natural + quasi-experiment

• natural experiment: a natural experiment is conducted when it is not possible for ethical or practical reasons to deliberately manipulate an IV, therefore it is said that the IV varies 'naturally' the DV may be tested in a laboratory
• effects of institutionalisation: studies of Romanian orphans and the effect their early experiences had on their subsequent emotional and intellectual development
• effects of institutionalisation: the IV in such a study may be adoption either before or after the age of 6 months, it would not be ethical to deliberately control this IV deciding that some babies might be adopted early but other would have to wait in order for researchers to study the effects
• effects of institutionalisation: in these studies the DV might be behaviour in the Strange Situation or performance on an IQ test, both of these would probably be tested in a lab
• effects of TV: before 1995 people living on the small island of St. Helena in the middle of the Atlantic had no TV, the arrival of TV gave researchers a chance to see how exposure to Western programmes might influence behaviour overall Charlton et al (2000) found no difference in either pro- or anti social behaviour after the introduction of Western TV
• effects of TV: in this study the IV was no TV and later exposure to TV
• effects of TV: this IV was not controlled by the researchers they took advantage of something which would be practically quite difficult to control, the DV was measures of pro- and anti-social behaviour using questionnaires, observations and psychological tests
• quasi-experiment: in a quasi-experiment the IV is also naturally occurring and the DV may be measured in a lab, the key feature is that the IV has not been made to vary by anyone it is simply a difference between people that exists
• gender differences: Sheridan and King (1972) tested obedience by asking male participants to give genuine electric shocks of increasing strength to a puppy, they found that 54% of male participants delivered the maximum (non-fatal) shock but the obedience rate for female was a staggering 100% the IV in this study was gender - a difference that can't be manipulated and thus not a 'true' IV
• locus of control: consequences of having an internal or external locus of control, the IV is internal or external locus of control this is a personal attribute of the people, not something that was caused to vary by the situation in 1 study (Hutchins and Estey, 1978) the DV was performance in a stimulated prisoner-of-war camp situation
• natural means 'derived from nature, not made or caused by humankind'
• in a field experiment the thing that is natural is the environment meaning that it hasn't been engineered by the experimenter
• in a natural experiment the thing that is natural is the IV, in a natural experiment the environment may not be natural e.g. the DV may be tested in a lab
• natural experiments: can take place in laboratories or natural settings, the IV is a variable which is controlled by someone other than the researcher often involves exploiting an event that is happening
• quasi experiments: can take place in laboratories or natural settings, the IV is a variable that occurs naturally in the population and can't be manipulated
• evaluation natural S: the change or difference being investigated in the IV is not being controlled by the experimenter meaning they are less likely to influence the data due to experimenter bias thus increasing validity
• evaluation natural S: as the IV is something that is actually happening any changes in the DV are more likely to be realistic and not artificially created
• evaluation natural L: as the experimenter can't directly control the IV they don't know how reliable the change is and therefore can't interfere cause and effect
• evaluation natural L: the lack of control in changing the IV means that there is more chance of confounding variables influencing results
• evaluation quasi S: the IV is naturally occurring difference between people meaning changes in the DV may have more realism than if the IV was artificially created
• evaluation quasi S: participants are likely to be aware they are being studied making consent easier to gain and so there may be fewer ethical issues
• evaluation quasi L: quasi experiments can only be used where a naturally occurring difference between people can easily be identified so they are difficult to set up
• evaluation quasi L: the task used to gather data for the DV may still be unrealistic meaning that the data itself has little mundane realism