A schema is a mental representation of a typical instance. Schema theory suggests that people understand new experiences by activating relevant schemas (also called ‘schemata’) in their minds. They then assume, unless there is evidence to the contrary, that the new experience conforms to their schematic representation. Schematic processing allows people to interpret new experiences quickly and economically, making intelligent guesses as to what is likely, even before they have explicit evidence.
Thus, if I tell you that ‘I went to a restaurant last night’, you are likely to assume (without being told) that I sat on a chair, ordered a meal, paid, and left. If you later discover that I sat on the floor, cooked the meal myself, robbed the till at gunpoint, or stayed all night, you will adjust your understanding accordingly. Schemas vary according to cultural norms and individual experience: whether restaurants are expected to serve alcohol, whether they are routine or special places to eat.