First Born Smarter

Robert Zajonc and Gregory Markus came up with a theory relating your birth order to your intelligence. This statement was something that was applied to after using other resources of data, rather than actually conducting an experiment. Zajonc and Markus sought out a research project which studied the effects of malnutrition on the intelligence of children post World War II. "As part of this research, an intelligence test called the Raven test, similar to the IQ test, was given to over 350,000 Dutch males when they became 19 years of age." The results of this test showed that the larger the family and further down the birth line, the worse they scored on the test. Zajonc and Markus theorized that "children will attain higher intellectual capacities if they grow up in environments that provide greater
intellectual stimulation.
The stimulation they were referring to was a parents own passing of knowledge and siblings. Depending on how much each family member contributes to the learning of the child usually determines how smart they will become. The theory is that the first child receives all the attention from parents and so he is usually the smartest. A second child though, would retain knowledge passed on by his parents and his older sibling, and depending on how old the sibling was would determine how much knowledge the second child would receive. If the first born was of an older age, the second born would be able to receive much more knowledge, but at the cost of the older sibling leaving the home at an earlier date, thereby ending how much knowledge could be passed. After a long line of children though the intelligence begins to rise again and even increase past the first. This is due
to the fact that the younger children have many older siblings to receive knowledge from. "In other words, children who are born late into very large families benefit from the intellectual contributions of their older brothers and sisters." There were two findings which went against what Zajonc and Markus found. "One of these was that only-children performed more poorly than firstborns in families with up to four children." The other was the last child born, which suffered a huge drop in average intelligence. The theory to answer the question of why this was happening was that the final children never became teachers, as all of their knowledge was already being instilled in them. Teaching obviously had a large role in how intelligent you were, and since the last children missed out on this experience they typically were not the most intelligent. Criticism of the model Zajonc and Markus came up with was that the average difference between the first child born and final child born was not that significant. Scores usually were only higher from the first child by 5 points in comparison to a 9th final child. Other theories have played off of Zajonc and Markus's model, such as the Resource-dilution theory, which says as a family expands the chance for younger children to succeed, becomes worse as they receive fewer opportunities for growth. These criticisms and applications on Zajonc and Markus still are applied today to try and understand the difference in intellectual abilities.