5 – Forgetting Demo: On a penny, what appears to the left of Lincoln? To the right? We forget almost everything we once knew. What causes forgetting? Can forgetting be avoided or at least diminished?
Scenario 3:00 pm 4:00 pm 5:00 pm You study History French Lab History exam Your Friend study History rest History exam Does the French Lab affect the score on History Exam? Two possibilities: “no” decay amount forgotten depends solely on time elapsed since event “yes”interference learning A interferes with the learning of B
Experiment Ss studied nonsense syllables Then Ss slept or remained awake for 0 – 8 hours Ss given test Predictions Decay: Sleep = Awake Interference: Sleep > Awake Results (Jenkins & Dallenbach, 1924) Test Score sleep awake 0 8 Test Delay (h)
Follow-up Experiment Roaches learned to avoid shock. Then placed on treadmill or squeezed in matchbox. 1 day later, “still” Ss showed no forgetting. (Minami & Dallenbach, 1946) Karl M. Dallenbach
Study Ss played on rugby team. All Ss missed at least one game during the season. Example Games 1 2 3 4 5 6 7 8 9 Player A Player B Sample Test Question After game 9, Ss were asked “Who did you play in the 1st game?” Predictions: Decay: accuracy depends on # of days since 1st game A = B Interference: accuracy depends on # of games played since 1st game A < B Results supported interference. (Baddeley & Hitch, 1977)
Two kinds of interference: Proactive Interference (PI): prior learning hinders subsequent learning Day 1 Day 2 Day 3 PI group Spanish French Test on French Controls - - - - - - French Test on French PI occurred if PI group did worse Retroactive Interference (RI): subsequent learning hinders prior learning Day 1 Day 2 Day 3 RI group Spanish French Test on Spanish Control Group Spanish - - - - - - Test on Spanish RI occurred if RI group did worse
Example In 10th grade, Brielle took French 1 In 11th grade, she took Spanish 1. In 12th grade, she took Spanish 2. On the first day of Spanish 2, she took pop quiz. For green, she wrote “vert.” (French) What kind of interference explains her error? Answer PI French Spanish Spanish Quiz Prior learning interfered with what she was trying to remember
Example Today, for the first time in her life, Jill used a numeric keypad. She entered data for about an hour. Then she phoned her friend. (She has used a phone all her life.) When she tried to press “9,” she mistakenly pressed “3”. What kind of interference explains her error? RI Use phone (before today) use keypad Test on phone subsequent learning interfered with what she was trying to remember
Example A Brit flies to Tampa for his first trip outside the UK. He rents a car and drives around Tampa for several days. Then, while in Tampa, and while driving on narrow road at night, he sees oncoming car. He veers left. What kind of interference explains his error? PI drive in UK drive in US test on US learning
Associated Press- Tampa - November 29, 2002 “A driver killed in a high-speed, head-on collision Wednesday after crossing the Sunshine Skyway on the wrong side was identified Thursday as a British citizen.”
Why does Proactive Interference occur? Usually, PI occurs only if cue is paired with more than one target. Example 1:00 pm2:00 pm3:00 pm study French (red-rouge) study Spanish (red-rojo) Spanish test (red-?) rouge red rojo This explanation of interference is called cue overload theory (e.g., Watkins, 1977)
Example of cue overload theory Today, Joe parked in the same lot for the 10th consecutive day (different spot each day) cue = where in this lot did I park? cue is paired with 10 targets cue overload cannot find car Today, Moe parked in a lot the first time cue = where in this lot did I park? cue is paired with 1 target No cue overload can find car
Why does Retroactive Interference occur? Sometimes, RI occurs because cue is paired with more than target. Example 1:00 pm2:00 pm3:00 pm study French (red-rouge) study Spanish (red-rojo) French test (red-?)
But RI happens even if cue is linked to only one target Example 1:00 pm2:00 pm3:00 pm study French (red-rouge) study History French test (red-?) History impairs French test score! So cue overload theory cannot be only cause of RI.
consolidation theory 1. Memory needs time to strengthen or “consolidate.” jello must harden 2. Until consolidation is complete, memory is vulnerable. jello can spill 3. Consolidation is disrupted by concurrent new learning. fridge door open Example 1:00 pm2:00 pm3:00 pm Mr. X study French study History Test on French Mr. Y study French rest Test on French Mr. X does worse because studying History impaired consolidation of French (e.g., Wixted, 2005)
Evidence for Consolidation Observational data After car accident, victim cannot recall last 15 minutes prior to accident. Experiment ECT = electroconvulsive therapy Mr. X study …ECT…………………………………….test Mr. Y study ………………………………….ECT……test Mr. X does worse. ECT erased memory before it had a chance to consolidate. (Ribot, 1881; Squire et al.,. 1975)
Example One day, Ned and Fred studied History. Then, Ned napped while Fred studied French. Then, they took History test. Ned History (1492 Columbus) Nap History Test (1492-?) Fred History (1492 Columbus) French (dog-chien) History Test (1492-?) According to consolidation theory, who should do WORSE? Fred. His nap impaired consolidationof History.
Example One day, Holly and Spence studied French vocabulary Then, Holly studied History while Spence studied Spanish. Then, they took French vocabulary test. Holly French (dog-chien) History French Test (dog-?) Spence French (dog-chien) Spanish (dog-perro) French Test (dog-?) a. According to cue overload theory, who should do WORSE? Spence because his cue (DOG) is paired with 2 targets – not just 1. b. According to consolidation theory, who should do WORSE? Equally poor. For each, consolidation disrupted.
Recognition Often times, we cannot recall item but we can recognize it. Example You cannot recall his name, but you would recognize it if you heard it. Other times, we can neither recall nor recognize. How should we measure recognition?
Yes-No Recognition method Example Study: S is shown 4 words: girl, wall, rope, sign Test: S is shown 4 original words (targets) and 5 new words (foils), one at a time. Test ItemItem TypeDid you see it before? rain foil no sign target yes hit = said yes to target boat foil no wire foil no food foil yes false alarm = said yes to foil girl target no rope target yes hit rake foil no wall target yes hit
Example Hypothetical Experiment Study phase: Each S saw 50 face photos, one at a time. Test. Each S saw random mix of the 50 old faces (targets) and 80 new faces (foils). For each face, S was asked if he or she recognized face. Jane said “yes” to 40 targets and 20 foils. 1. Find H. 2. Find FA.
Why measure both H and FA? H is not sufficient. Why? A subject could simply say “yes” to every item and achieve perfect score (100%) FA is not sufficient. Why? A subject could simply say “no” to every item and achieve perfect score (0%)
But measuring both Hit rate (H) and False Alarm rate (FA) can lead to ambiguity. Example Ann: H = 80% FA = 60% Ben: H = 50% FA = 20% Who did better? Ann had better H, but Ben had better FA. Thus, we need a single measure that combines H and FA. A simple but crude measure is H – FA A better measure is d’ (“d prime”), which is beyond the scope of this course.
Example A researcher conducts a face recognition experiment. During the study phase, Ss saw dozens of faces, one at a time. During the test, Ss saw a random mix of the original faces and many new faces. For each face, S was asked, ”Do you recognize this face?” 1. Anna performed perfectly. Find H – FA. H = 100% FA = 0% H – FA = 100% 2. Beth said “yes” to every face. Find H – FA. H = 100% FA = 100% H – FA = 0% 3. Carol said “no” to every face. Find H – FA. H = 0% FA = 0% H – FA = 0% 4. Donna flipped a coin for each test face (heads = yes). Estimate H – FA. H = 50% FA = 50% H – FA = 0% 5. For Emma, H = 10% and FA = 90%. What can you conclude? She misunderstood instructions or sabotaged your experiment.
Face Memory Demo You’ll see several faces, one at a time. Just look at each face.
Get ready for Test phase You’ll see 14 faces. Your page is numbered 1 – 14. For each test face, write “yes” or “no” Twist: If your answer is yes, also write 1 if face appeared in Part 1 (these faces had blue border) or 2 if face appeared in Part 2 (these faces had orange border)
Source Memory Demo 1 2 3 target Part 2 4 5 6 target Part 2 7 8 9 10 target Part 1 11 target Part 1 12 13 14 www.bbc.co.uk/science/humanbody/sleep/tmt/instructions_1.shtml H = / 4 = FA = / 10 = H – FA =
Source Memory Often we can recall a fact while forgetting its source Where I did I read that? Who told me that? When did I learn that? Examples You know that Alaska is the largest state, but you cannot recall where you learned this. You know that Bunny broke up with Chad, but you cannot recall who told you this.