Psychology 9990


There are primarily 5 research methods in psychology that are used to collect various forms of data that makes for a case and argument from a psychological perspective.

1. Experiments

2. Self-reports

3. Case Studies 

4. Observation

5. Correlations


An experiment is an objective, scientific procedure used to make a discovery, run and test a hypothesis and to present a known fact – to check validity.

An investigation that is conducted to establish a primary cause-and-effect relationship, is called an experiment. The ‘cause-and-effect’ relationship in question, is basically the direct proportion of both entities meaning if a cause may occur, so may the effect. This factor is what may explain the onset of events in the experiment, with the ‘cause’ being the event that triggers another event known as the “effect”. 

By finding out the ‘cause-and-effect’ relationship, the experiment can be designed to manipulate, isolate and maneuver certain variables to achieve a desired aim of the study. 

These variables are known as the ‘Independent Variable’ and the ‘Dependent Variable’. The IV has a causal effect on the DV – meaning the IV is the variable that researchers systematically use, manipulate and control and the DV is the variable which bears the effect and thus is measured by the experimenter.

An example of this would be, how if an experiment is conducted to determine the effect of increased inclination on the treadmill, on an athlete’s subsequent pace and stamina (as a conditioning test). The increased inclination which is can be adjusted, manipulated and controlled time to time, in order to check different scenarios and possibilities (such as categories like ‘low’ and ‘high’) would be the IV in this case. The athlete’s reactionary response which is being measured (his pace and stamina in the given conditions ‘high’ and ‘low’) would be our DV, which would be measured by quantitative and objective measures such as the speed monitor, timer and his pulse rate. 

Another important set of variables are; the ‘confounding variable’ which has an unintentional, undetermined effect on the DV and the ‘extraneous variable’ which could affect the DV but it is a variable that can be controlled by the experimenter. In reference to the above mentioned example – an example of the ‘confounding variable’ would be the athlete’s own willingness and ambition to do the test/challenge which might affect his pace and stamina stats. Whereas, the ‘extraneous variable’ would be the athlete’s diet routine which is possibly already designed and followed by the athlete but if interfered with substance abuse like alcohol may alter his performance on the test. 

Experimental Designs

This segment of the research method refers to how participants in the study, are assigned to different settings, environments and scenarios in an experiment.

A lot of the core studies are primarily experiments (either lab or field) and in order understand how they work, we need to understand the ‘design’ aspect. 

There Are Primarily 3 Types Of Experimental Designs:

Repeated Measures Design 

This method employs the strategy of using the same group of participants (the same people) in different conditions and scenarios repeatedly. 

For example, a group of participants consists of 20 people and the set of conditions in the experiments are 2 different ones; Condition A and Condition B. In accordance with this design, all 20 participants will go through Condition A and then the repeating the group of participants as per design, they will go through Condition B subsequently. 

Independent Groups Design

This method employs the strategy of taking the group of participants, randomly dividing them into different factions and then making them go through the conditions, scenarios so that each participant may only be in one condition and thus have limited exposure to the aim of the study. Independent measures involve using two separate groups of participants; one in each condition.

An example of this would be, how a group of participants consists of 20 people, divided into Groups A and B would go through Condition A and Condition B respectively – one being the main group and one being the control group who’s variables are different than that of the aforementioned group.

Matched Pair Design

This method employs the strategy of categorizing participants based on similar characteristics and variables such as age, gender, ethnicity, IQ levels, etc into pairs and then randomly assigning them to the differing conditions such as Condition A and Condition B in the experiment. One member of each matched pair must be randomly assigned to the experimental group and the other to the control group. Each condition uses different participants, but they are matched in terms of similar variables.  

An example of this would be Group A (10 random participants who do not have similar characteristics) known as the control group and Group B the experimental group (10 participants matched for differing variables and characteristics) into the set of conditions.

Repeated Measures Design

Independent Groups Design

Matched Pair Design


•  Less chances of participant variables, as each participant experiences all levels of the IV. Therefore, it is less likely to misrepresent the effects of the IV on the DV. 

•  Fewer people needed to conduct the experiment, hence it is quicker may warrant faster results in a study with less logistical issues.


•  Different participants are used in each level of the experiment so less order effects are to be expected.

•  Less demand characteristics as they do not experience or witness all levels of the IV.

•  Difference in results (an abnormality per say) will be detected quickly.


•  Participants are exposed to only one level of the IV, hence there are reduced Demand Characteristics.

•  Less participant variables because the experimenter has attempted to pair up the participants so that each condition has people with similar abilities and characteristics.
•  Reduced order effects.


•  Order effects are more likely to follow (the effects of an experimental order design which may distort results and thus reduce validity.)

•  Participants may exhibit demand characteristics as they are familiarized with the objective of the study.


•  The results may be altered based upon the factor of Participant Variable, given there may be significant individual differences on each respective level of the IV. 

•  More participants are needed to use this experimental design and thus may be more expensive and time-consuming. 


•  It is extremely risky in the sense that the loss of one participant will warrant the loss of 2 participants’ data. 

•  Its very time consuming. 

•  Also has the chance to distort results unless a reliable and validated matching criteria is established as having the same similarities are very difficult and rare. 

•  Small sample size and thus not generalizable for the larger context.

The Types Of Experiments

Laboratory Experiments:

In many studies of psychology, experimental procedures are conducted in artificial, controlled settings such as a laboratory or other settings where controls are applied to administer and operationalize effective measurements and variables. To put it precisely, a lot of the participants who part-take in this study are not in their usual environment for the behavior they are being tested on along with a strict and structured set of controls which govern the situation, which are set up by the experimenter.


  •  High controls, meaning more controls on extraneous variables from effecting the DV.
  • High controls – standardized procedures (more reliable)
  • When variables are controlled and monitored finding out the cause and effect relationship is faster and easier.
  • This improves validity. (Accuracy and authenticity of a research)
  • High controls also mean LOW ecological validity. 
  • Participants getting an idea of the aim and the setting might make the results prone to demand characteristics. 
  • Low ecological validity also limits generalizability of the outcomes to a real-life context.
  • This makes the findings also prone to researcher bias, a confounding variable. 

Example: (SYL)

The study conducted by Milgram et al. which tested ‘The levels of obedience’ – under an ‘authority figure’ to test his “German Hypothesis”. 

It was conducted at the Yale University and the procedure was highly controlled and standardized. With the experimenter advising verbal prods, the environmental setting of the laboratory. For instance, the interview was conducted in a room where an ‘electrical shock generator’ was placed which had a range of 15V-450V, which the “teacher” (the fixed participant via ballet draw) would have to use on the confederate, “the learner” to reprimand him for leaning errors under command from the experimenter. This makes the procedure highly standardized.

Field Experiments:

A field experiment takes place in a normal and regular environment that is usually the participants’ real-life setting, for the behavior that is being studied. While the IV can still be controlled and monitored, the influence of extraneous variables cannot be as strictly controlled.

  • It has high Ecological Validity, as it is more reflective of the participant’s    behavior in real-life situations. 

  • As it is being conducted in a natural setting, where the participants are unaware of the aim or the objective of the study, having less exposure to the IV – there is an immunity to Demand Characteristics. 

  • They are high in generalizability and representativeness of the group being studied.
  • It is harder to control variables in the study, which makes it difficult to standardize and thus to replicate. 

  • This may threaten credibility of the study. 

  • If certain controls are not established, vital information and data can be missed out depending on the scope of the experiments. 

  • Human Errors in researching are highly probable, which are difficult to account for.

  • May raise the ethical issue of consent as participants are unaware of them being studied. 

Example: (SYL)

In the study by Pillavin et al. the setting of the experiment was that of New York’s infamous underground subway station and its running train carriages which New Yorkers used for their everyday commute, to test the theories of “Bystander Apathy” and “Diffusion of Responsibility” – in an emergency situation. With the pre-set controls (variables) involved the victim being Male, of black/white ethnicity, drunk or ill and all in the same standardized attire.

The researchers were 2 males and 2 females (to limit gender and researcher bias) and were instructed to complete the whole experimental procedure on a pre-scheduled 7.5 minute train circuit to record and asses participant behavior.

Moreover, “Victim” behavior and “Helper” behavior were modelled and staged respectively. The criteria of participant behavior (voluntary helping) was also operationalized respectively as of that in help initiated in Critical Area -‘Early (70 secs) and Late (150 secs)’ and Adjacent Area – ‘Early (70 secs) and Late (150 secs). The spontaneity of the public’s helping or neglecting behavior based upon the named variables in their natural, habitual setting makes this a field experiment, with high ecological validity.

Natural Experiments

A natural experiment (like a field experiment) is conducted in the participant’s natural, every-day life setting where they are unaware that they are being researched making it a covert observation. 

However, here the experiments have no control over the monitoring or manipulation of variables or the levels of the IV. They happen, change and occur by themselves and so do the differences and variations in the experiment – meaning that the IV is naturally occurring. This according to many psychologists deems this type of experiment “untrue” as the researcher cannot assess, operationalized or control the variables.

  • Has extremely high ecological validity and representativeness as participants are exhibiting the most natural of their behavior patterns. 

  • Less prone to demand characteristics as it is a covert observation.

  • Less prospects of standardizing or controlling procedures which may add confounding variables, which may alter the result of the experiment entirely. 

  • Low validity.
  • Possibly more time-consuming and expensive than lab or field experiments. 

  • There is no control over the variables in the study – which may expose it to multiple limitations:
- Standardization and replication

- Credibility

- Researcher bias

-Validity of the DV

- Generalizability of the results.

Example: Non-SYL

In a study by Hodges and Tizard et al. which was aimed at investigating the effects of: institutional upbringing on later attachments, of privation on later social and emotional development, if the effects of privation can be reversed – on 65 kids in residential nurseries since they were a couple of months old.

It was primarily a longitudinal study, and a natural experiment where the IV (what happened to the children at age 4) followed naturally. The children were assessed for social and emotional competence at four, eight and sixteen years old which comprised of interviewing the children and their parents and teachers with a set of questionnaires.

The care provided was good, but they were not encouraged to form attachments with the children (i.e. privation transpired).At age 4, almost 24 kids were adopted, 15 were restored to their actual, original homes, and the rest stayed in institutions. 

The control group was closely accorded the experimental group - in sibling number, home location (London), parental profession, situation in family, age, gender etc.

Experiments And Ethics

In laboratory experiments, where observations are overt – the participant can be promptly asked for their informed consent. However, in order to lessen the probablity of demand characteristics and to hid the aim of the research, the particiapnts may possibly be decieved. It is imperative that after the experiement has concluded, the participants are apologized to for being lied to and then be told the the aim of the research. This is known as debriefing.  

Whereas, in Field and Natural experiments, because the observation is covert it is highly unlikely that the participants are aware of the situation (the experiment) taking place. The ethical issue arises when considering the withdrawl rights in a covert scenario.  

Because they do not know the implications or the effects of the procedure in the experiement they will also not know when to withdraw and backout in order to protect themselves from plausible physical and psychological harm. 

To maintain objective integrity of the experiment, privacy and confidentiality is a necessity in the cases. In lab experiments, confidentiality can be respected as if there are interviews and questionnares they are most probably pre-planned and set carefully with the prospect in mind.

However, the invasion of privacy is a risk when considering field or natural experiments, as they are usually covert but are in the daily, personal spaces of the participants’ lives. 

Confidentiality however, can be respected in all the experiements by keeping their participation (via names and other identity details) anonyomous. The prospect of them having any trace or link to the study in the future, which might reveal sensitive information such as their workplace, home or name - risking compromosing classified participation (confidentiality) must also be taken care of when designing a study.

Ethical Considerations In Psychology:

  • Informed Consent
  • Deception and Debriefing
  • Withdrawal rights (participant choice)
  • Protection from physical harm
  • Protection from psychological harm
  • Confidentiality
  • Privacy

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