The purpose of this week’s lab is to take you through the results and analyses of the Experiment conducted in last week’s lab to prepare you for the write-up and submission of the Laboratory Report. The Laboratory Report is to be submitted by the due date via the Turnitin link on the PSYC2400 Blackboard site.
PSYC2400 Psychology Assignment – Australia.
The broad aim of the Experiment was to collect data that enables us to examine the relationships between personality characteristics, and both physiological and self-reported responses to emotional (or at least evocative) sounds. There is a wide range of potential research questions that could be answered with such a data set, and in this lab report you get
to decide what research questions you will address. For example, you might be interested in whether there is a sex difference in physiological responding to positive sounds, but only for low intensity ones, or that people high in N might show more physiological responding to high intensity negative sounds, or that people high in E might show a dissociation between their physiological and self-reported responses to the sounds, or anything else that you can justify using logic, evidence-based theories, and previous research.
The purpose of the Laboratory Report itself is to provide you with further experience in the analysis and presentation of scientific research relevant to the field of Biological Psychology. This will build upon your previous experience in research analysis and scientific writing that you started in 1st year and will continue throughout your psychology program.
Whether you choose a research or clinical career, or even a career outside psychology, basic research skills, and the ability to produce and understand scientific reports, is an important part of your training, and these skills set you apart from graduates in other disciplines,there by making you a much more attractive prospect for future employers!
Post any questions you have regarding any aspect of the Laboratory Report in the appropriate forum on the PSYC2400 Blackboard. Use some text in your subject line indicating the nature of your question. It would also be really useful to monitor this Forum for information requested by other students.
Learning Objectives:
By the end of this laboratory you should be able to:
1.Generate and test hypotheses based on prior research using the data from the Lab.
2.Use graphs and tables as appropriate for the Laboratory Report.
3.Write a Lab Report using an appropriate structure and style.
The Hypotheses:
The hypotheses are the most important aspect of your Lab report,since only information that is relevant to your hypotheses should be included in your Lab Report. The decision regarding which, or how many, hypotheses you will test is entirely up to you. However, the hypotheses you decide to test with the data must be relevant to previous research/theories defined in the literature that you will review/define in the introduction section of your Laboratory Report.
A hypothesis is essentially a prediction about some effect or relationship that you can test using the data. Because they are predictions based on a theory, hypotheses are usually stated formally as an ‘if-then’ statement. For example, we could state a hypothesis to be tested as:‘IF individuals with a higher levels of Neuroticism are physiologically more sensitive to negative stimuli, THEN Neuroticism score should be positively correlated with mean EDA, HR and Respiration Rate in response to negative sounds.’
If you are expecting a particular result only because people have found that result previously,then that is a simple expectation, it is not a hypothesis.
The Data:
There is a total of 31 variables in the study that we ran over the last two weeks. We measured each participant’s sex and their score on each of the big 5 personality dimensions (that’s 6 variables). We also measured 5 different responses (Rated Valence, Rated Arousal, EDA, HR and Respiration Rate) to 5 different kinds of sounds (neghigh, neglow, poshigh, poslow and start). Combined, that makes another 25 variables for which we have data. Which and how many of these variables you use in your analyses will depend on the hypotheses you decide to test. Your selection of hypotheses should be based on your reading of the relationships between these variables in the reading list for the Lab Report, and on your own reading, as well as hypotheses you can logically derive from existing theories.
There is a spreadsheet on Black Board containing the data for all students who participated in the experiment.
YOU WILL NOT BE ABLE TO INCLUDE ALL THESE VARIABLES OR THE RESULTS OF THE RESULTS SECTION OF THE LAB REPORT. YOU SHOULD ONLY INCLUDE THOSE VARIABLES AND RESULTS THAT ARE RELEVANT TO THE HYPOTHESES THAT YOU CHOOSE TO TEST.
The Design:
The experiment was a mixed design in which we are interested in looking at the relationships between a number of variables. Your experiment included one clear independent variable (Sex), which is also a between-subjects variable. The personality scores can also be thought of/used as between-subjects independent variables if they are used to categorise participants into high/low O, C, E, A, and N. They can also be used/thought of as covariates – variables that might also affect the dependent variables, or that might affect relationships between other variables, or as continuous variables that you can correlate with other variables.
The study also contained 4 within-subjects independent variables, that were manipulated factorially. The sounds that were played were a 2 x 2 cross between two independent (manipulated) variables, valence (positive or negative) and intensity (high or low), making the 4 sound variables pos high, po slow, neg high and ne glow. There were 4 sounds that fit each of those characteristics (making 16 sounds in total), that we averaged across to get a mean score in each category for each participant.
The fifth kind of sound played was a sudden noise (named “start”) designed to produce a startle response. It was just played 4 times at random in the sequence.
The other variables in our study are the dependent variables – the responses made to the sounds, both self-report and physiological (Rated Valence, Rated Arousal, EDA, HR and Respiration rate).
Statistical Analyses:
It is always a good idea to have a look at the descriptive statistics for any variable you include in your analysis, just to check that it is relatively normally distributed and has been collected and recorded properly.
The table above shows an example of the descriptive statistics for the data from the extraversion variable and the arousal ratings given to positive, high arousal stimuli(from data I created) using SPSS (you could also get most of this info with formulas in excel, but SPSS, or even better JASP, enables you to do it for all of the variables at once). I’ve provided all of this info, and frequency histograms for each variable, in the JASP file online in which I analysed your actual data. From the example above, produced using SPSS, we can see that of all the students providing data for this variable (n = 49) that the mean E percentile was 52.88 (with a SD of 24.16), and the data was reasonably normally distributed, since Skewness = -0.414.
You can use these kinds of results in a number of ways in your lab report; to describe the data you are analyzing, to create graphs for use in your lab report, and to determine what type of statistical analysis you will use to test your hypotheses.
In order to test the hypotheses you choose based on your readings, you will need to understand the results of the appropriate statistical analyses of these variables. In the class exercises below we will work through the statistical results provided to learn how to interpret the JASP output of the results provided on Blackboard.
While the results below are limited to t-tests and correlations you are also welcome to undertake your own analyses using the data files also provided on Blackboard. If you do choose to do your own analyses (using JASP or any statistical package you like) your write-up of the analyses must conform to the format of the Lab report described below.
Example t-test comparing the difference between two groups.
Suppose you wanted to test a hypothesis that predicted a difference between males and females in terms of Extraversion or self-reported arousal in response to Positive High intensity sounds. The appropriate statistical test of this hypothesis would an independent samples t-test. As with most statistical tests there are always assumptions about the data that you must meet in order for the statistical results to be valid. For the independent samples t- test, the data should be independent, random samples with the same population variance. A two- sample t-test is fairly robust to departures from normality but both groups need to have reasonably equal variances.
From the table, it can be seen that poshigharousal is not normally distributed (since Levene’s test is significant (p<0.05). In such cases you need to use the t statistic where “equal variances are not assumed” or do a non-parametric test. In the cases above, neither t-test is significant, and so it doesn’t really matter. Again, this is an example using SPSS, but I have provided these test results in the JASP output from analysing your actual experimental data.The t-test results are on the right section, which shows the t statistic (t), the degrees of freedom (df) and the two-tailed significance (Sig, two-tailed). Since the significance is greater than 0.05 we cannot conclude that there is a significant difference between males and females in terms of Extra version (p = 0.889) or in terms of Arousal ratings given to positive high intensity stimuli (p = 0.238).
It is important to remember that if our hypothesis predicted the direction of the difference(and most hypotheses do) then we could use a one-tailed significance level (i.e. half the two-tailed significance). If you have a directional prediction (and so can run a more powerful 1-tailed test), then you cannot support the hypothesis even if the p-value is < 0.05, if the difference is in the wrong (not predicted) direction. This is the other reason it is good practice to make directional predictions – it helps to reduce the type I error rate.
In your Lab Report you would write up the above results as “…the results indicate that males (N=13, M=53.69, SD=19.05) and females (N=36, M=52.58, SD=25.96) do not significantly differ on Extraversion t(47) = -0.141, p = 0.889”, although if you have a graph illustrating these results then you don’t need to report the means and standard deviations in the text.
Example Spear man’s correlation between two variables
Since we are also interested in looking at the relationships between a number of variables,correlations are also an appropriate statistical test to use in your analyses. An example of a correlation analysis you could include in your lab report is to examine the relationship between the personality dimensions and the responses to the sounds. An example hypothesis that could be tested in this kind of analysis would predict that people higher in extraversion would give larger arousal ratings responses to high intensity positive sounds, since they are sensation seekers.
The table above shows the Spear man Correlation Coefficient (0.667), the p value (.000), which provides the Two-tailed test of significance. NOTE: p can’t be 0.000, of course, so we report it as <0.001. If we are predicting the specific direction of the correlation (i.e. positive) between these variables a 1-tailed test of significance could be used. If we are predicting (i.e hypothesising) a relationship where the direction of the relationship isn’t specified then we can only use the 2-tailed test of significance.
These results show that there is a significant correlation between Extraversion and the Arousal rating given to positive, high intensity stimuli. Therefore, we would conclude that the hypothesis above is supported.
PSYC2400 Psychology Assignment – Australia.
This could be written in the results section of your lab report as “There was a significant positive correlation between Extra version and the Arousal rating given to positive, high intensity stimuli, (r(49) = 0.667, p < 0.001).” Note that in reporting a correlation, degrees of freedom aren’t included. Instead, N (number of valid cases) is provided. Degrees of freedom aren’t relevant to correlation analysis, but N is. Don’t forget to mention whether the correlation is positive or negative. This is critical information. Also, state in words what tends to happen to one variable as the other changes.
The Laboratory Report:
The Laboratory Report has a word length of 1200 words (+- 10%) and should conform to the style appropriate for a psychology report (i.e APA format). Since the report is only 1200 words in length you will need to choose your words wisely…be concise and don’t waffle! Figures and tables are not counted in the word length.
PSYC2400 Psychology Assignment – Australia.
General Information:
1.Word count: 1200 words; does notinclude title page, abstract, reference list, figure captions & list of hypotheses
2.Hypotheses are to be written separately and submitted at the start of the assignment (after the abstract, but before intro); they don’t count towards your word count
3.No less than 3 hypotheses
4.Your hypotheses should tell a coherent “story”. Your introduction and discussion should then be about that “story”. You are advised to firstly conduct some background literature research to come up with your approach to this lab report (what exactly you are trying to achieve; your“story”) and then choose your hypotheses based on this research. You will not be marked down if some of your hypotheses are not supported by the data, but you will be marked down if your hypotheses are not coherent – do not have a related theme.
5.Report should be formatted to the APA style with the exception of two points: you are required to submit a list of hypotheses (see below) and for the sake of space you are allowed to shorten references to the surname of the first author followed by “et al.” if there are 3 or more authors (current APA guideline is that this is allowed if there are 6 or more authors). So a reference to Miller and Reedy (1990) has to be written (Miller & Reedy, 1990), but a reference to Bartoshuk, Duffy, Lucchina, Prutkin and Fast (2006) can be written as (Bartoshuket al., 2006).
Title page:
a.Indicate your word count without references, figure captions, abstract and the list of hypotheses
b.Separately indicate the word count of your abstract
PSYC2400 Psychology Assignment – Australia.
Abstract:
1.No more that 120 words (no + 10%, like in scientific journals or conferences)
2.1st sentence – describe general background; but get straight to the point.
3.Include any definitions, if needed, very briefly
4.2nd sentence – brief description of our study
5.3rd & 4th sentences – brief description of our results (doesn’t have to be everything)
List of hypotheses:
In a list form, write your hypotheses. For example:
1.we hypothesize that XXX will be positively correlated with XXX
2.we hypothesize that XXX will significantly higher in males than in females
Note: This section is not normally a part of an APA-style lab report. We only ask you to do it for training purposes, although this requirement is very similar to current requirements of some scientific journals that require a brief list of findings (highlights).
PSYC2400 Psychology Assignment – Australia.
The hypothesis and abstract sections do not count towards your 1200 word count.
PSYC2400 Psychology Assignment – Australia.
Intro:
1st paragraph
opening sentence should be broad, saying that personality or sex, or whatever affects responsiveness to emotional or surprising stimuli(with (a) reference(s))
i) then a few general background sentences, that would describe findings that justify, why are we using the physiological measures we took (if you have those in your hypotheses), why are we measuring personality (if you have it in your hypotheses) and how these things are related to self-report ratings and other kinds of responses to emotive sounds(i.e. this section should logically outline previous studies that you used to come up with the hypotheses)
ii) Most of the sentences in this paragraph should have references, as you are describing background of our study. You should have at least 5 references here
iii) a concluding sentence should indicate something that is still unknown (links between XXX and XXX still remain unknown/are currently unknown; or… sex (or personality) differences in XXX were never directly investigated)
*Not everything that we investigate needs to be novel. ie. we might investigate a particular correlation as a check that the general assumption of these two things being related works in our sample. And then, after we confirmed that they are related, we might investigate something else that is novel.
PSYC2400 Psychology Assignment – Australia.
2nd paragraph:
i) You need to detail specific aims of our study or hypotheses. In order to make it flow better,each of your hypotheses can be written either as an aim or as a specific prediction. For example, ‘In this study we aim to investigate a relationship between XXX and XXX/ we aim to investigate a correlation between XXX and XXX / we will investigate sex/age differences in XXX / we expect that XXX is related to XXX / if that is true, then we expect that XXX is
correlated with XXX.
ii) This section SHOULD flow well; you should not use the same sentence template and just change the variable names.
Methods:
You only need to describe the procedures that are relevant to your hypotheses– just say that other things were also measured, without giving details.
PSYC2400 Psychology Assignment – Australia.
Depending on your hypotheses, you might need to describe the following:
- Number of participants (their mean age and number of males and females in brackets) recruited from a 2nd year Biological Psychology Course.
- Methods relating measuring personality – online, which test, etc.
- Methods related to playing the sounds – through headphones, in random order, etc.
- Methods relating to self-reported valence and arousal – scales used, how reported, etc.
- Methods relating to physiological recording – what measures taken, with what recording equipment, etc.
Results:
You should write all your results in 1 paragraph with references to corresponding Figure numbers (can be done in brackets). For example:
PSYC2400 Psychology Assignment – Australia.
We found a significant positive correlation XXX and XXX, ρ =.184, p = .0139 (Figure 1).
Females had a significantly higher XXX than males, t (134.1) = 3.645, p =.043 (Figure 2).
Revise-revise-revise to make it flow well! But use only professional language
For any t-test differences results: you do NOT need to report means and standard deviations in the text, since you are to report them in the graph(s).
PSYC2400 Psychology Assignment – Australia.
For correlation results: you SHOULD report a mean and a standard deviation in the text or figure caption, as you do not have that information in a graph(s).
To make it flow better you can briefly summarise findings, but don’t link it to previous literature. You should have a graph for each hypothesis: column graphs for sex or personality differences hypotheses (with Standard Error bars) and scatter plots for correlation hypotheses with a line of best fit (scientific reports don’t usually have scatter plots of correlations, but as an educational exercise, you should include them to remind yourself of what exactly the correlation measures).
Discussion:
You should start the 1st paragraph with a phrase like “The principal finding of our experiment is…”. In this paragraph you should describe/repeat all of your findings relating to the hypotheses that you had. You should not write it as “Our first hypothesis was supported; our second hypothesis was not supported”, but rather “We found that…”, “XXX was significantly related/different to/from”, “Interestingly/surprisingly/unexpectedly XXX was not different/not related from/to…”
In the 2nd paragraph you should link our findings with the previous literature (at least 3 references, some of them (or all) should not have appeared in the intro). For example, “our study further extends a study by XXX by demonstrating…” or “We have found support for the findings of…” – and then briefly discuss what it means (i.e. “Therefore, higher XXX is
associated with greater responses to XXX”). Towards the end of this paragraph you should have a broader link with research describing real world, or broader theoretical implications No stats or references to figures in the discussion
PSYC2400 Psychology Assignment – Australia.
Your discussion should flow well, but use only professional, scientific language You should try to “sell” our study here, describe what is novel about it and how it complements previous literature