Friday, 1 August 2014

Types of Sampling in Psychology Research

Ok, this is quite a technical topic, not one that will attract hundreds of fascinated readers to this blog, I know! But Psych students really need to understand the main types of sampling for school/university studies.

The same principles will also apply to other subjects where you conduct primary research on people.

What is sampling?

Sampling means selecting people to take part in your research. There are two key steps:

  • First, define the group of people that you want to study. Perhaps you live in London and you want to do a survey on elderly people. This is know as the 'population' for your research. However, you need to define it specifically. Instead of 'elderly people', you could say 'adults aged 70+ living in London'.
  • Now you have to pick a smaller group from this population, and conduct the research on them. Unless the population is very small, you can't study all of them! This smaller group is called your 'sample'.

An analogy...

If you have done Geography/Geology at school and collected rock samples, the concept is very similar. Rather than taking the whole rock/mountain, you collected a small piece and studied that.

The problems are also similar. What if the area of the mountain that you collected the rock sample from just happened to have a different type of rock than 99% of the mountain? Perhaps that rock was moved there by a glacier, and originated in a different place. The problem is that the sample is not representative of the whole. The results of the study on that rock sample can't be generalised to the whole mountain!

 
The concept of sampling applies to other subjects. Image: luigi alesi

It is very similar in Psychology. In the above example, if you selected a sample of elderly people by asking your grandmother's friends, they might not be representative of the whole population of people aged 70+ in London. Perhaps they are more affluent, in better health, or better educated than the average? Perhaps they are not as ethnically diverse as the whole population?

If your sample is not representative of the population, then it is difficult to generalise the findings of your research. What you find out might be true of your sample, but it may not be true of the whole population.

To put it another way, your sample is biased!

Types of sampling

The example above - sampling family or friends - is called an 'opportunity' or 'convenience' sample. Other sampling methods can get a much more representative sample, and, therefore, better data! Here are the main types to be aware of:

  • Random sampling: this means that everyone in the population studies has an equal chance of being chosen. This is a lot more difficult than it sounds! How do you ensure that everyone has exactly the same chance? Putting all the names in a hat might work, but not if there are 1000s of names! Psychologists typically use a random number table, together with a numbered list of members of the population. But what if the people you randomly select don't want to take part in your study? The problems are obvious!



  • Stratified: Here, the researcher makes sure that groups within the population are represented fairly within the sample. For example, having a 50-50 mix of males and females. it may depend on what is important to the research. If religious belief was likely to affect the results, then researchers may try to ensure that their sample had the same proportions of religions as the population as a whole.


  • Systematic: A systematic sample involves picking people at fixed intervals from a list of the whole population. So if you have a list of 1000 students in your year and pick every 50th name, that is a systematic sample.


These other types are less representative, but often used:

  • Opportunity: as described above, this is where participants are chosen on the basis of convenient availability. This might mean approaching people who walk past and asking them to take part. Like fishing in a lake, you take whatever comes along! This tends to lead to a biased sample, but is often used because it is quick and easy to do.


  • Self selecting: Also called 'volunteer sampling', this is when people come forward to take part in your study rather than you finding them. Milgram's (1963) study of obedience used people who responded to an advert, and were therefore a self-selecting sample. They may differ from average members of the population in various ways, for example, by being more interested in helping scientific research, or more in need of the money paid to participants!

  • Quota sample: similar to stratified sample, but here you simply ensure that you have some from every category (e.g. every religion) rather than keeping the proportions the same as the population. It may be that some groups have a very tiny population, so you set a minimum 'quota' to ensure that they are not missed out. For example, you might select two people from every religion, regardless of how common those religions are.



Syllabus note

For Scottish Higher, you should be aware of all of the above types. For A-Level, all except quota are included. At university level, these will cover you well at least for 1st and 2nd year.

To conclude...

In some situations, an opportunity sample might be adequate. A random sample is ideal, but has many practical problems in obtaining one. A good compromise might be to use a stratified sample.

Many thanks to the University of California, for permission to use their images on this post. Read their article on sampling here.

Any questions, feel free to ask in the comments!

Tuesday, 1 July 2014

Simple guide to citing research studies

At the end of every report or article in Psychology, the author puts a list of references, giving the sources of information and ideas mentioned in the text.

But how should you format them? Every reference list that you look at seems to be slightly different!

This post is not meant to be a complete guide, but it should cover the vast majority of sources of that new Psychology students will need to cite, because these tend to fall into three categories: books, journal articles, and websites.

A reference list helps a reader to find your sources. Image by Farrukh

Books

Author(s), initials (year). Title of book. Place of publication: publisher.

  • Example: Selye, H. (1956). The Stress of Life. New York: McGraw-Hill.
Articles

Author(s), initials (year). Title of article. Journal Title, issue number, pages numbers.

  • Example: Tajfel, H. (1970). Experiments in intergroup discrimination. Scientific American, 223, 96-105.
Websites

Author(s), initials (year). Title. Retrieved (date) from (url).


What about capitals and italics?

The convention is to use italics and capital letters for the title of a book or journal, and italics for the journal's issue number, as with the examples above. Otherwise just use capitals as in everyday English grammar.

Where do I find the place of publication?

Usually this detail appears just inside the front cover, before the contents page of a book.

Is this true in all countries?

This style of referencing is called Harvard Style and is used in Psychology throughout the world. The examples above are based on the British BPS format, and there are minor variations in other countries- check with your school/university, but above all, try to be consistent!

What should be in the references section?

Only things that are mentioned in an 'in line citation' during your text, e.g. "Smith, 2000". All such citations should link to a full reference at the end. Nothing else at all should appear in your reference section - it is not a general bibliography, so don't include background reading.

What if there is no name?

If the source is an organisation rather than an individual, use that instead of surname, e.g. Wikipedia (2014).

Any questions, please leave them in the comments!

Tuesday, 24 June 2014

Have we evolved to fear snakes and spiders?

A phobia is a strong and irrational fear of something, a fear which is out of proportion to the dangers presented. If it is irrational, then why do we have them?

The psychology of phobias has been influenced by some of the biggest names in the field - Sigmund Freud felt that a phobia is the result of a repressed unconscious fear of one's parents (Freud, 1909), while the eminent behaviourist John B. Watson thought that while fear was a basic human emotion, any specific fear could be learned or unlearned through experience (Watson and Raynor, 1920).

Evolution

Later, researchers began to think that our evolutionary past might play a major role in phobias. People tend to develop phobias of things which would could have been harmful for our ancestors, such snakes, spiders or heights. In contrast, it seems to be much rarer to have a phobia of things which have only recently presented a danger, e.g. cars, guns or electricity.

The idea that evolution has prepared us to fear certain harmful things is called preparedness theory, and it was proposed by Seligman (1971).

Mineka research on monkeys

Susan Mineka and colleagues conducted several studies of rhesus monkeys. They noted that when brought up by a parent who feared snakes, infant monkeys in captivity did not develop a fear of snakes, while wild monkeys did. They reasoned that this was because the captive infant monkeys were never exposed to snakes, and so they did not get a chance to observe their parents' fear reactions (Mineka et al., 1984).

Rhesus monkeys in the wild. Image by Kai Yan, Joseph Wong.

To test this theory, Mineka and colleagues conducted a controlled experiment to see whether the infant monkeys could learn a fear. Using 5 wild-reared and 6 captivity-reared infants, they exposed them to their parents acting fearfully in the presence of a snake. The infants rapidly learned to fear the snake - and their new fear was found to be permanent!

This shows that fears can be passed on from parent to child.

Will a monkey learn to fear something irrelevant, like flowers?

How strong is this tendency to learn fears through observation? Researchers know that we can learn some evolutionary 'newer' fears from observation - Townend et al. (2000) report that parental anxiety about dental visits is a factor in whether children learn to fear the dentist, even though dentists did not exist in our evolutionary past. Would a monkey learn to fear an irrelevant stimulus like a toy rabbit or a bunch of flowers?

To test this, Cook and Mineka (1989) spliced a video of an adult monkey reacting with fear to make it look like it was afraid of one of the following four objects:
  • A toy snake
  • A toy crocodile
  • A toy rabbit
  • A bunch of flowers
Each of the four versions of the video was shown several times to a group of around 10 young monkeys (42 monkeys were used in total). Researchers then measured how long it would take the monkeys to collect food, if the toy from the video was placed beside the food. It was found that the time greatly increased when the toy snake or crocodile was present (i.e. these objects made the monkeys more wary) but there was no increase in time with the rabbit or flowers present.

It appeared that a monkey will only learn a fear though observation if the object is biologically relevant.

Conclusion

So it appears that it is much easier to learn a phobia if it is biologically 'prepared' - but learning some form of anxiety through observation is still possible without preparedness. As with other experiments on animals, though, it is important to be cautious about generalising the results of the above research to humans.

See also: Fear and ugliness of animals (Bennett-Levy and Marteau, 1984).

References

Cook, M and Mineka, S. (1989). Observational conditioning of fear to fear-relevant versus fear-irrelavant stimuli in rhesus monkeys. Journal of Abnormal Psychology, 98, 448-459.
Mineka, S., Davidson, M., Cook, M. and Keir, R. (1984). Observational conditioning of snake fear in rhesus monkeys. Journal of Abnormal Psychology,  93(4), 355-372.
Seligman, M. (1971). Phobias and Preparedness. Behaviour therapy, 2, 307-320.
 

Thursday, 19 June 2014

Do People Conform When They Have Strong Beliefs?

Research into conformity has shown a rather dismal tendency for people to be swayed by others around them, even if their gut feeling is telling them not to.

For example, the classic experiment of Solomon Asch showed that people will say that two lines of unequal length are the same, just because everyone else is saying so (Asch, 1955).

But who really cares about the length of lines! What about conformity to the bigger issues in life? What happens when people are pressured to abandon their political or moral values?

Will people abandon their political views and conform? Image: Tom Hagerty

This was the question asked by Hornsey et al. (2003). Using questionnaires, they identified 205 Australian university students (152 female, 53 male) who identified themselves as being 'pro' same-sex marriage - a controversial topic at the time of the research.

They then told the participants that they were either in a majority or a minority on the issue relative to their peer group of other students - by showing faked graphs of student attitudes to this and other issues.

Behaviour on both private and public statements of opinions was measured using further questionnaires which asked about willingness to engage in private behaviours (e.g. voting, signing a petition) or public behaviours (e.g. distributing information leaflets, attending a rally).

Findings

A key aspect to the study was that the researchers had asked how much each participant's beliefs were based on a strong sense of morals. This had an effect on results. For example, for those with weaker moral beliefs, there was a tendency to go with the majority regarding private actions, but the majority view made no difference to private actions for those with strong beliefs - they were unaffected.

Even more interestingly, those with strong moral beliefs were likely to become stronger in their attitudes in terms of public behaviours, rather than conforming. Researchers call this 'counter-conformity'. The sense of others being against them actually made them firmer in their statements.

Evaluation

This study provides an interesting counterpoint to the classic 20th century research on conformity which tended not to examine political or moral issues. In contrast, this study had a strong real-world element, boosting its ecological validity.

However, it did rely entirely on questionnaires. It has long been established that what people say in a questionnaire and how they actually behave can differ (e.g. LaPierre, 1934)

Also, the participants were all university students - a social group which can place a high value on being politically outspoken and radical. It is hard to say how the results would generalise to social groups which traditionally avoid public expressions of their political views.

Overall, it does provide a bit of hope that we are not all socially malleable, and that people are capable of holding on to the views that matter.

References

Asch, S.E. (1955). Opinions and social pressure. Scientific American, 193, 31-35.
Hornsey, M.J., Majkut, L., Terry, D.J. and McKimmie, B.M. (2003). On being loud and proud: Non- conformity and counter-conformity to group norms. British Journal of Social Psychology, 42(3), 319-335.

Tuesday, 17 June 2014

Substances that affect sleep

Quality of sleep is a key issue in health - and according to widely-reported recent research, sleep is also of vital importance in the consolidation of memory.

A major factor that affects brain function in relation to sleep is the use of drugs. A drug, in this context, means any substance that crosses the blood-brain barrier and directly affects our brain cells - not necessary an illegal drug.

Stimulants are drugs which can help keep people awake - and can reduce the quality of sleep. One example of a stimulant is caffeine. It is the world’s most popular psychoactive drug, and is present in popular food and drinks such as coffee, tea, chocolate and red bull. It can also be taken in tablet form.

Coffee is a popular source of caffeine. Image by Toshiyuki IMAI

People - such as myself - drink coffee and other caffeinated drinks to keep them alert, but taking it in the evening can make it harder to get to sleep. It can take over 5 hours for caffeine levels in your body to halve - and therefore considerably longer for it to leave your system entirely. This is worth considering if you drink coffee in the evening. Even if you manage to get to sleep ok, your brain's natural sleep cycles may be disturbed.

Illegal stimulants have an even more powerful effect. Amphetamine (street names include 'speed') directly stimulates the central nervous system, making the user more alert for longer. This occurs because it increases the activity of dopamine neurons in the brain’s reward system. In the UK it is a 'class B' drug, used illegally for socialising and sometimes in the workplace e.g. by people working long shifts. It is also prescribed for ADHD and for some sleep disorders.

Prescription drugs can also affect sleep - for example, antidepressants such as fluoxetine (branded as Prozac or Sarafem). These are prescribed to millions of people around the world and can be effective in reducing the symptoms of depression, but one of the more common side effects is to disrupt sleep. They especially impact on REM sleep - the stage of sleep where you dream.

Friday, 6 June 2014

Weekly round up 3 - best Psychology from around the web!

Eye-catching articles on Psychology and related matters that appeared on the internet over the last week or so:

Sinister! Threats from the Left Are Scarier

LiveScience reports on this peculiar research finding, which suggests that our response to threat may be based on visual processing.

Narcissists can be taught to empathise...

Narcissism means having an inflated sense of your own value, a lack of empathy, and a tendency to use other people. It is often viewed as a fixed personality trait, but according to new research summarised by Christian Jarrett for BPS, narcissistic people are able to show empathy, if given the right type of instruction.

Learning second language 'slows brain ageing'

Or at least, the two are correlated. Still, this useful research links to other findings on second language learning/bilingualism, and paves the way for future studies to test the role of language learning in cognition and ageing.

How to Raise a Moral, Responsible Child - without Punishment

Psychology Today blogger Laura Markham discusses what is surely one of the most important and trickiest issues for any parent - how to raise a child into a good human being without being overly directive. Should be popular with the kids, too!

Image by Brett Davies

Thursday, 5 June 2014

Women more aggressive than men? - Anderson and Dill's (2000) study of violent video games

Studies of the effects of violent games are often non-experimental, making it hard to separate out confounding variables. If you compare gamers v's non-games in the real world, there may be some pre-exisiting differences between the groups - perhaps more violent people are drawn to violent video games, rather than video games making people violent...

An experimental study

Anderson and Dill (2000) tried to avoid this confounding variable by assigning a randomly allocated group of psychology students to a violent video game (Wolfenstein 3D) in a lab experiment. A control group played a non-violent game (Myst). Overall, 210 students were used (106 male, 104 female).

The researchers wanted to test the effect of violent v's non violent games. However, it was important to hide the aim from participants, to avoid demand characteristics. They therefore told participants that the study aimed to test how quickly they learned motor skills required in games, and how it affected later tasks.

Image by Katherine McAdoo

Participants played the game for 30 minutes, stopping after 15 mins to complete a questionnaire provided by researchers.

One week later, researchers invited participants back to play a competitive 1-to-1 reaction time game. They were led to believe that there was another participant in the next cubicle, who they were playing against. In fact they were alone, and the researchers had fixed the outcome so that they would win around half of the tasks. After each trial, they could 'punish' their opponent by playing a blast of noise in the neighbouring cubicle. Crucially, participants could pick the noise volume and duration.

Findings

The key finding was that those who had played the violent game gave longer blasts of noise to their (fictional) opponents.

Males generally show more violence throughout society, but in this task, the reverse was found - women showed a greater degree of aggression, by delivering longer blasts of noise than men did.

Conclusion and evaluation

The researchers concluded that violent video games can lead directly to long-term increases in violent behaviour. It can also be concluded that sex differences in aggression have more to do with culture and environment (e.g. males playing more violent games) than to do with biological differences. It was a lab experiment, replicable and well controlled, and used a large sample.

However, there are some flaws in this research:

  • Although the participants were decieved, they were psychology students, and may still have guessed what the researchers were looking for. They may have altered their behaviour to fit expectations.
  • The differences in noise duration were statistically significant but nevertheless rather small in real terms - a mean of 6.81 seconds for the violent game v's 6.65 seconds for the non-violent game condition.
  • Also, the task is unrealistic. Showing aggression by playing loud noises is quite different in scale/degree from attacking someone in real life. People may have found it funny or not taken it seriously. It can't be concluded that they would be more likely to stab/shoot someone.
  • Also, the participants were implicitly given permission by the researchers to be aggressive. Real world violence tends to break laws, and is therefore more deviant than the experimental task.
  • There is the possibility of researcher bias, as the conclusions supported their theory.
  • No differences were found in choices of noise intensity. It might have been expected that more aggressive people would use louder blasts of noise.

Overall it is an interesting study in what is still an emerging picture about the role of video games in violence. More recent research by Goodson and Pearson (2011) suggests that the brain does not treat violent video games as 'real' and responds less strongly to simulated violence than to other events. The is still a lot of work to be done in order to figure out exactly what long term effects - if any - video games have on aggression.

Syllabus note: this is a key study for Edexcel GCSE Psychology (2012 onwards 'linear' version)

References

Anderson, C.A. and Dill, K.E. (2000).  Video games and aggressive thoughts, feelings, and behavior in the laboratory and in life. Journal of Personality and Social Psychology, 78(4), 772-790.

Goodson, S. and Pearson, S. (2011). The boot is mightier than the gun! Virtual football elicits real strong emotional responses but virtual violence gives only despair in death: A dense array EEG comparison of football and violent video games. Proceedings of the British Psychological Society Conference. Retrieved 15 May 2014 from http://abstracts.bps.org.uk