Editing Human intelligence (section)

=== Piaget's theory and Neo-Piagetian theories ===
{{Main|Piaget's theory of cognitive development|Neo-Piagetian theories of cognitive development}}

In [[Piaget's theory of cognitive development]] the focus is not on mental abilities but rather on a child's mental models of the world. As a child develops, the child creates increasingly more accurate models of the world which enable the child to interact with the world more effectively. One example is [[object permanence]] with which the child develops a model in which objects continue to exist even when they cannot be seen, heard, or touched.

Piaget's theory described four main stages and many sub-stages in the development. These four main stages are:
# sensorimotor stage (birth–2 years)
# pre-operational stage (2–7 years)
# concrete operational stage (7–11 years)
# formal operations stage (11–16 years)<ref name="Piaget, J. 2001">{{cite book|last=Piaget|first=J.|year=2001|title=Psychology of intelligence|publisher=Routledge}}</ref>
Progress through these stages is correlated with, but not identical to psychometric IQ.<ref>{{multiref2
|1={{cite book|editor-last1=Elkind|editor-first1=D.|editor-last2=Flavell|editor-first2=J.|year=1969|title=Studies in cognitive development: Essays in honor of Jean Piaget|location=New York|publisher=Oxford University Press}}
|2={{cite journal | last1 = Weinberg | first1 = Richard A. | title = Intelligence and IQ, Landmark Issues and Great Debates | journal = American Psychologist | volume = 44 | issue = 2| pages = 98–104 | doi=10.1037/0003-066x.44.2.98| year = 1989 }} }}</ref> Piaget conceptualizes intelligence as an activity more than as a capacity.

One of Piaget's most famous studies focused purely on the discriminative abilities of children between the ages of two and a half years old, and four and a half years old. He began the study by taking children of different ages and placing two lines of sweets, one with the sweets in a line spread further apart, and one with the same number of sweets in a line placed more closely together. He found that, "Children between 2 years, 6 months old and 3 years, 2 months old correctly discriminate the relative number of objects in two rows; between 3 years, 2 months and 4 years, 6 months they indicate a longer row with fewer objects to have 'more'; after 4 years, 6 months they again discriminate correctly".<ref>{{cite book|last=Piaget|first=J.|year=1953|title=The origin of intelligence in the child|location=New Fetter Lane, New York|publisher=Routledge & Kegan Paul}}</ref> Initially younger children were not studied, because if at the age of four years a child could not conserve quantity, then a younger child presumably could not either. The results show however that children that are younger than three years and two months have quantity conservation, but as they get older they lose this quality, and do not recover it until four and a half years old. This attribute may be lost temporarily because of an overdependence on perceptual strategies, which correlates more candy with a longer line of candy, or because of the inability for a four-year-old to reverse situations.<ref name="Piaget, J. 2001"/>

This experiment demonstrated several results. First, younger children have a discriminative ability that shows the logical capacity for cognitive operations exists earlier than previously acknowledged. Also, young children can be equipped with certain qualities for cognitive operations, depending on how logical the structure of the task is. Research also shows that children develop explicit understanding at age five and as a result, the child will count the sweets to decide which has more. Finally the study found that overall quantity conservation is not a basic characteristic of humans' native inheritance.<ref name="Piaget, J. 2001"/>

Piaget's theory has been criticized on the grounds that the age of appearance of a new model of the world, such as object permanence, is dependent on how the testing is done (see the article on [[object permanence]]). More generally, the theory may be very difficult to test empirically because of the difficulty of proving or disproving that a mental model is the explanation for the results of the testing.<ref>{{Cite journal | last1 = Kitchener | first1 = R. F. | title = Piaget's epistemic subject and science education: Epistemological vs. Psychological issues | doi = 10.1007/BF00592203 | journal = Science and Education | volume = 2 | issue = 2 | pages = 137–148 | year = 1993 |bibcode = 1993Sc&Ed...2..137K | s2cid = 143676265 }}</ref>

[[Neo-Piagetian theories of cognitive development]] expand Piaget's theory in various ways such as also considering psychometric-like factors such as processing speed and working memory, "hypercognitive" factors like self-monitoring, more stages, and more consideration on how progress may vary in different domains such as spatial or social.<ref>{{multiref2
|1={{cite book|last=Demetriou|first=A.|year=1998|chapter=Cognitive development|editor-first1=A. |editor-last1=Demetriou|editor-first2=W.|editor-last2=Doise|editor-first3=K.F.M.|editor-last3=van Lieshout|title=Life-span developmental psychology|pages=179–269|location=London|publisher=Wiley}}
|2={{cite book| last1=Demetriou | first1=Andreas | last2=Mouyi | first2=Antigoni | last3=Spanoudis | first3=George | chapter=The Development of Mental Processing | publisher=John Wiley & Sons, Inc. | publication-place=Hoboken, N.J.| year=2010 | isbn=978-0-470-39013-9 | doi=10.1002/9780470880166.hlsd001010|editor-first=W.F.|editor-last=Overton|title=Biology, cognition and methods across the life-span|series=the Handbook of life-span development|volume=1}}
|3={{cite book|last=Nesselroade|first=J.R.|year=2011|chapter=Methods in the study of life-span human development: Issues and answers|pages=36–55|editor-first=W.F.|editor-last=Overton|title=Biology, cognition and methods across the life-span|series=the Handbook of life-span development|volume=1| publisher=John Wiley & Sons, Inc. | publication-place=Hoboken, N.J.}} }}</ref>