT OTHERWISE BE IGNORED, AND THIS OFTEN HAPPENS TO BE PEOPLE WHO ARE OLDER, WHO ARE ELDERLY OR PEOPLE WITH CHILDREN OR FROM MARGINALIZED GROUPS, AND THAT'S ACTUALLY A KEY TO HOW COLLECTIVE MEMORY CAN BE IMPROVED, AND SO THIS IS SCIENCE.

THIS ISN'T JUST SOME POLITICAL STATEMENT.

IT'S JUST THE WAY THINGS ARE.

>> CHARAN RANGANATH, THE BOOK IS CALLED "WHY WE REMEMBER, UNLOCKING MEMORY'S POWER TO HOLD ON TO WHAT MATTERS," THANK YOU SO MUCH FOR JOINING US.

>> THANK YOU, HARI, IT'S BEEN GREAT TO BE HERE.