Hypothetico-Deductive Model

1. Hypothetico-Deductive Model How Science Works

2. 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

3. 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!

4. 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

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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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”.