coding capacity and duration

Coding

The way info is changed to be stored in memory

Capacity

How much the memory store holds

Duration

How long info can be stored in the memory

Long term memory

Permanent memory store, events in distant past, unlimited capacity due to systematic coding

STM

Events in the immediate past, lasts 18 seconds, limited capacity. Lost if not rehearsed

Baddeley on coding procedure

4 different groups each with a list to memorise

Group 1→ words that were acoustically similar

Group 2→ words that were acoustically different

Group 3→ words that were semantically similar

Group 4→ words that were semantically different

They were then asked to recall them in the correct order straight away to test their STM, and after 20 minutes for their LTM

Baddeley on coding Findings

When tested straight away the ppts struggled to remember words that sounded similar (acoustic) and for LTM(20 mins later) words that were semantically similar

Baddeley on coding Conclusions

LTM coded semantically, STM coded acoustically

Baddeley on coding Strengths

Replicable, has low order effects and demand characteristics. It has high internal validity as its lacks extraneous variables

Baddeley on coding Weaknesses

Lacks mundane realism making it lack external validity and has high ppt variables

Jacob’s study on capacity of STM procedure

Tested digit span. Had 4 digits read to ppts if they recalled them correctly then they would more onto 5 digits and so on. He also did this with letters.

Jacob’s study on capacity findings

Mean span for digits was 9.3 whereas letters was 7.3

Strength of Jacob’s study on capacity

Replicable

Weaknesses of Jacob’s study on capacity

Lacks mundane realism as it was a lab experiment making it have low external validity.

Repeated measures design meaning it has order effects decreasing the validity and increasing demand characteristics

Millers study on chunking procedure

Made observations on everyday things

Millers study on chunking Findings

Majority of things come in sevens so STM span may be 7 +/- 2

And that people found it easier to recall words than letters due to chunking

Millers study on chunking Weakness

Low mundane realism

Peterson and Peterson study in duration of STM procedure

Tested 24 students in 8 trials they were given a constant syllable and 3 digits number to remember. To prevent rehearsals they had to count back from a number (3,6,9,12,15 or 18 seconds)

Peterson and Peterson study in duration of STM Findings

The longer they waited the lower the percentage of active recall

Peterson and Peterson study in duration of STM Weakness

Results could be due to interference not decay so they may not be valid

Bahrick et al study duration of LTM procedure

Tested ppts from ages 17-75 using photo recognition test including 50 photos and recalling names from their graduate class.

Bahrick et al study duration of LTM Finding

As years since graduation increased recall declined

Photo recognition→ 15 years post remembered an average of 90% and 48 years 70%

Bahrick et al study duration of LTM Conclusion

LTM can last a lifetime

Bahrick et al study duration of LTM Strength

High external validity as it’s based on meaningful memories