PSY294 – Lab Report
Throughout the course, you’ve learned that the world is complex and ambiguous, so we all have to rely on heuristics and biases to get by. These shortcuts aren’t perfect, but they help us a great deal. Many of the failures of these everyday heuristics are traceable to a failure to make use of the safeguards built into scientific procedures. To improve everyday thinking, we ought to become better intuitive scientists.
One way to become a better intuitive scientist might be to pretend that you are one, and apply the tools of the trade. Your task, therefore, is to write a journal-style report for Lab 02 – Memory Span. A large portion of the report is research. If you’re going to write a lab report, then you had better know everything possible about this topic so you can write, speak, and reason about it effectively.
We’re interested in whether you genuinely understand the material that we’ve been discussing in the course and how well you can apply it. The lab report is worth 40% of your final grade. Become familiar with the marking guide. The majority of marks go to the introduction and discussion, and not just reporting the results correctly (although this will get you marks too!). The points below are also important for gaining good marks, even though some may not be specifically outlined on the marking guide.
Introduction
• Review relevant literature- aim here is to build up a rationale for your study culminating with the specific aims and hypotheses.
• Including irrelevant information will lose you marks.
• Ensure you are using past research to build up an argument, rather than simply ? describing the research (i.e., Do not just simply state what the researchers did and what their main findings were – also think about how this past research relates to your current aims/predictions) (make sure that your arguments all flow logically from one another. Tip: use linking sentences at the start of each paragraph to direct your reader- i.e.,: Accordingly, Consequently, Conversely, Additionally, However, Nevertheless.)
• Marking guide states- “displays evidence of understanding of theoretical issues/ questions underlying chosen topic”. Won’t be able to demonstrate this by simply listing past research findings.
• Be sure to include a clear statement of the overall aim of the study. ?Hypotheses
• Good idea to set context for hypotheses “i.e. To examine whether…. participants were required to….. and X was measured as an indication of Y”
• Should also link clear rationale to hypotheses… e.g.., “based on the theory that…./ based on previously found effects of…. it was hypothesised that…..” not simply “based on past research it was hypothesised that….”- this is not clear/explicit enough.
• Make hypotheses very clear. i.e., state “it was hypothesised….” to ensure reader is clear that these are your explicit hypotheses. Must state hypotheses in terms of the explicit variables measured (need to be clear on what IVs and DVs are).
Method
• Include separate subsections: i.e., Design, Participants, Materials and Procedure. if you are unsure what to include in these sections, you should consult a writing for psychology guide, such as those written by Burton or O’Shea (copies available in the library). APA style.
• Participants were presented with a range of visual stimuli representing either a string of letters, numbers or words. The items of each list flashed sequentially on the screen for a brief amount of time. Participants were asked to recall the string of items in order by pressing the correct sequence among a range of choices shown on the screen using the computer mouse. There were 30 trials to this experiment.
• Write up methods as if this was a controlled experiment, not a tutorial class. We know that you did this in a classroom, but we want to see whether you can write this report as a researcher, not as a student. Thus, do not include details such as which tutorial class, the classroom number, etc.
• Should be as detailed as possible (i.e., replicable) and demonstrate your understanding of why the experiment was conducted in the way it was, but still CONCISE (not repetitive or wordy)- so try not to give information that is not pertinent to the design of the study.
• It is important to give details of the stimuli (materials section) and make it clear how the stimuli were presented (e.g position on screen), and why they were presented in that way (e.g.., so each half of stimuli is presented to a different visual field). Consider attaching stimuli lists as an appendix- but even if you do this, you still have to describe the stimuli to some degree, and must refer to the appendix in text. ?Results
• Do not fully interpret results here (i.e., what the results say with regards to theory/ methodology etc), but still a basic interpretation of where significant differences or relationships were/were not and direction of these differences/relationships: to do this inferential statistics must be interpreted in relation to descriptive statistics:
i.e., The descriptive (means) show DIRECTION (i.e which group/stimuli was higher/lower, faster/slower, whether a response increased or decreased compared to baseline. etc. But descriptive alone do not show whether these differences in responses/groups etc are significant).
The inferential stats show SIGNIFICANCE (i.e significant differences but not the direction of these relationships). (which is why you need to report and interpret BOTH).
• May want to consider the use of figures to display meaningful comparisons, or tables if have several means to report. All must be in APA format.
Discussion
• Directly address the hypotheses! Were they met or not? What results indicated this?
• Compare and interpret results in light of previous theory/literature- are they consistent with previous results? If not, why might this be (alternative explanations for results)? Should also consider alternative explanations to your results based on existing literature even if your hypotheses were met.
• Methodological limitations of this study- Explain carefully exactly HOW limitations may have affected the results. Pointing out a possible limitation without explanation of how specifically it might have affected your results is not useful (and will not receive any marks).
• Simply stating that because the sample consisted only of uni students, the results of the study are not generalisable to the greater population is NOT a sufficient limitation. Only talk about the “uni student” limitation if you can explain logically and specifically how using this sample may have affected the results in some way. However, there will likely be much more relevant limitations on which you you could be focusing.
• Implications of this study in terms of theory and how these results might be used to inform real-life problems (i.e., practical applications?). Future research suggestions- may tie into limitations. Include a short (but solid!) conclusion- do not introduce new info here.
•
PSY294 – Lab Report – Memory Span – Data
Many theories of cognition propose that there is a short-term 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 short-term 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 short-term
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 repeated-measures 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, then you have two options for error bars: 1) plot the
standard error as the error bars, or 2) plot the 95% Confident Interval. 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 line-graph; 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]
Within-Subjects Factors
Measure: Length
ListType
Dependent
Variable
1
2
3
Digits
Letters
Words
Measure: Length
Descriptive Statistics
Mean
Std.
Deviation N
Digits
Letters
Words
6.6267 1.40252 150
5.8933 1.41491 150
4.0667 .92444 150
Multivariate Testsa
Effect Value F
Hypothesis
df Error df Sig.
Partial Eta
Squared
ListType Pillai’s Trace
Wilks’ Lambda
Hotelling’s Trace
Roy’s Largest Root
.766 242.737b 2.000 148.000 .000 .766
.234 242.737b 2.000 148.000 .000 .766
3.280 242.737b 2.000 148.000 .000 .766
3.280 242.737b 2.000 148.000 .000 .766
Design: Intercept
Within Subjects Design: ListType
a.
b. Exact statistic
Mauchly’s Test of Sphericitya
Measure: Length
Within Subjects Effect Mauchly’s W
Approx. ChiSquare
df Sig.
Epsilonb
GreenhouseGeisser
Huynh-Feldt Lower-bound
ListType .988 1.775 2 .412 .988 1.000 .500
Measure: Length
Tests the null hypothesis that the error covariance matrix of the orthonormalized transformed dependent variables is
proportional to an identity matrix.
Design: Intercept
Within Subjects Design: ListType
a.
May be used to adjust the degrees of freedom for the averaged tests of significance. Corrected tests are displayed in
the Tests of Within-Subjects Effects table.
b.
Page 1
Tests of Within-Subjects Effects
Measure: Length
Source
Type III Sum
of Squares df Mean Square F Sig.
Partial Eta
Squared
ListType Sphericity Assumed
Greenhouse-Geisser
Huynh-Feldt
Lower-bound
Error(ListType) Sphericity Assumed
Greenhouse-Geisser
Huynh-Feldt
Lower-bound
521.404 2 260.702 264.914 .000 .640
521.404 1.976 263.810 264.914 .000 .640
521.404 2.000 260.702 264.914 .000 .640
521.404 1.000 521.404 264.914 .000 .640
293.262 298 .984
293.262 294.489 .996
293.262 298.000 .984
293.262 149.000 1.968
Measure: Length
Tests of Within-Subjects Contrasts
Measure: Length
Source ListType
Type III Sum
of Squares df Mean Square F Sig.
Partial Eta
Squared
ListType Linear
Quadratic
Error(ListType) Linear
Quadratic
491.520 1 491.520 450.742 .000 .752
29.884 1 29.884 34.047 .000 .186
162.480 149 1.090
130.782 149 .878
Measure: Length
Tests of Between-Subjects 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
Measure: Length
Transformed Variable: Average
Estimated Marginal Means
ListType
Estimates
Measure: Length
ListType Mean Std. Error
95% Confidence Interval
Lower Bound Upper Bound
1
2
3
6.627 .115 6.400 6.853
5.893 .116 5.665 6.122
4.067 .075 3.918 4.216
Measure: Length
Page 2
Pairwise Comparisons
Measure: Length
(I) ListType (J) ListType Mean Difference (I-J) Std. Error Sig.b
95% Confidence Interval for Differenceb
Lower Bound Upper Bound
1 2
3
2 1
3
3 1
2
.733* .112 .000 .462 1.005
2.560* .121 .000 2.268 2.852
-.733* .112 .000 -1.005 -.462
1.827* .111 .000 1.559 2.095
-2.560* .121 .000 -2.852 -2.268
-1.827* .111 .000 -2.095 -1.559
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
ListType
1 2 3
Estimated Marginal Means 7.00
6.50
6.00
5.50
5.00
4.50
4.00
Estimated Marginal Means of Length
Page 3
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
There are articles on LMS under Lab 02. These are just to give you a starting point for
your assignment. You will need to make use of additional citations, both those referred
to within these articles (make sure you get them yourself – no secondary citations!)
and ones that you have located yourself (e.g., on PsychInfo).
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
peer-reviewed. That is, only use published journal articles. Do not copy from or cite
the slides.
Your hypothesis is very important. Your hypothesis would 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 hypothesis 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.
