Goldilocks principle

[1] The concept of "just the right amount" is easily understood and applied to a wide range of disciplines, including developmental psychology, biology,[2] astronomy, economics[3] and engineering.

In cognitive science and developmental psychology, the Goldilocks effect or principle refers to an infant's preference to attend events that are neither too simple nor too complex according to their current representation of the world.

[4] This effect was observed in infants, who are less likely to look away from a visual sequence when the current event is moderately probable, as measured by an idealized learning model.

As Stephen Hawking put it, "Like Goldilocks, the development of intelligent life requires that planetary temperatures be 'just right'".

[10] In statistics, the "Goldilocks Fit" references a linear regression model that represents the perfect flexibility to reduce the error caused by bias and variance.