Aim, Hypothesis, and IV/DV
Title: Experiment to look at acoustic similarity of words and the effect on STM
Aim: To investigate the effect of acoustic similarity on STM
Experimental Hypothesis: More acoustically dissimilar words will be recalled that acoustically similar ones. WHY? - STM uses acoustic encoding so similar sounding words are more difficult to encode.
Null Hypothesis: There will be no difference in the number of acoustically similar words and acoustically dissimilar words recalled; any changes in results are due to chance.
IV: Acoustically dis/similar words,all 3 letters,one syllabal,same freq in life,10 words for each list
DV: number of words recalled
Important Aspects of Procedure
All 16-18 yrs old - gave consent
Opportunity Sampling - memory is universal so no special attributes needed
Standardised Procedure - to repolicate same experience
Word lists - Kept standardised to increase reliabilty
Time to learn words/recall words - set time so no ppt had advantage over another
Controlled environment - to ensure no interference from extreneous variables
Indepedent Measures Design (each ppt takes part in only one condition) - to avoid demand characteristics, and order effects, thus increases validity.
Consent - gave to a degree possible without impacting results
Right to withdraw - we told them this at the start, and asked at the end if it was ok to stil use their data
Confidentiality - No ppt names used
Debrief - told ppts aim at end, and asked if they had any questions
The observed value of the Mann-Whitney test was 16.5. This was equal to/less than/greater than the observed value of 27 for a one/two tailed test at P<0.05 with N=10. Therefore the result is/isnt significant and the experimental/null hypothesis can be supported. This states that: People can recall acoustically dissimilar words better than acoustically similar words.
- Standardised Lab experiment and standardised procedure so can be replicated; high reliability.
- Can be applied to revision techniques.
- Ethical study
Weaknesses and Solutions
- All 16-18 paston students thus cant generalise results - Use a sample including adults and students from other colleges
- Opportunity sampling used so may present researcher bias - Use a random sample so all ppts have equal chance of being selected.
- Didnt test for dyslexia or other learning difficulties that may have affected results - Use a questionnaire beforehand to check their abilties.
- Ppts may have been aware of the study beforehand - ask them to check and exclude them if they have
- Demand charactersitcs may have been presented - Use a single/double blind procedure
- Low Ecological Validity and lacks mundane realism - Carry out tests in more natural setting
Independant design: Mann-Whitney U test
1. Rank score for all ppts
2. Calculate sum of all the ranks for each group seperately
3. Use formula to calculate Ua for each group
4. Smallest number is the observed value of U
Repeated Measures: Wilcoxon test - used as a test of difference between two conditions when data is ordinal
1. Calculate differnece in scores from each condition, and rank the differences.
2. Calculate sum of the ranks for positive differences, then sum for negative differences
3. T value is the smallest number