Hypothetico-Deductive Model How Science Works

What is the hypothetico-deductive model? A model which describes the way in which all the different branches of science work It describes the process of finding out new information about the world

Stages in Scientific Discovery Observe something about the world Come up with a theory about the world From the theory, develop a testable hypothesis Test the hypothesis; observe results Use results to modify theory….and back to 3) - round and round we go!

An Example From Psychology Observation: Children sometimes struggle to understand the idea of conservation of number Piaget: At what age do children develop this skill? Theory: Children develop cognitive skills in stages

Piaget’s Conservation Experiments Children shown a row of counters like this: Or like this: Which row contains the most counters?

Piaget’s Conservation Experiments Children under the age of 7 (pre-operational) thought that there were more counters in the spaced-out line than in the other line Children over the age of 7 (concrete operational) were able to say that there were the same number of counters in both lines

Piaget’s conclusions Children develop cognitive skills, such as conservation, in stages By the age of about 7, they are “de-centred” enough to be able to successfully solve this problem

A Challenge to Piaget McGarrigle and Donaldson (1974) Criticised Piaget’s study because of a lack of ecological validity They had observed that children under the age of 7 seemed to be able to solve conservation problems They thought that Piaget’s task was difficult because it lacked context for the children

Naughty Teddy Method was similar to Piaget’s However, after seeing the first line of counters: A “naughty teddy” came and knocked the counters off the table

Naughty Teddy The counters were then rearranged: And the children were asked which line had more counters This time, children aged 3-4 could answer correctly Suggests that children can perform conservation tasks at a younger age than predicted by Piaget if they are given a context for the problem

Hypothetico-Deductive Model We have seen how theory can be modified and new questions generated as research progresses Interestingly, “Naughty Teddy” was not the end of the story, and further modifications to the theory of cognitive development have been suggested. Science is constantly evolving: it is never about “correct answers”, only about “best guesses”.