Practical Investigation

• Aim


  To investigate recall of acoustically similar and dissimilar words in the short-term memory.
• Experimental hypothesis


  To investigate whether acoustically dissimilar words are more easily recalled by STM than acoustically similar words, by providing a list of similar and dissimilar words to participants. This is a directional hypothesis.
• Null hypothesis


  Acoustically similar and dissimilar words will be remembered equally, no difference.
• Independent variable


  Changing whether the 10 words on the list are acoustically similar or dissimilar.
• Dependent variable


  Measuring how many of the 10 words each participant remembers after 10 seconds.
• Type or experiment


  Laboratory experiment.

  + High control, minimising extraneous and confounding variables.

  + Easy to replicate, procedure and instructions are standardised.

  - Contrived situation, participants behaviour may not be natural.

  - Demand characteristics, researcher bias reduces validity.
• Sampling method


  Opportunity sampling.

  + May be only technique available as whole target population can't always be reached.

  + Most convenient, takes little prep as you use first people available.

  - Biased as sample is drawn from small part of target population (people free, e.g. unemployed).

  - Participants may refuse to participate even if they're available, it ends up as volunteer sample.
• Experimental design


  Repeated measures design, chose as it means each ppt takes part in all conditions, which gives good control.

  + Good control of ppt variables as same person is tested twice.

  + Fewer ppts needed, important as more data makes conclusions more dependable.

  - Order effects produced.

  - Ppts may guess aims of study and act in a way to please experimenter.
• Which variables other than the IV are you going to control?

  You would also need to control the noise levels of the rooms participants are in as this can cause distractions and effect the ability of their STM, as this would make the results obtained from the study less valid.
• Ethical considerations


  We gained full consent of participants before we conducted the experiment on them. We also informed them they have the right to withdraw from the study if they wanted. We also didn't put them in harms way. But deception and withholding aims was necessary as we needed to avoid participants from guessing the aims and demonstrating demand characteristics.
• Standardised instructions


  -First you will be presented with list A, you have 10 seconds with the list to try to remember as many as you can.

  -Once the 10 seconds is up you'll have another 10 seconds without them in-front of you.

  -You'll them be asked to recall as many of the words as possible. We will keep track of this number.

  -You will then be given list B and we will repeat the same procedure but with different words.
• Results of acoustically similar words

  Mean: 7.2

  Mode: 7

  Median: 7

  Range: 4

  Standard deviation: 1.32
• Results of acoustically dissimilar words

  Mean: 6.9

  Mode: 6 and 7

  Median: 7

  Range: 3

  Standard deviation: 0.99
• Wilcoxon singed rank test results

  T=9

  Critical value of T=2

  There is no significant difference between remembering acoustically similar and dissimilar words, as observed value of T (9) is not equal to or less than the critical value of T (2).
• Conclusion


  In conclusion, I found from the results, that my original hypothesis was wrong. Instead we found that acoustically similar words were more easily remembered/recalled than acoustically dissimilar. Supported by the average number of similar words remembered being 7.2, whereas dissimilar words were 6.9. This links to classic study Baddeley (1966b), as their study found more acoustically similar words were remembered than dissimilar.
• Strengths of my experiment

  -Validity: I believe my results were valid as the lists as well as instructions were standardised and used on all participants were the same.

  -Reliability: The results obtained are reliable as the lists used were the same for all participants, meaning it is easily replicated.

  -Generalisability: Results are fairly generalisable as I conducted the experiment on participants on a range of ages and sexes.
• Weaknesses of my experiment

  -Ecological validity: Lacks ecological validity as it was a lab experiment, settings were artificial and participants may behave in a way as to please the experimenter (demand characteristics).

  -Mundane realism: The task of remembering words from two lists isn't an everyday task that participants would take part in.

  -Reliability: Couldn't be so reliable as the repeated measure design means participants take part in both conditions, they may guess aims and behave how they think the experimenter wants them to.
• aim

  to investigate whether acoustically dissimilar words are easier to remember in STM than acoustically similar words
• hypotheses - experimental


  ppts will recall more words in the correct order from a list of 10 acoustically dissimilar words compared to a list of acoustically similar words
• hypotheses - null


  there will be no difference in the number of words recalled between acoustically similar and acoustically dissimilar word lists
• method - what was the IV

  the type of word list - acoustically similar or dissimilar
• method - what was the DV

  the number of words correctly recalled in 1 minute
• what type of participant/experimental design was used, how

  independent groups - one group did acoustically similar condition, the other did acoustically dissimilar condition
• why was an independent groups design used

  to reduce demand characteristics and order/practice effects
• what kind of sample was used

  an opportunity sample - the year 12 students in the class at the time, mainly female, mainly 16 years old
• procedure


  1 - informed consent gained

  2 - class split into two groups (acoustically similar/dissimilar)

  3 - words presented at rate of 1 word every 3 seconds

  4 - ppts given 1 minute to recall as may words as they could in the correct order

  5 - scored out of 10 for how many were correct
• what kind of data was collected

  quantitative
• what was calculated first

  measures of central tendency
• what were the values of mean, median, and mode for condition A ppts

  mean = 8.75, median = 10, mode = 10
• what were the values of mean, median, and mode for condition B ppts

  mean = 8, median = 8, mode = 10
• what was calculated next

  measures of dispersion
• what was the range for condition A

  7
• what was the rang for condition B

  6
• what was the standard deviation for condition A

  2.14
• what was the standard deviation for condition B

  2.13
• what statistical test was used

  Mann Whitney U
• what was the calculated value for Ua (condition A)

  74
• what was the calculated value for Ub (condition B)

  81
• what was the critical value of the experiment

  38
• were the results significant, why

  no, our calculated values were greater then the critical value for a one tailed test at p≤0.05