Your fourth approach to study is the Developmental Approach. You will need to bring your notes and answers to class to be assessed on your understanding of the study.
1983 was a year for births and babies. Heather and Todd Tilton were twins, but also the world's first test tube babies, conceived through in vitro fertilisation. Another birth in this year was the Internet itself, with the adoption of the TCP/IP protocol and the word "internet" becoming official. The charts liked babies too, with Rod Stewart croaking Baby Jane and Michael Jackson denying the kid was his in Billy Jean.
The study by Samuel & Bryant is partly a lab experiment, because the researchers set different sort of tasks for the children and introduced them in different ways. It's also a natural (or quasi-) experiment because they compared the results from children of different ages. Samuel & Bryant were replicating a groundbreaking study conducted years earlier by the child psychologists Jean Piaget. You will need to understand Piaget's theories and how they were criticised in order to appreciate this study.
The Holah website has excellent summaries of this study, quizzes and a link to the original research article
There's a short 'n' sweet summary on Gary Sturt's homepage too
There's an explanation of "conservation" on Wikipedia
Still baffled? Then watch this clip of the conservation tests on YouTube
This study is inspired by the work of the Swiss psychologist Jean Piaget. Piaget spent his life researching children because he had noticed that many of the illogical things children do and say in fact have a logic all of their own. He described children as "cognitive aliens" because their thought processes are completely different from adults'. He identified four stages that children go through in their cognitive development. The first stage is the sensory motor stage, when the infant learns to control its body. The next stage is the PRE-OPERATIONAL STAGE which lasts until the child is about 7 years old; at this age children are learning about language and rules. At this critical age children enter the CONCRETE OPERATIONAL STAGE where they can start to think logically and question rules. The final stage is the formal operational stage, which is sophisticated adult thinking.
One of the key abilities children acquire is CONSERVATION. At an early age, children cannot reverse mental operations, they can't "rewind the tape" in their heads to figure out how something has come about. Piaget showed children two rows of counters and asked, "Which one has more counters?" The child correctly replied, "They're both the same." Then, in full view of the child, Piaget spread out the bottom row of counters (the TRANSFORMATION) and asked the question again. Older children (concrete operational stage) would reply, "They're still both the same," but younger children in the pre-operational stage would point to the bottom row and say, "This row has more." Piaget concluded that young children don't realise that quantity stays the same (is CONSERVED) even when the appearance changes.
In the 1970s, Rose & Blank questioned Piaget's method and carried out a variation on his experiment: they only asked the child a question once. In other words, they showed the child the two rows of counters, then transformed the bottom row, and only then did they ask the child, "Which one has more?". They found that children gave the correct answer much more often than with Piaget's two-question approach.
This suggests that the reason children fail the test is not because they cannot conserve quantity, but because they get confused by the questions. Think about it: normally when adults ask children a question, then after getting an answer repeat the exact same question again, it's because there was something wrong with the child's answer. This is DEMAND CHARACTERISTICS; the child changes their answer to keep the adult happy, not because they really think the two rows have different numbers of counters in them.
Rose & Blank only tested 6-year olds and only looked at number conservation. Samuel & Bryant wanted to find out if the same results would occur with a wider range of ages and with different conservation tasks.
Samuel & Bryant recruited 252 school children from Devon, England. The boys and girls were divided into four age groups: 5 year olds, 6 year olds, 7 year olds and 8 year olds. In other words, some of these children would be in Piaget's pre-operational stage, some in the concrete operational stage and some in between.
Each age group was divided into three task groups:
The children were given three different conservation tasks:
There are three sets of IVs in this experiment:
Samuel & Bryant measured how many correct answers the children gave to the conservation tasks. There were three tasks (number, mass and volume) and each child got to attempt the task four times, so the total number of correct answers from each child was a score out of 12. This is purely quantitative data.
Here is a table showing how the question style affected the average number of mistakes children made:
This table shows how the type of conservation task affected the average number of mistakes made:
This partly supports Piaget's theory because the older the children got, the easier they found the conservation tasks. We can tell they must have been using their power of conservation (rather than just guessing or counting) because they did so much worse in the Fixed Array condition where they didn't get to see the transformation.
On the other hand, this research partly rejects Piaget's ideas because it shows that some of his findings were down to the way he put his questions to the children. By asking the same question twice, he made the children think they needed to change their answer the second time.
The point is that children probably do possess different cognitive abilities from adults, but they are very susceptible to demand characteristics and you have to be careful how you question them.