How to Improve Your Memory & Cognitive Function at Any Age | Dr. Alan Castel

KEYPOINTS

• 01

  Memory is reconstructive, and we misjudge how well we know things

  Castel, a UCLA memory researcher, notes that two people can see the same event and remember it differently a day later. Awareness of your own thinking (metacognition) is often poor: we feel we know something we don't. As a child he rehearsed a single line in The Wizard of Oz ('there's a cyclone on the way, hurry and get into the cellar') and on opening night swapped 'cyclone' and 'cellar.'

• 02

  Seeing something often doesn't mean you remember it

  People have seen the Apple logo thousands of times but can't say which side the bite is on or whether it has a stem or a leaf, an update of the classic penny study. Drawing it while looking helps. Better still is struggling to draw it from memory first and then checking. Making mistakes before seeing the answer produces stronger learning than simply studying.

• 03

  Desirable difficulties beat easy studying

  Castel cites work by his UCLA colleagues on 'desirable difficulties': learning that feels uncomfortable often sticks better, even though teachers and students tend to make it easier. Students who highlight 80% of a textbook and still get a C show the real skill is picking out what matters and organizing it around themes, such as findings that make intuitive sense versus counterintuitive ones.

• 04

  Name tricks are workarounds, and forgetting names is normal

  Mnemonics like 'Castel rhymes with pastel' require extra effort and cause predictable errors ('Pastel'). Names get harder with age because there are more Davids and Andrews competing in memory. Using the name several times and practicing recall help. Castel argues that remembering what you talked about, or whether you can trust someone, matters more.

• 05

  Confidence is not accuracy, as eyewitness cases show

  In the Ronald Cotton case, a woman who was assaulted deliberately studied her attacker's face so she could identify him. She confidently picked Cotton, and he was convicted. Decades later DNA evidence exonerated him. Factors included cross-race identification, which is less reliable, and the way an identification can overwrite the original memory. Castel says memory should be treated as one source of evidence that can be contaminated, like DNA.

• 06

  Under stress we fall back on habit, so rehearse plans ahead of time

  Castel walks to the fire exits when he checks into a hotel, after guests once asked him which way to go during an alarm. Under high arousal people default to what they already know. Prospective memory, remembering to do something in the future, is especially prone to failure when attention wanders, as when you suddenly realize you've driven home on autopilot.

• 07

  Walking can enlarge the hippocampus

  The hippocampus, key for remembering facts and events, shrinks about 1–2% a year in later life. In a randomized trial, older adults who walked three to four times a week for 40 minutes grew hippocampal volume by about 1% compared with a stretching group, and their memory was better a year later. Castel sees exercise as a stronger memory tool than any pill.

• 08

  Brain pathology doesn't fully determine behavior

  In the Nun Study, some nuns whose brains showed Alzheimer's plaques and tangles after death had functioned well cognitively in life. Castel suggests purpose, social connection, exercise and sleep may help explain the gap. The amygdala, which tags memories with emotion, stays active with age, which is one reason embarrassing mistakes stick so well.