PSY294 – Lab Report – Memory Span – Data
Many theories of cognition propose that there is a shortterm or working memory
system that is able to hold a limited amount of information for a short period of time.
The memory span experiment is one measure of working memory capacity. In this
experiment, participants are given a list of items and asked to recall the list. The list
length is varied to see at what list length participants will make make few errors. That
list length is the memory span for that person on that task. Individuals with larger
memory spans can better keep in mind different stimuli, and this seems to give them
an advantage for a wide variety of cognitive tasks. Memory span has been linked to
performance on intelligence tests, standardised tests, reading skills, problem solving,
and a variety of other cognitive tasks.
The very existence of shortterm memory is largely based on memory span types of
experiments, as it was noted that memory span was approximately seven items (plus
or minus two) for a wide variety of stimuli. This suggested a simple storage system
that held approximately seven items. Later studies demonstrated that memory span
could be systematically influenced by a variety of stimulus characteristics, including
the type of item. These findings have suggested that the capacity of shortterm
memory is controlled by verbal processes. This experiment allows you to measure
your memory span for three different stimulus types.
Methods
On each trial, you saw a list of items presented one at a time in random order and
were asked to recall the items in the same order in which they were presented. If you
got a list correct, the list length increased by 1 for that type of material. If you got a list
incorrect, the list length decreased by 1.
The independent variable is the type of material you were asked to recall: digits,
letters, or words. Memory span can be measured in lots of different ways. In this lab,
the dependent variable is the length of the last list you correctly recalled.
The first list of each type of item was 3 items long. The longest list that was shown
was 10, so the maximum score possible is 10.
Independent Variable
Our Independent Variable (IV) is “Type of List” or “List Type” or “Stimulus Type”: digits,
letters, or words.
Dependent Variable
Our dependent variable (DV) is the length of the last list that was correctly recalled.
Data
The data were not screened for outliers. Raw data is available on LMS under Lab 02.
Analyses
A repeatedmeasures ANOVA was conducted with an alpha level of 0.05.
It’s your job to interpret and present this data, in APA format, in your lab report.
If you are going to use a graph, be sure to include appropriate error bars. If you are
reporting the descriptives in text or in a table, then you can report the Standard
Deviation (SD) found in the descriptives table.
Consider the use of tables or graphs to display descriptive statistics. Continuous
variables should be displayed in a linegraph; categorical variables should be
displayed in a bar graph.
GLM Digits Letters Words
/WSFACTOR=ListType 3 Polynomial
/MEASURE=Length
/METHOD=SSTYPE(3)
/PLOT=PROFILE(ListType)
/EMMEANS=TABLES(ListType) COMPARE ADJ(BONFERRONI)
/PRINT=DESCRIPTIVE ETASQ
/CRITERIA=ALPHA(.05)
/WSDESIGN=ListType.
General Linear Model
[DataSet0]
WithinSubjects Factors
Measure: Length
ListType  Dependent Variable 
123  Digits Letters Words 
Descriptive Statistics
Mean  Std. Deviation 
N  
Digits Letters Words 
6.6267 5.8933 4.0667 
1.40252 1.41491 .92444 
150 150 150 
Multivariate Testsa
Effect ListType Pillai’s Trace . Source 
766 242.73 Type III Sum of Squares 
7b df 
2.000 148. Mean Square 
000 F 
.000 Sig. 
.766 Partial Eta Squared 
Wilks’ Lambda Hotelling’s Trace Roy’s Largest Root . 3. 3. ListType Sphericity Assumed GreenhouseGeisser HuynhFeldt Lowerbound 
234 242.73 280 242.73 280 242.73 521.404 521.404 521.404 521.404 
7b 7b 7b 2 1.976 2.000 1.000 
2.000 148. 2.000 148. 2.000 148. 260.702 263.810 260.702 521.404 
000 000 000 264.914 264.914 264.914 264.914 
.000 .000 .000 .000 .000 .000 .000 
.766 .766 .766 .640 .640 .640 .640 
Design: Intercept Within Subjects Design: ListTy a. b. Exact statistic Error(ListType) Sphericity Assumed GreenhouseGeisser HuynhFeldt Lowerbound 
pe 293.262 293.262 293.262 293.262 
a .984 .996 .984 1.968 
298 294.489 298.000 149.000 
Value F
Hypothesis
df Error df Sig.
Partial Eta
Squared
Mauchly’s Test of SphericityMeasure: Length
Within Subjects Effect M Source ListType ListType near (I) ListType (J) ListType 
auchly’s W Approx. C Square of Squares df 491.520 1 Mean Difference (IJ) 
i df Mean Squ 491.5 Std. Error 
Sig. are F 20 450.74 Sig.b 
Greenhouse Sig. Squared 95% Confidence Interval for Differenceb 

Tests the null hypothesis Quadratic Error(ListType) Linear 1 2 3 
that the error covariance 29.884 1 162.480 149 .733* 2.560* 
matrix of th 29.8 1.0 .112 .121 
e orthonorm 84 34.04 90 .000 .000 
alized transformed depe 7 .000 . .462 2.268 
ndent variables 186 1.005 2.852 
proportional to an identit Design: Intercept a. Quadratic 2 1 3 
y matrix. 130.782 149 .733* 1.827* 
.8 .112 .111 
78 .000 .000 
1.005 1.559 
.462 2.095 
May be used to adju b. 3 1 2 
st the degrees of freedom 2.560* 1.827* 
for the ave .121 .111 
raged tests o .000 .000 
f significance. Correcte 2.852 2.095 
d tests are displ 2.268 1.559 
2 .000 .7 Lower Bound 
52 Upper Bound 
Epsilonb
Geisser HuynhFeldt Lowerbound
ListType .988 1.775 2 .412 .988 1.000 .500
Within Subjects Design: ListType
the Tests of WithinSubjects Effects table.
Page 1
Tests of WithinSubjects Effects
Measure: Length
Tests of WithinSubjects Contrasts
Measure: Length
Type III Sum
Partial Eta
Tests of BetweenSubjects Effects
Measure: Length
Transformed Variable: Average
Source
Type III Sum
of Squares df Mean Square F Sig.
Partial Eta
Squared
Intercept
Error
13755.876 1 13755.876 4817.459 .000 .970
425.458 149 2.855
Estimated Marginal Means
ListType
Estimates
Measure: Length
ListType
Mean Std. Error
95% Confidence Interval
Lower Bound Upper Bound
123
6.627 .115 6.400 6.853
5.893 .116 5.665 6.122
4.067 .075 3.918 4.216
Page 2
Pairwise Comparisons
Measure: Length
Based on estimated marginal means
*. The mean difference is significant at the
b. Adjustment for multiple comparisons: Bonferroni.
Multivariate Tests
Value F
Hypothesis
df Error df Sig.
Partial Eta
Squared
Pillai’s trace
Wilks’ lambda
Hotelling’s trace
Roy’s largest root
.766 242.737a 2.000 148.000 .000 .766
.234 242.737a 2.000 148.000 .000 .766
3.280 242.737a 2.000 148.000 .000 .766
3.280 242.737a 2.000 148.000 .000 .766
Each F tests the multivariate effect of ListType. These tests are based on the linearly independent
pairwise comparisons among the estimated marginal means.
a. Exact statistic
Profile Plots
ted Marginal Means
7.00
6.50
6.00
5.50
Estimated Marginal Means of Length
Style Guides
These guides tell you how to write and format a psychology lab report.
Writing for Psychology
6th Edition
Robert P. O’Shea, Wendy McKenzie
http://prospero.murdoch.edu.au/record=b2721143
An interactive approach to writing essays and research reports in psychology
3rd Edition
Lorelle J Burton
http://prospero.murdoch.edu.au/record=b2154828
Background Reading and Tips
One of the skills that these assignments require you to use and develop is being able
to quickly distinguish between literature that is and isn’t relevant. Don’t get swamped
reading up on many different theories, unless you have reason to think they will
provide information that is directly relevant to our experiment. Make sure you know
how to direct your PsychInfo searches.
Refer frequently to the lab report criteria posted on LMS.
You must go beyond the textbook and what was discussed in the tutorial. Use
PsycInfo, Google Scholar, the library, etc. Do not cite internet websites that are not
peerreviewed. That is, only use published journal articles. Do not copy from or cite
the slides.
Your hypotheses are very important. They should be a specific positive prediction
about what you expect to happen, stated in terms of the variables you are measuring
and manipulating. Predict that participants in group A will score more highly than
participants in group B on measure C.
Your hypotheses should be a logical extension of the evidence and arguments you
present in your introduction. In your introduction, you should construct a rationale for
your hypotheses. Do not just base your hypotheses on the results obtained.