Duration of STM

STARTER:Quick Quiz – 2 minutes

Swap papers – Mark (as a class)Hand back – How did you do? What do you

need to go over?

Experiment

• I am going to show you a trigram (3 consonants), I want you to look at them and then count backwards in 5s from the number I give you. I will then ask you to write the trigram down, after a timed period.

CPW

NGV

RPW

TMK

FGH

TWY

LFR

MJG

CXZ

PDW

SBQ

Class Graph

0 3 6 9 12 15 18 21 24 27 30 330

10

20

30

40

50

60

70

80

90

100

Findings from our study into the duration of STM

Recall interval in seconds

Perc

enta

ge o

f trig

ram

s co

rrec

tly re

calle

d

Peterson and Peterson (1959)

• Using your text books on p. 83 complete the table in your booklet.

• How do our results compare to theirs?

Peterson and Peterson 1959• Aim: To investigate the duration of short-term memory.

• Procedure: A lab experiment was conducted in which 24 participants (psychology students) had to recall trigrams (meaningless three-consonant syllables, e.g. TGH). To prevent rehearsal participants were asked to count backwards in threes or fours from a specified random number until they saw a red light appear. This is known as the Brown Peterson technique. Participants were asked to recall trigrams after intervals of 3, 6, 9, 12, 15 or 18 seconds.

• Results: The longer the interval delay the less trigrams were recalled. Participants were able to recall 80% of trigrams after a 3 seconds delay. However, after 18 seconds less than 10% of trigrams were recalled correctly.

• Conclusion: Short-term memory has a limited duration when rehearsal is prevented. It is thought that this information is lost from short-term memory from trace decay.

Factors affecting the duration of STM

• Read through the texts on p. 83-84

• Summarise each factor into one sentence, add to the page in your booklet

Factors affection duration

• Rehearsal – Helps things stay longer in the STM, without rehearsal it is quickly lost

• Deliberate intention to recall – Unless we are trying to remember the information it is lost within seconds

• Amount of info to be retained – as with capacity, it is the number of chunks that are important not the number of letters.

Short Term MemoryExam Questions

Outline and evaluate research into the nature of short-term memory (12 marks)

Essay Plan using Assessment Objectives

AO1• Knowledge and

Understanding - OUTLINE

AO2• Application of Knowledge -

EVALUATE

ENCODING CAPACITY

DURATION

Homework

• Complete essay on STM• To be handed in Monday 22/09/14 or Wednesday 24/09/14