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”.