forgetting intro 2009

William James, philosopher & psychologist

‘’In the practical use of our intellect, forgetting is as important as remembering’’

forgetting – a definition

The inability to recall or recognise material which was previously stored in memory. A distinction can be made between:

Lack of availability – material that was placed in memory and which has now disappeared.

Lack of accessibility – material that is still in

memory but cannot be recalled

why do we forget?

1. Encoding failure

2. Storage decay

3. Retrieval failure

4. Motivated forgetting

but first…a quick attention test

http://www.youtube.com/watch?v=Ahg6qcgoay4&feature=related

forgetting or failure to encode?

"We must never underestimate one of the most obvious reasons for forgetting, namely, that the information was never stored in the first place" Loftus

1. Failure to encode

Remember that everything in short term memory is lost unless it is moved to long term memory. That isn’t so much forgetting as the failure to encode and store incoming data.

Such transference to LTM requires attention and usually intention.

The Brown-Peterson experiment 1) on each trial you will see three words that you will

try to remember 2) following the three words you will see a three digit

number (eg. 526) 3) As soon as that number appears you are to begin

silently counting backwards from that number in 3’s (eg. 526, 523, 520, 517)

4) Keep counting until you see a set of question marks. This is your cue to write down the three words you saw at the beginning of the trial

5) This same procedure will continue for several trials 6) Questions?

DOG SHIRT TREE

8 4 1

? ? ?

CAR LEG MOUSE

3 1 5

? ? ?

PENCIL SPOON ARM

4 4 2

? ? ?

CUP TABLE SHOE

7 5 5

? ? ?

BOOK CORD TOE

2 1 4

? ? ?

FINGER WORD RUG

3 7 8

? ? ?

SOCK WINDOW GRASS

5 3 2

? ? ?

BACK COFFEE PAGE

4 8 2

? ? ?

VOICE HAT PEN

6 3 4

? ? ?

Scoring

1. DOG SHIRT TREE

2. CAR LEG MOUSE

3. PENCIL SPOON ARM

4. CUP TABLE SHOE

5. BOOK CORD TOE

6. FINGER WORD RUG

7. SOCK WINDOW GRASS

8. BACK COFFEE PAGE

9. VOICE HAT PEN

Find the total # you got right on the following sets of trials:

6 sec: trials 1,5,712 sec: trials 2,4,918 sec: trials 3, 6, 8

class data

Typical Data

2. Storage Decay (Lack of availability)

Trace Decay theory proposes that unless information in memory is regularly refreshed or used it will spontaneously begin to fade or weaken over time.

This is based on the assumption that memories have a physical basis, the trace. Over time, metabolic processes break down this trace (decay) making the information unavailable. Conversely, with rehearsal, the trace becomes stronger and is less likely to be forgotten

Ebbinghaus (1885)

First person to conduct systematic scientific research on forgetting

Had subject memorize lists of 13 nonsense syllables

Measured retention at different intervals

Ebbinghaus (1885)

Ebbinghaus’s findings suggests forgetting occurs early, suggestingthat the information was never properly placed in long term memory.

Evaluation of trace decay

Peterson and Peterson (1959) (+)Research demonstrated that all but 10% of memories were lost after 18 seconds when rehearsal was prevented through an interference task. This is evidence that trace decay occurs within 18 seconds

Low ecological validity (-)The use of nonsense trigrams and lists of numbers doesn’t represent learning in everyday life and thus findings cannot be easily generalised

But...is it trace decay or displacement?

Forgetting in STM is usually attributed to the limited capacity (displacement) and duration (trace decay) of STM

Displacement theory explains forgetting in terms of capacity (7 +/- 2: Miller, 1956). Once STM is full, any new information to be remembered must push out old information. The old information is forgotten

Participants in Peterson & Peterson’s study were given a distractor task which might have led to interference or displacement of the original trigrams.

Ideally you would study decay by having participants learn material and recall it later without doing anything in between learning and recall. However, it is difficult to prevent rehearsal without an interference task.

3. Retrieval Failure (Lack of accessibility )

Rapunzel – available but not accessible

Types of retrieval task

Recall

Recognition

Relearningi

Tip of the tongue phenomenon

Memory cues or prompts can sometimes aid retrieval

Interference - a cause of retrieval failure

Interference or ‘inhibition’ by other material is a common problem. Learning some items may interfere with the retrieval of another.

Two types of

interference: Retroactive inhibitionProactive inhibition

Interference in studying

4. Motivated forgetting

This is a type of forgetting which seems to be motivated by unpleasant events. For example, forgetting a dentist appointment

Freud argued that all forgetting was motivated by an UNCONSCIOUS willingness not to remember information which is in some way uncomfortable

Freudian idea of repression Traumatic events pushed below consciousness

Evaluation motivated forgetting

Little empirical support for this idea

If anything, traumatic events are too easily remembered: i.e., Post-traumatic Stress Disorder (PTSD)

conclusion

Forgetting has several possible causes Encoding failure: the memory never gets stored Decay: the memory deteriorates and fades Retrieval failure: we just can’t find the memory Motivated forgetting: we don’t want to find the memory

Can We Trust Memory?

A memory is a sheet of paper in a filing cabinet.

We take it out of the file.

Look at it.

Edit it!

And put it back.

What do we take out the next time?

The edited version!