Mental Anchors

Pieces of knowledge act as anchors for new knowledge to be attached to. This is per schema theory.

See also: Levels of Processing model - Wikipedia (Craik & Lockhart, 1972).

Don’t confuse with anchoring bias; see e.g. Anchoring Bias - The Decision Lab

a mental structure of preconceived ideas, a framework representing some aspect of the world, or a system of organizing and perceiving new information

from Schema (psychology) - Wikipedia. Cites an archived psyctherapy glossary:

schema a concept or framework that organizes and interprets information a mental structure that represents some aspect of the world. People use schemata to organize current knowledge and provide a framework for future understanding. Examples of schemata include stereotypes, social roles, scripts, worldviews, and archetypes.

In Piaget’s theory of development, children adopt a series of schemas to understand the world. 

The importance of schemata for thought cannot be overstated. Sufferers of Korsakov’s syndrome are unable to form new memories, and must approach every situation as if they had just seen it for the first time. Many sufferers adapt by continually forcing their world into barely-applicable schemata, often to the point of incoherence and self-contradiction. 

Schemas are an effective tool for understanding the world. Through the use of schemata, most everyday situations do not require effortful thought — automatic thought is all that is required. People can quickly organize new perceptions into schemas and act effectively without effort. For example, most people have a stairway schema and can apply it to climb staircases they’ve never seen before. 

However, schemas can influence and hamper the uptake of new information (proactive interference), such as when existing stereotypes, giving rise to limited or biased discourses and expectations (prejudices) may lead an individual to ‘see’ or ‘remember’ something that has not happened because it is more believable in terms of his/her schema: for example, if a well-dressed businessman draws a knife on a Rastafarian, the schemas of onlookers may (and often do) lead them to ‘remember’ the Rastafarian pulling the knife. Such distortion of memory has been demonstrated. See Background research below. 

Schemas are often related to one another, and multiple conflicting schemata can be applied to the same information. Schemata are generally thought to have a level of activation, which can spread among related schemata. Which schema is selected can depend on factors such as

• current activation
• accessibility; and
• priming.

Accessibility is how easily a schema comes to mind, and is determined by personal experience and expertise. This can be used as a cognitive shortcut; it allows the most common explanation to be chosen for new information. See availability heuristic.

With priming, a brief imperceptible stimulus temporarily provides enough activation to a schema so that it is used for subsequent ambiguous information. Although this may suggest the possibility of subliminal messages, the effect of priming is so fleeting that it is difficult to detect outside laboratory conditions. Furthermore, the mere exposure effect — which requires consciousness of the stimuli — is far more effective than priming. 

A schema representation is a way of capturing the insight that concepts are defined by a configuration of features, and each of these features involves specifying a value the object has on some attribute. The schema represents a concept by pairing a class of attribute with a particular value, and stringing all the attributes together.

They are a way of encoding regularities in categories, whether these regularities are propositional or perceptual. They are also general, rather than specific, so that they can be used in many situations.  

References:   Anderson, J.R. (1990). Cognitive psychology and its implications . New York, NY: Freeman.

Some modifications to the above (formatting).