Methods of psychology (II)
An example of a common activity that was given totally different explanations 
by two scientists--neither of who established his claims with experimental 
evidence--is language acquisition (speech development). The fact that 
everybody learns to speak makes it easy to forget that acquiring a language 
is a very complex process. B. F. Skinner and Noam Chomsky gave two 
diametrically opposed versions of this process. According to Skinner, if a 
person asks for water with the phrase "Water, please" it is not because he is 
applying some set of grammar rules, but because he has learned in the past 
that these two particular words will get him water when he is thirsty. So, 
for Skinner speaking was a learned skill ruled by the laws of conditioning.
Chomsky, on the contrary, considered that there were innate capacities at 
play when learning to speak. He supposed that the child is born with a 
language-acquisition device that enables him to derive the rules of the 
language from what he hears. This device would contain some features 
universally applicable to all languages such as the structure subject-
predicate. In Chomsky's view, no learning theory can explain the competence 
to produce an infinite number of grammatically correct sentences.
Research based on observation can use the observation of natural groups, can 
conduct experiments, or may center in a person or small group of persons as 
in a case study. The comparison of natural groups consists in observing two 
groups of individuals of the same kind that differ in some way of interest to 
the researcher. For example, children reared at home and at an institution. 
Generally, the observation is made in their ordinary everyday setting, but it 
can also be made in laboratory: two samples of children can be brought to 
laboratory to perform the same task.
When experiments are done, the groups are generally selected randomly to 
ensure that the experiment is not affected by any bias. They are given a 
different experience and the response is recorded. All the same, many 
behaviors that are of importance cannot be studied experimentally. Field 
observation of some animal and human behaviors is sometimes possible. In this 
method the individuals are observed in the surroundings were they naturally 
live. When observation is limited to a single person or a small group, as a 
family, it is called a case study. Although general conclusions cannot be 
drawn from case studies, they have served as a significant source of new 
ideas. The development of psychodynamic psychology by Sigmund Freud was 
achieved mainly with the help of case studies.
Some kinds of observations have been standardized and constitute the work of 
a class of psychologists called psychometricians. Psychometricians work in 
the field of psychological measurement. They design and give tests that 
attempt to cover a wide range of people's characteristics: intelligence, 
talent, personality, job aptitude, are some of the areas covered by 
psychometric tests. Tests have been used in research projects to conduct 
longitudinal studies of groups of people. In these studies, people are given 
the same test across a long period of their lives. The goal is to find how 
development affects, for example, intelligence or personality.
    
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