COGN. PRACTICAL INVESTIGATION
Background:
Baddeley (1966b): acoustically similar perform worse but forgotten less
= words still in STM for semantically similar words lost by the time of retest
Aim: to investigate effect of acoustic similarity on STM
IV: acoustically similar/dissimilar words
DV: n. words recalled from list of 10 in a free-recall memory test
Experimental hypothesis: more acoustically dissimilar-sounding words recalled than
acoustically similar-sounding words
Null: no significant difference in n. Acoustically similar/dissimilar-sounding words recalled
(due to chance)
Independent groups design (test for difference btw diff conditions, ordinal data)
Opportunity sample
P:
1) 20s to learn list of acoustically similar words
Screen blank: 30s to recall list in any order
2) 20s to learn list of acoustically dissimilar words, then 30s recall
R:
Acoustically similar Acoustically dissimilar
Mean 6.2 6.6
Median 6 7
Mode 6,7 7
Range 2 3
SD 0.67 1.02
More acoustically dissimilar words recalled
Mean : 6.6 > 6.2 acoustically similar
SD: 1.02 >0.67 similar = greater spread of results for acoustically dissimilar (some easier to
recall, but others harder to recall )
Mann-Whitney U test:
U = 9.5 > 4 (ct) for 1-tailed test at p<0.05 with N1/2= 5
Result is not significant and null hypothesis accepted
C: Baddeley (1966b) recall of acoustically similar words worse
U = no significant difference in recall
Background:
Baddeley (1966b): acoustically similar perform worse but forgotten less
= words still in STM for semantically similar words lost by the time of retest
Aim: to investigate effect of acoustic similarity on STM
IV: acoustically similar/dissimilar words
DV: n. words recalled from list of 10 in a free-recall memory test
Experimental hypothesis: more acoustically dissimilar-sounding words recalled than
acoustically similar-sounding words
Null: no significant difference in n. Acoustically similar/dissimilar-sounding words recalled
(due to chance)
Independent groups design (test for difference btw diff conditions, ordinal data)
Opportunity sample
P:
1) 20s to learn list of acoustically similar words
Screen blank: 30s to recall list in any order
2) 20s to learn list of acoustically dissimilar words, then 30s recall
R:
Acoustically similar Acoustically dissimilar
Mean 6.2 6.6
Median 6 7
Mode 6,7 7
Range 2 3
SD 0.67 1.02
More acoustically dissimilar words recalled
Mean : 6.6 > 6.2 acoustically similar
SD: 1.02 >0.67 similar = greater spread of results for acoustically dissimilar (some easier to
recall, but others harder to recall )
Mann-Whitney U test:
U = 9.5 > 4 (ct) for 1-tailed test at p<0.05 with N1/2= 5
Result is not significant and null hypothesis accepted
C: Baddeley (1966b) recall of acoustically similar words worse
U = no significant difference in recall
