| concept | info | evaluation | ||||
| Variables | Independent – variable that’s manipulated or changed by researcher
Dependent – variable that is measured Operationalising variables – making them measurable and specific Extraneous variables – variables other than the IV that may affect the DV |
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| Controlling ext. variables | Order effects
Where participants are affected by order/routine of experimental conditions (gaining practice, becoming bored or tired) |
– Counter-balancing
Each participant randomly assigned to first or second condition |
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| – Randomisation
Half the participants experiencing 1st then 2nd condition, and other half experiencing conditions opposite way round Order effects of improvement or decline are equally distributed to cancel each other out |
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| Demand characteristics
When participant can guess aims of study and changes behaviour accordingly
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– Single-blind technique
Participants unaware of aims or expectations of study |
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| Investigator effects
If investigator gives unintentional hints – through facial expressions or gestures – indicating participant’s progress |
– Double-blind technique
Neither researcher nor participants aware of aims of study Controlling demand characteristics encouraged by investigator effects |
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| – Standardised procedure
Keeping whole procedure and situation the same across all conditions |
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| Hypotheses | N U L L
– There will be no difference in DV, whether participants (experimental condition) or (control condition). Any difference will be due to chance A L T E R N A T I V E – Participants who (experimental condition) will (relevant section of DV) significantly more/less (relevant section of DV) than participants who (control condition) |
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| Sampling methods | Random sampling | – Identify every member of target population, assigning them a number and drawing numbers out of a hat | Strengths
– Free from researcher bias – researcher has no input on who’s selected – Representative – every member of target population has equal chance of being selected Weaknesses – Time consuming – If participants refuse – less representative |
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| Stratified sampling | – Subgroups/stratums within target population identified
– Participants chosen from each subgroup in proportion to their occurrence in target population |
Strengths
– Free from researcher bias– researcher has no input on who’s selected – Representative – each subgroup represented in sample Weaknesses – Time consuming to ensure all subgroups represented – If participants refuse sample may be less representative |
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| Volunteer sampling | – Gathering sample who are willing to take part
– E.g., responding to ads |
Strengths
– Minimal effort – Informed consent – participants automatically give permission Weaknesses – Not representative – Biased sample – volunteers tend to be certain type of person e.g., more cooperative |
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| Opportunity sampling | – Select anyone who is available and willing at the time | Strengths
– Quickest and easiest method – cheapest Weaknesses – Biased sample – not every member of target population around during time of study – Unreliable findings – if study replicated at different time or day, sample will likely differ |
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| Experimental design | Independent groups – normally 2 separate groups of participants completing only one condition | Strengths
– No order effects such as boredom, practice or fatigue Weaknesses – Time consuming as more people needed – Individual differences – extraneous variable |
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| Repeated measures – same participants completing all conditions | Strengths
– Easier to organise – fewer participants – No individual differences Weaknesses – Demand characteristics more likely – Order effects more likely – reducing validity of findings |
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| Matched pairs – two separate groups completing only one condition, but groups are matched on important characteristics e.g., age or gender | Strengths
– No order effects such as boredom, practice and fatigue – Fair comparisons can be made – groups equally matched Weaknesses – Time consuming – Individual differences as not all characteristics can be matched – extraneous variable |
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| Ethical issues
codes or rules of conduct considered by psychologists, carrying out research to protect participants from harm |
Deception
When participants are misled or lied to about nature of study
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– Debrief held afterwards | ||||
| Informed Consent
Agreement of participants to take part once fully aware of aims and nature of study
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– can be told aims before taking part in study and sign a consent form
– retrospective consent – can be told aims afterwards and asked if they’re okay with their results being included in study |
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| Protection from harm
Participants should be protected from both physical and psychological pain
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– participants should be reminded of right to withdraw throughout and after
– researcher should terminate experiment if level of harm is higher than expected |
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| Right to Withdraw
Participants should be aware that they can leave the study at any point
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– should be reminded before, after and during experiment that they can leave
– after study, should be able to withdraw and have results destroyed if they wish |
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| Confidentiality
Identities should be anonymous – shouldn’t be easy for public to identify them
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– participants’ real names shouldn’t be used – referred to by fake name or number
– personal data secured in a safe place and destroyed after suitable amount of time |
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| Experiments | Lab experiments | – Controlled artificial conditions, minimise effect of extraneous variables
– IV is manipulated – Participants aware they’re being studied |
Strengths
High internal validity – High level of control over extraneous variables – Establishing direct cause and effect relationship – Ensure that any change in DV is due to IV High reliability – High level of control – Study can be replicated exactly to check consistency of findings Weaknesses Demand Characteristics – Participants knowing they’re being studied Low ecological validity – Artificial environment – Behaviour observed may not reflect that of real life |
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| Field experiments | – Natural settings
– IV is manipulated – Participants might not know they’re being studied |
Strengths
High ecological validity – Natural settings – Behaviour observed more reflective of behaviour in real life Weaknesses Low internal validity – Difficult to control extraneous variables – So unable to establish direct cause and effect relationship Ethical issues – Lack of informed consent – Participants unaware they’re being observed |
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| Piliavin et al. (1969) conducted a field experiment to test bystander behaviour. Models were positioned in a subway carriage to see if passengers on the train would help the model who fell over and lay on the floor of the carriage.
· The model was either black or white. · The model dressed an average passenger with a guide stick or carrying a brown paper bag with a bottle in it. Researchers were positioned around the carriage to observe the responses of different passengers, their locations and how long they took to help the model. Evaluate the use of field experiments to investigate human behaviour. (12 marks)
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| Natural experiments | – Natural settings
– IV naturally occurring and not manipulated |
Strengths
High ecological validity – Natural settings and naturally occurring IV – Behaviour observed more reflective of behaviour in real life as real life issues being investigated No ethical issues – IV naturally occurring and not manipulated or generated by researcher
Weaknesses Low internal validity – Difficult to control extraneous variables – Can’t be sure that any change in DV is only due to IV Low Reliability – Hard to replicate and check for consistency
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| Interviews
Weaknesses of all types
– Social desirability bias – Interviewer effects |
Structured | – Standardised list of pre-set questions
– Suitable for large scale studies – Qualitative data from a lot of respondents |
Strengths
– Lots of info gathered relatively quickly – Requires little training – Same qs asked, consistent, can check for reliability |
Weaknesses
– Reduced usefulness and validity – set qs mean participant can’t respond freely |
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| Unstructured | – Conducted like conversation
– Only broad topic decided in advance – Qualitative info from small groups of respondents |
Strengths
– Increased detail and validity – without predetermined qs, participants can justify answers |
Weaknesses
– More time consuming and costly – require more training – Difficult to check reliability – can’t replicate as not standardised |
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| Semi-structured | – Qs mostly decided in advance
– Can be supplemented with additional qs depending on what seems appropriate at the time |
Strengths
– Providing benefits of both structured and unstructured |
Weaknesses
– Providing weaknesses of both structured and unstructured |
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| Questionnaires | Open qs
– Produces qualitative data – No pre-set responses
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Strengths
– Allow respondents to give detailed answers – Can give researchers a deeper understanding of their thoughts – Increasing validity of findings Weaknesses – Qualitative data produced can be difficult to analyse – Subjective – different researchers could interpret answers differently – May lack reliability and consistency
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Strengths
Inexpensive way to gather lots of info from large sample No interviewer effects – Unlike interviews – Respondents not influenced by attitudes or behaviours of the researcher No ethical issues – People can easily choose not to answer – In answering, respondents providing informed consent to take part in research Weaknesses Low population validity – Response rates tend to be low – Ignored most of the time so hard to generalise findings from questionnaires to wider population |
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| Closed qs
– Produces quantitative data as answers can be tallied up – Has pre-set list of answers that respondent can choose from (e.g., yes/no) |
Strengths
– Quantitative data – straightforward to analyse in graphs and tables – Therefore, patterns in answers more easily seen Weaknesses – Can be too restrictive – Respondents may feel that their preferred answer is not available – Reducing usefulness and thus validity of research and findings |
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| Correlation studies | – Techniques used to simply study relationship between two co-variables – rather than having researcher manipulate IV
– Positive correlation – co-variables move in same direction – Negative correlation – co-variables move in opposite directions – Zero correlation – co-variables lack any relationship – Illustrated on scatter graphs – Represented with correlation co-efficient (figure between -1 and +1) |
Strengths
Ideal place to begin preliminary research – Can provide valuable insight for future research – Informs us whether or not further research would be worthwhile
No ethical issues – Researcher doesn’t manipulate any variables whatsoever – Variables are merely studied – Can allow researchers to investigate subject areas which would otherwise not be safe or permissible through laboratory experiments
Weaknesses Lacks internal validity – Researcher not manipulating variables – So, no control over extraneous variables – Unable to establish direct cause and effect relationship – May be other factors influencing relationship |
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| Case studies | – In-depth investigation into an individual or small group of people
– Range of research methods used – e.g., interviews, experiments and observations – Gathering qualitative data |
Strengths
No ethical issues – Useful for studying rare or unique individuals and circumstances e.g., people with brain-damage – Unethical for researcher to stage themselves High validity – Detailed findings – providing useful and unique insight into people’s behaviour and mind
Weaknesses Low reliability – Each case is unique – can’t be replicated in exact same way – No way to check consistency Subjective – Researcher heavily involved in gathering data – Findings based on researcher’s own opinions and interpretations – Another researcher may have different interpretation Low population validity – Focusing on unique individuals – Findings not generalisable to wider population
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| observations | Strengths | Weaknesses | ||||
| Naturalistic | High ecological validity
– Naturally occurring behaviour recorded in real life |
Low reliability
– Impossible to replicate – Consistency can’t be checked |
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| Controlled | High reliability
– Can be replicated due to high control over extraneous variables – Consistency can be checked |
Low ecological validity
– Behaviour observed may not be natural or reflective of real life behaviour |
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| Overt | No ethical issues
– Participants know they’re being observed so can give their informed consent |
Low validity
– Investigator effects – May change behaviour and act unnaturally – May show demand characteristics |
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| Covert | High validity
– Avoids investigator effects – Less chance of demand characteristics |
Ethical issues
– Can’t give informed consent – No right to withdrawal |
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| Participant | – Allows researcher to gather in depth data and unique insight |
Low validity
– Investigator effects – Group may change behaviour unnaturally – Undermines validity |
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| Non-participant | Higher validity
– Avoids investigator effects – Behaviour observed therefore more natural |
Researcher might fail to see behaviour of interest
– If not being close to group or individual when observing |
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