Availability

How frequently does it occur? (e.g., Do more words start with k or have k as the third letter?)

The ease with which information comes to mind.

Some factors that affect the ease with which information comes to mind are unrelated to frequency.

Representativeness

Is an item a member of a given category? (e.g., Is Linda a bank teller or a bank teller active in the feminist movement?)

The resemblance between the item and the category.

Representativeness can distract people from information about base rates—the overall likelihood that any item is in a given category.

Anchoring and Adjustment

How many are there? (e.g., What percentage of the world’s nations is African?)

Adjustment from an initial guess.

Even irrelevant anchor values are influential, and adjustment away from them is often insufficient.