Cognitive development refers to the gradual unfolding of the child's abilities to think, to reason, and to use language. At the other end of the life-span, cognitive development looks at how certain cognitive capacities such as memory can diminish with age. 
Witness/courtroom procedures. A witness is someone who observes or is subjected to an event. The term is often used in a legal context, where eyewitness testimony (and its reliability or otherwise) is a key issue in many criminal trials. Researchers have shown how eyewitness memory can be unreliable, being affected by leading questions, but good interviewing can facilitate and increase the amount of accurate information recalled. Witnesses have been found to make crucial mistakes in identification of people. This obviously has a great potential for influencing juries and creating miscarriages of justice, so is an important area of research for psychologists.
Surveys involve the collection of much less detailed information than case studies, but include much larger samples. Survey data can be either descriptive (finding out about certain characteristics of the group being examined) or explanatory (aiming to provide information that researchers can use to look at potential cause-effect relationships). In practise, most surveys probably have elements of both the descriptive and the explanatory, though perhaps in different proportions. This is because the survey method is comparatively weak at finding out cause-effect relationships (compared with experiments, for example), and even 'descriptive' surveys will usually aim to provide some explanations for the results. Questionnaires make up the basic type of survey, which simply ask people to answer a list of questions. Often this may involve giving them a pre-printed checklist of questions, which they fill in themselves and return, though it could also involve being asked questions by the researcher (the usual form with political opinion polls, for example). The questions can be closed questions, where the range of responses is restricted to those provided by the research, or more open-ended questions which do not limit so much the kind of response that can be given (which, however, can then be more difficult to code/analyse). There could of course be a mixture of open and closed questions. Attitude surveys could be seen as a particular specialised type of questionnaire, finding out about peoples' attitudes on a given topic, e.g. levels of crime, whether drug-taking should be decriminalised etc. This method uses an attitude scale to indicate the strength with which people hold the attitude being investigated, by presenting them with a series of questions relating to the topic. For example, with the drug-taking topic, one item might be 'criminalising drug-taking does nothing to reduce the overall level of drug use in society'. Participants would then give their response to this item as either 'strongly agree/agree/disagree/disagree strongly' etc. Correlational methods\nThis approach investigates statistical relationships between two or more variables, where there is some kind of orderly association between the variables (i.e. as one changes, the other also tends to). This can be reflected mathematically in a correlation coefficient, indicating the strength of the association. For example, a researcher might look for correlations between a child's reading age and IQ score. Note that the presence of a correlation doesn't prove that one variable is acting directly to cause the other to change, so care must be taken with interpreting these data (contrast with experiments, which are designed to reveal causal connections).
Observation is clearly distinguished from experiments by the absence of any intervention. The method is often used in everyday social settings to observe behaviour 'naturalistically', but it is also sometimes used in laboratory settings (though often the reason for the latter setting is for careful control of experimental variables). Data can be both quantitative and qualitative, though most observation tends to involve the latter (see earlier section on qualitative observation under 'qualitative methods'). The data can be structured, and collected in terms of a pre-existing checklist, or unstructured, leaving observers free to write down their overall impressions in any way they see fit. It should be pointed out that even the 'unstructured' approach will still be affected by choices made by the observer to do with selection and construction (see 'construction of data' under 'qualitative methods'). However, 'unstructured observation' is essentially defined as not pre-structured in any way, leaving the observer free to pick up on whatever they think are salient issues, may be missed by more structured data.\nOne particular type of observational method is called participant observation, where a researcher will join in a particular group or social setting, participating in the activities of the group, usually without revealing they are a researcher. Because of its covert nature, this necessarily informal method of data collection raises significant ethical issues. However, it can be the source of very useful data. This approach has a number of factors in common with ethnographic methods (though with the latter, researchers are more likely to be open about what they are engaged in). A key ethical issue in observation in general in fact is that with naturalistic observation the 'participants' are usually unaware that they are being observed. However, if the participants know they are being observed, their behaviour may well change, so destroying the very natural behaviour the researcher wants to observe. This is analogous to the Heisenberg Uncertainty Principle in quantum physics, where bouncing light rays off an electron to find out its location will itself make the electron fly off somewhere else, which means you no longer know where it is! There are no simple answers to such dilemmas: researchers have to take decisions based on the particular research topic and setting they are looking at.
Views: METHODS, Ainsworth, Bowlby, Ceci, Darwin, Ekman, Freud Anna, Falschung, Galton, Milgram, Piaget, Taylor, Vrij Aldert , Watson, Vygotsky, Whiten