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Introduction to psychology

Curriculum statement topic

Introduction to psychology

Chapter contents

Quantitative and qualitative research ...... 000 Investigation designs ............................... 000 Comparing qualitative and quantitative

investigations ................................... 000 Reliability and validity in research ........... 000 Sample and population ........................... 000 Objective and subjective data .................. 000 Methods of assessing psychological

responses ......................................... 000 Making sense of research findings........... 000 Ethical considerations in psychological

research ........................................... 000

In chapter 1, you learnt that psychology uses scientific methods to study behaviour, feelings and thoughts. Psychologists can choose from a range of research methods and investigation designs to systematically collect data in order to test a hypothesis and answer questions about behaviour. Research methods are the tools, or techniques, psychologists use to obtain accurate and reliable information about thoughts, feelings and behaviour. These research methods are used as a part of an investigation design, which is the plan used by a researcher. Each investigation design has its specific purposes, advantages and disadvantages. The choice of investigation design depends on what is most appropriate for the specific topic of research interest.

QUANTITATIVE AND QUALITATIVE RESEARCH

Sometimes psychologists refer to research investigation designs as being either qualitative or quantitative. For example, they may refer to an investigation design as quantitative observational or qualitative. This is basically a way of categorising different research methods or the specific design of the research. Essentially, qualitative research designs involve the collection of qualitative (non-numerical) data and quantitative research designs involve the collection of quantitative (numerical) data. All of the investigation designs used in psychology involve the collection of information called data. The data may be considered as the `evidence' which will form the results of the study and be the basis of the conclusions that will be made.

is experienced. They may be collected as images, or as written or verbal statements made by participants, or as descriptions of behaviour observed and recorded by the researcher. In one study, a psychologist collected and analysed pictures drawn by schoolchildren to obtain information about how they felt when bullied. Sometimes psychologists audio or video record participants to collect data in research. Psychologists studying self-esteem in young children may collect qualitative data by asking children openended questions related to their self-esteem. Likewise, a researcher interested in learning about the factors that enable some people to cope better than others with personal trauma may collect qualitative data through focus groups in which participants talk about how they felt in a specific traumatic situation and how they dealt with their feelings.

Quantitative data

Quantitative data are numerical information about the `quantity' or amount of what is being studied; that is, how much of something there is. They may be heights or weights of prematurely born infants, percentages of participants who respond with `Yes' or `No', or the mean (average) reaction time of participants when a light is flashed onto a screen in an experiment, and so on. Thoughts, feelings

Qualitative data

Qualitative data are information about the `qualities' or characteristics of what is being studied. They may be descriptions, words, meanings, pictures, texts, and so on. These data can describe any aspect of a person's thoughts, feelings or behaviour; more specifically, what something is like, or how something

Figure 2.1 Qualitative data can be collected as verbal statements through focus groups

in which participants talk about their opinions and experiences.

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and behaviour can all be described in quantitative terms. For example, in a survey, a question might ask participants to use a five-point scale to rate their feelings on issues such as compulsory school uniform or the persuasiveness of a particular advertisement. Information about individuals' scores on a range of psychological tests such as intelligence tests, personality tests and aptitude and interest tests are also provided as quantitative data. In addition, data collected during experiments are typically collected in a numerical form and are therefore usually quantitative.

Although qualitative data are typically expressed in the form of words, they can be converted into a quantitative form. For example, participants' responses to open-ended interview questions about their thoughts and feelings when anxious could be summarised as numbers based on the frequency (`how often') with which certain feelings, such as nausea, are reported.

The majority of studies referred to in this text used quantitative data. This reflects the preference for quantitative data in most psychological research. The use of numerical data makes it easier and faster to summarise and interpret the information collected. This is why quantitative data are often preferred to qualitative data. However, this does not mean that qualitative data are less important or less useful than quantitative data.

LEARNING ACTIVITY 2.1

Review questions

1. Define the terms qualitative data and quantitative data.

2. What is a key difference between these two types of data? Explain with reference to an example.

3. Indicate whether the data collected in each of the following research studies are qualitative data, quantitative data or both. Explain your answers. (a) A videotaped recording of a focus group discussion by year 12 students about the effect of paid work on study time and year 12 results. (b) Records of reaction times for people who have and have not slept a minimum of eight hours. (c) An account by business executives of how stress affects them, both physically and socially. (d) Heart rate and blood pressure readings from business executives to assess their level of stress. (e) Amount of time it takes an elderly person to complete a cognitive ability task. (f) A mother's description of changes in her child's behaviour after the child walked unassisted for the first time. (g) Pictures drawn by refugee children about their experiences in a detention centre. (h) Ratings on a five-point attitude rating scale. Participants are asked to rate their feelings about the statement, `I support compulsory school uniforms for students'.

Figure 2.2 Quantitative data are collected when a person

takes an intelligence or aptitude test.

INVESTIGATION DESIGNS

Data may be collected using one or more investigation designs. In the SSABSA Stage 2 Psychology course, there are three key investigation designs: experimental, quantitative observational and qualitative. The design(s) that a researcher chooses to use will be determined by the question or hypothesis they are investigating. For example, a researcher could study the effect of using particular study techniques on exam performance by using an experimental, quantitative observational or qualitative design.

Introduction to psychology 11

Figure 2.3 A researcher could use an experimental,

quantitative observational or a qualitative design to investigate how study techniques impact on exam performance.

Experimental investigation design

One of the most scientifically rigorous and controlled investigation designs used in psychology is the experimental design. An experimental design is used to test whether one variable, or factor, influences or causes a change in another variable. For example, whether talking on a hand-held mobile phone while driving (one variable) influences or causes a change in driver reaction time (second variable). Essentially, an experiment enables the researcher to investigate and find out the causes of things. For example, if talking on a hand-held mobile phone while driving actually causes drivers to react more slowly and therefore increases the likelihood of an accident.

Experimental designs can be conducted under strictly controlled conditions in a laboratory setting or outside the laboratory in a field setting. In a field setting, conditions may be less strictly controlled, but a field setting has the advantage of enabling observations of a participant's behaviour in a `realworld' environment where their behaviour occurs more naturally.

Characteristics of an experimental design

There are different ways of designing an experiment, and some experiments have more simple or complex designs than others. All experiments, however, have a number of common features; the manipulation of the independent variable by the researcher, random assignment and control groups. We consider the key distinguishing characteristics of the psychological experiment and why the experiment can be used to investigate causes of behaviour.

Independent and dependent variables

A variable influences or causes a change in another variable. In research, a variable is something that can vary (change) in amount or kind over time. If research involved testing whether a particular anger management technique reduced the incidence of road rage in people who had previously been convicted of road rage, the two variables being tested would be the anger management technique and the incidence of road rage.

Psychologists distinguish between two types of variables called independent variables and dependent variables. Independent variable In an experiment, one variable is manipulated or changed by the experimenter to observe whether it affects another variable and what those effects are. The variable that is manipulated or changed is called the independent variable (IV). It is called an independent variable because the experimenter can

Figure 2.4 An example of a dependent variable could be

the amount of road rage behaviour displayed as a result of using or not using an anger management technique.

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independently vary it in some way. The IV is said to be the cause of any changes that may result in the other variable of research interest. For example, in the road rage experiment, the IV would be the anger management technique. The experimenter would have control over which group of participants would learn the anger management technique and which participants would not, in order to test the effect(s) of the technique on the incidence or extent of road rage-related behaviour; that is, the dependent variable.

Dependent variable The variable that is used to observe and measure the effects of the IV is called the dependent variable (DV). The DV is often the response(s) given by a participant(s) in an experiment and it usually has a numerical value. It is called the dependent variable because whether or not it changes and the way in which it changes `depend' on the influence of the independent variable. In terms of a cause? effect relationship, the DV is the effect(s) caused by manipulation of or exposure to the IV. In the road rage example, the DV is the measured change in the amount of road rage behaviour displayed by participants as a result of using or not using the anger management technique, the IV.

LEARNING ACTIVITY 2.2

Identifying independent and dependent variables

1. Identify the independent and dependent variables in the following hypotheses. (a) People will behave differently in a crowd from the way they behave when alone. (b) Drinking water while driving a car increases driver alertness. (c) Listening to music while studying for a test decreases performance on the test. (d) Eating food high in sugar increases hyperactivity in children. (e) The colour of a room affects students' ability to focus on school work. (f) High levels of stress increase incidences of insomnia. (g) Brainwave activity changes when awake compared to when asleep. (h) Children who eat breakfast perform better on cognitive tests at school.

Experimental and control groups

In a simple experiment, the participants are often divided into two groups. One group of participants, called the experimental group, is exposed to the experimental condition, where the IV is present. A second group of participants, called the control group, is exposed to the control condition, where the IV is absent. For example, in an experiment to investigate the effectiveness of a new study technique on exam performance, the IV is the use of the study technique and the DV is performance on the exam. The experimental group will learn, and then use, the study technique and the control group will not use the study technique. The control group provides a standard of comparison against which the experimenter can compare the performance of the experimental group in order to determine whether the independent variable has affected the dependent variable. If the exam performance of the experimental group is significantly better than the exam performance of the control group, the experimenter may conclude that the IV (use of the study technique) affected the DV (exam performance of participants).

Some experiments do not have both an experimental and a control group. Instead, they have one group who are exposed to both the control condition and the experimental condition. For example, to study the influence of drinking caffeinated drinks on people's concentration while driving, a group of participants could have their driving abilities tested in a driving simulator (control condition) having consumed no caffeinated drinks. The same group could later be tested again in the simulator (experimental condition) after having consumed caffeine. The test results of the same participants under the two different conditions would then be compared.

The experimental group and the control group need to be as similar as possible in all personal characteristics that can affect the DV, and to be treated the same except for the time when the experimental group is exposed to the independent variable. This is necessary so that if a change occurs in the experimental group and does not occur in the control group, the researcher can be more confident in concluding that it is likely the independent variable caused the change.

It is to be expected that people have different abilities, personality traits and other characteristics that might affect the outcome of the experiment. One way of minimising differences in the composition of the control and experimental groups is to randomly assign or allocate participants to the groups or conditions.

Introduction to psychology 13

Random assignment

In random assignment (also called random allocation), participants selected for the experiment are just as likely to be in the experimental group as the control group. In other words, every person to be used as a participant in the experiment has an equal chance of being selected in any of the groups to be used. This can be achieved by simply flipping a coin, drawing names out of a hat, or using some other kind of lottery method in which chance alone will determine in which group each participant will be. With a sufficiently large number of participants, it is reasonable to assume that each group will contain about equal numbers of most participant variables that can affect the results. For example, in the experiment investigating the new study technique, if the experimental group is `more intelligent' overall than the control group and the experimental group performs significantly better on the exam, it will be difficult for the researcher to isolate the effect of the study technique on exam performance. Was it a participant's higher intelligence that enabled better exam performance, rather than use of the study technique, or was it a combination of both?

The purpose of random assignment of participants is to obtain groups that are as alike as possible in terms of participant characteristics before introducing the IV so that the effects of the IV can be estimated. With random assignment of participants to the experimental and control groups, researchers can conclude that if two groups think, feel or behave differently at the end of the experiment, it very probably has something to do with the effect of the independent variable. Consequently, random assignment is an important means of experimental control.

Random assignment is different from random sampling. Random assignment is used to place participants in groups, whereas random sampling is one of the methods that can be used to select participants for an experiment.

Participants

Random assignment

Experimental group (IV present)

Control group (IV not present)

Measure effect on DV

Measure effect on DV

Is there a difference?

Figure 2.5 Flow chart of an experimental design

LEARNING ACTIVITY 2.3

Class activity

This classroom activity enables you to test whether random assignment actually produces groups that are very alike in participant characteristics.

You will need to determine easily observed and measurable characteristics of class members; for example, sex, hair colour, eye colour, short socks versus long socks and left-handed versus righthanded. Each class member should describe themselves in relation to each characteristic, on a separate card or sheet of paper.

The descriptions for each characteristic are then collected, mixed up and distributed into two `groups', using a random assignment procedure. The means (averages) of the different characteristics for each group should then be calculated and a profile produced for each group in terms of the characteristics so that the `equivalence' of the groups can be compared. 1. How close were the means for each characteristic? 2. How `equivalent' were the groups? 3. Would you expect equivalence to increase as

group size increases? Explain your answer.

LEARNING ACTIVITY 2.4

Review questions

1. Summarise the key characteristics of an experimental design.

2. Explain the main difference between independent and dependent variables in an experiment.

3. Choose a research topic of interest that could be investigated using an experiment. Write a hypothesis for this experiment, ensuring the hypothesis refers to the independent and dependent variables for the experiment.

4. What is an experimental group? What is a control group?

5. What is the main procedure that distinguishes the experimental and control groups?

6. Why is a control group used in an experiment? 7. What is random assignment and why is it often

used in an experiment?

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Factors that influence the outcome of an experiment

In an experiment to test whether sleep deprivation causes headaches, the IV is the amount of sleep obtained and the DV is the frequency of headaches reported. The results of this experiment are described in table 2.1.

Table 2.1 Frequency of headaches reported by

participants and amount of sleep obtained

Hours of sleep

Frequency of headaches reported Never Sometimes Often

8 or more

40

18

2

7

38

20

6

6 or less

15

35

7

The results suggest that the frequency of headaches is likely to increase if people experience six or less hours of sleep. However, what would happen if participants who had eight or more hours of sleep also took sleeping pills which reduced the likelihood of headaches occurring, or participants had different definitions of what constitutes a headache, or participants who had six or less hours sleep also were experiencing considerable stress in their lives?

There are many variables that might influence the DV in an experiment. Experimenters try to predict what these might be when planning an experiment and develop their research design to control or minimise the influence of as many of these unwanted variables as possible. However, some of these unwanted variables are difficult to control, and sometimes the experimenter is not able to predict variables that might affect the DV.

Many of the factors that influence the outcome of an experiment, apart from the IV, are called extraneous variables. The different kinds of extraneous variables are often classified as participant variables, situational variables and experimenter effects.

Extraneous variables

An extraneous variable is a variable other than the IV that can cause a change in the DV in an experiment. When extraneous variables are present in an experiment, they can make it difficult to conclude with confidence that changes which have occurred in the DV have resulted because of the IV and not some other variable.

In the sleep study described above, extraneous variables that may have resulted in headaches developing or not developing could include the amount of stress in the person's life, illness (for example, a

cold), eye strain, or the use of particular medication. Thus, in the group who had six or less hours of sleep, the greater likelihood of them experiencing a headache may not have been a result of insufficient sleep if one or more relevant extraneous variables were present. In order to conclude that the frequency of headaches will increase as a result of reduction in the amount of sleep obtained, all relevant extraneous variables must be controlled or eliminated.

Sometimes potential extraneous variables can be identified prior to the research, at other times they become apparent as the experiment progresses and, in some instances, the experimenter is totally unaware of their influence. Extraneous variables may include: participant variables (individual differences in personal characteristics among research participants such as intelligence, motivation, mood and so on); situational variables (such as the impact of the experimental situation on the participant's responses); and experimenter effects (ways in which the presence or expectations of the experimenter may influence the behaviour of the participants).

LEARNING ACTIVITY 2.5

Predicting extraneous variables

For each of the following research topics, identify the (a) IV, (b) DV and (c) two potential extraneous variables. 1. The effect of anxiety on the ability to make new

friends. 2. The effects of sleep deprivation on exam

performance. 3. The effects of stress on aggressive behaviour. 4. The number of car accidents that occur when

drivers listen to very loud music.

Participant variables The individual characteristics that participants involved in research bring with them to the experiment are called participant (or subject) variables. Participant variables include biological sex, intelligence, personality characteristics, motivation, emotional state, cultural background and so on. Each of these variables, and many other specific participant variables, can affect the way participants respond in an experiment. Thus experimenters try to take the relevant participant variables into account when they design their experiment. For example, a psychologist might test the notion that ignoring

Introduction to psychology 15

attention-seeking children who are misbehaving will reduce the incidence of attention-seeking behaviour. However, a reduction in the frequency of attention-seeking behaviour after a month of ignoring this type of behaviour may not have occurred only as a result of ignoring the misbehaviour. Factors relating to the children or their respective personal experiences may have impacted on their changed behaviour. For example, if a child's family situation becomes more or less unsettled, their behaviour may change, irrespective of the psychologist's behaviour. A child's health, mood or self-esteem may also have an impact on the child's behaviour.

Researchers attempt to control the impact of participant variables by ensuring, as far as possible, that participants in different groups of the experiment are as similar as possible in important personality characteristics and abilities that may influence the results of the experiment. The use of random assignment helps researchers to achieve this.

Placebo effect One of the more subtle and therefore less obvious participant variables is known as the placebo effect. Generally, the placebo effect refers to an improvement in health or wellbeing due to an individual's belief that the treatment given to them will be effective. The placebo effect is seen in medicine when a patient recovers from an illness or pain when they have been given a substance or a treatment with no actual medicinal or therapeutic value. The mere suggestion that a treatment will be used or is being used is often enough to make the person feel better. For example, some people begin to feel better if they are put on a waiting list for treatment, as compared to how they might feel if not on the waiting list.

In psychology, the placebo effect occurs whenever a participant's response is influenced by their expectation of what to do or how to think or feel, rather than by the specific procedure which is used to produce that response (Zimbardo, 1992). For example, in an experiment to determine the effects of nicotine on driving performance, an experimental group and a control group could be used. Participants in the experimental group could smoke cigarettes just before a driving test and participants in the control group would not. However, the act of lighting up a cigarette and inhaling smoke just before the test, might set off certain expectations in members of the experimental group; for example, feeling relaxed, nervous, confident or alert.

These expectations, in turn, might affect driving performance. Therefore, it would be better to have the control group do everything that the experimental group does, except use nicotine. So, instead

of the control group simply not smoking, the experimenter might give them a placebo, or fake treatment. In this experiment, a placebo would be to give the participants in the control group fake cigarettes to smoke which do not contain nicotine, but which burn, taste and smell like the real thing. The control group participants will not know their cigarettes are fake and will have no way of distinguishing them from real ones. After the driving test is taken, and, if the results show that control group participants have significantly fewer accidents than the experimental group, the researcher can be more confident in concluding that nicotine increases the probability of a car accident (Wade & Tavris, 1990). There are many different types of placebos. Placebos which are used in drug research often take the form of pills or injections.

The placebo effect shows that when human participants take part in an experiment, they are not simply passive participants whose behaviour is controlled solely by the independent variable being tested by the experimenter. The participants usually know they are being observed, and it is possible that this knowledge may affect their behaviour in some way. In some cases, participants actually try to outsmart the experimenter by acting in a way that is opposite to what they think is expected (Carlson, 1987). Most participants, however, are usually cooperative and motivated to do whatever is asked of them. But in their efforts to please, they may act in an experimental situation in ways that they would not act in real life. In other words, experimental participants sometimes do what they think the experimenter wants them to do. When experimental participants are reacting to their perception of the experimenter's wants, they are not responding truly to the independent variable(s) of the experiment (Gerow, 1992).

Because participant expectations can influence the results of an experiment, it is important that participants do not know whether they are in an experimental or control group. To enable this, the experimenter can use a single-blind procedure so that participants are not aware of (are `blind' to) the condition of the experiment to which they have been assigned.

Situational variables Important differences in the individual characteristics of research participants are not the only factors that can have an unwanted effect on the dependent variable and therefore the results of an experiment. All participants of different groups of the experiment must be tested under the same conditions and in the same situation in order for the experimenter to more confidently conclude that any change in the

16 Psychology for South Australia: Stage 2

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