Experimental Methods Flashcards
(18 cards)
What is a laboratory experiment?
An experiment carried out in a controlled setting, allowing the
researcher to exert a high level of control over the independent variable, and to eliminate or
control for confounding variables. The IV (independent variable) is manipulated to observe
the effect on the DV (dependent variable) under controlled conditions.
What are the strengths of a lab experiment?
Control over variables: It is easier to control potential confounding variables in the
laboratory than in the natural environment of the field experiment or with any other
research method. If all variables are controlled successfully or eliminated, then cause and
effect can be established.
2. Replicability: A laboratory experiment that is carried out well can be easily repeated by
other researchers to see if they obtain similar results. If other researchers do get similar
results the experimenters can conclude that the results are reliable. This ability to
replicate the laboratory experiment is advantageous compared to the field or natural
experiment where researchers would have to wait indefinitely for the same circumstances
to occur again to check the reliability of their results.
What are the limitations of a lab experiment
Artificial: Due to the high levels of control in the laboratory it can become artificial and
recognisably different from real life situations. The artificiality of the laboratory
experiment may make it difficult to generalise the findings to other settings, which means
it can lack ecological validity. Other methods such as naturalistic observation and field
experiments are more likely to represent real life.
2. Demand characteristics: These occur when the participants try to make sense of the
situation they find themselves in and act accordingly. Participants may try to help the
experimenter, or they may set out to deliberately confound the results. Demand
characteristics do not occur in the field or natural experiment as the participant is
unaware they are taking part in a study.
What is a field experiment
An experiment carried out in the natural environment (real world setting)
of the individuals being studied. The experimenter has control of the IV. The participants may
not know they are being studied. (e.g. Bickman investigated the effect of uniform on
obedience at a New York bus stop).
What are the strengths of a field experiment?
Improved ecological validity: This experiment is carried out in the natural environment
and therefore the findings can be generalised to other real-life settings. This is an
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advantage over the laboratory experiment, which lacks ecological validity because it is
carried out in the artificial environment of the laboratory.
2. Reduction of demand characteristics: The participants may be unaware they are taking
part in a research study and so the influence of demand characteristics may be minimised.
This is an advantage over the laboratory experiment as participants often respond to the
cues in the artificial environment as they are aware they are taking part in a study.
What are the limitations of a field experiment
Less control: it is difficult to control for confounding variables in a field experiment and as
a result it may be difficult to replicate precisely. As a result, it is more difficult to establish
cause and effect. Whereas in the laboratory establishing cause and effect is easier
because of the high level of control over the variables.
2. More time consuming: Field experiments can take longer to complete as there may be a
process of waiting for certain conditions to occur. This is not an issue for the laboratory
experiment as the experimenter controls the timing of the study.
What is a natural experiment ?
A type of experiment where the IV is not directly manipulated but
occurs naturally. The allocation of participants is outside the control of the researcher, (e.g.
when the government in Fiji decided to introduce western TV into and psychologists
measured the effect of eating disorders in teenage girls).
Strengths of natural experiment
Reduction of demand characteristics: The participants may be unaware they are taking
part in a research study and so the influence of demand characteristics may be minimised.
This is an advantage compared to the laboratory experiment where participants are aware
they are taking part in an experiment and may respond to the cues in the artificial
situation.
2. Lack of direct intervention: The experimenter does not intervene directly in the research
situation, which means there is more opportunity to gain an insight into real life
behaviour. This is an advantage when compared to the laboratory experiment where the
behaviour is more likely to be artificial.
What are limitations of natural experiment ?
Loss of control: Since the IV is not directly controlled by the investigator; the degree of
control is less than in either a laboratory or a field experiment. This reduces the likelihood
of cause and effect being established because of the many confounding variables.
2. Replication impossible: The naturally occurring situation that the researcher wishes to
study may occur only rarely, therefore replication will be a it will be difficult to check the external validity of the findings whereas in the laboratory
replication is possible because of the control of variables.
What is quasi experiment?
An experiment that has an IV that is based on an existing difference
between people. No one has manipulated this difference it simply exists. E.g. gender
differences or psychological disorder. Quasi experiments often resemble laboratory and field
experiments, quasi means ‘almost’. The experimenter does not directly manipulate the
independent variable. This means there is a resemblance between natural and quasi
experiments however they differ in that quasi experiments are typically carefully planned
whereas natural experiments are not.
What are the strength of quasi experiment ?
Replicability: Quasi experiments are often carefully planned and carried out under
controlled conditions which means that they can be replicated.
2. Quasi-experiments are useful to make comparisons between types of people where it is
impossible or impractical to manipulate variables.
What are the limitations of quasi experiment?
Confounding variables: Quasi experiments cannot randomly allocate participants to
conditions and therefore there may be confounding variables which means we cannot
establish causality.
2. Demand characteristics: Quasi experiments are often carried out in a laboratory and
therefore there may be demand characteristics.
What is an aim?
A general statement of what the researcher intends to investigate, to be clear about
the purpose of a study
What is a hypothesis?
is a precise testable statement made at the beginning of an investigation about
what the researcher expects to happen
What is an alternative hypothesis ?
An alternative
hypothesis is used in any study regardless of the research method. The alternative hypothesis
can be called an experimental hypothesis when an experimental method is used and must
include the independent and dependent variable. The alternative hypothesis can be called
a correlational hypothesis when a correlational method is used and so must include the two
co-variables. Alternative hypothesis can be directional or non-directional.
What is a directional hypothesis?
states the direction in which the results go. It states which set of
scores will be better/faster/positively or negatively correlated. This is used when previous
research suggests a direction. E.g. Participants remember significantly more words when
they study in short bursts of 10 minutes than when studying for longer sessions of one hour.
What is a non directional hypothesis ?
that there will be a difference but does not state the
expected direction of the outcome. A non-directional hypothesis is used when there has been
no previous research or previous research has found contradictory results. E.g. There is a
significant difference in the number of words recalled by participants who study in short
bursts of 10 minutes compared to those who study for longer sessions of one hour.
What is a null hypothesis?
s: states there is no difference and the results are due to chance. E.g. There is
no significant difference in the number of words recalled by participants who study in short
bursts of 10 minutes compared to those who study for longer sessions of one hour
