Consciousness

Topic: Sleep’s relationship to other variables (academics, mood, illness, personality)

Statistical Concepts Covered: In this applet, you’ll explore correlational data – data that show a relationship between two variables, but which cannot be used to make claims about causation. You will also think about the potential drawbacks of collecting data by asking individuals survey questions about their habits.

Introduction:

In Chapter 5 you read about the debate surrounding how much sleep you need. While you might think that you can function well on less sleep, studies show that there is a solid relationship between sleeping and learning and memory. In this activity, you will analyze data from the National Longitudinal Study of Adolescent Health, which measured adolescents on a wide range of variables including sleep habits and emotional and academic well-being. Nearly 5000 individuals were measured for the study, and you will analyze representative data from 500 of them to draw conclusions about how sleep (or lack thereof) can affect academic and social variables.

Richard Alan Hullinger, Indiana University, Bloomington
Melanie Maggard, University of the Rockies

Question

1) Using the drop down menu below the graph area, create a histogram that shows the distribution of reported hours of sleep for the students. (Select “Sleep Frequency” for the y-axis.) How would you describe the distribution?

All of the students fall into a narrow range of values between 6 and 9 hours of sleep per night.

Most of the students report getting 7 or 8 hours of sleep per night, with many fewer students getting either more or less sleep than that.

Most of the students either get very little or very large amounts of sleep, with only a few students getting the average of 7 to 8 hours per night.

The students are evenly distributed across all the values, with roughly the same number of students reporting 5 hours as reporting 7, 8, or even 10 hours.

Correct.

Incorrect.

Question

2) The textbook cites a study (Stickgold et al., 2000) showing that a lack of sleep results in reduced learning if individuals are kept up all night. Does the same relationship hold if people are allowed to sleep, but just get less sleep? Generate a plot that shows the number of students (i.e., frequency) who report earning As in History classes based on their reported hours of sleep per night.(Choose “Grade History” for the Y axis and “A” as the level to display for a frequency type of graph.) Which of the following statements best describes the data?

The more sleep a student gets, the more likely he/she is to earn an A.

The less sleep a student gets, the more likely he/she is to earn an A.

The amount of sleep a student gets does not have a clear relationship to History grades.

Too little sleep or too much sleep both appear to have a negative relationship with grades.

Correct.

Incorrect.

Question

3) Looking at a graph of frequency data can sometimes lead to incorrect, or at least misleading conclusions. It could be that 8 hours of sleep is the magic number, and students who get too much or too little sleep perform worse in school. However, all we know from the data is that within the group that reported 8 hours of sleep per night, 46 of them earned As, and within the group that reported 5 hours of sleep per night, only two of them earned As. What is one potential problem with viewing the data this way? (Hint: Think about the graph you created for the first question in this exercise, and how many students reported 5 hours of sleep in comparison to those that reported 8 hours of sleep.)

It could be that the students who get 8 hours of sleep per night are more likely to be lying about their grades, so we cannot trust those responses.

The students who get less sleep per night have more time available for studying, so the graph should show that they get better grades.

Most students do not earn an A in History, so the data should not be used to generate any conclusions about sleep and learning.

Since fewer students overall get 5 hours of sleep per night, we would expect there to be fewer total students who get 5 hours of sleep and also get As, so the frequency data could be misleading.

Correct.

Incorrect.

Question

4) One way to account for the fact that there were many more students getting 8 hours of sleep per night than there were getting 5 (or 10) hours of sleep is to use percentages: What percentage of the students who got 8 (or 5, or 10) hours of sleep also earned As in History? (Modify the graph from the second question to show the percentage of students who receive an A in History and note how the graph changes.) Which of the following statements best describes these results?

Too little sleep or too much sleep both appear to have a negative effect on grades.

The amount of sleep a student gets does not have a clear relationship to History grades.

The less sleep a student gets, the more likely he/she is to earn an A.

The more sleep a student gets, the more likely he/she is to earn an A.

Correct.

Incorrect.

Statistical Lesson. It is important, when interpreting graphs that show frequency data, to think about the base rates: the underlying frequency of an event regardless of a secondary variable that you are studying. In this example, because most students report getting 7 or 8 hours of sleep per night, it shouldn’t be surprising that the number of students who earn As is higher in those categories. Looking at the data as percentages, comparing what portion of all 8-hour sleepers earned As compared to what portion of all 10-hour sleepers earned As, can provide a less biased view of the underlying relationship.

Question

5) In the section on sleep deprivation, the authors state that “even for healthy young humans, a few hours of sleep deprivation can have a cumulative detrimental effect: reducing mental acuity and reaction time [and] increasing irritability and depression... (Coren, 1997)”. Is this statement borne out by the data? Graph the relationship between hours of sleep per night and reports of “having the blues all the time.” (Choose “Had The Blues” for the Y axis and “3-All the time” as the level to display for a frequency type of graph, then look at the percentage graph.) What do the data show?

Reports of having the blues increase as the amount of sleep increases.

Few students reported having the blues all the time but the percentage reports decrease as the amount of sleep increases.

Few students reported having the blues all the time but the percentage reports are the smallest with 8 – 9 hours of sleep per night, and increase with more or less sleep.

Reports of having the blues are independent of the amount of sleep per night.

Correct.

Incorrect.

Question

6) The data indicate that there is a relationship between the reported amount of sleep per night and “the blues.” Based on the results you just graphed, which of the following theories could be true?

Increasing amounts of sleep, to a point, causes a reduction in sadness or ”the blues”.

Being sad or having the “blues” typically causes individuals to sleep less or much more than typical.

Some third factor, such as stress about school or family matters may be causing a loss of sleep and also causing ”the blues”.

All of these explanations are supported by the study data.

Correct.

Incorrect.

Question

7) Based on the relationship between sleep and “the blues” you may expect to see a similar (but opposite) relationship between sleep and feeling hopeful about the future. Explore the data associated with feeling hopeful about the future and sleep. (Choose “Hopeful About Future” for the Y axis and “3-All the time” as the level to display for a frequency type of graph, then look at the percentage graph.) How does it compare to the data for “the blues”?

As sleep increases, hopefulness increases, and the relationship is stronger than it is for ”the blues”.

It is difficult to see a clear relationship between sleep and hopefulness.

The same relationship holds, as sleep increases, hopefulness decreases drastically and then rises again.

The opposite relationship occurs, as sleep increases, hopefulness decreases drastically.

Correct.

Incorrect.

Question

8) Several studies show that sleep is related to memory, learning, and mood, but is it also related to overall intelligence? That leads to another question, does more sleep make you smarter (or do smarter people get more sleep)? Create a graph that can answer this question based on the given data. (Choose “Intelligence” for the Y axis and observe how the graphs change as you change the level from “Moderately below average” up to “Extremely above average”.) What is your conclusion?

Individuals with average intelligence levels all get between 7 and 9 hours of sleep per night.

Increasing amounts of sleep is associated with higher intelligence levels.

Individuals with the highest intelligence need less sleep than those with lower intelligence.

There is no clear relationship between intelligence levels and hours of sleep.

Correct.

Incorrect.

Question

9) Surveys are a very powerful research tool, but they are not perfect. One potential downside is that many individuals have a tendency to provide the responses that they think the researcher expects (remember demand characteristics from Chapter 2?), or that they present themselves in the most favorable light, even when they know that the answers are anonymous. How could these factors influence the data collected in this survey?

Participants may be overstating the amount of sleep that they actually get because they know they are supposed to be getting around 8 hours of sleep per night.

Participants may be under-reporting their sadness or illnesses.

Participants may be over-reporting their academic performance or hopefulness.

It is possible that the participants are doing all of these things.

Correct.

Incorrect.

Question

10) Which of the following techniques would be the best method to minimize the demand characteristics when collecting data for studies similar to this one?

Using medical records and school transcripts to collect the grade and illness data.

Making sure that each participant knows that the data is anonymous.

Having a researcher follow participants and write down when they go to bed and wake up in the morning.

Asking parents to report sleep and happiness data for their children instead of having the children do it themselves.

Correct.

Incorrect.

Chapter . Consciousness

Consciousness

Question

Question

Question

Question

Question

Question

Question

Question

Question

Question