Experimental methods explained

brain-153040_640True experiment, field experiment, quasi-experiment or natural experiment? The answer is often a wild look in the eyes and a shrug of the shoulders.  It is not always easy to be certain! See below for an explanation of the differences. All sources used are referenced at the bottom of the page, and linked study summaries are, of course, from Psychology Sorted.

The easiest one to define is the true experiment. 

Often called a ‘laboratory/lab’ experiment, this does not have to take place in a lab, but can be conducted in a classroom, office, waiting room, or even outside, providing it meets the criteria.  These are that allocation of participants to the two or more experimental (or experimental and control) groups or conditions is random and that the independent variable (IV) is manipulated by the researcher in order to measure the effect on the dependent variable (DV).  Other variables are carefully controlled, such as location, temperature, time of day, time taken for experiment, materials used, etc. This should result in a cause and effect relationship between the IV and the DV. Examples are randomised controlled drug trials or many of the cognitive experiments into memory, such as Glanzer and Cunitz_1966.

A field experiment is similar, in that individuals are usually randomly assigned to groups, where this is possible, and the IV is manipulated by the researcher. However, as this takes place in the participants’ natural surroundings, the extraneous variables that could confound the findings of the research are somewhat more difficult to control.  The implications for causation depend on how well these variables are controlled, and on the random allocation of participants.   Examples are bystander effect studies, and also research into the effect of digital technology on learning, such as that conducted by Hembrooke and Gay_2003.

A quasi-experiment is similar to either or both of the above, but the participants are not randomly allocated to groups.  Instead they are allocated on the basis of self-selection as male/female; left or right-handed; preference for coffee or tea; young/old, etc.  or researcher selection as scoring above or below and certain level on a pre-test; measured socio-economic status; psychology student or biology student, etc.  These are therefore, non-equivalent groups.  The IV is often manipulated and the DV measured as before, but the nature of the groups is a potential confounding variable.  If testing the effect of a new reading scheme on the reading ages of 11 year olds, a quasi-experimental design would allocate one class of 11 year olds to read using the scheme, and another to continue with the old scheme (control group), and then measure reading ages after a set period of time.  But there may have been other differences between the groups that mean a cause and effect relationship cannot be reliably established: those in the first class may also have already been better readers, or several months older, than those in the control group. Baseline pre-testing is one way around this, in which the students’ improvement is measured against their own earlier reading age, in a pre-test/post-test design.  In some quasi-experiments, the allocation to groups by certain criteria itself forms the IV, and the effects of gender, age or handedness on memory, for example, are measured. Examples are research into the efficacy of anti-depressants, when some participants are taking one anti-depressant and some another, or Caspi et al._2003, who investigated whether a polymorphism on the serotonin transporter gene is linked to a higher or lower risk of individual depression in the face of different levels of perceived stress.

Finally, natural experiments are those in which there is no manipulation of the IV, because it is a naturally-occurring variable.  It may be an earthquake (IV) and measurement of people’s fear levels (DV) at living on a fault line before and after the event, or an increase in unemployment as a large factory closes (IV) and measurement of depression levels amongst adults of working age before and after the factory closure (DV). As with field experiments, many of the extraneous variables are difficult to control as the research takes place in people’s natural environment. A good example of a natural experiment is Charlton (1975) research into the effect of the introduction of television to the remote island of St. Helena.

The differences between quasi experiments and correlational research, and between natural experiments and case studies are sometimes hard to determine, so I would always encourage students to explain exactly why they are designating something as one or the other. We can’t always trust the original article either – Bartlett was happy to describe his studies as experiments, which they were not! Here’s hoping these examples have helped.  The following texts are super-useful, and were referred to while writing  this post.:

Campbell, D.T. & Stanley J.C. (1963). Experimental and Quasi-Experimental Designs for Research. Boston: Houghton Mifflin (ISBN 9780528614002)

Coolican, H. (2009, 5th ed.). Research Methods and Statistics in Psychology. UK: Hodder (ISBN 9780340983447)

Shadish, W.R., Cook, T.D. & Campbell, D.T. (2001, 2nd ed.). Experimental and Quasi-experimental Designs for Generalized Causal Inference. UK: Wadsworth (ISBN 9780395615560)

Ethics of animal research

monkey-3512996_1280A few months ago, we posted about how we could use animals for research.  Today we are looking at the ethics surrounding the decision to conduct research using nonhuman animals. Most students can reel off the ethics involved in conducting research on humans (informed consent, lack of harm, right to withdraw, privacy, etc.) but when we talk about the ethics of conducting research using nonhuman animals as proxies for humans, they are less clear. Often the argument gets stuck at the level of “It’s OK for medical research, but not for cosmetics.”  This is not good enough for an understanding of the complexities (nor for an exam answer).  For students that wish to argue that conducting research on nonhuman animals in order to avoid causing pain or distress to humans can never be ethical, point out that this is a worthy philosophical question, and could even be a counter-argument in a psychology debate on the topic, but again, it cannot constitute the main argument of an exam essay on ethics.

The APA,  BPS and Australian government publish guidelines for conducting nonhuman animal research ethically. What emerges from the guidelines are the ‘3 Rs’ of animal research:

  • Replace animals with other alternatives – such as computer simulations, use of lesser species (such as single‐cell amoebae and nematode worms),  use micro-dosing, CRISPR DNA editing, or human cell cultures – known more colloquially as ‘patient in a dish’ or ‘body on a chip’.  But animals are used to generate new hypotheses, so CRISPR editing was tried out on animals first, as was stem cell research. 
  • Reduce the number of individual animals used, by using data from other researchers, or by repeated micros-sampling on one animal in a repeated measures design.
  • Refine procedures to minimise suffering, by using appropriate anaesthetics and painkillers, and training animals to cooperate with procedures to minimise any distress. Imaginative research, where faecal matter is analysed to investigate stress levels, rather than drawing blood from an obviously stressed animal, has a part to play here.

In Psychology Sorted Book 1, we provide summaries of studies by Xu et al. (2015) and Stanton et al. (2015) which show how nonhuman animals may be used more ethically, to contrast with others such as Barr et al. (2004) and Weaver et al. (2004) which cause more stress to the animals used. These will help to keep your students more closely focused on the complexities of whether and how we should use nonhuman animals in psychological research.

Extended Essays made easier

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It’s that time of year again, when students who have only been studying psychology for a few months are asked to think of an area of research in which they are interested.  And out come the titles, and questions: ‘What makes a psychopath?’  ‘Does the media cause eating disorders?’ ‘Why do more girls than boys get depressed?’ Aaargh!

Teachers sigh and raise their eyebrows, because none of these is a good question for an extended essay, though of course all are potential topics, and students’ interest in them is understandable.

This is where Psychology Sorted can help.  Underneath the overview tables are links to stimulating news articles, journal discussions and TED talks that will extend the students’ thinking beyond the superficial.  The hyperlinks and QR codes are included, and an hour or two of browsing can help direct students’ interests. For example, if students are interested in the area of new biological treatments for mental disorders, see this page.  If they would like to research the effects of digital technology, see here, and if they are interested in strategies of acculturation and immigrants, see this section.

Even if some students are determined to stick to eating disorders, the book can give them a new approach  – to opportunistic eating and obesity, for example.  Preface any of these topics with ‘To what extent?’ and you get much more nuanced, in-depth and interesting questions to research:

  • To what extent can neural feedback techniques treat phobias?
  • To what extent can artificial intelligence enhance working memory?
  • To what extent may marginalisation be responsible for terrorism?
  • To what extent can brain chemical dysfunction explain overeating?

It is not that there are any ‘off-bounds’ topics; just that a new approach is needed, to get your students out of the trees and on the sunlit route to extended essay success!

 

 

We’re all just animals, aren’t we?

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The question of when to use non-human animal studies as evidence for human behaviour is a tricky one. Because it remains unethical to lesion the brain of a live human to look for a correlation between brain damage and behaviour (at the moment!), animal studies are used in large numbers at the biological approach. However, many people are becoming more disturbed by this than previously as over the years we have come to realise that animals also suffer pain, fear and anxiety as we do, and maybe other ways should be sought to conduct animal studies.

In Psychology Sorted, this is part of the Biological extension: the British Psychological guidelines for working with animals (2012) state that researchers should: Replace animals with other alternatives. Reduce the number of animals used. Refine procedures to minimise suffering.  But isn’t how they are used a large part of the problem?  After all, observation under natural conditions should be no problem.  Xu et al. (2015) researched naturally-occurring depression in macaque monkeys by observing monkeys living at a research base in China in environmental conditions that closely resembled what they would experience in the wild, for nearly 3 years.  The monkeys were housed in colonies, usually of two males and 16-22 females, with offspring of under six months.

Instead of unnaturally separating baby chimpanzees from their mothers, as Bowlby and others have done, causing distress,  Stanton et al. (2015) ‘picked up poo’: they investigated the effect of maternal stress on the glucocorticoid levels of infant chimpanzees by examining and measuring faecal glucocorticoid metabolite (FGM) concentrations of mothers and babies in the wild.  Much less stress for the monkeys, though maybe not for the researchers! 

Bearing in mind that we are animals too, it is time empathy stretched to our non-human cousins, and these methods seem to be a first step on the way.  See Psychology Sorted for more examples of ethical animal research.

 

Research from Psychology Sorted: Social Identity Theory

sitHow we develop our social identity is still a hot topic today, and for those of you studying the effect of technologies, especially social media, on social identity, there is a developing literature on the subject.  But we should start with the classic minimal groups paradigm from Tajfel (1971), found in our new book Psychology Sorted, as it is still so relevant today.

The predominant 1960s theory of social identity formation came from Sherif et al.’s (1961) study which led to the development of his 1966 realistic conflict theory that competition for scarce resources is the foundation for group (social) identity, and also one cause of conflict. Think of the worldwide competition for water and oil on a large scale and maybe sporting competitions on a smaller scale. Why do you think that schools have ‘houses’, ‘sporting colours’, ‘house badges’?

However, Tajfel’s research contradicted this, demonstrating that only minimal conditions were necessary for group identity to form: his experiment randomly allocated schoolboys to two groups.  The boys thought they had been allocated their group according to their preference for a painting by either Klee or Kandinsky, but this was a deception and the allocation was random. This perception of belonging to a certain group was enough for boys to show in-group favouritism when allocating virtual money via a complex matrix of rules.  The minimal groups paradigm formed the basis of Tajfel and Turner’s social identity theory, which remains a powerful explanation of in-group favouritism and out-group discrimination.

The three sequential steps Tajfel & Turner (1979) deemed necessary for social identity to form are:

  • social categorisation – we understand that people (and things) can be grouped
  • social identification – we identify with a group
  • social comparison – we compare ourselves favourably with another group

Social comparison underlies stereotyping, gang fights (though these can also be seen as competition for scarce resources), between-class competitions, girl/boy competition, online identities…how many more can you think of?

Tajfel’s theory can be used extensively in the curriculum, from his lab experiments in the 1970s (research methods), to an argument for the formation of stereotypes (sociocultural approach), to an explanation of how competition and maybe even conflict is generated in human relationships, to how images are cultivated socially on Snapchat, Instagram and (amongst us oldies) Facebook for cognitive psychology.  This is an example of a classic theory that can be easily accessed through Psychology Sorted.

Psychology Sorted cognitive research: The effect of digital technology on memory and learning

There has been a lot in the news recently about the effect of social media on mental health, but less about the effect on school and university students of reading or responding to texts during lectures.  As students expect to be ‘connected’ throughout the day, gradually mobile phones have been finding their way into classrooms and lecture halls. Students often argue this makes no difference to their learning, as they can disregard texts and interruptions.  But is this true? Another study from Psychology Sorted  is explored today, with examples of how it may be used.

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Rosen et al (2011) conducted a field experiment to examine the direct impact of text message interruptions on memory in a classroom environment and found the effects to be a slight, but significant, reduction in memory.  This is an example of a study that can be used to illustrate research into the influence of technology and also to explore a common method used to research the influence of technology – the field experiment.

The researchers conducted their experiment in a classroom during a lecture.  The independent variable was the  number of texts received and sent (3 groups, no/low, medium and high), and the dependent variable was the score on a test based on the lesson content. 185 college students (148 female and 37 male) were told that they were going to view a 30-minute videotaped lecture relevant to their course and that during the session some of them would receive texts from the researchers to which they should respond as promptly as possible. They were informed that they would be tested on the material after the lecture.

The results were that the no/low texting group performed 10.6% better than the high texting group in their tests. The test score was significantly negatively correlated with the total number of words sent and received. Those participants who chose to wait more than 4-5 minutes to respond to a text message did better than those who responded immediately.  But in all cases the difference was only just significant. This led the researchers to suggest that metacognitive skills (including learning to wait before responding to disturbances that make us lose focus) should be explicitly taught and that it might be wise for teachers and lecturers to use strategies that focus on when it is appropriate to take a break and when it is important to focus without distractions.

Some schools have opted to require all mobile phones to be turned off or left in lockers, but the problem is that just because the student’s technology is ‘out of sight’ it is not ‘out of mind.’ Maybe teachers should share the results of this study with their students?

Research from Psychology Sorted: Poverty and childhood cognitive development – a biological approach.

This is the first in a series of posts using research directly from our new bookpoverty3349068_640 Psychology Sorted.  The study we’re looking at today is Luby et al. (2013) on how children’s brain development and therefore their cognitive development are affected by poverty. The researchers found that exposure to poverty in early childhood impacts cognitive development by school age. However, the effect is mediated positively by good caregiving and negatively by stressful life events.

This is highly relevant in light of reports from the UK, USA and  South-East Asia of the large, and in some cases growing, number of children living in poverty.  This research can be used as an example of both localization and neuroplasticity within the Biological Approach,  and to illustrate the influence of poverty/socio-economic status on cognitive development, for those studying the Developmental Psychology option.

This was a longitudinal study of 145 children from a sample of children already enrolled in a 10-year study of preschool depression who, prior to being scanned by MRI,  had undergone regular testing.  Once a year (for a duration of 3-6 years) the children had taken part in a series of tests aimed at measuring their cognitive, emotional and social aptitudes. The involvement of significant adults in their lives was also recorded (e.g. how close they were to their caregivers) as well as the occurrence of any negative and stressful events in their lives. Once this collection of information had been amassed, each child underwent two MRI scans – one of the whole brain and one of the hippocampus and amygdala only. This study can therefore also act as an example of the use of brain-imaging technology as a technique used to study the brain in relation to behaviour.

Both the hippocampus and the amygdala showed less white and grey matter in the MRI scans of the poorer children in this study, with a positive correlation between income/needs being met and brain volume. While both the hippocampus and amygdala showed less development in poverty-affected children the researchers found that in cases where the child experienced positive care there was less negative effect on the hippocampus. Difficult and stressful life events only affected the left hippocampus.

Of course, students and teachers need to evaluate the use of this research as well: how valid is the study as an illustration of both localization and neuroplasticity? This was a relatively small sample of pre-schoolchildren from the USA who exhibited symptoms of depression.  Moreover, attempting to measure complex variables (e.g. the nature of caregiving and behavioural responses) is beset with difficulties as these variables are not exact and may lack construct validity.  Nonetheless, there was triangulation of methods, with the background data from cognitive testing providing a rich backdrop for the results of the scans, and this research is supported by other studies, such as that by Duval et al. (2017). 

Encourage your student to find and read media and academic examples of evidence and counter-evidence, and to engage in critical thinking and evaluation. For example, some poor families often cannot afford pre-school kindergartens for their children, who may be raised to some extent in isolation as well as in poverty.  This could be a confounding variable. Are there others? The student who is thinking like this is well on the way to writing a good argumentative essay on the effects of poverty on childhood cognitive development.