Strength - They used a large sample size of 100 children, improving generalisability of results to the target population.
Weakness - Participants were all from the same culture swizterland - it may be that egocentrism occurs at different ages within different cultures so we cannot necessarily generalise results to other cultures.
Strengths and Weaknesses of Reliability:
Strength - It was a standardised procedure meaning the study can be repeated easily to check for the consistency of results
Weakness - When the procedure was replicated by Borke, he found inconsistency as 3 and 4 year old could decentre, contradicting Piaget's conclusion.
Strengths and Weaknesses of Application:
Strength - They provide supporting evidence for Piaget's cognitive development theory, that children in the pre-operational stage cannot decentre.
Weakness - This found some children could "partly" complete the tasks and older children in one stage were able to show skills similar to older children and could show Piaget's stages are too "rigid".
Strengths and Weaknesses of Validity:
Strength - A laboratory experiment was used, meaning the researchers had full control over extraneous variables such as colour of the pictures, meaning they can be sure the IV has an impact on the DV.
Weakness - The mountains task lacked ecological validity as it is an unnatural way to measure viewpoints.
Ethics
As the participants were under 16 they recieved full consent so the procedure was not harmful to children.
