What is the principle by which two individuals differ in number alone?

A core concept is that individuals differ in how they learn.

Individuals differ in the degree of these tendencies and responses.

Furthermore, individuals differ in the types of strategies they use.

For each group is a person differing from other groups in character and experience somewhat as individuals differ.

Individual differences are essential whenever we wish to explain how individuals differ in their behavior.

Individuals can differ widely in their scores and this makes direct comparisons between them difficult.

Individuals with Down syndrome differ considerably in their language and communication skills.

Evidence has been found that individuals systematically differ in their processing capacity.